CA Review _RMC_
Meeting Date: Oct. 11, 2022
To: Mayor and City Council
From: Scott Chadwick, City Manager
Staff Contact: Katie Hentrich, Senior Program Manager
[email protected], 442-339-2623
Jamie Wood, Environmental Sustainability Director
[email protected], 442-339-2584
Subject:
Districts:
San Diego Regional Decarbonization Framework
All
Recommended Action
Receive a presentation on the San Diego Regional Decarbonization Framework from the County of San Diego staff.
Executive Summary
The San Diego Regional Decarbonization Framework is a document prepared by the County of San Diego that examines potential regional decarbonization efforts in partnership with the following institutions: the University of California San Diego’s School of Global Policy and Strategy, the University of San Diego, the Energy Policy Initiatives Center and the consulting firm Inclusive Economics. A summary for policy makers is included as Exhibit 1, and the full technical report is included as Exhibit 2.
Discussion
The Regional Decarbonization Framework provides technical and policy pathways to decarbonization in the medium-term to inform near-term policymaking in regional, county and city governments. Specifically, the framework in the summary for policy makers considers “how to achieve deep decarbonization of San Diego’s regional energy system, which is defined as the total production and consumption of energy in the electric power, transportation and buildings sectors, to align with state and national pathways to reach net zero” greenhouse gas emissions.
The document identifies what are referred to as “low-regret” strategies, which provide the best assessment of the least costly and most effective near-term solutions for reducing emissions in each sector. These strategies are presented as a menu of options for local and regional agencies to consider, as the county does not have land use authority over these entities.
The framework also examines greenhouse gas reductions embedded in local Climate Action Plans and identifies a “Best CAP Commitment Scenario,” or the most aggressive measures in each policy category, regardless of jurisdiction size or the year the climate action plan was Oct. 11, 2022
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adopted. Carlsbad is listed as having the “Best CAP Commitment” for its strategies related to Transportation Demand Management, a strategy to reduce single-vehicle trips; fuel reduction from traffic calming efforts; and residential and non-residential energy retrofits.
The framework finds that even when all the current Climate Action Plan commitments across the region are totaled up, the collective reduction targets are not sufficient to reach net zero greenhouse gas emissions by 2035. Specifically, a gap of seven million metric tons of carbon dioxide equivalent, mostly from natural gas combustion and transportation on roadways, still exists. The framework encourages a collective, region-wide approach to reach these reduction goals through the identified strategies and opportunities for collaboration.
Fiscal Analysis
No city funding is requested at this time.
Next Steps
County staff will be preparing an “Implementation Playbook” for the Regional Decarbonization Framework, with a draft anticipated in December 2022, and will continue to conduct outreach to the public and other stakeholders. The final Regional Decarbonization Framework and related documents are expected to be presented to the San Diego County Board of Supervisors for consideration and adoption in spring 2023.
City staff will continue to participate in meetings related to the Regional Decarbonization Framework and incorporate any relevant information into the ongoing Climate Action Plan Update.
Environmental Evaluation
This action does not require environmental review because it does not constitute a project within the meaning of the California Environmental Quality Act under California Public Resources Code Section 21065 in that it has no potential to cause either a direct physical change or a reasonably foreseeable indirect physical change in the environment.
Public Notification
This document was noticed in accordance with the Ralph M. Brown Act and was available for public viewing and review at least 72 hours prior to scheduled meeting date.
Exhibits
1. San Diego Regional Decarbonization Framework Summary for Policy Makers
2. San Diego Regional Decarbonization Framework Technical Report
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San Diego Regional
Decarbonization Framework
SUMMARY FOR POLICY MAKERS
Exhibit 1
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1 Project Team
Project Director
Gordon C. McCord
Associate Dean & Associate Professor of Economics
Director, SDG Policy Initiative
School of Global Policy and Strategy, University of California San Diego (UC San Diego) Project Manager
Elise Hanson, County of San Diego, Land Use and Environment Group (LUEG) San Diego County Representatives
Murtaza Baxamusa
Rebeca Appel
Sarah Aghassi
Yasamin Rasoulzadeh
Michael De La Rosa
Donna Durckel
Nicole Boghossian Ambrose
Jennifer Lawson
Renee Loewer
Chapter Authors
Introduction
Murtaza H. Baxamusa, LUEG
Study Approach
Ryan A. Jones, Evolved Energy Research
Geospatial Analysis of Renewable Energy Production
Emily Leslie, Montara Mountain Energy
Joseph Bettles, UC San Diego
Accelerating Deep Decarbonization in the Transportation Sector Katy Cole, Fehr & Peers
Chelsea Richer, Fehr & Peers
Eleanor Hunts, Fehr & Peers
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2 Decarbonization of Buildings
Philip Eash-Gates, Synapse Energy Economics
Jason Frost, Synapse Energy Economics
Shelley Kwok, Synapse Energy Economics
Jackie Litynski, Synapse Energy Economics
Kenji Takahashi, Synapse Energy Economics
Asa Hopkins, Synapse Energy Economics
Natural Climate Solutions and other Land Use Considerations Elise Hanson, UC San Diego
Emily Leslie, Montara Mountain Energy
Employment Impacts through Decarbonization in the San Diego Region Robert Pollin, Political Economy Research Institute (PERI), University of Massachusetts Amherst Jeannette Wicks-Lim, PERI, University of Massachusetts Amherst Shouvik Chakraborty, PERI, University of Massachusetts Amherst Gregor Semieniuk, PERI, University of Massachusetts Amherst Key Policy Considerations for the San Diego Region
Joseph Bettles, UC San Diego
Gordon C. McCord, UC San Diego
David G. Victor, UC San Diego
Emily Carlton, UC San Diego
Local Policy Opportunity Analysis
Scott Anders, Energy Policy Initiatives Center (EPIC), University of San Diego School of Law Nilmini Silva Send, EPIC, University of San Diego School of Law Joe Kaatz, EPIC, University of San Diego School of Law
Yichao Gu, EPIC, University of San Diego School of Law
Marc Steele, EPIC, University of San Diego School of Law The San Diego Region as a Model
Elena Crete, UN Sustainable Development Solutions Network (SDSN) Julie Topf, UN Sustainable Development Solutions Network (SDSN) Appendix A: Summary of Statewide Energy System Modeling Ryan Jones, Evolved Energy
Appendix B: Review of Authority for Local Jurisdictions and Agencies to Influence and Regulate GHG Emissions
Joe Kaatz, EPIC, University of San Diego
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3 Acknowledgments
Special thanks to the County of San Diego Board of Supervisors: Chair Nathan Fletcher, Vice Chair Nora Vargas, Supervisor Joel Anderson, Supervisor Terra Lawson-Remer, and Supervisor Jim Desmond for their direction and leadership in establishing this framework.
The authors thank David Victor for his advisory role across the project, as well as Joseph Bettles, Tyler Spencer, Emily Carlton, Elissa Bozhkov, and Jeffrey Myers for research and editorial support, and Isaac Wang for project management support.
The project team is grateful to the following individuals for their strategic advice to the County of San Diego representatives: Elizabeth King (California Environmental Protection Agency), Jamal Russell Black (San Diego Regional Policy & Innovation Center), Christiana DeBenedict (San Diego Foundation), Everett Au (San Diego Foundation), Amenah Gulamhusein (San Diego Foundation), and Susan L. Guinn (San Diego Regional Policy & Innovation Center).
The project team also wants to thank the Technical Working Group and all the participants and commenters who contributed their time and knowledge by submitting written/oral comments and attending our meetings and workshops.
Disclaimer
This report was funded by the County of San Diego. The authors declare no competing interests with relevant entities in the San Diego region.
This summary report should be cited as:
McCord, Gordon C., Elise Hanson, Murtaza H. Baxamusa, Emily Leslie, Joseph Bettles, Ryan A. Jones, Katy Cole, Chelsea Richer, Eleanor Hunts, Philip Eash-Gates, Jason Frost, Shelley Kwok, Jackie Litynski, Kenji Takahashi, Asa Hopkins, Robert Pollin, Jeannette Wicks-Lim, Shouvik Chakraborty, Gregor Semieniuk, David G. Victor, Emily Carlton, Scott Anders, Nilmini Silva Send, Joe Kaatz, Yichao Gu, Marc Steele, Elena Crete, and Julie Topf. San Diego Regional Decarbonization Framework: Summary for Policy Makers. County of San Diego, California. 2022.
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4 Introduction
The global scientific consensus is unequivocal: the world is experiencing a human-caused climate crisis and our window to meaningfully reduce greenhouse gas (GHG) emissions is closing.i Human activities have warmed the planet through rapid accumulations of GHGs in the atmosphere and the ocean, causing rapid and alarming changes. Global compacts, like the Paris Climate Agreement, and California policies from legislation and executive orders recognize the immediacy of decarbonization required across industries. Where past diplomatic efforts have failed to achieve enough progress on climate change, regional problem-solving models that account for both global commitments and local needs can represent a more effective approach.
The San Diego Regional Decarbonization Framework’s (RDF’s) Technical Report provides technical and policy pathways to decarbonization in the medium-term to inform near-term policymaking in regional, County, and city governments. The report models science-based pathways to net zero carbon emissions for the San Diego region by 2045, consistent with the Paris Climate Agreement and California State (State) mandates. The pathways provide a shared vision for the San Diego region to collectively reduce net GHG emissions in alignment with California’s net zero goal. This report is a technical analysis of how different sectors in the energy system can contribute to decarbonization, but does not identify the “right” pathway.
Instead, it shows numerous ways to achieve regional emissions goals in multiple sectors to highlight trade-offs, co-benefits, decision points, risks, and synergies. The analyses and pathways should be updated as technologies evolve or uncertainties are resolved or clarified.
To that end, the report explores policy processes to help regional jurisdictions learn about uncertainties and adjust strategies as information arises.
Study Framework and Key Policy Considerations
This report considers how to achieve deep decarbonization of San Diego’s regional energy system, which is defined as the total production and consumption of energy in the electric power, transportation, and buildings sectors, to align with State and national pathways to reach net zero. Deep decarbonization refers to the process of drastically reducing carbon dioxide (CO
2) and other GHG emissions throughout the economy. By “net zero,” this report means that human-caused CO2 emissions from the energy system equal human-caused CO2
i Intergovernmental Panel on Climate Change (IPCC), “Climate Change 2022: Impacts, A daptation, and Vulnerability. Summary for Policymakers.” WGII Sixth Assessment Report, February 2022. Available at:
https://report.ipcc.ch/ar6wg2/pdf/IPCC_AR6_WGII_FinalDraft_FullReport.pdf Oct. 11, 2022
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5 removal and storage, thus making net energy system emissions zero.i The RDF’s Technical Report does not rely on offsets outside the region to reach net zero targets. Importantly, emissions from other sectors such as waste were excluded from this analysis because they are outside the defined energy system scope, which accounts for 80% of regional emissions.ii Nevertheless, there are numerous co-benefits associated with drastically reducing emissions from other sectors and the emissions reductions and/or co-benefits may also align with State goals, as with reducing landfill emissions through waste diversion and composting.
The RDF’s Technical Report’s decarbonization pathways were modeled from larger national and State deep decarbonization scenarios to ensure alignment with Statewide pathways to decarbonization. Evolved Energy Research (EER) downscaled State and national models to develop regional models under five scenarios (also referred to as model cases).iii The deep decarbonization models allow for quantitative comparative analyses of regional policy options and decarbonization outcomes in different sectors. An example of EER’s modeling outputs for the energy sector show how the different model cases affect Statewide decarbonization in both the total installed electricity capacity required (Figure 1) and CO 2 emissions from energy and
industry processes through 2050 (Figure 2). Using these downscaled models is also important because local energy and transportation systems are interconnected with other regions and states, so regional jurisdictions should collaborate with other regional and state jurisdictions as they decarbonize.
i Note that the energy system modeling only considers CO2 emissions, whereas the natural climate solutions and Climate Action Plan analyses consider other greenhouse gases as well (such as methane, nitrous oxides, etc.).
These GHGs are converted to their “carbon dioxide equivalent” (CO2e) for easier comparison. ii More details on the scope of the study are available in Chapter 1 and Appendix A. More details on the sectoral contributions to total regional emissions are available in Chapter 8 and in the San Diego Association of Government’s 2021 Regional Plan’s Appendix X (https://sdforward.com/docs/default-source/2021-regional- plan/appendix-x---2016-greenhouse-gas-emissions-inventory-and-projections-for-the-san-diego- region.pdf?sfvrsn=8444fd65_2).
iii More details on the model cases can be found in Chapter 1 and Appendix A.
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6 Figure 1. Results for the total installed electricity capacity required in California to reach net zero Statewide emissions by 2050 under five different model scenarios (or cases) in the EER model. Appendix A offers more information about the EER model, downscaling, and model scenarios.
Figure 2. Results for CO2 emissions from energy and industrial processes in California from the EER model for five different scenarios (or cases). Colors above the x-axis represent positive emissions, and colors below represent offsetting negative emissions. The black line indicates net CO2 emissions. “Product and bunkered CO2” is either CO2 that ends up sequestered in materials (e.g., asphalt sequesters CO2 during its production) or CO2 reductions not counted in current inventories (e.g., interstate aviation emissions reductions are not included in a single state’s emissions accounting, but intrastate aviation is).
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7 Experts in renewable energy production, transportation, and buildings modeled technically feasible decarbonization pathways for the region to create a science-based roadmap of regional decarbonization to net zero emissions by mid-century. These models focused on proven, scalable technologies for decarbonizing the region’s largest GHG emitters (Figure 3) that are within the jurisdiction of local governments and agencies. This excluded technologies in experimental or early phases because regional authorities cannot immediately deploy them at scale. Similarly, renewable energy development in State and federal waters were not included in modeling efforts except to contextualize resource availability in the San Diego region.
Additionally, the RDF’s Technical Report highlights uncertainties in the decarbonization process and the need for ongoing planning processes that can adapt as the technology and policy landscapes evolve. For example, increased renewable energy availability from Imperial County or Mexico may affect the San Diego region’s renewable energy mix, which could avoid the need to build higher-cost renewable energy infrastructure locally. Similarly, State and/or Federal development of offshore wind could reduce the need for onshore renewable infrastructure development in the San Diego region.
Figure 3. Region-wide estimates of the emissions of carbon dioxide equivalent (CO2e) measured in million metric tons. The “other” category includes emissions from industrial sources, off -road transportation, waste, aviation, water, etc., which were not considered in the RDF’s Technical Report. Note that 2035 values account for the impacts of certain State and federal actions. Source: the SANDAG 2021 Regional Plan’s Appendix X, available here:
https://sdforward.com/docs/default-source/2021-regional-plan/appendix-x---2016-greenhouse-gas-emissions- inventory-and-projections-for-the-san-diego-region.pdf?sfvrsn=8444fd65_2
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8 Key Policy Considerations
The RDF’s Technical Report identifies “low-regret” strategies which provide the best assessment of the least cost and most effective near-term solutions for reducing emissions in each sector. These strategies represent robust decarbonization actions in the near-term, regardless of how uncertain factors resolve, but whether they are the best pathways over the long term remains unknown (Table 1).
Successful decarbonization requires both technical solutions and policy strategies that can adapt with changes in scientific understanding and local political and economic conditions.
Effective learning and policy adjustment requires that local actors – both leaders and people on the front line – first implement initial solutions and then engage in systematic and continuous review of results to drive meaningful learning about what works and what does not. The “best” solutions and pathways can and should evolve over time as science and technology advance and as local actors learn what is effective in the San Diego region.
Table 1 Examples of “Low Regret” Strategies in the Four Sectoral Pathways.
Renewable Energy Siting
● Support distributed solar resources
(including rooftop solar and infill solar in
areas like parking lots), particularly in low-
income communities.
● Begin planning for utility-scale
development in areas identified by most
scenarios (e.g., the planned JVR region).
Transportation
● Encourage denser and mixed-use development
around existing and new trolley stops, transit
corridors, and mobility hubs.
● Electrify fleet vehicles (jurisdictions, agencies,
school districts, etc.).
● Require electric vehicle (EV) hookups in new
construction or additions; streamline building
permits for EV retrofits.
Buildings
● Create incentives for replacing end-of-life
space and water heaters with electric
alternatives.
● Make new buildings “all-electric.”
● Focus on electrifying low-income,
disadvantaged, and rental residences.
Land Use and Natural Climate Solutions
● Protect natural and working lands.
● Bolster carbon farming throughout the region.
● Increase tree, shrub, and plant cover in urban
and suburban areas.
The RDF’s Technical Report proposes region-wide institutional governance to facilitate continued collaboration and learning across jurisdictions.i Organized into a Regional Steering Committee, Sector Working Groups, and Front-Line Advisors, this structure would unite government officials, planning bodies, regulators, industry stakeholders, experts, and front-line
i More information on collaboration and learning across jurisdictions is available in Chapter 7.
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9 workers in each sector from across the region to test, evaluate, and adjust strategies. Such a structure is necessary because achieving the significant changes and rapid learning needed to address climate change is a collective action problem. Individually, local jurisdictions and agencies in the San Diego region have limited authority over the suite of actions needed to decarbonize. Region-wide cooperation can increase collective impact through clear, credible, and consistent policy signals, joint problem-solving, pooling of experience about what works, and greater leverage and capacity from combined resources. As discussed in Chapters 7 and 8, examples of regional cooperation include setting incentives for action, collecting data, conducting analyses, supporting policy development and implementation, convening stakeholder and working groups, and monitoring progress. A Regional Climate Action Joint Power Agreement (JPA) or other formal mechanism could facilitate such cooperation, thereby scaling strategic thinking and decision-making around decarbonization. Figure 4 outlines an institutional process through which regional governance, informed by the technical solutions proposed in the RDF and ongoing stakeholder engagement, can drive meaningful learning in each sector.
Within this institutional process, the RDF’s Technical Report also proposes two strategies for engaging with actors and agencies beyond the San Diego region to maximize impact within the region. First, regional decarbonization leaders must engage continually with outside agencies, especially at the State level, to influence policies that affect local efforts (e.g., renewable energy regulations). Second, local leaders should leverage the region’s technology- focused private sector and multiple universities to establish the San Diego region as a test bed for pilot and demonstration projects. While regional-scale investments in innovation alone are unlikely to dramatically impact technological readiness across all sectors, local testing and deployment of technologies developed elsewhere can contribute to the global effort to push the frontier of science on climate solutions. External engagement not only supports local emission reductions, but also promises to bring outside resources and attention from State and federal policymakers, with potential positive effects on the local economy.
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10 Figure 4. The RDF’s Technical Report as part of an Integrated Decarbonization Framework and institutional structure. This structure could include San Diego’s regional governance bodies and a conference of governments, for example.
In sum, the RDF proposes institutionalizing a highly transparent, cooperative process for eliciting new information about "what works" with deep decarbonization, comparing best practices within the region, and engaging outside the region with policymakers, industry stakeholders, and other experts contributing to the evolution of national strategies. These not only maximize local emissions reductions, but also enable the San Diego region to influence State and federal climate policy and become an effective leader for other jurisdictions. The San Diego region makes up just 0.08% of global emissions, so generating followership represents the region’s best route to truly make an impact on mitigating climate change.
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11 Decarbonizing Electricity
The RDF’s Technical Report identifies low-environmental-impact, high-quality, and technically feasible areas for renewable energy infrastructure development in the San Diego region and neighboring Imperial County. Electricity emissions accounted for approximately 20% of the 2016 Regional Greenhouse Gas Emissions Inventory for the San Diego region and comprise the second largest emissions source in the region (Figure 3). Decarbonizing electricity production will require substantial deployment of new renewable resources. Siting renewable energy infrastructure and facilities can have significant impacts on the environment and will require new and upgraded transmission infrastructure. Thus, the RDF includes a series of scenarios with different land footprints that are meant to inform the political discussions in jurisdictions across the region on the trade-offs regarding land use and renewable energy costs.
The San Diego region has sufficient available land area for wind and solar generation to approach a fully decarbonized energy system in line with the California-wide system model.
However, meeting standards for reliability will require significant, but uncertain, investments in a suite of additional resources, including excess intermittent and flexible generation, storage, and demand-side management. The region can produce the projected 2050 energy demand of 49,979 gigawatt hours (GWh) per year with local utility-scale onshore wind and solar development (Table 2). However, demand for energy may be higher or lower than the renewable energy supply at a given time (for example at night or on cloudy days), necessitating investments in additional energy storage infrastructure to supply reliable renewable energy to the region. However, the costs of these additional resources, such as batteries and pumped storage hydropower, remain highly uncertain.
Levelized Cost of Energy (LCOE), which is the adjusted cost of electricity production per megawatt hour (MWh) that includes transmission costs, was used as a metric to compare project costs. LCOE allows for both direct comparison of projects and flexibility as uncertainties are resolved and as infrastructure (power plants, transmission lines, interconnections, etc.) is built. LCOE can estimate the wholesale cost of electricity for utility- scale projects. LCOE includes costs of initially building the wind or solar plant and the cost of interconnecting that project to the grid, which are divided by total energy production to get a cost per unit of energy output. Transmission costs are included in the project capital costs and are based off the California Independent Systems Operator (CAISO) Transmission Planning Process documents. LCOE is a way to compare different types of energy projects based on a per unit of energy produced. For example, LCOE metrics make it possible to compare a solar power plant to a natural gas power plant based on cost per MWh that it can produce.
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12 Table 2. Candidate project areas (CPAs) and total annual resource potential in San Diego County and Imperial County. Utility-scale resources refer to large scale projects for solar, wind, and geothermal resources. Other resources are from smaller scale projects, including rooftop solar, infill solar or wind, and brownfield solar or wind.
Geothermal CPAs are discrete areas and are listed as the number of potential sites rather than by their total area.
Total annual demand for the San Diego region by 2050 is estimated as 49,979 GWh.
San Diego County San Diego County + Imperial County
Findings
Utility-
Scale Only
With Rooftop, Infill,
and Brownfield
Utility-
Scale Only
With Rooftop, Infill,
and Brownfield
Solar
Area (sq km) 661 985 3,417 3,741
Potential (GWh) 54,784 102,925 84,888 109,742
Onshore Wind
Area (sq km) 86 86 3,712 3,749
Potential (GWh) 730 730 22,540 22,572
Offshore Wind
Area (sq km) 1,660 1,660 1,660 1,660
Potential (GWh) 9,869 9,869 9,869 9,869
Geothermal
Number of sites 0 0 5 5
Potential (GWh) 0 0 10,680 10,680
Total Renewable Resource
Potential (GWh) 65,382 113,523 117,296 142,183
Electricity Resource Balance (GWh) 15,403 63,544 67,317 92,204
The RDF’s Technical Report creates multiple site-selection scenarios for renewable energy infrastructure to inform decision-making. These include least-cost scenarios; scenarios that include Imperial County solar, wind, and geothermal resources; scenarios that minimize impacts to different land types; and scenarios with different mixes of wind and solar resources (both distributed and utility-scale) in urban, greenfield, and brownfield sites. The least-cost scenarios (Scenarios 1 and 2) selected utility-scale renewable energy sites from lowest to highest LCOE. Additional scenarios prioritize different policy goals such as avoiding certain lands (Scenarios 3 – 5) or prioritizing development on certain lands (Scenarios 6 and 7).
Other scenarios combine resources and policy priorities (Scenarios 8 and 9). The scenarios are as follows (see Table 3 for values):i
1. Least-cost, high local capacity (San Diego county only) (Figure 5);
2. Least-cost, high transmission deliverability (San Diego and Imperial counties) (Figure 6);
3. Minimize Loss of Land with High Conservation Value (Figure 7);
4. Minimize Loss of Land with High Monetary Value;
5. Minimize Loss of Land with High Carbon Sequestration Potential;
6. Utilize only Developable Land;
i See sections 2.4.5 and 2.4.6 for descriptions of the data and methods for site and candidate project area selection. See sections 2.5.1 and 2.5.2 for scenario results, discussion, and maps.
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13 7. Infill and Rooftop Solar Scenario;
8. Mixed Mode Scenario (includes a combination of developable areas in the region and nearby areas with transmission upgrades, nearby geothermal, rooftop solar, brownfield solar and wind, and battery storage) (Figure 8); and
9. Maximize Rooftop Solar, Minimize Impact to Conservation and Agricultural Lands.
Table 3 Scenario summary of renewable energy resource potential and energy deficit with predicted demand. All values are in GWh. The “deficit with demand” values are based on the EER model’s Central Case annual demand estimates of 49,979 GWh for the San Diego region by 2050.
Scenario
number Scenario Description
Resource
Type
Resource
Potential
(GWh)
Excess (Deficit)
with Demand
(GWh)
Scenario 1 Least-cost (San Diego county only) Solar, Wind 49,979 – Scenario 2 Least-cost (San Diego and Imperial counties) Solar, Wind,
Geothermal 49,979 –
Scenario 3 Low Environmental Impact Solar, Wind 15,777 (34,202) Scenario 4 Low Land Value Solar, Wind 52,394 2,415
Scenario 5 Carbon Sequestration Potential Solar, Wind 22,844 (27,135) Scenario 6 Developable Solar, Wind 13,894 (36,085)
Scenario 7 Rooftop and infill solar Solar 17,478 (32,501) Scenario 8
Mixed-mode resource mix (San Diego and
Imperial counties)
Solar, Wind,
Geothermal 50,147 168
Scenario 9
High Rooftop, Low-Impact to Conservation
Lands, Avoid Valuable Agriculture Lands (San
Diego and Imperial counties) Solar, Wind 44,177 (5,802)
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14 Figure 5. Scenario 1: Least-cost scenario in the San Diego region only. This analysis selects utility-scale solar and onshore wind resources from lowest to highest cost to meet projected energy demand. The three panels show the build-out required by each year that would allow the region to approach full energy decarbonization by 2050.
Lighter colors represent Candidate Project Areas (CPAs) that would be built earlier because they are less expensive.
Blue colors are wind resources and orange/red colors are solar resources. This scenario has an average levelized cost of energy (LCOE) of $40.65 per megawatt hour (MWh).
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15 Figure 6. Scenario 2: Least-cost scenario in San Diego and Imperial counties. This analysis selects solar, onshore wind, and geothermal resources from lowest to highest cost to meet projected energy demand. These maps show build out over three time periods where colors represent build out year (lighter colors are earlier) and resources (red/orange for solar, blue for wind, and green for geothermal). The inset shows the Jacumba Hot Springs area site selection by 2050 and the area that includes the proposed/planned Jacumba Valley Ranch (JVR) sites. This scenario has an average LCOE of $42.04 per MWh.
Figure 7. Scenario 3: Exclude land with high conservation value. This scenario minimizes impacts to areas of high conservation value and other areas that are environmentally sensitive or important. It does not meet regional energy demand and is relatively more expensive (with an average LCOE of $84.5 per MWh).
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16 The mixed-mode scenario utilizes a mix of proven, scalable technologies that are within the jurisdictions of San Diego county, Imperial county, or regional entities to build in order to meet regional demand both in the near-term (2025) and by mid-century (shown in Figure 8). The technologies include brownfield infrastructure development (solar and wind infrastructure built on currently or formerly contaminated sites); utility-scale solar and wind in both San Diego and Imperial counties; rooftop and infill solar (where “infill solar” is defined as solar projects built in dense, urban settings); and geothermal (which is a clean source of baseload power that does not rely on wind, sun, or other variable energy sources).
Figure 8. Scenario 8: Mixed-mode Scenario 2050. This figure shows sites selected to meet the 2050 electricity demand using a variety of resources: 12% rooftop solar, 23% brownfield solar, 0.1% brownfield wind, 6% utility scale solar on developable land in San Diego county, 0.4% utility-scale wind on developable land in San Diego county, 38% Imperial solar, 21% Imperial geothermal. The addition of rooftop solar and brownfield resources together results in 35% reduction in land area impacts. This meets regional energy demand, but it has a high average cost (with an average LCOE of $109/MWh) partly because of the high costs of rooftop and brownfield development, as well as the high cost of geothermal.
There are some commonalities across scenarios in the results, suggesting that these might be “low-regret” renewable energy infrastructure options. The geospatial analyses of renewable energy siting have demonstrated that rooftop solar, infill solar, and brownfield development reduce overall land use change in natural and working lands. Additionally, these resources can bring co-benefits to communities, such as pollution reduction and economic opportunities.
Thus, despite the relatively high costs compared to utility-scale development, building distributed and urban renewable resources are low-regret strategies that have low impacts on Oct. 11, 2022
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17 habitats, agriculture, and rural communities and can provide attractive job training opportunities where few such opportunities currently exist relative to utility-scale development.i
Given the high commercial interest and relative proximity to planned or existing renewable sites, the models highlighted the Jacumba Valley Ranch (JVR) renewable area in most scenarios.
State planning proceedings favor this area, including those by the CAISO (California’s grid operator) and the California Public Utilities Commission (CPUC), and it may represent a low- regret scenario for utility-scale infrastructure expansion. These scenarios are not prescriptive and any policy decision will require careful consideration of environmental justice and a deeper understanding of the effects that these energy developments will have on communities of concern, low-income communities, rural communities, and/or disadvantaged communities.
Imperial County has significant solar and geothermal resources that could provide energy to the San Diego region, but this may require upgrades to the transmission network. As renewable energy infrastructure develops in neighboring areas – such as Imperial County, Mexico, or offshore – the site selection scenarios will change in iterative energy supply and demand analyses. Similarly, as new technologies and permitting make additional renewable energy resources available (e.g., offshore wind, wave energy, etc.), the scenarios must update to account for the energy supply from those novel resources (see Table 3 for geothermal and offshore wind values). This framework is flexible enough to account for additional renewable energy supply as it becomes available.
The region should coordinate with State agencies to ensure the reliability of the system. The San Diego region is a part of a larger energy system network, so coordination across agencies must underpin decision-making, planning, and implementation of renewable energy infrastructure into the future. For example, there are State-level Integrated Resource Plan (IRP) proceeding at the CPUC. Load Serving Entities (LSEs) throughout the State are Parties to this proceeding, and local LSEs, such as San Diego Gas and Electric (SDG&E) and Community Choice Aggregators (CCAs), are required to submit annual procurement plans. These submittals help the State anticipate potential reliability issues and help the CAISO plan transmission upgrades needed to accommodate the LSE plans and climate goals. LSE submissions to the CPUC should indicate their expected local distributed generation, rooftop solar, community solar, equity- eligible contractor projects, or other specifications. Additionally, regional government officials often serve on CCA boards and participate in procurement, planning, and target setting. Board
i See the complementary workforce development report by Inclusive Economics, Inc. for a larger discussion on the job quality and access characteristics of utility-scale renewable energy versus distributed energy. The report, titled “Putting San Diego County on the High Road: Climate Workforce Recommendations for 2030 and 2050,” is available on the County’s website: https://www.sandiegocounty.gov/content/dam/sdc/lueg/regional -decarb- frameworkfiles/Putting%20San%20Diego%20County%20on%20the%20High%20Road_June%202022.pdf .
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18 members can help ensure that LSE plans are implemented for consistency with regional and State GHG reduction targets. This is especially important where local targets are more ambitious than State targets.
Beyond the IRP, there are additional State agency proceedings which could benefit from input from local players (e.g., the CPUC Resource Adequacy proceeding, CAISO Transmission Planning Process, and the CAISO Local Capacity Requirements proceeding). In the Resource Adequacy proceeding, CPUC staff analyze power grid reliability. In the Transmission Planning Process, the CAISO assesses reliability, policy compliance, and cost-effectiveness of planned transmission system upgrades. In the Local Capacity Requirements proceeding, the CAISO conducts a more local reliability analysis than other proceedings. For example, Section 3.3.10 of the CAISO 2022 Local Capacity Technical Study is devoted to the San Diego-Imperial Valley region. LSEs such as SDG&E, San Diego Community Power, and Clean Energy Alliance should coordinate on procurement, resource adequacy and other issues addressed in these proceedings.
Numerous State goals affect electricity decarbonization, including requirements for rooftop solar on certain new buildings, requirements for a fully decarbonized electricity system by 2045, and allowances for additional decarbonization efforts beyond State goals. Electricity decarbonization is the most common CAP measure analyzed and on average contributes more GHG reductions than any other measure. Most CAPs include a measure to form or join a CCA program, and additional jurisdictions can increase CCA participation or commit to 100% carbon- free energy prior to the State 2045 deadline. Additionally, local efforts can enhance or complement State rooftop solar requirements by adopting reach codes (regulations that go beyond State requirements) and evaluating mandates or incentives for energy storage systems paired with rooftop solar to decrease marginal emissions during the electric system’s peak GHG emission and increase reliability.
Additional work would be needed to make carbon-free electricity supply more accessible.
Historically, rooftop solar has been installed in higher-income neighborhoods and in areas with higher levels of homeownership. Numerous levers could address the inequitable distribution of rooftop solar installations, including targeted incentives and financing. Additionally, CCA programs can maximize participation in the Disadvantaged Communities Green Tariff Program, subsidize customers in income-qualified discount programs to opt-up to 100% carbon-free electricity service options, and support inclusive financing for energy upgrades.
Legal authority to regulate energy production:
i Jurisdictions in the San Diego region have the
authority to require levels of carbon-free electricity supply through CAPs and procure carbon-
i See Chapter 8, section 8.7 “Decarbonize the Electricity Supply” and Appendix B for further discussion of legal authority.
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19 free electricity supplies through CCAs and can therefore supply more carbon-free energy than required by State agencies. However, State and/or federal agencies or entities still regulate local energy supplies for reliability, which complicates fully decarbonizing the electricity supply with renewable energy. Additionally, local jurisdictions are also authorized to support alternatively fueled thermal power plants and related infrastructure that can provide low- or zero-emission electricity to meet reliability and air quality requirements (e.g., green hydrogen production and/or power plants). Local jurisdictions are also authorized to streamline permitting and increase distributed generation through CCAs and reach codes. Further regulating most fossil-fueled thermal power plants emissions is limited given current State regulation and uncertainty over federal preemption.
Decarbonizing Transportation
The transportation sector is the largest contributor to regional GHG emissions. In 2016, on- road transportation was responsible for almost half of regional emissions. In 2035, emissions from on-road transportation are projected to account for about 41% of the total projected emissions (Figure 3).i Statewide legislation, executive orders, and State agency targets have set GHG reduction goals to address these emissions. Additionally, the San Diego region has implemented measures to reduce regional transportation GHG emissions, including a variety of vehicle miles traveled (VMT) reduction and vehicle electrification strategies.
The region has a strong policy foundation for reducing emissions related to transportation.
However, current commitments through CAPs and other policies are inconsistent with the scale of reductions required by State executive orders for carbon neutrality. Even the best CAP commitments to reduce on-road transportation emissions through VMT reduction, EV adoption, and fuel efficiency strategies, if applied to the whole region, are not projected to achieve the State’s zero emissions goals.
Opportunities to accelerate EV adoption and VMT reduction exist based on current regional policies and patterns of vehicle ownership, travel behavior, and land use development.
Current policies and consumer, driver, and developer behaviors are already increasing EV adoption and reducing VMT. However, there are additional opportunities to accelerate regional transportation decarbonization. To reduce VMT, jurisdictions can focus on high-density development around transit corridors, rail, and trolley stations, and enhance transit and active transportation (e.g., biking and walking). Adopting “smart growth” policies improves urban and suburban connectivity, encourages mixed-use developments, shortens trip lengths by changing
i See Chapter 8, section 8.5 for a detailed analysis of CAP commitments as they relate to transportation. Note that this value includes projected EV sales changes but does not include CAP measures.
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20 zoning, and disincentivizes free parking.i To further reduce emissions, jurisdictions can establish and enforce existing anti-idling requirements (especially around schools), identify areas for traffic calming measures, and provide driver behavior incentives. Further, local jurisdictions can affect vehicle retirement, which can be prioritized in communities of concern to rapidly reduce local air pollution burdens. Finally, local governments can increase adoption of zero-emission vehicles (ZEVs) through provision of public EV charging stations and use of alternative, low- carbon fuels and EVs, particularly for medium-and heavy-duty vehicles, in existing and future fleets. Figure 9 shows a menu of policy opportunities to increase ZEV adoption, illustrating policy options that range in both effectiveness (i.e., how well the policy increases ZEV adoption) and breadth (i.e., how many people it reaches).
Figure 9. A spectrum of policy options to accelerate ZEV adoption. Policies are likely to be more effective moving right and are likely to have a broader application moving down. Thus, the bottom right is predicted to be the most effective and to have the broadest application of the policy measure shown where the top left is predicted to be the least effective and to have the narrowest application of the policy measures shown.
Multiple opportunities for regional collaboration and coordination exist. The nature of on- road transportation and of existing institutions that coordinate transportation decisions suggest that regional collaboration on transportation decarbonization will be more effective than individual CAP measures. CCAs provide an example of a local mechanism, usually through JPAs,
i Opportunities to increase density in in-fill areas have been identified in Chapter 3. Chapter 8 offers more details on how to reduce VMT.
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21 that can support transportation electrification by developing programs to locally incentivize EV uptake beyond State and federal programs. Similarly, other regional collaboration efforts may be identified which can promote local funds for transportation decarbonization. Local jurisdictions can further collaborate to assess the equitability and effectiveness of investing in EV deployment versus increased mass transit in various communities and align regional transportation equity analyses (e.g., SANDAG’s equity analyses) with CAP equity analyses (e.g., the City of San Diego’s equity analyses).
Legal authority to regulate transportation decarbonization:i Local jurisdictions and agencies in the San Diego region have broad authority over transportation, based both on locally derived land use authority over planning and development and based on delegated State and federal authority. However, such delegated authorities can be limited or preempted by State or federal laws, as with fuel and tailpipe emission regulations. Through their authorities, local jurisdictions can establish climate change policies and regulations to reduce GHGs from transportation in general plans (GPs), CAPs, zoning, or transit-oriented development regulations. Further, they can require infrastructure for fuel switching in buildings (e.g., EV charging equipment), build supporting infrastructure in public right-of-ways or on public land, and support alternative fuel production and infrastructure, such as hydrogen. Local jurisdictions can regulate their own fleets through purchasing, maintaining, or changing their fleets. They also have the authority to regulate indirect transportation emissions to keep local emissions in line with federal and State air quality standards. State statutes and regulations create an opportunity to align local action that decreases implementation costs by bringing State funded projects to the region, particularly in communities of concern, and deploying technology developed by State or federal funding. Finally, jurisdictions appear to have additional legal authority through land use, transportation infrastructure siting, delegated authority, and taxation powers to reduce transportation GHGs than represented by commitments in CAPs. Assessing the limits of local authority to increase on-road transportation GHG reductions requires additional work.
i See Chapter 8, section 8.5 “Decarbonize Transportation” and Appendix B for further discussion of legal authority.
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22 Decarbonizing Buildings
The RDF’s Technical Report studies the building mix and associated emissions from the region’s infrastructure and building sector. Direct emissions from buildings come from on-site fossil fuel combustion and contribute to regional GHG emissions (Figure 3). This analysis focuses on electrifying systems responsible for end-use emissions, like space and water heating, and using lower-carbon fuels (such as biomethane and hydrogen) where electrification is not yet feasible.
The chapter considers three modeled pathways to reach a carbon-free building sector by 2050:
a pathway emphasizing high electrification of fossil-fuel systems, a pathway with highly efficient electric heat pumps, and a pathway using low-carbon fuels to reduce emissions in the interim while electrification occurs more slowly.i
There are several near-term, low-regret actions for building decarbonization. First, replacing end-of-life fossil fuel heating systems with electric versions is a near-term priority, as some existing fossil fuel systems will only turn over once by 2050. Second, setting “electrification- ready” or “all-electric” standards for new construction and major renovations through building energy codes will reduce costs associated with transitioning away from fossil fuels. Third, improved data gathering represents a low-cost, foundational action for future policy development. More data on building emissions and decarbonization will better inform decision makers crafting policies for the building sector’s contributions to a net zero region.
Replacing fossil fuel-based space heating and water heating systems with electric systems should be a primary policy focus for building emission reductions. Space heating and water heating together consume the vast majority of the natural gas supplied to residential buildings in the SDG&E service area (Figure 10). Commercial buildings are more varied in their energy consumption (Figure 11), but space and water heating still consume a large portion of total energy, and around two-thirds of commercial buildings space heaters use natural gas. Replacing space and water heating systems and other fossil fuel-based systems like ovens and dryers with electric versions will yield significant building decarbonization. Current heat pump technologies for space and water heating are readily available and outperform natural gas systems by providing more heating per unit of energy used, making these systems especially conducive to electrification. For building temperature regulation, electric heat pumps offer both heating and cooling from the same unit, making them ideal for homes that do not yet have air conditioning.
Thus, regional policies should support adoption of efficient heat pump-based space and water heating systems to replace fossil fuel-based systems in both new and existing buildings.
Additionally, policies aimed at replacing fossil-fuel based space and water heating systems should focus assistance efforts on increasing uptake among low-income residents and rental
i More details on the modeled pathways are available in Chapter 4, section 4.4 and elsewhere in the chapter.
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23 building owners. Such policies would address historic inequities in housing quality, environmental injustice, health disparities due to indoor air pollution, and utility costs. Further, they would ensure that building decarbonization includes low-income residents and renters, rather than leaving them to pay increasingly higher gas rates.
Figure 10. Average annual natural gas usage (measured in therms) by end use and by utility for households who use gas as the primary fuel for major end uses. Source: DNV GL Energy Insights (2021). 2019 California Residential Appliance Saturation Study (RASS).
Figure 11. San Diego regional energy end-use profiles by commercial building type. Percentages are relative to total end-use energy within each building sector. Annual energy consumption, measured in metric million British thermal units (MMBTU), for each building type is shown in blue at the top of the fig ure. Water heating is in light gray (third from the bottom in each bar) and space heating is in medium gray (second from the bottom in each bar). Natural gas consumption per system varies by commercial building type, but space and water heating are still significant natural gas consumers, as is visible in the leftmost column (“Total”). Source: Synapse model.
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24 Policies for decarbonizing existing and new buildings are crucial. 80% of the buildings that will exist in 2050 have already been built, so decarbonizing the building sector requires decarbonizing the current building stock. While State building codes, like Title 24, regulate building alterations and additions to certain existing structures, local policies could further encourage or require energy efficiency and electrification in many other places.i For instance, decarbonizing municipal buildings through cost-effective electrification should reduce operation costs and may encourage property owners to follow suit, making it a low-regret policy.
To decarbonize new buildings, jurisdictions can set local “electrification-ready” or “all-electric” standards for new construction. Policymakers can benefit from lessons learned in the adoption of all-electric reach codes or ordinances—which are local codes or ordinances that go beyond state or federal requirements codes or ordinances—in the cities of Carlsbad, Encinitas, and Solana Beach.
Low-carbon gaseous fuels can be used for hard-to-electrify end uses, though research and piloting are required. Some building systems are hard to fully electrify, so one way to reduce GHG emissions from those systems is to use fuels that do not emit net GHGs into the atmosphere.
ii Similarly, such fuels can be used for these or other systems prior to electrifying them. Low-carbon gaseous fuels could include biomethane and/or hydrogen. However, each of these alternate fuels have cost and efficiency trade-offs as well as uncertainties, requiring more research and piloting before implementation.
Minimizing unnecessary extensions or replacements of the gas pipeline system and accelerating depreciation of existing utility assets mitigates the gas utility’s risk of not recovering its investment in assets (i.e., its stranded cost risk). Phasing out end-use natural gas consumption in buildings can lead to stranded assets, defined as infrastructure that is shut down before the end of its useful life. For companies like SDG&E, stranded assets represent potential financial losses because of the high capital costs to build or replace gas infrastructure.
Mitigating these stranded assets will be an important policy consideration.iii One step is to minimize unnecessary pipeline extensions or replacements. Policies requiring full electrification in new construction would mitigate stranded asset losses for pipe investments going to new
i See Chapter 8, section 8.6, for more details on examples of local authorities decarbonizing existing buildings. Also see Chapter 7 section 7.3.1 for a local example.
ii One such example are district energy plants that provide high-temperature steam or hot water to geographic clusters of buildings. There are several such systems in the San Diego region that serve military bases, hospitals, or universities. System operators should evaluate the relative costs and benefits of low- carbon fuels and electric heating technologies (such as high-capacity heat pumps, heat recovery chillers, and electric boilers). iii At the time of this writing, the Public Utility Commission is evaluating key aspects of long -term natural gas planning in California under proceeding R2001007.
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25 customers, but not from replacing aging infrastructure. Exploring and piloting non-pipeline alternatives to both new and replacement infrastructure, including electrifying end uses instead of replacing infrastructure, could identify opportunities to mitigate risk.
CAPs have relatively few measures to electrify buildings and the GHG impact of those measures is relatively low, despite the sector’s importance to regional decarbonization. Only seven CAPs in the San Diego region include measures related to building electrification and the GHG reductions in CAPs associated with efficiency and electrification are relatively low. i
Compared to the level of electrification needed in both new and existing buildings as outlined in Chapter 4, the CAP measures fall short of the building decarbonization pathway findings in the RDF’s Technical Report.
There is an opportunity and a need to assess social equity considerations of building decarbonization policies. Replacing appliances is expensive, so building decarbonization policies should account for incentivizing electrification equitably, especially in communities of concern, low-income communities, rural areas, and for renters. Developing the capacity and tools to understand and address the equity implications of building decarbonization policies in the San Diego region requires additional work.
Legal authority to regulate building decarbonization:
ii Local jurisdictions have the authority to
regulate GHG emissions from building end-use of fossil fuels and other energy sources, which represents the primary means of decarbonizing buildings. Local jurisdictions also act with delegated authority over the built environment to require more stringent energy codes, directly regulate air pollution emissions from buildings, and procure alternate energy supplies in public buildings. Additional authority may come from the California Environmental Quality Act (CEQA) by setting more stringent thresholds to determine environmental impact. Local governments are preempted from establishing energy efficiency appliance standards, regulating natural gas supply, transmission, and storage, and high global warming potential refrigerants (e.g., HFCs).
i See Chapter 8, Figure 8.33 for details on CAP commitments relating to building electrification. ii See Chapter 8, section 8.6 “Decarbonize Buildings” and Appendix B for further discussion of legal authority.
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26 Natural Climate Solutions
The RDF’s Technical Report investigates the natural climate solutions (NCSs) available in the San Diego region and their potential to naturally sequester and store CO2 and other GHGs. NCSs are processes that protect or enhance natural and working lands’ (NWLs) ability to capture and store GHGs from the atmosphere through plants and soils or reduce emissions from NWLs. “Working lands” include agricultural lands like orchards, vineyards, pastures, nurseries, rangelands, croplands, etc. “Sequestration” is an annual measure of how many GHGs are removed from the atmosphere and “storage” is the total amount of GHGs that have been sequestered in plants and soils. Existing carbon stocks (Figure 12) are generally stable and can store carbon for decades if left undisturbed, so careful regional planning can minimize land use change that would emit this stored carbon. By understanding a landscape’s carbon storage and sequestration potential, areas with high levels of stored carbon can be preserved as such and areas with high sequestration potential can be protected.
Figure 12 Total stored carbon (metric tons (MT) of CO2 equivalent per hectare (ha)) estimates for the San Diego region. Darker colors represent larger carbon stock estimates and lighter colors represent lower stock estimates.
Regionwide storage totals per vegetation category were calculated from these values and are in Table 5.2. Note that eelgrass beds were not included because they were not included in the SanGIS shapefiles. However, eelgrass beds are prevalent in both Mission and San Diego bays and are important blue carbon habitats.
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27 Regional NWLs sequester and store large amounts of carbon dioxide, although not enough to account for human-caused emissions. NWLs can act as stronger net sinks than they currently do, though this will require investments in bolstering NCSs and minimizing carbon emissions from land and land use activities. To accurately account for net carbon land use emissions, local data need to be collected and integrated into regional carbon calculations. The region can expand annual carbon sequestration and long-term carbon storage through investing in NCSs that both increase natural sequestration and reduce emissions from the land, such as protecting NWLs; investing in “carbon farming;” restoring and expanding “blue carbon” habitats; planting trees and other plants in urban areas; preventing large-scale, destructive wildfires; and planting trees in NWLs or otherwise restoring them. Collecting and integrating local data into NCS policies, incentives, and management techniques can increase regional sequestration.
Avoiding land use changes by protecting natural and working lands represents the most effective and inexpensive NCS policy in the San Diego region, except where other decarbonization actions necessitate land use change (such as siting renewable energy infrastructure). Existing natural and working lands are natural carbon sinks, so preventing urbanization of these lands allows for continued annual sequestration and prevents one-time emissions from vegetation removal, soil disturbance, etc. This report estimates that natural annual sequestration in NWLs may be up 2 million metric tons (MMT) of CO 2 under ideal
circumstances and that there may be 58 MMT of CO2 stored in vegetation, woody debris, leaf litter, and soils, some of which would be released with land use change.
Housing development and renewable energy infrastructure siting are important activities and will require some land use change. Implementing these changes to minimize impacts on NWLs with large natural carbon stores, high sequestration potential, and/or high co-benefits (such as habitats that improve air and water quality, protect biodiversity, and support public health) will be critical.
Other important regional NCSs considered by the RDF’s Technical Report may be less effective and/or more expensive for carbon sequestration, though they yield important co- benefits. These include carbon farming (farming practices that increase carbon sequestration and storage and minimize GHG emissions on agricultural lands), increasing wetland extent and quality (through protection, restoration, and expansion), and urban forestry and greening.
Wildfire prevention will also be important for emissions and numerous other economic, ecological, and social reasons. Large-scale habitat restoration and reforestation, which were not considered in this report, are expensive and may not be effective. Other NCS options require significant capital investments and typically have smaller short-term sequestration returns than preservation.
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28 NCSs offer quantifiable co-benefits beyond decarbonization. Each of the analyzed NCSs offer numerous quantifiable co-benefits. These co-benefits include, but are not limited to: improved air and water quality, improved public health outcomes, biodiversity protection, ecosystem functioning protection, reduced heat island effects through shading, improved aesthetics in urban areas, decreased water and fertilizer requirements on farms and rangelands, and the potential to increase environmental justice. These co-benefits should be considered when crafting and implementing policies to build ecological, economic, and social resilience.
All NCS decisions must center on equity considerations. NCSs should be viewed through both decarbonization and equity lenses. Whenever possible, urban greening, tree planting, climate farming, and habitat restoration projects should prioritize communities of concern because these NCSs have outsized co-benefits of improving air and water quality as well as human health. NCSs can help address historic inequities and environmental injustice.
The only quantified CAP measure relevant to this pathway is urban tree planting, but there are opportunities to implement additional NCSs in a collaborative way. Additional measures are possible under local land use authority. Tree planting measures contribute on average just over 1% of local GHG reductions in CAPs. Jurisdictional collaboration can enhance this.
Additional NCS CAP measures are possible under existing authority and can contribute to land conservation, preservation, and restoration on natural and working lands. Private landowners and tribal governments can also preserve land, test and fund pilot projects for carbon removal and storage, and collaborate with public agencies. Collectively, there is an opportunity to expand protections for natural and working lands to fulfill the new California Senate Bill 27 (2021) mandate that calls for establishing NWL carbon removal and storage projects.
There are also opportunities to include local data in land management and planning and in CAPs. For instance, CAPs can utilize both publicly available data from agencies and universities and publicly available carbon accounting methodologies from agencies like the California Air Resource Board (CARB) to create stronger goals and measures. Additionally, the region can implement regular carbon accounting and track carbon stocks in NWLs over time to understand emission, preservation, and storage trends with land use decisions.
Legal authority to regulate negative emissions from NCSs and land use:
i It remains unclear
whether local jurisdictions’ ability to use their authority over land use, zoning, land preservation, and agricultural easements extends to activities on private natural and working land beyond land use designation that would affect GHG emissions or sequestration. The region’s land use jurisdiction is further complicated because it is composed of federal, State, tribal, and privately held land, submerged land, and waters. Various statutes and agencies
i See Chapter 8, section 8.8 “Natural Climate Solutions” and Appendix B for further discussion of legal authority.
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29 regulate different land types, with none focused on GHG emissions or sequestration as it relates to land use. State land use and regulating agencies also operate with a wide range of statutory mandates, which apply to lands under multiple jurisdictions and impact GHG emissions and accounting. California's statutes and executive orders require State land use agencies to account for GHG emissions from natural and working lands. Additionally, these State agencies are beginning to assess and regulate carbon removal and storage on these lands with significant targets in 2030. An opportunity exists for local jurisdictions to work with landowners and managers to achieve State, regional, and local goals related to NWLs.
Employment Impacts of Decarbonization for the San Diego Region The RDF’s Technical Report calculates the net change in energy sector jobs in response to the Central Case of the modeled decarbonization pathways from the EER model. Following California’s Jobs and Climate Action Plan for 2030, the analysis focuses on employment changes from 2021-2030 to inform workforce development strategies. Additionally, this report analyzes overall average annual job creation from 2020-2050, based on the full timeline in the EER model. For phasing out fossil fuels and modeling associated job losses, the analysis focuses on the 2021-2030 period, where the Central Case of the EER model estimates modest reductions in fossil fuel-based activities. This primarily stems from the model’s estimates of steady natural gas consumption and a 20% decrease in oil consumption by 2030 relative to current levels. The RDF’s Technical Report focuses on quantitative employment impacts resulting from deep decarbonization efforts in the energy, building, and transportation sectors and informs a report by Inclusive Economics on workforce development strategies. i
Between 2021 – 2030, the Central Case decarbonization pathway would generate an average of nearly 27,000 direct, indirect, and induced jobs per year in the San Diego region. These new jobs will be created by expenditures on energy demand (Table 4) and supply (Table 5), which contribute roughly equally to total annual job creation.ii Note that significant labor opportunities in the fossil fuel sector continue through 2030.
i The Inclusive Economics report titled “Putting San Diego County on the High Road: Climate Workforce Recommendations for 2030 and 2050,” is available at
https://www.sandiegocounty.gov/content/dam/sdc/lueg/regional -decarb- frameworkfiles/Putting%20San%20Diego%20County%20on%20the%20High%20Road_June%202022.pdf . ii For a more detailed accounting of these jobs, please refer to Chapter 6, section 6.3.
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30 Table 4. Average number of jobs created in the San Diego region annually through energy demand expenditures from 2021-2030, by subsectors and technology. Figures assume 1 percent average annual productivity growth.
Investment Area
Average
Annual
Expenditure
Direct Jobs Indirect Jobs Direct Jobs +
Indirect Jobs
Induced
Jobs
Direct Jobs +
Indirect Jobs +
Induced Jobs
Vehicles $7.7 billion 3,427 1,427 4,854 1,508 6,362
HVAC $897.0 million 1,345 699 2,044 764 2,808
Refrigeration $761.9 million 1,315 491 1,806 711 2,517
Appliances $188.6 million 143 77 220 78 298
Construction $113.4 million 263 149 412 146 558
Lighting $106.6 million 177 95 272 100 372
Manufacturing $45.7 million 40 32 72 27 99
Other commercial
and residential $38.9 million 59 30 89 33 122
Agriculture $17.2 million 144 21 165 45 210
Mining $2.4 million 1 1 2 1 3
TOTAL $9.9 billion 6,914 3,022 9,936 3,413 13,349
Source: IMPLAN 3.1
Table 5. Average number of jobs created in the San Diego region annually through energy supply investment from 2021-2030, by subsectors and technology. Figures assume 1 percent average annual productivity growth.
Investment Area Average Annual
Expenditure
Direct
Jobs
Indirect
Jobs
Direct Jobs +
Indirect Jobs
Induced
Jobs
Direct Jobs +
Indirect Jobs +
Induced Jobs
Fossil fuels $4.4 billion 2,538 3,777 6,315 3,805 10,120 Clean renewables $629.5 million 1,488 601 2,089 848 2,937 Transmission and
storage $45.9 million 34 17 51 31 82
Additional supply
technologies $45.1 million 118 35 153 57 210
Other investments $4.5 million 10 3 13 6 19
TOTAL $5.1 billion 4,188 4,433 8,621 4,747 13,368
Source: IMPLAN 3.1
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31 The RDF’s Technical Report estimates that no jobs in the region’s fossil fuel-based industries will be displaced before 2030, even with contractions in fossil fuel demand. The energy supply mix in the EER model suggests that there will be small to no changes in the consumption of fossil fuels before 2030 and few to no changes in the region’s fossil fuel-related jobs before 2030 as a result.i
The County of San Diego and local governments should develop a viable set of just transition policies for the workers who will experience job displacement between 2031 – 2050. After 2030, the EER model’s Central Case estimates large contractions in both oil and gas. The model predicts 95% contraction rates in oil and 75% in gas by 2050. Regional governments must begin developing policies for a just transition for these workers now so that they can gradually transition into jobs of equivalent or better quality in the clean energy economy or elsewhere.
A just transition will cost much less if it proceeds steadily rather than episodically. Under a steady transition, the proportion of workers who will retire voluntarily in any given year will be predictable, which will avoid the need to provide support for a much larger share of workers at any given time. The rate of the transition from fossil fuel to renewable energy- based jobs will impact the equity and fairness of the transition. Rapid changes and contractions would be more likely to result in sudden job losses, where steady changes and contractions would potentially result in fewer job losses as employees could transition to new jobs or could voluntarily retire.
Geothermal energy production from the five sites identified in Imperial County would generate 1,900 jobs per year over a 10-year period in Southern California. Chapter 2 identifies five areas for geothermal energy production in Imperial County. This chapter’s analysis finds that there will be 1,900 jobs created per year in the Southern California region over a 10-year period for the development and operation of these five geothermal power plants, some of which may be in the San Diego region. These are in addition to the annual 27,000 jobs creation estimates in the chapter.
i Details on the EER model’s Central Case, which was used here, can be found in Appendix A.
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32 Local Policy Opportunity
The RDF’s Technical Report assesses current CO2 reduction commitments in CAPs to determine whether the region needs additional activity to set the region on a trajectory to meet decarbonization goals. Additionally, it identifies opportunities for local jurisdictions in the region to take further action to support the decarbonization pathways for energy production, transportation, buildings, and natural climate solutions.
Several novel analyses inform this chapter. First, it analyzes the authority of local governments and agencies to influence and regulate GHG emissions and summarizes the authority of key federal, State, and local agencies, and key legislation and regulation at the federal and State levels to clarify local governments’ ability to act to reduce GHG emissions. i Second, it reviews all
CAPs in the region to determine how frequently a given measure was included in CAPs, the relative GHG impacts of CAP commitments, and the integration of social equity considerations.ii Third, a scenario analysis estimates the total regional GHG reductions that would result from all adopted and pending CAP commitments. It then estimates the potential GHG impact of a scenario that applies the best CAP commitments to all jurisdictions. iii This scenario analysis
takes the CAP commitment for a given CAP policy category – for example, tree planting goals – that will produce the single greatest relative GHG reductions and then applies that commitment to every jurisdiction in the San Diego region, regardless of current or planned commitments in that category. This may be considered the upper limit of potential GHG reductions from current CAP commitments. Finally, this chapter applies the results from these approaches and other analyses to identify opportunities for further local action and regional collaboration on each of the four decarbonization pathways.
iv
Local jurisdictions have authority to influence and regulate GHG emissions. Local governments can influence and regulate GHG emissions by accelerating State statutory targets and policies, adopting ordinances to go beyond State law, and using unique authority to adopt and implement policies. Local authority comes from both constitutionally derived power, which grants a broad authority to promote public health, safety, or the general welfare of the
i See Appendix B for more details.
ii See Chapter 8, section 8.3 for an overview and sections 8.5-8.8 for sector specific findings. These are also used to illustrate the gap between the deep decarbonization goals in Chapters 2 through 5 and the regional CAP commitments.
iii See section 8.4.
iv These opportunities were included in each relevant section for this Executive Summary, but they are included in the sector specific section in Chapter 8.
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33 community, and delegated authority from State statutes. The full extent of a local jurisdiction’s power to regulate GHG emissions is unknown.i
Adopted CAP commitments are insufficient to reach decarbonization goals. GHG reduction commitments in adopted CAPs for transportation, electricity, and buildings contribute a relatively small portion of the total reductions needed to reach net zero GHG emissions in 2045 (Figure 13, dashed line). Even if the most aggressive adopted CAP measures are applied to all jurisdictions in the region, significant emissions would remain, mostly from natural gas building end-uses and on-road transportation (Figure 13, dash-dot line). The chapter also analyzed the City of San Diego’s pending 2022 CAP update, but even including these measures, significant emissions would remain.
Figure 13. This graph shows the projected GHG emissions in the San Diego region from electricity generation, natural gas end-use in buildings, and on-road transportation in each of the scenarios analyzed. The Reference Scenario (solid line), where there are no CAP commitments, only shows reductions based on State and federal laws, mandates, actions, and goals. The Adopted CAP Commitments Scenario (dashed line) shows the remaining GHG emissions from a subset of total emissions if all current CAPs were applied in full as written. The Best Adopted CAP Commitment Scenario (dash-dot line) shows the remaining GHG emissions if the best adopted CAP commitment from each policy category is applied to every jurisdiction in the regio n, regardless of adopted CAP commitments. This graph shows that no analyzed scenario will allow the region to reach net zero emissions by 2050. Note that these analyses assume no new State and federal laws, mandates, actions, and goals, and that current ones do not change at any point in this period. Further, these analyses do not include all GHG emissions for the region.
i See section 8.2 and Appendix B for a more detailed discussion of authority.
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34 Jurisdictions can adopt additional CAP measures and strengthen existing measures. Based on the review of CAPs, more jurisdictions can adopt stronger CAP measures, using other regional jurisdictions’ measures as examples. Similarly, based on the scenario analysis of the combined GHG impacts of CAP measures, most jurisdictions can strengthen their existing CAP measures, especially in the transportation and building sectors. These sectors produce large GHG emissions (Figure 14, right), but on average represent disproportionately low emissions reductions in CAPs in 2035 (Figure 14, left).
Figure 14. This graph shows the average contribution of each decarbonization pathway to total GHG reductions from adopted and pending local CAP measures in 2035 (left) and the distribution of 2016 regional emissions by emission source (right). It shows that emissions from transportation (blue, right side) account for nearly half of regional emissions, but on average corresponding reductions from CAP commitments only represent slightly more than a quarter of local GHG reductions in CAPs (blue, left side). Similarly, electricity accounts for about a quarter of regional emissions (dark orange, right side) but associated reductions contribute on average just under half of GHG reductions from CAP commitments (dark orange, left side). Note that because emissions associated with buildings come from both onsite natural gas combustion and electricity production, the building decarbonization portion of the bar is shaded to show both light and dark orange to correspond with both natural gas buildings (light orange) and the electricity supply (dark orange).
Integrating social equity into climate planning requires additional work. Based on a preliminary review, the integration of social equity in adopted and pending CAPs is limited, inconsistent, and lacks specificity. Additional work would be needed to develop the capacity and tools to understand and address the equity implications of all decarbonization policies in the San Diego region, including data collection and analysis; regional guidance documents; and regional working groups to coordinate, advise, track, and monitor how equity is being addressed in climate planning.
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35 The San Diego Region as a Model
Although the San Diego region only accounts for 0.08% of global emissions, its regional decarbonization efforts can impact global emissions by generating followership among others and sharing durable, scalable, and replicable innovations. San Diego should actively highlight its efforts and communicate lessons learned in national and international fora. The creation of the San Diego RDF can serve as a case study for other jurisdictions across the U.S. and globally to learn from and adapt to their own long-term decarbonization planning endeavors. In addition to showcasing this effort in various national and international fora, i the United Nations
Sustainable Development Solutions Network (SDSN) has produced a Guide that will serve as a toolkit for other communities, governing bodies, research groups, and sustainability practitioners to follow the process undertaken by the County of San Diego in their own decarbonization pursuits.
SDSN is working to share the RDF within three horizontal levels across its networks. SDSN will share the RDF and its key findings in national meetings and fora in the United States, international groups and consortiums, and the United Nations. For example, the project was presented during the Innovate4Cities Conference in October 2021 and the feedback and insights from this event will serve to inform the 2022 IPCC Sixth Assessment Report on impact, adaptation, and vulnerability to global climate change. These events provide an opportunity to showcase the results of this project and the San Diego region as a model for the world. With access to these audiences, the RDF can help inform global roadmaps and pathways to net zero.
The Guide for Regional Decarbonization will aid local jurisdictions in creating unique decarbonization frameworks. This Guide will provide background information as well as specific steps and advice on logistics, methodology, stakeholder engagement, long-term planning, and more. Although the resources within this Guide are relevant and applicable to decarbonization framework project teams beyond the US, frameworks being created in the context of emerging economies will likely use different approaches, perspectives, and strategies in climate action planning. This Guide will be free and available online at UC San Diego’s SDG Policy Initiative’s website (http://sdgpolicyinitiative.org/guide/) as a way to facilitate the creation of regional decarbonization frameworks and provide a practical roadmap for jurisdictions working toward net-zero goals.
i Chapter 9 and Appendix 9.A present extensive lists of US and global consortiums that San Diego County and other jurisdictions with decarbonization frameworks can connect with, attend, and join the networks to disseminate their findings across different scales.
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San Diego Regional
Decarbonization Framework
TECHNICAL REPORT
Exhibit 2
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1 Project Team
Project Director
Gordon C. McCord
Associate Dean & Associate Professor of Economics
Director, SDG Policy Initiative
School of Global Policy and Strategy, University of California San Diego (UC San Diego) Project Manager
Elise Hanson, County of San Diego, Land Use and Environment Group (LUEG) San Diego County Representatives
Murtaza Baxamusa
Rebeca Appel
Sarah Aghassi
Yasamin Rasoulzadeh
Michael De La Rosa
Donna Durckel
Nicole Boghossian Ambrose
Jennifer Lawson
Renee Loewer
Chapter Authors
Introduction
Murtaza H. Baxamusa, LUEG
Study Approach
Ryan A. Jones, Evolved Energy Research
Geospatial Analysis of Renewable Energy Production
Emily Leslie, Montara Mountain Energy
Joseph Bettles, UC San Diego
Accelerating Deep Decarbonization in the Transportation Sector Katy Cole, Fehr & Peers
Chelsea Richer, Fehr & Peers
Eleanor Hunts, Fehr & Peers
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2 Decarbonization of Buildings
Philip Eash-Gates, Synapse Energy Economics
Jason Frost, Synapse Energy Economics
Shelley Kwok, Synapse Energy Economics
Jackie Litynski, Synapse Energy Economics
Kenji Takahashi, Synapse Energy Economics
Asa Hopkins, Synapse Energy Economics
Natural Climate Solutions and other Land Use Considerations Elise Hanson, UC San Diego
Emily Leslie, Montara Mountain Energy
Employment Impacts through Decarbonization in the San Diego Region Robert Pollin, Political Economy Research Institute (PERI), University of Massachusetts Amherst Jeannette Wicks-Lim, PERI, University of Massachusetts Amherst Shouvik Chakraborty, PERI, University of Massachusetts Amherst Gregor Semieniuk, PERI, University of Massachusetts Amherst Key Policy Considerations for the San Diego Region
Joseph Bettles, UC San Diego
Gordon C. McCord, UC San Diego
David G. Victor, UC San Diego
Emily Carlton, UC San Diego
Local Policy Opportunity Analysis
Scott Anders, Energy Policy Initiatives Center (EPIC), University of San Diego School of Law Nilmini Silva Send, EPIC, University of San Diego School of Law Joe Kaatz, EPIC, University of San Diego School of Law
Yichao Gu, EPIC, University of San Diego School of Law
Marc Steele, EPIC, University of San Diego School of Law The San Diego Region as a Model
Elena Crete, UN Sustainable Development Solutions Network (SDSN) Julie Topf, UN Sustainable Development Solutions Network (SDSN) Appendix A: Summary of Statewide Energy System Modeling Ryan Jones, Evolved Energy
Appendix B: Review of Authority for Local Jurisdictions and Agencies to Influence and Regulate GHG Emissions
Joe Kaatz, EPIC, University of San Diego
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3 Acknowledgments
Special thanks to the County of San Diego Board of Supervisors: Chair Nathan Fletcher, Vice Chair Nora Vargas, Supervisor Joel Anderson, Supervisor Terra Lawson-Remer, and Supervisor Jim Desmond for their direction and leadership in establishing this framework.
The authors thank David Victor for his advisory role across the project, as well as Joseph Bettles, Tyler Spencer, Emily Carlton, Elissa Bozhkov, and Jeffrey Myers for research and editorial support, and Isaac Wang for project management support.
The project team is grateful to the following individuals for their strategic advice to the County of San Diego representatives: Elizabeth King (California Environmental Protection Agency), Jamal Russell Black (San Diego Regional Policy & Innovation Center), Christiana DeBenedict (San Diego Foundation), Everett Au (San Diego Foundation), Amenah Gulamhusein (San Diego Foundation), and Susan L. Guinn (San Diego Regional Policy & Innovation Center).
The project team also wants to thank the Technical Working Group and all the participants and commenters who contributed their time and knowledge by submitting written/oral comments and attending our meetings and workshops.
Disclaimer
This report was funded by the County of San Diego. The authors declare no competing interests with relevant entities in the San Diego region.
This report should be cited as:
McCord, Gordon C., Elise Hanson, Murtaza H. Baxamusa, Emily Leslie, Joseph Bettles, Ryan A. Jones, Katy Cole, Chelsea Richer, Eleanor Hunts, Philip Eash-Gates, Jason Frost, Shelley Kwok, Jackie Litynski, Kenji Takahashi, Asa Hopkins, Robert Pollin, Jeannette Wicks-Lim, Shouvik Chakraborty, Gregor Semieniuk, David G. Victor, Emily Carlton, Scott Anders, Nilmini Silva Send, Joe Kaatz, Yichao Gu, Marc Steele, Elena Crete, and Julie Topf. San Diego Regional Decarbonization Framework: Technical Report. County of San Diego, California. 2022.
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4 Table of Contents
Introduction ................................................................................................................................ 6
1. Study Framework ..................................................................................................................... 7
1.1 Introduction ............................................................................................................................... 7
1.2 Study Questions ....................................................................................................................... 11
1.3 The Role of Pathways in Planning ............................................................................................ 11
1.4 Notes on Reading this Report .................................................................................................. 13
2. Geospatial Analysis of Renewable Energy Production ............................................................. 16
2.1 Introduction ............................................................................................................................. 16
2.2 State-Level Context .................................................................................................................. 19
2.3 Data .......................................................................................................................................... 20
2.4 Methods, Assumptions, Total Resource Availability, and Least-Cost Areas ........................... 21
2.5 Results and Discussion ............................................................................................................. 40
2.6 Trends Across Scenarios .......................................................................................................... 52
2.7 Conclusion ................................................................................................................................ 53 Appendix 2.A List of Spatial Data Sources .................................................................................... 57 Appendix 2.B List of Spatial Data Sources ..................................................................................... 58 Appendix 2.C List of Key Assumptions ........................................................................................... 60 Appendix 2.D QGIS Processing Modeler ....................................................................................... 61 Appendix 2.E Floatovoltaics ........................................................................................................... 62 Appendix 2.F Transmission Upgrade Options and Costs ............................................................... 63 Appendix 2.G Downscaling Method .............................................................................................. 64 Appendix 2.H San Diego Vegetation Types with High CO2 Sequestration Potential ..................... 65
3. Accelerating Deep Decarbonization in the Transportation Sector ............................................ 66
3.1 Introduction ............................................................................................................................. 66
3.2 Regional Policy Context ........................................................................................................... 68
3.3 Transportation Modeling & Emissions Forecasts .................................................................... 76
3.4 Decarbonization Strategies: Policy Pathways to Close the Emissions Gap ............................. 79
3.5 Key Actions .............................................................................................................................. 95
3.6 Remaining Challenges and Gaps ............................................................................................ 109
4. Decarbonization of Buildings ................................................................................................ 117
4.1 Introduction ........................................................................................................................... 118
4.2 Buildings in San Diego County ............................................................................................... 119
4.3 Technologies and Fuels for Decarbonizing Buildings ............................................................ 127
4.4 Pathways to Decarbonization of San Diego’s Buildings ......................................................... 139
4.5 Gas Utility and Rate Impacts .................................................................................................. 151
4.6 Key Policy Actions .................................................................................................................. 163
5. Natural Climate Solutions and Other Land Use Considerations .............................................. 171
5.1 Introduction ........................................................................................................................... 172
5.2 Natural and Working Lands – Ecological Carbon Dioxide Sequestration and Storage .......... 180
5.3 Agriculture and Working Lands ............................................................................................. 188
5.4 Blue Carbon and Sea Level Rise ............................................................................................. 195
5.5 Urban Forestry and Greening ................................................................................................ 200
5.6 Additional Natural Climate Solutions .................................................................................... 204
5.7 Regional Natural Climate Solutions Policy Recommendations and Conclusions ................. 206 Oct. 11, 2022
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5 Appendix 5.A Methods, data, and sources for carbon stock and flow data and sources ........... 216 Appendix 5.B Blue carbon methodology details and blue carbon value sources ....................... 221
6. Employment Impacts through Regional Decarbonization Framework for the San Diego Region ............................................................................................................................................... 223
6.1 Overview of Job Creation Estimates ...................................................................................... 224
6.2 Methodological Issues in Estimating Employment Creation ................................................. 225
6.3 Job Creation Estimates .......................................................................................................... 229
6.4 Job Quality Indicators and Worker Characteristics in Energy Demand and Supply Employment ................................................................................................................................. 233
6.5 Job Contraction for Workers in Fossil Fuel-Based Industries ................................................ 246 Appendix 6.A Employment Impacts of Geothermal Energy Projects for Imperial County ......... 256 Appendix 6.B Estimating San Diego Region-Specific Employment .............................................. 257 Appendix 6.C Urban Reforestation And Job Creation For The San Diego Region ....................... 260
7. Key Policy Considerations for the San Diego Region .............................................................. 263
7.1 Introduction ........................................................................................................................... 264
7.2 Achieving Deep Decarbonization across the San Diego Region: the Need for more Experimentation, Collaboration, and Learning ........................................................................... 265
7.3 Case Studies for Regional Action ........................................................................................... 273
7.4 Institutional Structure Built for Learning and Adaptation ..................................................... 280
7.5 Creating Followership: Acting at Home but Impacting Outside the Region .......................... 286
7.6 Conclusion .............................................................................................................................. 290
8. Local Policy Opportunity ...................................................................................................... 294
8.1 Key Findings ........................................................................................................................... 296
8.2 Authority of Local Jurisdictions and Agencies to Influence and Regulate GHG Emissions .... 297
8.3 Review of Climate Action Plans in the San Diego Region ...................................................... 301
8.4 Scenario Analysis of GHG Impacts from Adopted CAPs in the San Diego Region ................. 318
8.5 Decarbonize Transportation .................................................................................................. 327
8.6 Decarbonize Buildings............................................................................................................ 365
8.7 Decarbonize the Electricity Supply ........................................................................................ 399
8.8 Natural Climate Solutions ...................................................................................................... 415
8.9 Other Limitations ................................................................................................................... 429
8.10 Conclusions .......................................................................................................................... 430 Appendix 8.A Assumptions for Estimating GHG Impact of Best CAP Commitment ................... 432 Appendix 8.B Supporting Material for Decarbonize Transportation Policy Assessment ............ 439
9. The San Diego Region as a Model ......................................................................................... 443
9.1 Purpose .................................................................................................................................. 443
9.2 Opportunities for Scaling Impact ........................................................................................... 444
9.3 Planning Across Jurisdictions – Horizontal and Vertical Alignment ...................................... 445 Appendix 9.A Relevant US and Global Communities of Practice Lists ........................................ 449
10. Conclusion ......................................................................................................................... 454 Appendix A. Summary of Statewide Energy System Modeling .................................................. 457 Appendix B. Review of Authority for Local Jurisdictions and Agencies to Influence and Regulate GHG Emission .......................................................................................................................... 472 Appendix C. Technical Working Group ................................ ...................................................... 521
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6 Introduction
Recognizing the need for a regional approach to addressing climate change, on January 27th, 2021, the San Diego County Board of Supervisors voted to create a Regional Decarbonization Framework. This framework is intended to inform our collective future actions on reducing greenhouse gas emissions in the San Diego region. It is intended to supplement climate action planning efforts that are currently underway and chart collaborative pathways to implement our regional goals.
This study is the first step in positioning the San Diego region as a global leader in climate planning. It is authored by a team led by the University of California San Diego School of Global Policy and Strategy, working in collaboration with the Energy Policy Initiatives Center at the University of San Diego School of Law and other consultants with technical expertise in energy, transportation and building systems. This is the first study of its kind that quantifies the magnitude of the challenge in achieving meaningful reductions in regional greenhouse gas emissions. It shows that even if all the municipalities in the region met their current climate commitments, we would fall far short of our goals in reducing planet-heating gases in each sector of the region’s economy. Each of us clearly need to do more individually, however, that is still not going to be enough.
So what do we do with all of this information? The San Diego region is uniquely positioned to implement deep decarbonization. The implementation of decarbonization pathways in the years and decades ahead is going to be the true test of the success of this framework. An equitable implementation strategy would position our region competitively for public and private investments in the future, while ensuring that our underserved communities are not left behind. The scale and pace of this effort will require partnerships between local governments, tribal governments, businesses, labor unions, environmental advocates, community-based organizations and residents of our communities.
This framework provides the scientific basis for us to convene and spark creative and collaborative solutions that can benefit us all as well as the planet. These are regional solutions that cannot be achieved in silos by an individual, government, or business alone. But together, our greener future is bright!
Murtaza H. Baxamusa, PhD, AICP
Program Manager for Regional Sustainability
Land Use and Environment Group
County of San Diego
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7 1. Study Framework
Ryan A. Jones, Evolved Energy Research
Key Takeaways
● Detailed analyses of land use and the energy, transportation, and building sectors should inform regional and local decarbonization policies consistent with a system-wide path to decarbonization at regional, state, and national scales. ● Energy system modeling of pathways to net zero emissions for California and the United States inform the sectoral analyses in this report, described in more technical detail in Appendix A.
● Te
chnical pathway studies can identify dead-end
strategies, key decision points,
pathways commonalities under sensitivity analyses, while also situating near-te rm policy
targets relative to long-te
rm goals.
● Unc
ertainty necessitates an ongoing and iterative planning process, with periodic updating as new information arises and progress is or is not achieved.
1.1 Introduction
The Paris Agreement calls for “holding the increase in the global average temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to
1.5°C.”
1 Following the scientific evidence and consensus around climate change, countries, states, and local jurisdictions around the world have begun adopting the goal of reaching carbon neutrality, or “net zero.” Executive Order (EO) B-55-18 directs California to reach such a target by 2045.
The RDF begins with the premise that regional and local policies should be informed by detailed analysis of the energy system consistent with a system-wide path to decarbonization at regional, state, and national scales. The RDF focuses on the energy system, defined as the total production and consumption of energy in the electric power, transportation, and buildings sectors. This work endeavors to show pathways for the San Diego region that are consistent with national-level and state-level pathways to reach net zero carbon dioxide emissions from the energy system by 2045. By “net zero,” this report means that anthropogenic carbon dioxide emissions from the energy system equal anthropogenic carbon sequestration, and therefore humans do not contribute net emissions to the atmosphere. We note from the outset that the energy system does not represent the totality of greenhouse gas flows: GHGs are emitted from sectors beyond those considered in this report (e.g., wastewater treatment, landfills, aviation, Oct. 11, 2022
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8 off-road transportation, etc.); anthropogenic carbon sequestration does not include natural carbon sequestration in regional ecosystems, including natural and working lands (discussed in Chapter 5); and GHGs are emitted when materials are created or utilized (see Box 1.1).
Box 1.1 - Embodied Carbon
The RDF Technical Report analyzed energy system emissions from the three primary emissions sources in the region: electricity production, transportation, and natural gas combustion in buildings.
A different way of calculating emissions considers the process-based emissions that result in a good or service. These emissions are sometimes called "embodied carbon" and they result from the full production lifespan of a good like a building. Embodied carbon represents the carbon intensity of a good or material.2 Embodied carbon is applicable to the building, electricity generation, and transportation sectors.
Buildings require large inputs of carbon intensive materials, like cement or steel, making embodied carbon a major source of building emissions. Though beyond the RDF Technical Report’s scope, policy levers at the local, State, and federal level could reduce the significant building material emissions.
Chapter 4, section 4.6 ("Key Policy Actions") provides some examples of policies to reduce embodied carbon in buildings from around the State and Appendix B ("Review of Authority for Local Jurisdictions and Agencies to Influence and Regulate GHG Emissions"), Section B.3 ("Local Authority Related to Building Decarbonization") provides a discussion of local, State, and federal jurisdictions' authority to reduce embodied carbon. The California Legislature has introduced a number of bills recently that have not made it through the legislative process but this continues to be a priority each session. At the end of the 2022 session, AB 2446 may possibly reach the Governor’s desk to develop a method to measure and reduce embodied carbon in materials for new construction 40% by 2035. Importantly, California passed one major piece of legislation in 2021, SB 596 (Becker, Chapter 246, Statutes of 2021), that addresses embodied carbon in cement manufacturing through a net-zero emissions strategy targeting net-zero emissions by 2045 and an interim 40% reduction target of carbon intensity by 2035.
Renewable electricity generation requires carbon intensive infrastructure, including solar panels and wind turbines. So, despite the fact that operating solar and wind power plants produces few emissions, there is embodied carbon in the materials and infrastructure that produce renewable energy.
Finally, transportation decarbonization pathways – such as electric vehicles (EVs), increased public transit, electric bicycles – also require materials and infrastructure that have embodied carbon. For example, electric vehicles have zero tailpipe emissions, but they require large batteries that are carbon intensive to produce.
The embodied carbon of renewable energy infrastructure and electric vehicles are beyond the scope of this study. There are fewer policy options for local jurisdictions and agencies to reduce embodied carbon in renewable energy infrastructure and EVs because their supply chains are global and complex.
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9 to achieve emissions reductions consistent with California’s 2045 net zero emissions goal, established by EO B-55-18. The analytical approach consists of five main pieces. First, models of the whole energy system, both at national and state levels, are used to identify five technically and economically feasible pathways for achieving net zero emissions. These models are presented in Appendix A. Second, these results are used to guide detailed sector-level analyses for the San Diego region, presented in Chapters 2 through 4, to best follow these pathways.
Third, additional analyses were conducted on the natural climate solutions available to the region (Chapter 5), which describes the scope for natural carbon sequestration and storage in the region, and on changes to regional employment that result from the investments in energy demand and supply following the Central Case of the energy system decarbonization modeling (Chapter 6).
i Fourth, there are two analyses of policy strategies. Chapter 7 analyzes key policy considerations in the region and discusses political frameworks that may foster regional collaboration to achieve deep decarbonization. Next comes an analysis of current Climate Action Plan (CAP) commitments throughout the region, identification of local opportunities, and associated legal and jurisdictional authority considerations for instituting decarbonization strategies. These are presented in Chapter 8 and in Appendix B. Finally, Chapter 9 provides a description of how the San Diego region can be a model for other jurisdictions, both domestically and abroad, along with a guidebook for jurisdictions, agencies, and practitioners to frame their own decarbonization efforts.
Due to the complexity of our energy and climate systems, many analytical approaches examine a single sector at a time, often in great detail, but do not explicitly consider interactions between sectors. Such an approach risks insufficient cumulative actions from each sector, inefficient actions that prove costlier than viable alternatives, or that interactions lead to unintended negative consequences (for example, multiple sectors transitioning to the same alternative fuel beyond its sustainable supply). To avoid such outcomes, sectoral analyses in the RDF are informed by five pathways to net zero emissions identified by state and national-level models of the whole energy system. Evolved Energy Research performed this systems-level pathways analysis using the EnergyPATHWAYS and RIO models, drawing on the methodology and data in an earlier, national-level pathways analysis by Williams et al. (2021) that used these models.
3 The modeling effort will hereafter be called the Evolved Energy Research (EER) model.
For the RDF, modeling tools were updated for consistency with the 2021 EIA Annual Energy Outlook
4 and specific zones were created for Northern and Southern California to aid in
i A separate component of the RDF is a workforce development report by Inclusive Economics, titled “Putting San Diego County on the High Road: Climate Workforce Recommendations for 2030 and 2050.” It is a qualitative workforce report that complements Chapter 6’s quantitative analyses of changes to regional employment. Using Chapter 6’s quantitative data, Inclusive Economics analyzed the qualitative effects of decarbonization on labor markets and workforce development strategies This report is available here:
https://www.sandiegocounty.gov/content/dam/sdc/lueg/regional -dec arb-
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10 downscaling the insights from the U.S. at large. Appendix A presents methods, key assumptions, and results of energy system modeling for the state-level, with those for the national-level in Williams et al. (2021).3 Importantly, in instances where the particular circumstances in the region differed from those at a state or national level, the San Diego specific insights were retained. Thus, the pathways for larger geographic areas informed but did not prescribe the San Diego region’s pathways.
Guided by the energy system decarbonization pathways for California as a whole, pathways analysis within each sector in the RDF details what the San Diego region needs (e.g., infrastructure investments, local policy commitments, or policy action in other domains) for alignment with a net zero emissions trajectory in California. Sector-level pathways are necessary because technical and political challenges vary by sector, necessitating sector-level pathways and practical policy strategies. Of note, each sector is not expected to arrive at net zero emissions independently; rather, each will work in conjunction with other sectors and California regions as an interconnected system to decarbonize.
A system-wide technical pathway to decarbonization by 2045 guides the RDF, aligning with California’s commitments and statewide energy system analysis. This brings a system-wide approach to ensure consistency of effort and overall success in reducing emissions, but is not a binding policy solution setting requirements or prescriptions in each sector. The interconnected nature of the energy system necessitates that national, State, and local governments move in concert in their policies and investments to decarbonize.
This report does not set out to identify which, if any, of the pathways is the “right” pathway for the San Diego region because the best pathway remains unknowable. Instead, it shows multiple ways forward to elucidate the trade-offs, decision points, risks, and synergies in decarbonization efforts. This is a unique effort to chart how to reduce carbon dioxide emissions in the region through fostering collaboration among various municipalities, promoting active learning and experiments to test diverse ideas, and positioning the region to attract State and federal resources. Decarbonization will require that each level of government utilize policy levers within its respective jurisdiction, while also collaborating vertically and horizontally across jurisdictions to align long-term goals. The RDF Technical Report provides policymakers, private industry, and stakeholders in the San Diego region the information needed to chart a path forward, starting with policies necessary to reach interim 2030 targets. It also provides a framework of regional institutional governance that emphasizes collaborative policy experimentation and review across governments, industries, and academia, with the understanding that such cooperation can allow goals, strategies, and policies to improve over time as lessons are learned and circumstances change.
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11 waters form the geographic limits of this study.
1.2 Study Questions
The research team set out to answer two primary questions: (1) what changes are required to renewable energy infrastructure, patterns of energy use in transportation and buildings, and modes of transportation for the San Diego region to decarbonize consistent with the State’s goals; and (2) what policy actions must local officials take for the region to achieve these changes?
Based on past modeling exercises, this report assumes that it is technologically and financially possible for California to reach net zero emissions by 2045. Indeed, monetary savings from air quality improvements or avoided adaptation costs associated with GHG emission reductions are expected to exceed GHG mitigation costs. Nevertheless, the RDF recognizes that many policies necessary for reaching net zero emissions fall under State or federal authority, beyond local governments.
i The San Diego region can and should vocally advocate for these policies (e.g., federal tax incentives), but this study focuses on local actions.
1.3 The Role of Pathways in Planning
The discussion of the role of pathways in planning below draws heavily from a recent report from the Commonwealth of Massachusetts.5 Rather than simply referring the reader to that report, we have summarized key ideas from that text here.
The RDF Technical Report uses the term “pathway” to mean a blueprint for the energy and land systems that reach future GHG reduction targets. The term can refer to both a specific strategy and to a set of possible blueprints (as in, “multiple pathways to deep decarbonization”). The Deep Decarbonization Pathways Project (DDPP) coined the term “pathway” in 20146 to capture the path dependency within different decarbonization strategies. While the physical transformations represented by these pathways are informed by economic, social, and political constraints, they should not be mistaken for the impacts of a specific policy or market intervention.
The
study of long-te
rm decarbonization pathways has been a growing trend after early success using them in California.7 Modeling such decarbonization pathways depends on the ability to
i For a larger discussion of the authority of local jurisdictions to decarbonize, see Chapter 8 (Local Policy Opportunity) and Appendix B of this report.
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12 represent the existing energy system with a high degree of accuracy. Significant effort goes into benchmarking and stress testing the models of current energy systems until researchers have a high degree of confidence that changes in inputs will produce meaningful outputs. After California, other states (Washington, New York) followed suit with their own pathways analyses. While pathways analysis has become an integral part of energy planning processes,the breadth of topics covered and the time horizon analyzed has meant it remains a unique activity within state
-lev
el public policy processes and merits some clarification.
Th
e most critical clarification is that pathways are not forecasts of what will happen. While the energy system physics and emissions accounting that underpin our models are well-established, projecting technological progress (particularly cost) and energy service demand has a mixed track record, even over time spans much shorter than 30 years. This means that selecting a single pathway as the basis for public policy is fraught because the assumptions underpinning current evaluations may shift over time. Uncertainty necessitates an ongoing planning process, with periodic updating as new information becomes available and as decarbonization does or does not progress. Further, uncertainties in these pathways support the need for a flexible framework that allows for integration and adaptation to meet continuously changing political and technological realities.
Rather than predicting the future, pathway studies are valuable for four reasons:
● Ide
ntifying and decreasing the risk of dead-end
strategies;
● Ide
ntifying key decision points;
● Identifying commonalities in pathways under sensitivity analyses; ● Situ
ating near-te
rm policy targets with respect to long-te
rm goals.
Infr
astructure projects that produce, deliver, and consume energy are capital intensive and have long lifetimes. This is illustrated in Figure 1.1, which shows the number of replacement cycles for common infrastructure types between now and mid -ce
ntury.5 If a pathways analysis
looked only 10 to 15 years ahead, as is typical in electric utility integrated resource plans, and decisions were made that would efficiently reduce emissions to hit near -te
rm targets but were
inconsistent with long-te
rm goals, then those decisions would lock in higher emissions or increase costs due to necessitating early retirement. Thus, a 30-ye ar pathways study can test a
given decarbonization strategy against this backdrop of infrastructure lifetimes to understand whether an emissions dead
-end
will be encountered on a given path. Knowing the timing of key decision points can also help to avoid stranded assets.
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13 Figure 1.1. Typical lifetimes of common energy consuming or producing infrastructure. A simplified overview of the lifetimes of common energy consuming or producing infrastructure are compared against the 30 -year time period left to reach the net zero target. The black vertical lines delineate points of natural retirement, and the number of segments correspond to the number of replacement cycles between now and 2050. The lifetime of vehicles by location and duty-cycle. The lifetime of power plants and pipelines is longer than 30 years and thus no natural retirement is shown on this figure.
As mentioned, the future trajectories of many variables, including technology cost and performance projections, remain highly uncertain. However, it is possible to develop ranges of values in which the high and low estimates have a high probability of encapsulating the eventual revealed value for any variable. Creating multiple pathways within each sector allows for sensitivity testing of results based on a range of input assumptions. This framework identifies strategies common across all pathways and shows what drives differences between pathways. It thus offers more value than a precise blueprint reliant on uncertain assumptions.
This report details a set of “low-regret” strategies for the next 10 years common to all modeled pathways that successfully reach net zero emissions in that sector.
Finally
, pathways studies can be valuable in near-te
rm target settings. Backcasting from a mid-
century net zero energy system to the present reveals milestones or benchmark values (often ranges) consistent with reaching long-ter
m goals. Chapter 7, Key Policy Considerations for the
San Diego region discusses near-term targets and policy recommendations in more detail.
1.4 Notes on reading this report
Readers of this revised report should be aware of the following:
● This report provides technical analyses and intends to inform decision-making and implementation plans, but it is neither a decision-making document nor an implementation plan. As such, the findings in this report are not recommendations to the County, any city, jurisdiction, municipality, government or agency.
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14 ● Throughout the report, we use the term “San Diego region” when referring to the geographic extent of the county, and “San Diego County” to refer to the county government.
● Readers interested in high-level findings and recommendations for an institutional framework to promote decarbonization are encouraged to read Chapter 7, “Key Policy Considerations for the San Diego Region.” To inform the institutional structure and processes, Chapter 7 provides an overview of key decarbonization actions, areas of uncertainty, and County leverage points from each of the four sectors: land use, buildings, transportation, electric sector. The overview in Table 7.1 provides the basis of several takeaways that inform a proposed institutional structure to support decarbonization implementation among policy actors in the San Diego region.
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15 Works Cited:
1. UNFCCC. Paris Agreement to the United Nations Framework Convention on Climate Change.; 2015. https://unfccc.int/files/meetings/paris_nov_2015/application/pdf/paris_agr eement_english_.pdf
2. McKinsey & Company. Data to the rescue: Embodied carbon in buildings and the urgency of now. Our Insights https://www.mckinsey.com/business-func tions/operations/our-insights/data-to-the-rescue-embodied- carbon-in-buildings-and-the-urgency-of-now (2020).
3. Williams JH, Jones RA, Haley B, et al. Carbon-Neutral Pathways for the United States. AGU Adv. 2021; 2(1):e2020AV000284. doi:10.1029/2020AV000284
4. Nalley, S. & LaRose, A. Annual Energy Outlook 2021 (AEO2021); 2021. https://www.eia.gov/pressroom/presentations/AEO2021_Release_Presentation.pdf
5. Jones R, Haley B, Williams J, Farbes J, Kwok G, Hargreaves J. Energy Pathways to Deep Decarbonization: A Technical Report of the Massachusetts 2050 Decarbonization Roadmap Study . Commonwealth of Massachusetts; 2020.
6. Deep Decarbonization Pathways Project. Pathways to Deep Decarbonization 2015 Report . SDSN - IDDRI; 2015.
7. Energy and Environmental Economics, Inc. (E3). California Air Resources Board (CARB) Scoping Plan. NEWS:
DISTRIBUTED ENERGY RESOURCES, ENERGY AND ENVIRONMENTAL POLICY, RENEWABLES, RESOURCE PLANNING; https://www.ethree.com/california-air-resources-board-carb-scoping-plan/; 2017.
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16 2. Geospatial Analysis of Renewable Energy Production Emily Leslie, Montara Mountain Energy
Joseph Bettles, UC San Diego
Key Takeaways
● This chapter identifies low-impact, high-quality areas for wind and solar development in the San Diego region and neighboring Imperial County.
● The region has sufficient available land area for wind and solar generation to approach a fully decarbonized energy system in line with the California-wide system model in Appendix A.
● However, approaching a 100% decarbonized energy system that also meets societal expectations and regulatory standards for reliability will require significant but uncertain investments in a suite of additional resources, including excess intermittent and flexible generation, storage, and demand-side management.
● This chapter informs decision-making by providing a series of site-selection scenarios that prioritize land value, ease of development, infill solar development plus rooftop solar, and environmental impact as well as proposing a strategy to address reliability. ● The significant solar and geothermal potential of neighboring Imperial County is a large potential resource for the San Diego region that may warrant upgrades to the transmission network.
● San Diego regional jurisdictions should coordinate with State agencies (e.g., California Public Utilities Commission (CPUC) Integrated Resource Planning team, CPUC Resource Adequacy team, California Independent Systems Operator (CAISO) Transmission Planning Process team, CAISO Local Capacity Requirements team) to ensure the reliability of the system.
● Regardless of how utility-scale development will occur, adequate information supports early action to pursue growth in rooftop solar, especially in communities with high pollution burdens from electricity generation plants and low access to renewable energy opportunities, which have been prioritized for investment under California’s Climate Investments program.
2.1 Introduction
Decarbonization of the electric sector in the San Diego region will require substantial deployment of new renewable resources: 90% of the electricity in most decarbonization scenarios in the literature comes from commercially mature renewable technologies such as Oct. 11, 2022
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17 wind and solar photovoltaic (hereafter solar). Decisions on where to site clean energy facilities can have significant impacts on the environment1 and require development of new or upgraded transmission infrastructure.2 Many aspects of the energy system and related air quality and climate impacts of energy planning and procurement decisions are regulated at the State and federal levels. However, the land use related impacts of energy planning and procurement decisions tend to be local. This analysis explores the availability of suitable land area within the region and the siting opportunities and challenges within local governments’ jurisdictional control. While it is technically and legally feasible (and common practice) to procure clean energy resources from remote locations, the siting risks, challenges, impacts, and uncertainties of remote resources are difficult to quantify. The transmission deliverability and reliability benefits of remote resources are similarly difficult to quantify. A robust analysis at the local level can clarify what is at stake both locally and in the broader Southern California region, and it can better inform decision-making for both local and geographically distributed entities participating in regional energy planning and procurement.
In this chapter we use the electricity demand from the Central Case of Evolved Energy Research (EER) model and perform downscaling analysis to identify low-impact, high-quality areas for wind and solar development in the San Diego region.i We define high-quality resources as those having high energy yield (for example, high solar irradiance and high mean annual wind speed), close proximity to existing infrastructure, suitable techno-economic criteria (for example, slope), population density, and suitable environmental criteria. Such criteria include avoiding conservation priorities such as wetlands, endangered species habitat, and compatibility with other priorities such as carbon sequestration potential and other zoning designations and development needs. We compare the resource potential under a range of site suitability assumptions to the modeled 2050 demand forecast for a fully decarbonized economy to comment on magnitude and scale of anticipated supply and demand. This report considers simple least-cost scenarios in San Diego County and scenarios with increased power transfer between San Diego and Imperial counties. It also considers alternate scenarios of more low- impact candidate project area selection compared to the least-cost solution. One such scenario prioritizes rooftop solar and ground-mounted urban infill solar. In this scenario, we estimate the costs and capacity of prioritizing urban infill and rooftop solar and discuss the potential co- benefits, including equity benefits such as local economy job creation and pollution reduction.
Finally, we present least-cost actions in the near-term which are valid across site selection scenarios. The electric sector spatial analysis aims to inform planning and deployment of renewable electricity capacity in the region based on a range of techno-economic and environmental variables, including cost of energy, environmental impacts, and resource
i For more information on the macro energy modeling, see Appendix A.
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18 availability.
The purpose of this analysis is to identify plausible near-term options and provide visualizations indicating what a range of future scenarios might look like. It primarily focuses on current commercially available technologies, including onshore wind, utility scale solar, rooftop solar, renewable energy development on brownfields, battery energy storage, and long-duration energy storage. We also consider emerging technologies such as offshore wind energy. While offshore wind development is not yet commercially demonstrated in California and is outside local jurisdictional authority for siting and permitting, nevertheless the magnitude of its development would affect the required magnitude of land-based renewables. Exploratory clean energy supply technologies that have not yet demonstrated broad commercial deployment and market penetration at the time of this writing are considered out-of-scope. Examples of such technologies include small modular nuclear reactors, bioenergy, waste-to-energy, and mechanical direct air capture of carbon, floatovoltaics, and to some extent wave energy. The rationale for the technology scope is to utilize limited planning resources for efforts that are considered achievable with a high degree of confidence, and to limit exposure to uncertainty regarding cost, schedule, and technology performance. Additional technology types should be incorporated into future analyses if and when data becomes available demonstrating they have become proven and scalable or as they are built.
The geographic extent of this analysis is limited to San Diego County’s boundaries (referred to as the San Diego region) to focus on options within the jurisdictional control of the County and city governments therein. Additional geographic analysis is included for adjacent Imperial County for some scenarios because Imperial County is strongly electrically interconnected with the San Diego region.
Finally, it is important to note that the scenarios, results, and maps in this chapter are not recommendations. Instead, they are examples of how, under current land use, technology, and grid conditions, the San Diego region can generate enough renewable energy to meet the projected 2050 energy demand and thereby power other important decarbonization efforts, like fueling electric vehicles, public transit, and buildings. The scenarios demonstrate the methodology and current results of prioritizing different aspects of public interest, such as minimizing costs, impacts to natural and working lands, or legal and social barriers to renewable energy development. All analyses are snapshots of the current regional resources, infrastructure, and available technologies. These inputs will change over time and the resulting maps, analyses, and results will also change. This chapter is meant to demonstrate a flexible pathways methodology for energy decarbonization, and shed light on near-term investments that are common across pathways and set the region on a path toward decarbonization for consideration by decision-makers.
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19 2.2 State-Level Context
2.2.1 State-level renewable energy and electric sector decarbonization targets California's Renewable Portfolio Standard (RPS) program was established in 2002 by Senate Bill (SB) 10783 with the initial requirement that 20% of electricity retail sales must be served by renewable resources by 2017. The program was accelerated in 2015 with SB 350,4 which mandated a 50% RPS by 2030. SB 350 includes interim annual RPS targets with three-year compliance periods and requires 65% of RPS procurement to be derived from long-term contracts of 10 or more years. In 2018, SB 1005 was signed into law and increased the RPS to 60% by 2030 and required all the State's electricity to come from carbon-free resources by 2045.
The California Public Utilities Commission implements and administers RPS compliance rules for California’s retail sellers of electricity, which include large and small investor-owned utilities (IOUs), electric service providers (ESPs) and community choice aggregators (CCAs). The California Energy Commission (CEC) oversees certification of electrical generation facilities as eligible renewable energy resources and adopting regulations to enforce RPS procurement requirements of public-owned utilities (POUs).
6 2.2.2 State-level regulatory proceedings implementing targets Senate Bill (SB) 3507 created Public Utilities Code Sections 454.51 and 454.52, which mandated the “Integrated Resource Plan” (IRP) proceeding at the CPUC.8 The IRP proceeding ensures that load serving entities (LSEs) meet targets that allow the electricity sector to contribute to California’s economy-wide greenhouse gas (GHG) emissions reductions goals. To evaluate anticipated needs, the proceeding conducts a 10-year forecast of the following:
● System needs (reliability needs of the overall electric system); ● Local needs (reliability needs specific to areas with transmission limitations); and ● Flexibility needs (such as the resources needed to integrate renewables).
When needs are identified, the CPUC authorizes procurement in the form of a Commission Decision.
IRP modeling produces 10-year look-ahead portfolios, which are refreshed every two years to incorporate the latest LSE procurement status and plan information. The current “Preferred System Plan” is available online at the IRP website.9 The CPUC regularly submits 10-year look- ahead IRP portfolios to the California Independent System Operator (CAISO), to enable the CAISO to perform grid power flow modeling and identify future transmission upgrades which may be needed to accommodate high levels of renewable energy infrastructure expansion. This Oct. 11, 2022
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20 power flow modeling occurs in the CAISO Transmission Planning Process (TPP).10 The CPUC 10- year look-ahead portfolios for TPP are summarized in a regular report, “Modeling Assumptions for TPP.”11 This document specifies high-resolution location and magnitude of resources of each type needed to meet State GHG targets for the electric sector. This information helps State agencies and the local and regional LSEs work together iteratively toward common goals.
For the San Diego RDF, the CPUC IRP modeling data12 were used as a starting point to more closely examine existing conditions and current development activity at the county level. These data were paired with the 2050 EER modeling results to map a plausible trajectory from current conditions, through the TPP’s 10-year planning horizon (2032), toward an aspirational low- carbon 2050 future for the San Diego region.
2.3 Data
2.3.1 Candidate Project Areas
To identify the resource potential of utility-scale solar and wind candidate project areas (CPAs) in San Diego and Imperial counties, several data sources were considered: Princeton’s Net Zero America (NZA) and REPEAT studies (2021), The Nature Conservancy’s (TNC’s) Power of Place (PoP) study (2021), and the 2009 California Renewable Energy Transmission Initiative (RETI) (see Appendix 2.A for a full list of spatial data sources). The REPEAT CPAs were identified as the most recent and state-of-the-art, however, the spatial resolution is low due to the national scale of the REPEAT analysis. This low resolution resulted in underestimate of the total land availability; many small polygons had been removed. The PoP spatial data are also recent, but they occur at a similar resolution as the REPEAT analysis because they cover the entire Western U.S. Despite their relative age, this report used the RETI CPAs. 13 The higher granularity and the
California-centric nature of the RETI analysis made these data more appropriate for the San Diego region than other datasets, like the Princeton NZA dataset. RETI’s CPA creation process aimed to identify plausible visualizations of transmission development for renewable energy that were sufficient to meet California’s ambitious GHG emissions reduction targets. RETI identified CPAs by applying a series of environmental and GIS-based exclusions (Figure 2.1). For a full discussion of the spatial analysis performed to identify CPAs, see the NREL “Greening the Grid” toolkit (technical potential economic potential, and market potential assessments). 14 For
a full list of site suitability criteria that were applied to the RETI CPAs in this analysis, see Appendix Table 2.B.1, 2.B.2, and 2.B.3.
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21 Figure 2.1 A diagram of the CPA creation process for the RETI analysis. For more information and additional resources and case studies, see reading list provided by the Greening the Grid Initiative. 15 In addition to utility-scale CPAs in non-urban settings provided by RETI, this analysis considers CPAs within densely populated areas, or “infill CPAs.” The infill CPAs are added from a dataset under development by TNC in an update to the 2019 PoP study. Finally, this report considers the potential capacity and costs for rooftop solar in the San Diego region using spatial building footprint data from Microsoft.
16 2.4 Methods, Assumptions, Total Resource Availability, and Least-Cost Areas
2.4.1 RDF Candidate Project Areas and Downscaling
To identify low-impact, high-quality areas for renewable electricity development, this analysis used open-source QGIS software to constrain and analyze CPAs within San Diego and Imperial counties.i This section begins with the RETI CPAs in the San Diego region and excludes Conserved Lands identified by SANDAG.17 Lacking equivalent conservation land data for Imperial County, this analysis relies on the baseline RETI environmental exclusions in that County (see Appendix 2.B site suitability criteria). All utility-scale CPAs smaller than one square kilometer (km²) are excluded as unsuitable for development, whereas infill solar polygons of any size are retained. Based on satellite data, there are a total of 266 Megawatts (MW) over all existing and solar and wind developments in the region. These were included in the chapter’s “preliminary scenario” maps, (existing sites above 10 MW were converted into files created from Google Satellite images and planned sites were digitized from EIR plant maps using the QGIS Georeferencer tool), and these existing facility areas were erased from the generic future Candidate Project Areas. To divide the CPAs into developable sites, a grid of 4 km² for solar and 36 km² for wind is overlaid on the sites. Using nameplate power density assumptions of 30 MW per km² (MW/km²) for solar
18 and 2.7 MW/km² for wind,19 CPAs that produce roughly 100 MW
i See Appendix 2.A for Spatial Data Sources used, Appendix 2.C for Key Assumptions, and Appendix 2.D for the QGIS Processing Modeler.
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22 each are created, which is a typical capacity for project modeling. Finally, as utility-scale solar provides higher land use efficiency than utility-scale wind for all areas of overlap, solar is prioritized over wind.20,21
2.4.1.1 Energy Production Estimates
The
formula below estimates the total annual electricity generation for each CPA polygon:
𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃 𝑑𝑑𝑃𝑃𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑
𝑑𝑑 (𝑀𝑀𝑀𝑀/𝑘𝑘𝑘𝑘2) ∗ 𝑎𝑎𝑃𝑃𝑃𝑃𝑎𝑎 (𝑘𝑘𝑘𝑘2) ∗ 𝑐𝑐𝑎𝑎𝑐𝑐𝑎𝑎𝑐𝑐𝑑𝑑𝑑𝑑
𝑑𝑑 𝑓𝑓𝑎𝑎𝑐𝑐𝑑𝑑
𝑃𝑃𝑃𝑃 ∗ 87
60 (ℎ𝑃𝑃𝑜𝑜𝑃𝑃𝑑𝑑 𝑑𝑑𝑑𝑑 𝑎𝑎 𝑑𝑑𝑃𝑃
𝑎𝑎𝑃𝑃)
= 𝑎𝑎𝑑𝑑𝑑𝑑
𝑜𝑜𝑎𝑎𝑎𝑎 𝑔𝑔𝑃𝑃𝑑𝑑𝑃𝑃𝑃𝑃
𝑎𝑎𝑑𝑑𝑑𝑑𝑃𝑃𝑑𝑑
The nameplate capacity, or expected peak instantaneous output, is calculated using the power density assumptions stated above. The annual generation in MW hours (MWh) is calculated for each CPA polygon by first multiplying the hours in a year (8,760 hours) and a given capacity factor, or percentage of time when the site is expected to produce electricity. For utility-scale solar, the capacity factor is assumed equal to the fixed-tilt solar value in the urban areas (rooftop, infill, and brownfield sites), and the tracking value in non-urban areas. This is because tracking technology requires more space (wider row-spacing) and in non-urban areas there is more likely to be larger developments on open land suitable for less-dense tracking technology.
To identify urban areas, the 2019 US Census Urban Area dataset was used. 22 For brownfield solar and wind, data from the US Environmental Protection Agency’ (EPA’s) “RE- Powering America” initiative are used. RE-Powering America’s Land is an EPA initiative that encourages renewable energy development on current and formerly contaminated lands, landfills, and mine sites when such development aligns with the community’s vision for the site.
23 For most sites, the available data include an estimated magnitude of the resource potential. For sites where there is no estimated resource potential, a value of 5 MW is assumed.
For offshore wind, CPA data from the Princeton REPEAT study are used. 24 There is high
uncertainty regarding cost and economically viable offshore wind resource potential for the San Diego region, and thus it has not been incorporated into the scenario analysis, but the candidate project areas are shown for context.
For wave energy, data from the Electric Power Research Institute (EPRI) study “Mapping and Assessment of the United States Ocean Wave Energy Resource” are used.25 The total available wave energy resource along the outer continental shelf (notional 200 m depth contour) for the Southern California region is 43 TWh per year. The technically recoverable energy for this resource is 68%. This results in 29 TWh technically recoverable energy annually (assuming 15 MW/km packing density). There is high uncertainty regarding cost and economically viable wave resource potential for the San Diego region, and thus it has not been incorporated into the scenario analysis; however, the candidate project areas are shown for context. Wave, Oct. 11, 2022
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23 floatovoltaics, and offshore wind energy technologies could be incorporated into future scenarios if new data demonstrates commercial viability.i This analysis compares the magnitude of estimated renewable resource potential with the anticipated electricity demand for the San Diego region in 2050. Anticipated demand is based on the EER model’s Central Case, where the demand for Southern California is downscaled to San Diego by applying the percentage of Southern California population in San Diego (13.75%).
This downscaling method is consistent with methods used in the literature. See for example the Princeton Net Zero America Project. Next, the downscaling method accounts for existing and planned wind and solar generation within the San Diego region. Data from the EPA’s EIA-860 Form
26 were used to identify 470 MW of existing and planned wind and solar capacity.
Excluding the 470 MW from the downscaled electricity demand, a balance of 49,979 Gigawatt hours (GWh) of electricity generation is needed to achieve a 100% renewable target. The difference between this value and the amount identified through satellite imagery in the preliminary maps is ignored, due to lack of clear data indicating whether additional capacity will come to fruition.
Using the nameplate calculations described above, Table 2.1 shows that the total potential utility-scale, rooftop, brownfield, and infill annual generation from wind and solar CPAs within the San Diego region is 113,523 GWh. This is 63,544
GWh above forecasted demand. Figure 2.2
shows the relative capacities of solar and wind with and without infill compared to the estimated demand. Solar resources account for more than 80% of overall renewable resource potential in the region.
i Floatovoltaics in particular are just emerging as a technically feasible but co mmercially unproven technology that could benefit the region. See Appendix 2.E Floatovoltaics for more details.
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24 Table 2.1 Candidate project areas and total annual resource potential in San Diego County and Imperial County.
Utility-scale resources refer to large scale projects for solar, wind, and geothermal resources. Resources beyond utility-scale include resources from smaller scale projects, including rooftop solar, infill solar or wind, and brownfield solar or wind. Geothermal candidate project areas are discrete areas and are listed as the number of potential sites rather than area.
San Diego County San Diego County + Imperial County
Findings Utility-Scale
Only
With Rooftop, Infill,
and Brownfield
Utility-Scale
Only
With Rooftop, Infill,
and Brownfield
Solar
Area (sq km) 661 985 3,417 3,741
Potential (GWh) 54,784 102,925 84,888 109,742
Onshore Wind
Area (sq km) 86 86 3,712 3,749
Potential (GWh) 730 730 22,540 22,572
Offshore Wind
Area (sq km) 1,660 1,660 1,660 1,660
Potential (GWh) 9,869 9,869 9,869 9,869
Geothermal
Number of sites 0 0 5 5
Potential (GWh) 0 0 10,680 10,680
Total Renewable Resource
Potential (GWh) 65,382 113,523 117,296 142,183
Estimated 2050 Electricity
Demand (GWh) 49,979
Electricity Resource Balance
(GWh) 15,403 63,544 67,317 92,204
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25 Figure 2.2 San Diego region’s annual renewable resource energy potential (GWh) by resource type. The leftmost bar shows the annual generation in the base case, which is utility- scale production only (includes solar, onshore wind). Note that geothermal and offshore wind resources are beyond the jurisdiction of San Dieg o regional authorities). The middle bar shows the annual generation in the base case plus geothermal, rooftop solar, solar infill, and brownfield wind and solar development. The rightmost bar is the estimated 2050 electricity demand (gray) based on the downscaled Central Case scenario of the EER model for 2050. This figure shows that, in both cases, the resource potential in the region exceeds demand.
2.4.2 Levelized Cost of Energy (LCOE) Estimates
To estimate the wholesale cost of electricity for utility-scale CPAs, we calculate the levelized cost of energy (LCOE), or the adjusted cost of electricity production per MWh. Calculations first add the solar and wind plant capital cost and the costs of interconnection to the grid. The plant capital cost reflects a capital expenditure cost assumption for utility-scale solar (1,599 $/kW) and wind (1,556 $/kW) from the National Renewable Energy Lab (NREL) Annual Technology Baseline (ATB).
27 The interconnection cost is based on the distance to the nearest substation and a transmission cost assumption of 2,948 $/MW-mile from the NREL ReDS model.28 These values were cross-referenced with the latest Western Electric Coordinating Council Transmission Cost Calculator and the CAISO Participating Transmission Owner Per-Unit Costs to confirm reasonableness. These calculations use a substation dataset from the Department of Homeland Security
29 and the interconnection distance is the Euclidean distance to the nearest substation.
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26 𝐿𝐿𝑃𝑃𝑐𝑐𝑎𝑎𝑑𝑑𝑑𝑑𝑃𝑃𝑑𝑑 − 𝑑𝑑𝑐𝑐 𝑃𝑃𝑐𝑐𝑑𝑑𝑓𝑓𝑑𝑑𝑐𝑐 𝑑𝑑𝑑𝑑𝑑𝑑𝑃𝑃𝑃𝑃 𝑐𝑐𝑃𝑃𝑑𝑑𝑑𝑑𝑃𝑃𝑐𝑐𝑑𝑑𝑑𝑑𝑃𝑃𝑑𝑑 𝑐𝑐𝑃𝑃𝑑𝑑𝑑𝑑 = 𝑔𝑔𝑃𝑃𝑑𝑑
𝑃𝑃𝑃𝑃𝑑𝑑𝑐𝑐 𝑑𝑑𝑑𝑑
𝑑𝑑𝑃𝑃𝑃𝑃𝑐𝑐𝑃𝑃𝑑𝑑𝑑𝑑𝑃𝑃𝑐𝑐𝑑𝑑𝑑𝑑𝑃𝑃𝑑𝑑 𝑐𝑐𝑃𝑃𝑑𝑑𝑑𝑑 � $
𝑀𝑀𝑀𝑀 𝑘𝑘𝑑𝑑� ∗ 𝐶𝐶𝑃𝑃𝐶𝐶 𝑐𝑐𝑎𝑎𝑐𝑐𝑎𝑎𝑐𝑐𝑑𝑑𝑑𝑑 𝑑𝑑 (𝑀𝑀𝑀𝑀) ∗ 𝑑𝑑𝑑𝑑 𝑑𝑑𝑑𝑑𝑎𝑎𝑑𝑑𝑐𝑐𝑃𝑃 𝑑𝑑𝑃𝑃 𝑑𝑑𝑜𝑜𝑠𝑠𝑑𝑑𝑑𝑑 𝑎𝑎𝑑𝑑𝑑𝑑𝑃𝑃𝑑𝑑 (𝑘𝑘𝑑𝑑) For remote-located candidate project areas, such as those in Imperial County, transmission deliverability upgrade costs are added to the capital cost based on Table 2.F in Appendix 2.F, “Transmission Upgrade Options and Costs.” The selected transmission upgrade has a cost of $89 million, and transmission capability would increase due to an Area Delivery Network Upgrade (ADNU) of 2067 MW. Transmission upgrade assumptions are discussed in more detail in section 2.4.3.
𝐼𝐼𝑓𝑓 𝐶𝐶𝑃𝑃𝐶𝐶 𝑑𝑑𝑑𝑑 𝑎𝑎𝑃𝑃
𝑐𝑐𝑎𝑎𝑑𝑑𝑃𝑃𝑑𝑑 𝑠𝑠𝑃𝑃ℎ𝑑𝑑𝑑𝑑𝑑𝑑 𝑑𝑑𝑃𝑃
𝑎𝑎𝑑𝑑𝑑𝑑𝑘𝑘𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑃𝑃𝑑𝑑 𝑐𝑐𝑃𝑃𝑑𝑑𝑑𝑑
𝑑𝑑𝑃𝑃𝑎𝑎𝑑𝑑𝑑𝑑𝑑𝑑, 𝑑𝑑ℎ𝑃𝑃𝑑𝑑 𝑁𝑁𝑃𝑃𝑑𝑑𝑃𝑃
𝑃𝑃𝑃𝑃𝑘𝑘 𝑈𝑈𝑐𝑐𝑔𝑔𝑃𝑃𝑎𝑎𝑑𝑑
𝑃𝑃 𝐶𝐶𝑃𝑃
𝑑𝑑𝑑𝑑 = �$8
9 𝑘𝑘𝑑𝑑
𝑎𝑎𝑎𝑎𝑑𝑑𝑃𝑃𝑑𝑑
20 67 𝑀𝑀𝑀𝑀 � ∗ 𝐶𝐶𝑃𝑃𝐶𝐶 𝑐𝑐𝑎𝑎𝑐𝑐𝑎𝑎𝑐𝑐𝑑𝑑𝑑𝑑 𝑑𝑑 (𝑀𝑀𝑀𝑀)
The estimation of annual payments assumes a capital recovery factor of 7.36%.30 The LCOE is then calculated using the formula below to find the ratio of payments to generation, or the wholesale cost per MWh of electricity.
𝐿𝐿𝑃𝑃𝐿𝐿𝑃𝑃𝑎𝑎𝑑𝑑𝐿𝐿𝑃𝑃𝑑𝑑 𝑐𝑐𝑃𝑃𝑑𝑑𝑑𝑑 𝑃𝑃𝑓𝑓 𝑃𝑃𝑑𝑑 𝑃𝑃𝑃𝑃𝑔𝑔𝑑𝑑 =
(𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐+𝑐𝑐𝑖𝑖𝑐𝑐𝑖𝑖𝑖𝑖𝑐𝑐𝑖𝑖 𝑖𝑖𝑖𝑖𝑖𝑖𝑐𝑐𝑐𝑐𝑐𝑐𝑖𝑖𝑖𝑖+𝑖𝑖𝑖𝑖𝑐𝑐𝑛𝑛𝑖𝑖 𝑖𝑖𝑛𝑛 𝑢𝑢𝑐𝑐𝑔𝑔𝑖𝑖𝑐𝑐𝑔𝑔𝑖𝑖𝑔𝑔)∗𝑐𝑐𝑐𝑐𝑐𝑐 𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐 𝑖𝑖𝑖𝑖𝑐𝑐 𝑖𝑖𝑟𝑟𝑖𝑖𝑖𝑖𝑟𝑟 𝑓𝑓𝑐𝑐𝑐𝑐𝑐𝑐 𝑖𝑖𝑖𝑖 𝑐𝑐𝑖𝑖𝑖𝑖𝑢𝑢𝑐𝑐𝑐𝑐 𝑔𝑔𝑖𝑖
𝑖𝑖𝑖𝑖𝑖𝑖𝑐𝑐𝑐𝑐𝑐𝑐𝑖𝑖𝑖𝑖
Incorporating tax incentives exceeded the scope of this analysis. The LCOE calculations were provided for ordinal ranking only, not intended to be used for budgeting or investment decisions. Similarly, State Resource Adequacy (RA) payment programs for reliability were beyond the scope of this chapter’s LCOE calculations. RA payment structures are changing over time, and the timing of the peak demand hour on the grid is also changing over time as installed solar capacity increases. Incorporation of tax incentives and rebates such as RA payments may be considered in future work.
For infill solar development, the PoP CPAs are used and the annual generation formula above is applied. To calculate the LCOE, this analysis uses 2.7 $/W as the capital cost for rooftop solar installation, which is the average of large and small non-residential capital cost from the Lawrence Berkeley National Lab’s (LBNL’s) Tracking the Sun Report. 31 There is no additional
interconnection cost, as it is assumed within the LBNL capital cost. The same capital recovery factor of 7.36% is applied and the LCOE is calculated using the formula above. The range of LCOE across both infill and utility-scale solar and wind CPAs in San Diego county is shown in Figures 2.3 (solar) and 2.4 (wind). Figure 2.5 shows the combined wind and solar CPAs across San Diego and neighboring Imperial County. These figures show the full set of possible wind and solar CPAs.
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27 Figure 2.3 Utility-scale solar candidate project areas in the San Diego region by LCOE per CPA. Darker colors represent higher cost per CPA and the least cost CPAs are in yellow. These are the full set of possible solar CPAs in the region.
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28 Figure 2.4 Utility-scale onshore wind candidate project areas in the San Diego region by LCOE per CPA. Darker colors represent higher per CPA costs and the least cost CPAs are in yellow. These are the full set of possible wind CPAs in the region, including areas that may be better developed as solar installations.
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29 Figure 2.5 Solar and wind candidate project areas in San Diego (left) and Imperial (right) counties by LCOE per CPA. Darker colors repre sent higher per CPA costs and the least cost CPAs are in yellow. These are the full set of possible solar and wind CPAs in the two counties.
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30 Figure 2.6 Additional candidate project areas beyond those utility-scale solar and onshore wind resources mapped in Figures 2.3-2.5 in San Diego and Imperial counties. CPAs for offshore wind (dark blue, shown for context but not included in projections elsewhere), brownfield solar (red dots), brownfield wind (blue dots), rooftop solar (black areas), wave energy (green line, shown for context but not included in projections elsewhere), and geothermal development (green circles) are included here. The offshore wind CPAs are from the REPEAT dataset, brownfield CPAs are from the EPA RE-powering America dataset, and geothermal CPAs are from the RETI dataset. The offshore wind CPAs show that the LCOE is between $133-672 per MWh. i
i The forthcoming paper is in review in the journal Proceedings of the National Academy of Sciences: Wu, Grace, Ryan Jones, Emily Leslie, James Williams, Andrew Pascale, Erica Brand, Sophie Parker, Brian Cohen, Julia Prochnik, and Joe Fargione. “Minimizing Conservation Impacts of Net Zero Energy Systems in the Western United States.” Submitted: June 14, 2022. In review.
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31 2.4.3 Transmission
The EER model shows increased electricity demand as sectors electrify to decarbonize. As a result of this increased demand, most site selection scenarios will require an increase in the capacity of transmission to avoid higher costs32 and curtailment of renewable resources.33 Increased transmission capacity will also enable greater reliability due to interconnection with more resources that smooth out the hourly profiles of variable power generation. 34 Appendix 2.F shows costs and timelines of the six identified major transmission upgrade options for the region from an analysis by the CAISO.35 While transmission upgrades will be overseen by State agencies and the local utility, the process will interact with local communities where new transmission upgrades are sited. The planning process for these six transmission upgrades is still underway. These are transmission upgrades that have been studied by the CAISO, and are upgrade options in State-level modeling for the State's Integrated Resource Plan (IRP). In the IRP proceeding, a Statewide 2032 portfolio with high penetration of renewables is modeled and least-cost transmission upgrades are selected from this list of options to support and enable transmission planning for the State’s clean energy and climate goals.
The updated document “Modeling Assumptions for CAISO 2022-2023 Transmission Planning Process,” released in Q4 2021,
11,36, sheds light on which transmission upgrades on the list are identified as likely justified in IRP modeling: Greater Los Angeles area, Tehachapi, San Diego and Imperial, Southern Nevada, Southern PG&E, and Northern California. The report states that “the transmission constraint exceedance in the San Diego & Imperial area could be resolved by a transmission upgrade that would increase the estimated full capacity deliverability status (FCDS) transmission capacity by 2,000 MW, with a CAISO estimated cost of $89 million and 18- month time to complete.” This analysis assumes that this upgrade will occur and that it will be sufficient to accommodate additional electricity transmission between San Diego and Imperial counties. This is upgrade number five (highlighted green) in Appendix 2.F, Table 2.F, “Transmission Upgrades and Costs in San Diego Gas & Electric (SDG&E) Territory.” This upgrade is incorporated into the LCOE for each Imperial County CPA, on a prorated basis. Any transmission upgrade may or may not happen and that the process is iterative until the CAISO Board of Governor approves it and construction begins.
However, the timeframe of IRP modeling ends in 2032 and further upgrades beyond this are likely necessary in the 2050 timeframe, so the stated LCOE values represent the low end of the estimated costs to decarbonize the grid by 2050. The CAISO is separately undertaking a 20-year transmission outlook study process, so clean energy planning efforts in the San Diego region should incorporate findings from the CAISO 20-year transmission outlook study as they come available.
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32 2.4.4 Energy Storage
Any portfolio that includes high levels of wind and solar capacity will likely need energy storage to provide reliability and avoid energy curtailment.38 Curtailment means reducing output of a renewable resource below what it would otherwise produce, typically occurring when supply exceeds demand. It is calculated by subtracting the energy that was actually produced from the amount of electricity forecasted to be generated.
Energy storage in the 2032 IRP portfolio includes both battery energy storage (4-hour duration) and long duration energy storage in the form of pumped storage hydropower (PSH). Batteries come in many forms and utilize a range of chemical reactions to store energy. PSH is a system where water is pumped from a lower reservoir or body of water to an uphill reservoir when there is surplus renewable energy generation (for example, during midday when solar generation is high and demand is low). The water is then released from the upper reservoir to the lower reservoir through hydropower turbines when demand is high and renewable energy generation is low (for example, at night when households are using energy and the sun is not shining). The potential battery storage and PSH locations and energy storage amounts are shown in Figure 2.7 below. Both technologies are mature enough to allow for their inclusion in planning, and they can meet different planning needs for the San Diego region. In particular, battery system costs tend to mostly reflect the total energy stored, while PSH system costs are driven more by the desired power capacity. This reality justifies the use of batteries for short- duration storage and PSH for longer-duration storage. Longer-duration options also tend to become more cost-competitive when optimizing over longer decision timeframes. 39 Fuel cells were not included due to lack of spatially explicit site suitability data for this technology, but future work could possibly include fuel cell siting as well. SDG&E’s 2022 “Path to Net Zero” study estimates that by 2045, there will be demand for 6.5 million metric tons of clean hydrogen across the economy, 80% of which is projected to be used to enhance the reliability of the electric supply.
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33 Figure 2.7 Potential energy storage sites per “Modeling Assumptions for 2022- 23 Transmission Planning Process” storage system in the San Diego region.11 Battery energy storage (gray) and pumped storage hydropower (red) are included. Battery energy storage is measured in megawatts and the sizes of the gray circles correspond to energy storage capacity. These are potential sites that can be built to increas e regional energy storage, but they are not guaranteed.
2.4.5 Initial Scenarios
To sequence the CPA development needed to achieve 100% renewable energy by 2050, we use 10-year timesteps from the EER model’s Central Case. The estimated electric demand forecast for San Diego is identified starting in 2030. County-level demand is assumed to be a fraction of Oct. 11, 2022
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34 State demand in proportion to the county’s population as a fraction of the State.i We implement a site selection algorithm modeled after Wu et al. (2020)1 and run two initial scenarios:
● Scenario 1: San Diego-only (utility-scale solar and wind resources within the San Diego region). See Figure 2.10 in the Results section.
● Scenario 2: San Diego and Imperial Scenario (utility-scale solar, wind, and geothermal resources within San Diego and Imperial Counties). See Figure 2.11 in the Results section.
For geothermal resource analysis, the E3 and CPUC Statewide Integrated Resource Plan (R-20- 05-003) estimated geothermal resource potential in neighboring Imperial County is used (no geothermal sites have been identified in San Diego county).41 Several geothermal sites are identified in Imperial County with total generation of 10,680 GWh/year of electricity (seen as green circles in Figures 2.6 and 2.11). This analysis assumes these plants become fully operational by 2030 and supply the remaining capacity to San Diego after satisfying Imperial’s electricity demand. The total available generation for the San Diego region is downscaled using methodology from Section 2.4.1 and it is assumed that 94.7% of the power generated will go to San Diego for an estimated geothermal resource of 10,113 GWh. In the San Diego and Imperial Scenario, 10,113 GWh is subtracted from all three time-steps of the forecasted electricity demand.
2.4.6 Alternate Scenarios
In addition to the least-cost site selection scenarios, we analyze alternate scenarios that factor in five new policy-relevant variables: 1) environmental impact, 2) pecuniary value, 3) carbon sequestration potential, 4) developable land, and 5) prioritizing rooftop and infill solar. For each scenario, the methodology from Section 2.1 identifies the LCOE and available capacity of CPAs under more constrained land-use assumptions within the boundaries of San Diego County.
Scenario 3: Minimize Loss of Land with High Conservation Value (Figure 2.12) To show renewable energy site selection under a scenario in which environmental impact minimization is highly prioritized, the most low-impact siting level areas for wind and solar resource potential areas in the West are used (SL 4) from the Wu et al. (2020)1 study on low- impact renewable energy siting. The study incorporated high-resolution ecological and agricultural datasets to identify sites with low impact on the environment. Areas of conservation emphasis from the San Diego region’s Multiple Species Conservation Plan were also removed. Data were reviewed to ensure this scenario did not include any development on designated critical habitat for species of local concern, such as the endangered Peninsular
i See Appendix 2.G for more details.
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35 Bighorn Sheep. This scenario should not be used as a substitute for site-specific surveys and environmental impact reports in the style of Endangered Species Act, California Environmental Quality Act or the National Environmental Protection Act. That type of site-specific project development work is necessary for investment decisions and is beyond the scope of this analysis. In this scenario all urban infill CPAs are included because of lower environmental impacts in urban areas. Rooftop solar is not included because of its high costs.
Scenario 4: Minimize Loss of Land with High Pecuniary Value (Figure 2.13) To
identify CPAs that factor in the pecuniary value of land, the Cropland Data Layer raster from the US Department of Agriculture is used.42 To analyze the raster with the CPA sites, the zonal statistics tool is run on a 0.10 sq km grid to identify the mode land use within each cell. To restrict the CPAs to land with low pecuniary value, the data is filtered to include only “Fallow/Idle Cropland,” “Grassland/Pasture,” “Forest,” “Wetland,” “Shrubland,” and “Barren.” Urban infill is excluded in this scenario because of the higher relative value of land in the urban environment. Rooftop solar is not included because of its high costs.
Scenario 5: Minimize Loss of Land with High Carbon Sequestration Potential (Figure 2.14) In the third scenario, lands which have high carbon sequestration potential are excluded. We rely on analysis from Chapter 5, which identifies carbon pools within San Diego county.
SANDAG’s Vegetation Dataset is also used, which classifies the vegetation types in the county. 43 The data are filtered to vegetation with high CO2 sequestration potential (see Appendix 2.H for full list). These lands are excluded from the renewable resource potential to find CPAs under a scenario that prioritizes natural carbon sequestration. Urban infill sites are included in this scenario because of the lower carbon sequestration potential of infill land. Rooftop solar is not included because of its high costs.
Scenario 6: Utilize only Developable Land (Figure 2.15) This scenario minimizes legal and social barriers by selecting sites that exist on land that is identified as developable and is thus assumed to be subject to fewer legal and social barriers.
SANDAG’s Developable Land dataset is utilized, which classifies “Vacant” and “Agricultural Redevelopment” as suitable for development.
44 In this scenario, urban infill sites and rooftop
solar are excluded as having higher barriers to development.
Scenario 7: Infill and Rooftop Solar Scenario (Figure 2.16) Using publicly available building footprint spatial data published by Microsoft, the GIS analysis of public and private rooftops in the San Diego region identified approximately 2.7 billion square feet (61,000 acres) of usable roof area. This resulted in a total estimated region-wide rooftop solar potential capacity of approximately 3,360 MW AC. 16 At an assumed 20% capacity
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36 factor based on NREL System Advisor Model simulations,45 this corresponds to 5,930 GWh annual generation region-wide. This is 12% of estimated 2050 electricity demand.
A recent solar siting survey by Clean Coalition incorporates additional information about how much distributed generation could be accommodated on specific electric distribution system circuits in the City of San Diego, based on Integration Capacity Analysis (ICA) data from SDG&E.46 However, the geographic extent of this analysis includes only the City of San Diego and no other cities or the unincorporated county. Figure 2.3 shows that these non-residential solar systems are estimated to be on the high end of candidate project costs, with an average LCOE of $92/MWh. Future analyses should also perform a detailed ICA, expanding beyond the City of San Diego to include other jurisdictions throughout the region, to confirm distribution grid capability to accommodate rooftop solar resources.
The rooftop solar potential estimate is based on existing buildings only, and the rooftop resource potential would increase if it were updated to additionally include anticipated new buildings in 2050. Future analyses should estimate the 2050 rooftop solar potential, using the SANDAG 2050 forecasted footprint of developed land. Relevant GIS data are available through the SanGIS portal.
47 At a high level, urban land area in the U.S. is expected to grow by 1-4 times by 2100, thereby increasing the anticipated rooftop solar potential.48 The Climate Equity Index (CEI) was created for the City of San Diego in 2019 and updated in 2020 through a stakeholder process to address environmental justice and social equity.49 The CEI measures access to opportunity at the census tract level through 35 indicators covering health, housing, socioeconomic, mobility, and environmental categories (Figure 2.8). As with the SB 535 Disadvantaged Community designation, the communities that score as having “low access” are primarily in the southern areas of San Diego including Barrio Logan, Lincoln Park, Mountainview, and the Tijuana River Valley.50
SANDAG has identified Communities of Concern and has a stated goal to ensure that Low Income and Minority communities benefit from public investments, in particular from transportation and mobility investments. These county-designated Communities of Concern are spatially distributed throughout the county (Figure 2.9).51 The highest concentration occurs in the southwest part of the county on the coast.
These communities in the southwest part of the county are also designated Disadvantaged Communities (DAC) by the State (Figure 2.9). They are identified by the California Environmental Protection Authority as disproportionately burdened by and vulnerable to multiple sources of pollution.
52 Under California State law (SB 535 and AB 1550), DACs are specifically targeted for investment: 25% of State GHG Cap and Trade funds will be invested in and for Disadvantaged Communities. Known as California Climate Investments (CCI),53 these Oct. 11, 2022
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37 funds are aimed at improving public health, quality of life and economic opportunity in California's most burdened communities while simultaneously reducing pollution that causes climate change.
Figure 2.8 Communities identified as having Very Low (dark blue), Low (blue), or Moderate (light green) access to opportunity through the San Diego Climate Equity Index. The CEI scoring is averaged across 41 indicators. For more details on each indicator, including source information and methods, refer to Appendix B of the City of San Diego's 2019 Climate Equity Index Report.49 The 2021 CEI version added three indicators (Ozone, PM2.5, and Diesel Particulate Matter), replaced the Heart Attack Fatalities indicator for Cardiovascular Disease, and separated the Proximity to Waste Sites indicator into four separate indicators: Toxic Releases from Facilities, Clean Up Sites, Hazardous Waste Generators and Facilities, and Solid Waste Sites and Facilities. Working with commu nity-based organizations, the City has defined climate equity as efforts addressing historical inequities suffered by people of color, allowing everyone to fairly share the same benefits and burdens from climate solutions and attain full and equal access to opportunities regardless of one’s background and identity.
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38 Figure 2.9 State-identified Disadvantaged Communities (Cal Enviroscreen 4.0) and State -identified Low-Income Communities (Assembly Bill (AB) 1550). These communities have been specifically targeted for California Climate Investments (Greenhouse Gas Reduction Fund and appropriated by the Legislature). These funds aim to improve public health, quality of life, and economic opportunity in California’s most burdened communities while reducing pollution that causes climate change. These funds must be used for programs that further reduce emissions of greenhouse gases.
A scenario maximizing rooftop and urban infill solar and energy storage in these frontline communities could result in 5-30% reduction in impacts to previously undisturbed land (greenfield development). Such a scenario could also have multiple co-benefits, including progress toward county-level and higher-level equity goals, job creation in “green job” or “cleantech” sectors with corresponding well-paying wages,54 reduced GHG emissions from land use change for energy infrastructure, and availability of supplemental funding sources (e.g., from the State). Additionally, rooftop solar programs can be designed in such a way that they can lower energy bills for low-income residents, for instance through rooftop solar incentive programs. Further study to quantify the local economic and public health benefits of such a scenario would be valuable; however, adequate information currently exists to support early action to pursue growth in rooftop solar, especially in communities overly burdened with pollution and having low access to opportunities.
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39 Scenario 8: Mixed-mode scenario (Figure 2.17)
Because there are inherent trade-offs between and across scenarios, a mixed-mode multi- benefit scenario is identified, to provide an example of balancing many competing priorities.
This scenario includes:
● Rooftop solar throughout the county for the land-sparing benefits; ● High utilization of brownfield wind and solar sites;
● Lower-cost (but higher land-area) utility-scale wind and solar on SANDAG “developable” lands;
● Lower-cost utility-scale solar and geothermal from Imperial County, with corresponding transmission upgrades; and
● 4-hr battery energy storage and long-duration energy storage (pumped hydropower storage), for reliability.
Energy storage in this scenario occurs at levels below the commercial interest indicated in the CAISO interconnection queue (7600 MW in San Diego County as of January 2022), but much higher than any deployment rate in history.
The level of rooftop solar in this scenario assumes an increased level of adoption of rooftop solar in the communities identified as having very low, low, and moderate access to opportunity (per the San Diego Climate Equity Index, as seen in Figure 2.9) than in other communities in the region. This increase is driven by the State mandate requiring 25% of GHG Cap and Trade funds be invested in and for Disadvantaged Communities per SB 535.
This scenario is the only one that includes the brownfield sites identified by the US EPA RE- powering America Initiative, which encourages renewable energy development on current and formerly contaminated lands, landfills, and mine sites when such development is aligned with the community’s vision for the site.
23 Due to the barriers to development known to occur on contaminated soils, the total solar brownfield resource potential was discounted by 50% to account for uncertainty.
Scenario 9: High Rooftop, Low-impact (Figure 2.18)
This scenario is designed to maximize rooftop and infill solar, avoid impacts to important conservation lands per the Multiple Species Conservation Plan, avoid impacts to high-value agricultural lands, and include lower-cost resources from nearby jurisdictions, such as Imperial County. Unlike Scenario 8, no brownfield sites are included, no SANDAG “developability” screen is applied, and high protections for conservation and agricultural lands are assumed. The location of the resources is not limited to San Diego Community Power (SDCP) jurisdiction boundaries, but the total generation is compared to SDCP estimated demand.
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40 2.5 Results and Discussion
2.5.1 Initial Least-Cost Scenarios
The results of the least-cost scenarios are shown in Figures 2.10 & 2.11 below. Both figures show the CPAs that the algorithms selected to produce the estimated 49,979 MWh of total 2050 electricity demand (Table 2.5). In the San Diego-only Scenario (Figure 2.10) the 2030 sites selected based on LCOE cluster largely around Jacumba Hot Springs in the southeast and Borrego Springs in the northeast parts of unincorporated San Diego County. In the 2040 and 2050 time-steps, CPAs closer to urban areas are selected. Few urban infill CPAs are selected in the San Diego scenario as the LCOE for infill CPAs is relatively higher than utility-scale development due to lower capacity factors. This lower capacity factor is in part from the use of fixed-tilt installations that maximize land utilization in densely populated areas. The San Diego- only scenario also requires higher overall electricity generation from renewable resources due to the lack of geothermal resources from Imperial County. The lack of firm power, or power that does not rely on intermittent resource availability like wind or sunshine, would also require higher storage capacity for 100% reliance on intermittent resources. Battery energy storage and long-duration energy storage could be deployed to meet this need in the San Diego-only scenario. The 2020-2021 CAISO Transmission Planning model’s (base case) included 300 MW long-duration energy storage and 660 MW of 4-hr battery energy storage in San Diego county. 55 In the San Diego and Imperial Scenario (Figure 2.11) geothermal and solar resources from Imperial County are factored into the resource potential to meet San Diego’s electricity demand. While the area east of Jacumba Hot Springs remains an area with high commercial interest for solar and wind development within the San Diego region, most other CPAs from the San Diego-only Scenario are not selected as their costs are higher than resources from Imperial County. Geothermal resources (green points) reduce the overall requirement for wind and solar resources in either county. In the San Diego and Imperial Scenario, no infill resources are selected due to the availability of lower-cost sites in Imperial County.
While both scenarios meet forecasted electricity demands from the Central Case of the EER model, to ensure reliability for a 100% renewable energy supply, overcapacity is likely necessary. In their study of overcapacity and storage to meet reliability standards across the US, Shaner et al. (2018)
34 find that, for a 75% solar 25% wind scenario, 50% overcapacity and 12 hours of storage results in 98.74% reliability.i Guerra et al. (2020) find that energy storage can significantly reduce total system costs for grids with high (75%-90%) and ultrahigh (over 90%) renewable energy generation share, with higher reliance on renewable sources warranting
i Importantly, this level of reliability is below current norms in the U.S., which is currently 99.97% reliable.
Policymakers may choose to aim for greater overcapacity or storage to boost reliability closer to current levels.
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41 greater capacity and duration energy storage.56 In both scenarios, there are additional CPAs available to meet necessary overcapacity. However, the amount of overcapacity needed is subject to uncertainty around the future availability of storage, upgrade of transmission systems, and development of clean firm power. The degree of necessary overcapacity has been analyzed in the broader EER energy model.
Additionally, these scenarios are snapshots of existing resource potential and availability. As more resources come online within the San Diego region or outside of the region, such as Imperial County resources, offshore wind or resources from out of state or Mexico, the results of these and of the following scenarios would change. Generally, as more resources become available to the San Diego region for utilization, the reliance on renewable resource development within the region can be adjusted accordingly.
2.5.2 Alternate Scenarios
As policymakers consider alternate scenarios for siting renewable resources, priorities beyond the wholesale cost of energy may factor into decision-making. Figures 2.12 through 2.17 show solar and wind CPAs under several additional policy scenarios within the San Diego region.
Table 2.5 shows a summary of the resource potential for each scenario.
Table 2.5 Scenario summary of renewable energy resource potential and energy deficit with predicted demand. All values are in GWh. The “deficit with demand” values are based on the EER model’s Central Case annual demand estimates of 49,979 GWh for the San Diego region by 2050.
Scenario
number Scenario Description
Resource
Type
Resource
Potential (GWh)
Excess (Deficit) with
Demand (GWh)
Scenario 1 Least-cost (San Diego county only) Solar, Wind 49,979 – Scenario 2 Least-cost (San Diego and Imperial counties) Solar, Wind,
Geothermal 49,979 –
Scenario 3 Low Environmental Impact Solar, Wind 15,777 (34,202) Scenario 4 Low Land Value Solar, Wind 52,394 2,415
Scenario 5 Carbon Sequestration Potential Solar, Wind 22,844 (27,135) Scenario 6 Developable Solar, Wind 13,894 (36,085)
Scenario 7 Rooftop and infill solar Solar 17,478 (32,501) Scenario 8
Mixed-mode resource mix (San Diego and
Imperial counties)
Solar, Wind,
Geothermal 50,147 168
Scenario 9
High Rooftop, Low-Impact to Conservation Lands,
Avoid Valuable Agriculture Lands (San Diego and
Imperial counties) Solar, Wind 44,177 (5,802)
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42 Figure 2.10 Least-cost site selection scenario: San Diego county only. This analysis only included utility -scale solar and onshore wind resources and selected least-cost resources first before selecting more expensive resources. The three panels show the build out required by each year that would allow the region to approach full energy decarbonization by 2050. Lighter colors represent CPAs that would be built earlier because they are less expensive. Blue colors are wind resources and orange/red colors are solar resources. This scenario has an average levelized cost of energy (LCOE) of $40.65 per megawatt hour (MWh).
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43 Figure 2.11 Least-cost site selection scenario: San Diego and Imperial counties. This analysis only included utility -scale solar, onshore wind, and geothermal resources and selected least-cost resources first before selecting more expensive resources. As with Figure 2.10, this shows build out over three time per iods where colors represent build out year (lighter colors are earlier) and resource (red/orange for solar, blue for wind, and green for geothermal). The inset shows the Jacumba Hot Springs area site selection by 2050 and the area that includes the proposed/planned JVR sites. This scenario has an average LCOE of $42.04 per MWh.
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44 Scenario 3: Avoid Land with High Conservation Value (Figure 2.12) The low-impact CPAs taken from Wu et al. (2020)1 reduce the resource potential by 76.5%. Prior to removal, 1.7% of the Multiple Species Conservation Plan conservation areas were impacted by selected sites in this scenario. About 5% of the CPAs in this scenario occurred on pre- approved "take authorized" areas. Most remaining CPAs are in the urban infill areas, which were included without further restriction from the previous analysis. The remaining total resource potential is 15,777 GWh, requiring imports, rooftop solar, or brownfield site development to achieve 100% of electricity demand.
Figure 2.12 Scenario 3: Avoid land with high conservation value. This scenario minimizes impacts to areas of high conservation value and other areas that are environmentally sensitive or important. It does not meet regional energy demand and is relatively more expensive (with an average LCOE of $84.5 per MWh)
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45 Scenario 4: Avoid Land with High Pecuniary Value (Figure 2.13) The exclusion of land with high pecuniary value does not significantly lower the capacity of utility-scale renewable generation within the San Diego region because most of the land identified in the previous scenarios was not on high-value cropland. The resulting total resource potential is 52,394 GWh. Therefore, if 95.4% of the resource potential on land with low value is developed, the region would be able to achieve 100% of electricity demands with resources within the county.
Figure 2.13 Scenario 4: Avoid land with high pecuniary value. This scenario minimizes impacts to lands with high monetary values, such as agricultural lands or urban areas. It meets regional energy demand and is relatively less expensive (with a mean LCOE of $42.4/MWh).
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46 Scenario 5: Avoid Land with High Carbon Sequestration Potential (Figure 2.14) When CPAs are designed to avoid land with high carbon sequestration potential, the resulting capacity is 22,844 GWh, or roughly one-third the original capacity. Much of the remaining CPAs are located in the urban infill, which are included without further restrictions. In this scenario, the region would require imports, rooftop solar, or brownfield site development to achieve 100% of electricity demand with renewable energy.
Figure 2.14 Scenario 5: Avoid land with high carbon sequestration potential. This scenario minimizes impacts to lands with high carbon sequestration potential. It does not meet regional energy demand and is relatively expensive (with a mean LCOE of $80.7/MWh).
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47 Scenario 6: Focus on Developable Land (Figure 2.15)
Focusing on CPAs on developable land may provide decision-makers with low-hanging fruit in terms of ease of development. When CPAs are restricted to “Vacant” and “Agricultural Redevelopment” land types, there is 13,894 GWh of regional resource potential. This is not enough to fulfill the county’s electricity demand internally, but may provide a good starting point for near-term resource development.
Figure 2.15 Scenario 6: Focus on developable land. This scenario minimizes legal and social barriers to renewable energy development by only selecting CPAs on lands that are currently designated as “developable.” It therefore excludes infill. It does not meet regional energy demand and is relatively less expensive (with an average LCOE of $40.5/MWh).
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48 Scenario 7: Infill and Rooftop Solar Scenario (Figure 2.16) Together, infill and rooftop solar resource potential throughout the county is 17,478 GWh, making up 35% of the estimated 2050 demand (12% and 23% respectively). A higher level of rooftop solar deployment is assumed in communities having very low, low, or moderate access to opportunity per the San Diego Climate Equity Index (assuming 50% of rooftop area is usable instead of 30% assumed elsewhere). The rooftop solar resource potential in these communities is estimated at 726 GWh, which would provide about 1% of the estimated 2050 demand.
Overall, this focus on maximum possible rooftop and infill solar leaves a deficit of 32,501 GWh, which would need to come from utility-scale renewable development or from resources outside of the San Diego region.
Figure 2.16 Scenario 7: Infill and rooftop solar only. This scenario maximizes utilization of rooftop solar and in fill solar development in the region. It does not meet regional energy demand and is relatively expensive (with an average LCOE of $70/MWh) because of the high costs and lower capacity factors of rooftop and urban infill solar development.
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49 This preliminary analysis sought to understand rooftop, infill, and brownfield solar potential in the San Diego region. Other urban land uses and land covers such as parking lots or human- made bodies of water, such as reservoirs, irrigation ponds, and water treatment holding ponds may also be considered in future iterations. However, studies have shown that commercial parking lots have low market penetration partly due to the availability of other lower-cost options such as utility-scale ground-mounted solar. Innovative incentive or rebate design may be needed to support economic competitiveness. Results of the analysis on rooftop solar are summarized in Table 2.6 below.
Table 2.6 Comparative energy production cost scenarios, average LCOE, total energy, and percent of demand met by renewable energy sources of natural gas, Scenario 1 (Figure 2.10), rooftop solar only, and rooftop and infill solar (Figure 2.16).
Energy Production Cost Scenarios
Average LCOE
($/MWh)
Total GWh in San
Diego County
Percent of
Demand
Average US Combined Cycle Natural Gas Plant50 35 NA NA
Output of Scenario 1 (Sites selected based on LCOE) 41 49,979 100% Rooftop Solar 92 5,930 12%
Rooftop and Infill Solar 70 17,478 35%
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50 Scenario 8: Mixed-mode resource mix scenario (Figure 2.17) In this scenario, the 2050 annual generation from new renewable sources is as follows: 12% rooftop solar, 23% brownfield solar, 0.1% brownfield wind, 6% utility scale solar on developable land in the San Diego region, 0.4% utility scale wind on developable land in the region, 38% Imperial solar, 21% Imperial geothermal. This results in 50,147 GWh of resource potential and allows for a surplus of 168 GWh.
Figure 2.17 Mixed-mode Scenario 2050. This figure shows sites selected to meet the 2050 electricity demand, for the mixed-mode scenario. In this scenario, the 2050 annual generation from new renewable sources is as follows:
12% rooftop solar, 23% brownfield solar, 0.1% brownfield wind, 6% utility scale solar on developable land in San Diego county, 0.4% utility-scale wind on developable land in San Diego county, 38% Imperial solar, 21% Imperial geothermal. The addition of rooftop solar and brownfield resources together results in 35% reduction in land area impacts. This meets regional energy demand, but it has a high average cost (with an average LCOE of $109/MWh) partly because of the high costs of rooftop and brownfield development, as well as the high cost of geother mal.
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51 Scenario 9: High Rooftop, Low-Impact to Conservation Lands, Avoid Valuable Agriculture Lands (Figure 2.18)
In this scenario, the 2050 annual generation from new renewable sources is as follows: 28% rooftop solar, 16% infill solar, 3% utility-scale solar in the San Diego region, less than 1% utility- scale wind in the region, 53% Imperial solar. This results in 44,177 GWh of resource potential, which is 88% of estimated regional demand in 2050.
The estimated 2050 electricity demand for the newly formed entity, SDCP, is 72% of 2050 regional electricity demand, based on the population of the following member jurisdictions:
Encinitas, Chula Vista, La Mesa, Imperial Beach, National City, City of San Diego, and the Unincorporated County.
57 In this Scenario 9, the annual generation is 123% of estimated 2050 SDCP electricity demand. If the resources of this scenario were limited to include only those resources physically located within the member jurisdiction boundaries, then resource availability is reduced to 42% of estimated 2050 SDCP demand.
Figure 2.18 High Rooftop, Low-Impact on Conservation Lands, Avoid High-value Agriculture Lands 2050. This figure shows sites selected to meet the 2050 electricity demand, for the high rooftop, low -impact scenario, with high- value agricultural lands removed. In this scenario, the 2050 annual generation from new renewable sources is as follows: 28% rooftop solar, 16% infill solar, 3% utility-scale solar in San Diego County, less than 1% utility-scale wind in San Diego, 53% Imperial solar. It does not meet total 2050 regional electricity demand (88%), but it meets 123% of estimated 2050 SDCP electricity demand. It has a moderate average cost, with an average LCOE of $57/MWh.
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52 2.6 Trends Across Scenarios
Most scenarios in this analysis include some level of development of the high-quality resource potential in the Boulevard, Campo, and Jacumba areas. Based on CAISO interconnection queue data, high levels of commercial interest and development activity are already occurring in this area. Stakeholder comments indicated siting concerns in this region, including habitat loss, land use change, noise, shadow flicker, and electromagnetic interference. The latter three concerns are only applicable to wind turbines.
A recent LBNL study indicates that improved understanding of shadow flicker exposure could provide a basis for exposure thresholds and, in turn, potentially improve community acceptance of and experience with wind power projects. This study identified a prototypical EU regulatory threshold limiting wind turbine noise disturbance to no more than 45 dBA and limiting shadow flicker to no more than 8 hours per year. The majority of points in the study sample had shadow flicker below this threshold when sited 1500 m or more from residences or other structures. 58 Multiple scenarios (such as Scenario 1 and 2) limit the amount of wind and solar in these East County locations, but there are no scenarios in which development in this area is eliminated entirely. The recently passed NY Accelerated Renewable Energy Growth and Community Benefit Act may provide a helpful example of solutions to help alleviate development pressure and address community concerns in sensitive areas. See excerpted summary below:
59 "In order to ensure that renewable energy projects deliver benefits to the local communities where they are built, the Act establishes several programs.
First, NYSERDA will develop a Host Community Benefit Program as part of its build-ready initiative, which will offer property owners and communities tangible benefits and incentives for hosting renewable energy facilities.
The Act also creates a new program that will be established by the Public Service Commission, which will provide utility bill discounts or other environmental benefits or compensation for the benefit of residents of host communities.
Finally, in order for communities to participate in the new siting process, NYSERDA will administer a local intervenor fund for the benefit of local agencies and community intervenors. Further stakeholder input from residents in these counties is welcome and appreciated."
Additionally, in 2022 the California Energy Commission held a workshop 60 that described how
the State agencies collaborating on SB 100 will work to improve methods for how land use implications are included in energy resource planning.
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53 2.7 Conclusion
To develop the necessary renewable resources that satisfy 100% of electricity demand by 2050, the San Diego region will need to engage in near- and long-term planning to ensure priorities such as environmental protection, cost, carbon sequestration potential, equity, and land value are considered adequately in deployment. This report has shown that balancing these priorities is possible with available resources in the San Diego region and nearby Imperial County, although there will be trade-offs, including the need to import electricity and transmission upgrades needed to avoid congestion. There are opportunities for power transfer between San Diego and Imperial Counties, including solar and geothermal firm power, which can reduce storage requirements and increase reliability. To meet the estimated ~50,000 GWh of demand (or ~5,700 MW of capacity) for the San Diego region by 2050, there will need to be roughly two new operational 100 MW clean power plants coming online every year between now and 2050.
If the timeline is constrained to 2035, this would require roughly four new operational 100 MW clean power plants every year. Close coordination with State agencies such as the CAISO and the CPUC can help accelerate the deployment of clean energy infrastructure, including transmission.
A scenario maximizing rooftop and urban infill solar and energy storage could result in 5-30% reduction in infrastructure development on previously undisturbed land (greenfield development). It could also have multiple co-benefits, including progress toward county-level and higher-level equity goals, job creation in “green job” or “cleantech” sectors with corresponding well-paying wages,
54 reduced GHG emissions from land use change for energy infrastructure, and availability of supplemental funding sources for example from the State. If coupled with apprenticeship programs, job training opportunities could be significant. Further study to quantify the local economic and public health benefits of such a scenario would be valuable; however, adequate information exists to support early action in high-quality areas in East County as well as promoting growth in rooftop solar, especially in communities overly burdened with pollution and having low access to opportunities.
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60. “Joint Agency Workshop to Plan for Senate Bill 100 Resource Build – Analysis of Land Use Implications” California Energy Commission, February 22, 2022. https://www.energy.ca.gov/event/workshop/2022- 02/joint-agency-workshop-plan-senate-bill-100-resource-build-analysis-land-use Oct. 11, 2022
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57 Appendix 2.A List of Spatial Data Sources
Spatial Data Sources
1. On-Shore Wind and Solar Polygons: RETI Coordinating Committee, RETI Stakeholder Steering Committee. “Renewable Energy Transmission Initiative Report.” California Energy Commission, January 2009. Accessible online at http://www.energy.ca.gov/2008publications/RETI-1000-2008-002/RETI-1000-2008-002-F.PDF
2. Off-Shore Wind Polygons: Princeton REPEAT, 2022.
https://maps.princeton.edu/catalog?search_field=all_fields&q=netzeroamerica&utf8=%E2%9C%93
3. Infill Solar Polygons: The Nature Conservancy, Power of Place, 2019 (update to 2019 report, not published). https://www.nature.org/en-us/ about-us/where-we-work/united-states/california/stories-in-california/clean- energy/
4. Conserved Lands Exclusions: San Diego Association of Governments, 2021. https://rdw.sandag.org/Account/gisdtview?dir=Ecology
5. Existing Utility-Scale Solar and Wind Polygons: Polygons created based on existing and planned sites identified by EIA, 2021 https://www.eia.gov/electricity/data/eia860/
6. Existing Substations: Department of Homeland Security, Homeland Infrastructure Foundation- Level Data, 2021. https://hifld-geoplatform.opendata.arcgis.com/datasets/electric-substations
7. Urban Areas: US Census, 2019. https://catalog.data.gov/dataset/tiger-li ne-shapefile-2019-2010-nation-u-s- 2010-census-urban-area-national
8. Transmission Networks: Department of Homeland Security, Homeland Infrastructure Foundation- Level Data, 2021. https://hifld-geop latform.opendata.arcgis.com/datasets/electric-power-transmission- lines/explore?location=25.606388%2C-7.477918%2C2.79
9. Geothermal Sites: Points created based on data from E3 and CPUC as part of the statewide Integrated Resource Plan (R-20-05-003) https://www.ethree.com/tools/resolve-renewable-energysolutions-model/
10. Low Environmental Impact CPAs: Wu et al., 2020 Data Github https://github.com/grace-cc- wu/LandUsePathwaysTo100
11. Land Value: USDA Cropland Data Layer
https://www.nass.usda.gov/Research_and_Science/Cropland/SARS1a.php
12. High Sequestration Potential: Taken from analysis in the Land Use chapter, the SANDAG “Eco Veg” dataset is used. https://www.sangis.org/
13. Developable Land: Vacant or Agricultural Redevelopment Land Use. SANDAG, Developable Land, 2010. https://www.sandag.org/resources/maps_and_gis/gis_downloads/land.asp
14. Microsoft Building Footprints – Features. 125 million building footprints deep learning generated by Microsoft for the USA. https://hub.arcgis.com/datasets/esri::microsoft-building-footprints-features/about (accessed online December 1 2021).
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58 Appendix 2.B List of Spatial Data Sources
Table 2.B.1 Category 1 site suitability criteria. Adapted from RETI, 2009 Category 1 Lands
Federal Lands State Lands
Designated Federal Wilderness Areas Private Preserves of The Wildlands Conservancy Wilderness Study Areas
National Wildlife Refuges
Units of National Park System (National Parks,
National Monuments, National Recreation Areas,
National Historic Sites, National Historic Parks,
National Preserves)
Existing Conservation Mitigation banks under
conservation easement approved by the State
Department of Fish and Game, U.S. Fish and
Wildlife Service or Army Corps of Engineers
Inventoried Roadless Areas on USFS national
forests CA State Defined Wetlands
National Historic and national Scenic Trails CA State Wilderness Areas National Wild, Scenic and Recreational Rivers CA State Parks BLM King Range Conservation Area, Black Rock-
High Rock National Conservation Area, and
Headwaters Forest Reserve DFG Wildlife Areas and Ecological Reserves BLM National Recreational Areas
BLM National Monuments
Lands precluded by development under Habitat
Conservation Plans and Natural Community
Conservation Plans
Lands specified as of May 1, 2008, in Proposed
Wilderness Bills (S. 493, H.R. 3682)
Table 2.B.2 Category 2 site suitability criteria. Adapted from RETI, 2009 Category 2 Lands
BLM Areas of Critical Environmental Concern
USFWS designated Critical Habitat for federally listed endangered and threatened species
Special wildlife management areas identified in BLM's West Mojave Resource Management Plan. I.e., Desert Wildlife Management Areas and Mojave Ground Squirrel Conservation Areas
Lands purchased by private funds and donated to BLM, specifically the California Desert Acquisition Project by The Wildlands Conservancy "Proposed and Potential Conservation Reserves" in HCPs and NCCPs Oct. 11, 2022
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59 Table 2.B.3 Full List of site suitability criteria for CPA development.
RETI Excluded Lands
Geothermal Solar PV Wind Notes
Category 1 lands Yes Yes Yes
Category 2 lands Yes Yes Yes Pre-identified projects OK Wetlands and water
bodies Yes Yes Yes Dry lakes not excluded
Native American
reservations Yes Yes Yes Pre-identified projects OK
Military lands Yes Yes Yes Pre-identified projects OK
Mines (surface) Yes Yes Yes
Urban areas Yes Yes, +
buffer
Yes, +
buffer
buffer up to 3 miles depending on
population
Airports Yes Yes Yes, +
buffer
Major airports only. Wind buffer is up
to 5 miles
Military flyways No No Yes Pre-identified projects OK in red zones.
All other open
Williamson Act Prime
Agricultural Land No Yes No Pre-identified projects OK in red zones.
All other open
Williamson Act Non-
Prime Agricultural Land No Yes No Excluded until 2018, pre-identified projects OK
Renewable resource
quality No No < 6.3
m/sec
Min. contiguous square
acreage No 160 none 640 acres = 1 section = 1 sq mile
Land slope No > 5% > 20% Geothermal evaluated on case-by-case basis
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60 Appendix 2.C List of Key Assumptions
Key Assumptions
● Solar is prioritized over wind within San Diego County. ● For CPAs located in San Diego County, cost of transmission interconnection can be approximated by cost of Euclidian distance from CPA to nearest substation. For CPAs located outside of the county, it is assumed that a transmission upgrade will be required to alleviate the San Diego Internal constraint (see line 5 in table listing transmission upgrade options). ● Total geothermal resource potential identified by E3 and CPUC as part of the Statewide Integrated Resource Plan (R-20-05-003) will be operation by 2030.
● Geothermal supply in Imper ial is shared with San Diego in an amount equivalent to the ratio of their combined population.
● Electricity demand model results can be downscaled by the ratio of San Diego population to total Southern California population.
● Storage and geothermal will help alleviate intermittency pressures on the grid. ● Cost is a very important criteria for site selection. ● The Overall Energy Model Central Case is the best forecast for the purposes of the spatial analysis. ● The capacity factor is equal to the fixed-tilt solar percentage in the urban areas and tracking solar in non-urban areas.
● Infill solar sites are grid connected.
● All planned and permitted solar sites in San Diego County will be constructed. ● SANDAG’s Conserved Land areas are undesirable for renewable development.
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61 Appendix 2.D QGIS Processing Modeler
Solar CPAs Modeler
Wind CPAs Modeler
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62 Appendix 2.E Floatovoltaics
In addition to utilizing previously disturbed land areas for solar PV deployment, such as rooftop, brownfield, and urban infill, San Diego may also pursue deploying solar atop human-made bodies of water, such as reservoirs, irrigation ponds, and water treatment holding ponds. Siting solar panels atop human-made bodies of water, known as floatovoltaics (FPV), can help to alleviate land use conflicts with agriculture or biological conservation. Additionally, FPV can potentially offer unique co-benefits, such as increased panel performance and evaporation of the associated freshwater resources.
1 FPV is growing rapidly in California, with multiple
commercial scale multi-megawatt arrays being deployed in Sonoma County. This is a demonstration effort to simultaneously increase solar deployment to meet RPS standards, reduce the need for land use and land cover change for solar deployment, and preserve fresh water in a drought-prone state.
Techno-economic feasibility and potential analyses have been performed at both the State and national level to identify candidate water bodies within a strict inclusion criteria.2,3 Specifically, GIS-based techno-economic potential studies have been conducted to assess the viability and availability of human-made bodies of water for FPV deployment on a national scale.3 Viability requirements include categories such as primary water body use type, bathymetric characteristics, and distance to transmission and substation infrastructure. The analysis methodology and data used for this analysis is publicly available for potential future incorporation into this flexible framework.
Appendix 2.E Works Cited:
1. Cagle AE, Armstrong A, Exley G, Grodsky SM, Macknick J, Sherwin J, et al. The Land Sparing, Water Surface Use Efficiency, and Water Surface Transformation of Floating Photovoltaic Solar Energy Installations. Sustainability 2020;12:8154. https://doi.org/10.3390/su12198154.
2. Liber W, Bartle C, Spencer R, Jordan M, Cagle AE, Lewis T. Statewide potential study for the implementation of floating solar photovoltaic arrays. Denver, CO: 2019
3. Spencer RS, Macknick J, Aznar A, Warren A, Reese MO. Floating Photovoltaic Systems: Assessing the Technical Potential of Photovoltaic Systems on Man-Made Water Bodies in the Continental United States. Environmental Science Technology 2018;53:1680–9. https://doi.org/10.1021/acs.est.8b04735.
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63 Appendix 2.F Transmission Upgrade Options and Costs
Table 2.F Transmission upgrades and costs in San Diego Gas & Electric (SDG&E) Territory, based on CAISO Tran smission Capability Whitepaper, July 2021.35 Transmission
Constraint Affected Zones
Estimated Full Capacity Deliverability
Status Based on On-Peak Study
Resource Output
Area Delivery Network Upgrades (ADNU) & Cost Estimate Wind/Solar Area Designation
Existing
System
(MW)
Increase due to ADNU
(MW) ADNU Construction
Time (months)
Cost
($millions)
East of Miguel
Constraint
Arizona, Imperial,
Baja, Riverside 731 1,412 New Imperial Valley -
Serrano 500 kV line 120 $3,680 Solar
Encina-San Luis Rey
Constraint
Arizona, Imperial,
Baja, Non-CREZ
within San Diego
2,901 3,718 New Encina - San Luis Rey
230 kV line 120 $102 Solar
Imperial Valley
transformer
Constraint
Imperial 1,959 400 New Imperial Valley 500/230
kV Bank at new substation 105 $214 Solar
San Luis Rey-San
Onofre Constraint
Arizona, Imperial,
Baja, Non-CREZ
within San Diego
1,748 4,269 New San Luis Rey-San
Onofre 230 kV line 120 $237 Solar
San Diego Internal
Constraint
Imperial, Non-CREZ
within San Diego 968 2,067 Internal San Diego
reconductoring 18 $89 Solar
Silvergate-Bay
Boulevard
Constraint
Imperial, Baja, Non-
CREZ within San
Diego
1,202 2,119 Silvergate - Bay Blvd
230kV
3-ohm Series Reactor 72 $31 Wind
San Diego
Oceanside
Constraint
Non-CREZ within
San Diego 280 301 Oceanside ADNU 60 $133 Solar
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64 Appendix 2.G Downscaling Method
First, the proportion of the population of San Diego with respect to the population of Southern California (SC) is found. The SC population is defined as all counties south of the PG&E territory.i Therefore, using the following formula to find a result of 13.75%.
𝑃𝑃𝑃𝑃𝑐𝑐𝑜𝑜𝑎𝑎
𝑎𝑎𝑑𝑑𝑑𝑑𝑃𝑃𝑑𝑑 𝑃𝑃𝑓𝑓 𝑆𝑆𝑎𝑎𝑑𝑑 𝐷𝐷𝑑𝑑𝑃𝑃𝑔𝑔𝑃𝑃 𝐶𝐶𝑃𝑃𝑜𝑜𝑑𝑑𝑑𝑑𝑑𝑑 / 𝑃𝑃𝑃𝑃𝑐𝑐𝑜𝑜𝑎𝑎 𝑎𝑎𝑑𝑑𝑑𝑑𝑃𝑃𝑑𝑑 𝑃𝑃𝑓𝑓 𝑆𝑆𝐶𝐶 𝐶𝐶𝑃𝑃𝑜𝑜𝑑𝑑𝑑𝑑𝑑𝑑
𝑃𝑃𝑑𝑑
Tab
le 2.G.1 Proportion of Population in San Diego
San Diego Percentage of Southern CA
San Diego 3,315,404
Total 24,106,838
SD % 13.75%
Then the modeled final energy demand (“d-energy” in the Overall Energy System Model) is used. First, the total energy demand is filtered to “electricity” and “Southern California.” Then the sum of electricity demand is found for all years 2018 - 2050. The proportion of Southern California population in San Diego (13.75%) is applied to find the San Diego electricity demand. Finally, 4,115 GWh of existing and planned solar and wind resources within the County is removed. The total resource requirements based on demand are found in Table 2.C.2.
Table 2.G.2 Necessary Renewable Resources to Meet 100% of Demand Year Total GWh
2020 19,158
2025 20,919
2030 26,689
2035 34,825
2040 42,412
2045 47,045
2050 49,979
i PG&E, 2014. https://www.pge.com/tariffs/assets/pdf/tariffbook/GAS_MAPS_Service_Area_Map.pdf Oct. 11, 2022
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65 Appendix 2.H San Diego Vegetation Types with High CO2 Sequestration Potential Non-Native Vegetation
Disturbed Wetland
Disturbed Habitat
General Agriculture
Orchards and Vineyards
Southern Coastal Bluff Scrub
Coastal Scrub
Maritime Succulent Scrub
Diegan Coastal Sage Scrub
Diegan Coastal Sage Scrub: Coastal form
Diegan Coastal Sage Scrub: Inland form
Riversidian Sage Scrub
Riversidian Upland Sage Scrub
Alluvial Fan Scrub
Sonoran Desert Scrub
Sonoran Creosote Bush Scrub
Sonoran Desert Mixed Scrub
Sonoran Mixed Woody Scrub
Sonoran Mixed Woody and Succulent
Scrub
Sonoran Wash Scrub
Colorado Desert Wash Scrub
Encelia Scrub
Acacia Scrub
Mojavean Desert Scrub
Blackbush Scrub
Great Basin Scrub
Sagebrush Scrub
Big Sagebrush Scrub
Desert Saltbush Scrub
Desert Sink Scrub
Chaparral
Southern Mixed Chaparral
Granitic Southern Mixed Chaparral
Mafic Southern Mixed Chaparral
Northern Mixed Chaparral
Granitic Northern Mixed Chaparral
Mafic Northern Mixed Chaparral
Chamise Chaparral
Granitic Chamise Chaparral
Mafic Chamise Chaparral
Red Shank Chaparral
Semi-Desert Chaparral
Montane Chaparral
Mixed Montane Chaparral
Montane Manzanita Chaparral
Montane Ceanothus Chaparral
Montane Scrub Oak Chaparral
Upper Sonoran Ceanothus Chaparral
Ceanothus Crassifolius Chaparral
Scrub Oak Chaparral
Upper Sonoran Subshrub Scrub
Valley and Foothill Grassland
Native Grassland
Valley Needlegrass Grassland
Valley Sacaton Grassland
Non-Native Grassland: Broadleaf-
Dominated
Foothill/Mountain Perennial Grassland
Transmontane Perennial Grassland
Vernal Pool
San Diego Mesa Vernal Pool
San Diego Mesa Claypan Vernal Pool
Meadows and Seeps
Montane Meadow
Wet Montane Meadow
Dry Montane Meadows
Alkali Meadows and Seeps
Alkali Playa Community
Southern Coastal Salt Marsh
Alkali Marsh
Cismontane Alkali Marsh
Freshwater Marsh
Coastal and Valley Freshwater Marsh
Transmontane Freshwater Marsh
Emergent Wetland
Riparian and Bottomland Habitat
Riparian Forests
Southern Riparian Forest
Southern Coast Live Oak Riparian Forest
Southern Arroyo Willow Riparian Forest
Southern Cottonwood-Willow Riparian
Forest
White Alder Riparian Forest
Sonoran Cottonwood-Willow Riparian
Forest
Mesquite Bosque
Riparian Woodlands
Desert Dry Wash Woodland
Desert Fan Palm Oasis Woodland
Southern Sycamore-Alder Riparian
Woodland
Southern Riparian Woodland
Riparian Scrubs
Southern Riparian Scrub
Mule Fat Scrub
So
uthern Willow Scrub
Arundo donax Dominant/Southern
Willow Scrub
Great Valley Scrub
Great Valley Willow Scrub
Colorado Riparian Scrub
Arrowweed Scrub
Intertidal
Shallow Bay
Estuarine
Saltpan/Mudflats
Woodland
Cismontane Woodland
Oak Woodland
Black Oak Woodland
Coast Live Oak Woodland
Open Coast Live Oak Woodland
Dense Coast Live Oak Woodland
Engelmann Oak Woodland
Open Engelmann Oak Woodland
Dense Engelmann Oak Woodland
Peninsular Pinon and Juniper Woodlands
Peninsular Pinon Woodland
Peninsular Juniper Woodland and Scrub
Elephant Tree Woodland
Mixed Oak Woodland
Undifferentiated Open Woodland
Non-Native Woodland
Eucalyptus Woodland
Mixed Evergreen Forest
Oak Forest
Coast Live Oak Forest
Canyon Live Oak Forest
Black Oak Forest
Torrey Pine Forest
Southern Interior Cypress Forest
Lower Montane Coniferous Forest
Coast Range, Klamath and Peninsular
Coniferous Forest
Coulter Pine Forest
Bigcone Spruce (Bigcone Douglas Fir)-
Canyon Oak Forest
Sierran Mixed Coniferous Forest
Mi
xed Oak/Coniferous/Bigcone/Coulter
Forest
Jeffrey Pine Forest
Interior Live Oak Chaparral
Southern Maritime Chaparral
Coastal Sage-Chaparral Transition
Montane Buckwheat Scrub
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66 3. Accelerating Deep Decarbonization in the
Transportation Sector
Chelsea Richer, Fehr & Peers
Katy Cole, Fehr & Peers
Eleanor Hunts, Fehr & Peers
Key Takeaways
● Based on the regional policy context, including SANDAG’s 2021 Regional Plan, the County’s Electric Vehicle Roadmap, local jurisdiction policies and guiding documents, and the A2Z Gap Analysis, the region has a strong policy foundation for reducing transportation-related emissions.
● Nevertheless, projected annual emissions in 2045 and 2050 are inconsistent with the levels of reductions required by California Executive Order (EO) S-3-05, EO B-30-15, and EO-B-55-18 for carbon neutrality.
● This chapter shows where regional opportunity areas exist to accelerate zero-emissions vehicle (ZEV)/electric vehicle (EV) adoption and vehicle miles traveled (VMT) reduction based on existing countywide policies and patterns of vehicle ownership, travel behavior, and land use development.
● Both ZEV/EV adoption and VMT reduction strategies will be necessary to meet State decarbonization goals, and no policy will be a silver bullet.
3.1 Introduction
Over the last two decades, California has led the country in pioneering a number of policy solutions to mitigate climate change-related hazards and create a sustainable economy. In 2006, the state legislature passed Assembly Bill (AB) 32, which established a program to combat climate change and set a goal to reduce statewide greenhouse gas (GHG) emissions to 1990 levels by 2020. Recognizing that the transportation sector is the largest source of GHG emissions statewide,
1 California has adopted several additional transportation-focused measures since that initial landmark climate bill. One such law is the Sustainable Communities and Climate Protection Act of 2008 (Senate Bill (SB) 375). SB 375 targets cars and light-duty trucks and directs the California Air Resources Board (CARB) to set regional GHG reduction targets for each metropolitan planning organization (MPO). It requires MPOs to incorporate a set of GHG reduction strategies, called a Sustainable Communities Strategy, into their Regional Transportation Plans (collectively known as RTP/SCS). Transportation-related GHG reduction strategies included in the RTP/SCS often rely on reduction of vehicle miles traveled (VMT) and Oct. 11, 2022
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67 changes to the fleet mix to incorporate more Zero-Emission Vehicles (ZEVs).
A series of executive orders signed over the years have further contributed to the state’s climate platform. California Executive Order (EO) S-3-05 set a goal to reduce GHG emissions to 80 percent below 1990 levels by 2050, B-30-15 set an interim goal of reducing emissions to 40 percent below 1990 levels by 2030, and B-55-18 called for the state to achieve carbon neutrality by 2045 at the latest.
Electrification of end-use services, including vehicles, and decarbonization of electricity generation have been identified as key pathways to achieving a low-carbon future (Appendix A). Additional executive orders and state legislation have established targets for ZEVs, Electric Vehicles (EVs), and related charging infrastructure. EO B-48-18 established goals for 200 hydrogen fueling stations and 250,000 EV charging stations (including 10,000 DC fast chargers) to support 1.5 million ZEVs on the road in California by 2025 and 5 million ZEVs on the road by 2030. AB 2127, signed in 2018, requires the California Energy Commission, working with CARB and the Public Utilities Commission (PUC), to prepare a statewide assessment of EV charging infrastructure needed to support levels of EV adoption required to meet the goals of EO-B-48-
18. Finally, EO N-79-20 laid out a set of transportation decarbonization targets, including a mandate that 100 percent of in-state sales of new passenger cars and trucks are zero-emission vehicles by 2035 and that operations of medium- and heavy-duty vehicles are zero-emission vehicles by 2045.
Increasing the share of ZEVs and EVs on the road must come in tandem with strategies to improve overall travel efficiency through reducing VMT while allowing Person Miles Traveled (PMT) to remain the same. Transportation emissions are a product of emissions per mile and vehicle miles traveled, and the number of miles traveled is directly linked to land use and urban form. Even if all VMT were the product of ZEVs, the lifecycle emissions of vehicle manufacture, roadway maintenance, and waste management would still occur, along with the impact to carbon sequestration potential of agricultural or conservation lands that are developed.
Further, while not directly related to emissions, patterns of increasing VMT over time can worsen things like congestion and crash risks in a community, and limit access for people who cannot drive. Therefore, policies that emphasize active transportation in densely developed areas, discourage continued vehicle-dependent sprawl, and encourage construction of more housing near workplaces and services are critical to reducing VMT and meeting emissions reductions targets while still enabling people to reach the destinations they need to live fulfilling, high quality lives.
Neither substituting fossil fuel-based vehicles with ZEVs and EVs nor any single VMT reduction strategy will be a silver bullet. To meet local and state transportation decarbonization targets, the County and local jurisdictions will need to pair ZEV/vehicle electrification strategies with Oct. 11, 2022
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68 land use changes that reduce trip distance and car dependence. Strategies that simply focus on the shift to ZEVs and EVs will not lower VMT, and some VMT reduction strategies may limit movement if they are deployed in places that have no other transportation options beyond a personal vehicle. Therefore, decision-makers must decide how to best phase in EVs without encouraging additional driving, and how to best lower VMT without limiting access to destinations and opportunities. These decisions will be dependent on an area’s context and must consider environmental, social, and financial trade-offs.
The remainder of this chapter describes the regional policy context for the transportation sector, the modeling efforts that underpin land use and transportation plans in the region, and policy pathways to decarbonization through accelerated adoption of ZEVs and EVs, accelerated reduction of VMT, and continued investment in vehicle and fuel technology.
3.2 Regional Policy Context
The San Diego region has undertaken a number of transportation decarbonization efforts to date, which have included a variety of VMT reduction strategies and vehicle electrification strategies. This section details the relevant policy documents that will continue to shape the San Diego region’s ability to reach accelerated decarbonization targets.
3.2.1 SANDAG’s 2021 Regional Plan & 5 Big Moves
The San Diego Association of Governments (SANDAG) is the MPO for the San Diego region and has recently adopted the 2021 Regional Plan, a blueprint for land use and transportation planning in the San Diego region through 2050. This plan serves as the RTP/SCS and provides the big-picture vision for the future as well as an implementation program to make the region’s transportation system “faster, fairer, and cleaner.” The 2021 Regional Plan identifies a 2030 target of 771,000 EVs on the road in the San Diego region, supported by 155,200 chargers. 2 The 2021 Regional Plan articulates SANDAG’s future investments around the 5 Big Moves, an aspirational vision that provides a framework for the 2021 Regional Plan. The 5 Big Moves include VMT reduction strategies and strategies that encourage electrification of surface transportation vehicles.3 Over the next 30 years, SANDAG will refine the transportation network and discuss a set of policies and programs to support the following planned infrastructure and technology improvements: Complete Corridors, Transit Leap, Mobility Hubs, Flexible Fleets, and Next Operating System.
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69 1. Complete Corridors would provide a balanced and inclusive road and highway network to maximize capacity, reduce congestion, and enable a variety of travel choices. Key features include managed lanes, Active Transportation and Demand Management (ATDM)i, smart high-speed communication networks, priority for shared transportation modes, and curb management. Complete Corridors are the backbone for the Transit Leap and Flexible Fleets strategies.
2. Transit Leap would complement Complete Corridors by creating a comprehensive network of high-speed, high-quality transit services that connect residential areas with employment centers and attractions. Future transit services would build upon existing ones through expanded service times, higher frequency and capacity, transit priority, and better integration with other services.
3. Mobility Hubs are envisioned as a network of connected places with land use supportive of integrated mobility services and amenities, reducing the distance people need to travel to reach key destinations and enabling more transit, walking, and biking.
Mobility hub area amenities include interactive trip planning kiosks, electric vehicle charging, passenger loading areas, and secure parking for bicycles. SANDAG’s proposed network consists of the San Diego urban core, plus 30 surrounding mobility hub areas across the region. Mobility Hub prototypes have been developed for eight stops along the Mid-Coast Trolley route and eight additional locations across the region.
4. Flexible Fleets describes the strategy of shared, on-demand transportation services which include micromobility, rideshare, microtransit, ride hailing, and last-mile delivery.
This strategy relies on public-private partnership and assumes many of the new modes introduced would be electric-powered.
5. Next Operating System (OS) is a digital platform that compiles information from various parts of the transportation system into a centralized data hub, thereby linking residents, businesses, and operators to real-time transportation data and providing planners and policymakers with a new repository for analysis. Next OS also includes Intelligent Transportation Systems (ITS) strategies that can reduce VMT, such as expansion of broadband to enable remote work and apps to enable payment for mobility services.
The 5 Big Moves are strategies that directly and indirectly reduce VMT and accelerate EV adoption. In addition, Next OS is an underpinning strategy to improve data about the transportation sector so that it can continue to be analyzed and optimized over time.
i The ATDM program is intended to support agencies and regions considering moving toward an active management approach. It involves dynamic demand management, traffic management, parking management, and efficient utilization of other transportation modes and assets. Under an ATDM approach, the transportation system is continuously monitored and actions are performed in real-time to achieve or maintain system performance.
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70 3.2.2 Accelerate to Zero Emissions Electric Vehicle Gap Analysis (2021) The Accelerate to Zero (A2Z) Emissions Collaborative is an initiative by regional organizations invested in advancing zero-emissions transportation, including the City and County of San Diego, the San Diego Air Pollution Control District, SANDAG, and San Diego Gas & Electric (SDG&E). In July 2021, it published the San Diego Regional Electric Vehicle Gap Analysis, which identified existing efforts and conditions and evaluated zero-emission infrastructure gaps and barriers. As the A2Z Emissions Collaborative continues its work, the EV Gap Analysis will facilitate prioritizing Communities of Concern
i for transportation decarbonization investments.
The Gap Analysis identifies a 2030 target of 771,000 EVs on the road in the San Diego region, supported by 139,000 Level 2 chargers; 16,200 DC fast chargers; and 47 hydrogen fueling stations.4 Building on the Gap Analysis, A2Z has embarked on a Regional EV Strategy, scoped by SANDAG, which will guide the region in electrifying light-duty, medium-duty, and heavy-duty vehicles and infrastructure and implementing the Regional Plan.
3.2.3 San Diego County’s Electric Vehicle Roadmap (2019) The County of San Diego adopted an Electric Vehicle Roadmap in October 2019, which contains six goals and 11 recommendations that leverage the County’s land use authority, permitting processes, and outreach platforms in order to increase EV ownership and charging installations in the unincorporated area and at County facilities.
5 These are summarized in Table 3.1, below.
Because this document relates primarily to the unincorporated area of San Diego, the numbers reported for 2030 EV targets and charger targets are substantially different from the more current SANDAG or A2Z numbers.
i Pursuant to Title VI, Executive Order 12898 and the 1999 Department of Transportation Memorandum “Implementing Title VI Requirements in Metropolitan and State Planni ng,” SANDAG’s Regional Planning Stakeholders Working Group defined four types of “Communities of Concern” (Low Income Community of Concern, Minority Community of Concern, Low Mobility Community of Concern, and Low Community Engagement Community of Concern) as part of its 2050 RTP social equity analysis. Selection criteria are detailed at length in Chapter 4 of the SANDAG 2050 Regional Transportation Plan.
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71 Table 3.1. Summary of actions in San Diego County’s 2019 Electric Vehicle Roadmap. This table shows the goals, associated targeted outcomes, and recommendations in the roadmap.
Goal Targeted Outcome Recommendations
County Operations Recommendations
1. Further reduce the
County’s fleet of gas-
powered vehicles.
Increase the number of EVs
in the County’s fleet to 501
by 2027.
Amend three Board policies to assist fleet EV
conversion by requiring new light-duty vehicles
to be EV.
Convert 250 County fleet gas-powered vehicles
to EVs by 2025 and install necessary
infrastructure.
Convert an additional 251 County fleet gas-
powered vehicles to EVs for a total of 501 by
2027 and install necessary infrastructure.
Keep pace with technological trends, track the
costs and benefits of fleet conversion, and
update the Green Fleet Action Plan no later than
2025 to set goals for medium- and heavy-duty
fleet vehicle conversions.
2. Accelerate the installation
of EV charging stations at
public locations in County
facilities and in the
unincorporated County.
Contribute to the regional
EV charging network by
installing 2,040 Level II
charging stations at County
facilities and throughout the
unincorporated area by
2028.
Amend Board policy G-15, “Design Standards for
County Facilities” by 2019 to require charging
infrastructure development at new County
facilities.
Install an additional 63 publicly accessible EV
charging stations for a total of 100 chargers at
County facilities by 2021.
Prepare an EV charger site assessment for
County facilities and the unincorporated area
and install 2,040 Level II chargers.
3. Promote and incentivize
County employee EV
ownership.
Increase County employee
EV ownership and use to
reduce employee commute
emissions.
Promote and incentivize County employee EV
use by developing partnerships with banks,
credit unions, and dealerships to extend lending
and pricing benefits.
Unincorporated Area Recommendations
4. Incentivize and/or require
EV charging infrastructure in
new and existing private
multi-family residential
and/or non-residential
development.
Increase charging station
installations in new and
existing private
development.
Prepare a cost-benefit analysis of options to
incentivize and/or require EV charger
installations in private development.
5. Fund EV expert/consumer
advocate as a regional
resource.
Increase EV ownership and
charging station
installations through
education, outreach,
regional collaboration, and
incentives.
Identify regional partners and cost sharing
opportunities to fund a regional EV
expert/consumer advocate on an ongoing basis.
6. Collaborate with regional
partners to support public
and private fleet
electrification.
Increase EV use in regional
light-, medium-, and heavy-
duty fleets.
Develop public and private regional partnerships
to provide fleet electrification technical support
on an ongoing basis.
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72 3.2.4 San Diego County’s Climate Action Plan (2018)
Through Climate Action Plans (CAPs), the County of San Diego and most cities within the region have set out a series of measures to reduce GHG emissions over the coming decades. The County’s 2018 CAP, which is currently being revised to achieve compliance with the California Environmental Quality Act (CEQA), included 11 strategies and 26 measures which focus on activities that occur within the unincorporated area of the region and within County-owned facilities.5 The framework for the 2018 CAP is the GHG emissions inventory (baseline year 2014) and the state’s GHG reduction targets. San Diego County set total emissions targets of 3,147,275 and 1,926,903 metric tons of CO
2 equivalent (MTCO2e) for 2020 and 2030,
respectively. Measures in the Built Environment and Transportation GHG emissions sector specifically are projected to help the County achieve reductions of 233,758 MTCO 2e in 2030.6
3.2.5 City of San Diego’s Climate Action Plan (2015)
The City of San Diego adopted its landmark CAP in 2015 and projected that its implementation would help the city surpass the target of 51 percent below 2010 GHG emissions by 2035 and maintain its trajectory to meet its proportional share of the 2050 state target. Among the local strategies for achieving the GHG reduction targets are a range of activities that aim to decrease transportation-related emissions by improving mobility and reducing VMT. Specific implementation measures involve changing land uses, promoting alternative modes of travel, and enhancing vehicle fuel efficiency. As the largest jurisdiction in the region, the policies and actions of the City of San Diego can help provide resources and examples against which other jurisdictions can model their approach (more details on regional collaboration can be found in Chapter 7).
3.2.6 Summary of Additional State, Regional, and Local Goals and Actions In addition to the County and City of San Diego’s CAPs, the majority of jurisdictions in the region have also adopted CAPs, with relevant goals around VMT reduction, EV adoption, and emissions reductions for the transportation sector. Some have additionally developed targets and taken actions related to the adoption of EVs and/or the implementation of charging infrastructure.
This regional context was included in the A2Z Gap Analysis; the information in that document has been updated as part of this report and is summarized in Table 3.2 below.
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73 Table 3.2 San Diego regional jurisdictions’ relevant goals, targets, and actions that are relevant to encouraging ZEVs, EVs, and transportation decarbonization.
Jurisdiction Relevant Goals, Targets, and Actions
Regional and State Agencies
Caltrans
District 11
● Currently partnering with SDG&E to provide charging at park and ride facilities throughout the region.
● Installing corridor charging at rest areas and remote inter-city travel locations. ● Released a study in 2020 demonstrating the feasibility of building a railroad tunnel through the University City area to improve service between San Diego and Los Angeles.
County of San
Diego
● Established streamlined permitting processes in 2017, compliant with AB 1236, to encourage EV charging infrastructure in new developments.
● Adopted the Electric Vehicle Roadmap in 2019.
North County
Transit District
● Developed a Zero-Emission Bus Rollout Plan, detailing full transition by 2042. ● Planning to purchase six battery electric and eight hydrogen fueled buses by 2023.
Port of San
Diego
● Adopted the Maritime Clean Air Strategy to help the Port identify future projects and initiatives to improve health through cleaner air for those who live, work, and play on and around San Diego Bay.
SANDAG ● Adopted a Regional EV Readiness Plan in 2014 and launched Plug-In San Diego in 2015. ● Committed $2b for transportation electrification programs through 2050, including:
o $45m through 2025 to support build-out of the Level 2 charger network. o $52m through 2025 to a new regional zero-emission vehicle incentive program. o $100m through 2025 for zero-emission buses, zero-emission trucks, and associated infrastructure.
● Identified additional zero-emissions, electrification, and mode-shift opportunities through the 2021 Regional Transportation Plan and associated Big 5 Moves. ● Providing climate planning services for local jurisdictions, including the Regional Climate Action Planning (ReCAP) Framework and preparation of ReCAP Snapshots to assist local jurisdictions in monitoring CAP implementation.
● Administering the Smart Growth Incentive Program, Active Transportation Grant Program, Housing Acceleration program, and iCommute programs.
● Improving the LOSSAN rail corridor over the next 20 years, which will improve freight and passenger movement between major metropolitan areas of Southern California and the Central Coast, and from the Orange County line to the Santa Fe Depot in Downtown San Diego specifically within the region.
● Sponsored the Youth Opportunity Pass pilot program to provide free use of MTS and NCTD services to all riders 18 and under.
San Diego
County Air
Pollution
Control
District
(SDAPCD)
● Developed Community Emissions Reductions Plans to reduce cumulative exposure to air pollution in individual communities, such as the Portside Communities CERP in 2021. ● Administering grant funding through various incentive programs such as the Carl Moyer Program, which encourages a transition to cleaner-than-required engines, equipment, and other sources of air pollution.
● Updated an existing Memorandum of Understanding with CARB in 2021 to expand the District’s authority to conduct inspections and enforce air pollution regulations for mobile source pollution.
San Diego
Metropolitan
Transit System
● Developed a transition plan to convert its fleet of 800 buses to ZEV by 2040. ● Acquired thirteen battery electric buses by 2021 and will acquire a total of 25 by the end of 2022.
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74 Jurisdiction Relevant Goals, Targets, and Actions
Cities
Carlsbad ● Adopted residential and non-residential ordinances for EV parking. ● Adopted 2011 CAP goal to increase ZEV miles from 4.5% to 25% by 2035.
Chula Vista ● Currently, has 31% of alternatively-fueled fleet vehicles; continuing to work towards their CAP goal of 40% by 2020.
● Installed around 120 chargers for their fleet vehicles.
Coronado ● Identified “greening” the city’s 100 fleet vehicles as a way to reduce transportation emissions.
Del Mar ● Adopted CAP goal to increase alternatively-fueled VMT to 20% in 2020 and 30% in 2035. ● Adopted CAP goal to set aside 10% of on-street parking and in city lots for high-efficiency and clean vehicles by 2020.
El Cajon ● Plans to install 128 new EV charging stations at commercial developments and 79 new EV charging stations at multi-family developments by 2030. ● Launched a 5-year Vehicle-to-Grid pilot project with SDG&E to test electric school buses.
Encinitas ● Requires new residential units to install EV charging infrastructure. ● Multi-family developments must include EV charging infrastructure at 5% of the total number of parking spaces.
Escondido ● Plans to install 281 EV charging stations in park and ride lots by 2035.
Imperial Beach ● Encourages developers to install EV charging infrastructure for new and retrofit developments.
● Planning to assess their municipal fleet replacement timeline for switching to ZEVs.
La Mesa ● Partnered with SANDAG, SDAPCD, and local developers to develop strategies to increase EV infrastructure at existing multi-family complexes.
Lemon Grove ● Plans to adopt a zoning ordinance requiring installation of EV charging infrastructure at 5% of the total number of parking spaces at new multi-family and commercial developments.
National City ● Installed charging stations at City Hall. ● Partnered with SDG&E to install EV charging infrastructure across the City.
Oceanside ● Plans to require new single-family developments to include prewiring to enable 240-volt charging.
Poway ● Installed 11 EV charging stations around the City.
San Diego ● Adopted CAP goal to convert 90% of gas-powered municipal fleet vehicles to zero-emission by 2035.i
● Installed 57 public EV charging stations at City facilities. ● Partnered with SDG&E on its Power Your Drive project to make EV charging stations more accessible to apartment and condo dwellers, and workplace employees.
San Marcos ● Require new multi-family and commercial developments to include EV charging infrastructure at 5% of the total number of parking spaces.
Santee ● Requires all new residential and commercial developments to install e-chargers.
Solana Beach ● Collaborating with SANDAG to increase EVs in the City.
Vista ● Requires new multi-family developments to have 3% of total parking spaces equipped with EV charging infrastructure.
● Requires new commercial developments to have 6% of total parking spaces equipped with EV charging infrastructure.
Sources: San Diego Regional EV Gap Analysis, July 2021; SANDAG 2021 Regional Plan; input from San Diego jurisdictions.
i The City of San Diego’s current CAP was adopted in 2015. At the time of this publication, the city was in the process of gathering public comment on its 2021 CAP. The finalized 2021 plan may include additional commitments and/or stronger commitments for municipal fleet vehicles.
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75 3.2.7 Limitations of Regional and Local Efforts
As described above, various efforts on the local and regional level inform the direction of the San Diego region’s ability to reduce transportation-related GHG emissions. The number of entities, jurisdictions, and planning efforts with unique direct authority over different elements of transportation decarbonization underscore the need for coordinated action. It is especially important for regional and local entities to come together around shared goals and vision, despite each entity’s diverse needs, responsibilities, and direct authority.
For example, the CAP has emerged as one of the primary planning efforts that local jurisdictions undertake to describe the necessary steps to achieve GHG emissions reductions across all sectors. They are useful tools to document GHG reduction commitments and implementing actions and they can be powerful spaces to convene discussions around what is possible within a jurisdiction. However, they can also be somewhat limiting if a jurisdiction plans to utilize the CAP to streamline future CEQA reviews to evaluate GHG impacts of land use development or transportation projects. The CEQA process requires a rigorous level of evidence-based defensibility, which is not often available for many leading-edge or innovative ideas simply because they have not yet been established as evidence-based best practices. Therefore, CAPs often lack incentives to promote innovative transportation or mobility ideas that lack defensible GHG reductions.
In addition, because they are not interjurisdictional, individual CAPs’ transportation commitments can only affect local transportation emissions within that jurisdiction’s control, which may limit measures’ effectiveness at reducing regional VMT and GHG emissions. The projects that would be most effective at moving the needle on reducing VMT – such as major investments in rail infrastructure or bus rapid transit (BRT) corridors – are responsive to regional (e.g., interjurisdictional) travel patterns and needs. The land use commitments in a jurisdiction’s CAP can complement regional investments and have a major effect on creating a more compact, walkable, transit-oriented community, thereby reducing local VMT. To have the greatest effect, these land use goals and commitments must also be reflected in the jurisdiction’s General Plan, which may or may not be updated on the same timeline as the CAP.
In contrast, SANDAG’s regional planning efforts, such as the 2021 Regional Plan and efforts through the A2Z Collaborative, can help align local jurisdictions with regional agencies that implement regional transportation projects, such as MTS and North County Transit District. This can be a powerful space to convene around a shared vision and set of climate goals. However, SANDAG lacks the land use and zoning authority to maximize the investments through changes to land use development patterns that are more compact, diverse, and transit-oriented.
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76 because they are not constrained by CEQA requirements, fiscal limitations, or limited control/authority. This effort aims to identify the key priority actions that can be taken at each level of authority throughout the San Diego region to maximize a coordinated effort at reducing VMT, while maintaining access to opportunity and destinations, and accelerating EV and ZEV adoption for those trips that must be taken in a vehicle.
3.3 Transportation Modeling & Emissions Forecasts
In support of this report, Fehr & Peers has undertaken a review of the assumptions and outcomes of the SANDAG regional model and Evolved Energy’s EnergyPATHWAYS model described in Appendix A. There are fundamental differences between the two models. SANDAG uses an activity-based model (ABM) that simulates individual and household transportation decisions at a detailed level. The most current model is ABM2+, which is being used to support the 2021 Regional Plan. EnergyPATHWAYS estimates energy use and GHG emissions given a specific electrification trajectory and fleet composition.
SANDAG’s ABM2+ simulates travel behavior in the San Diego region using land use and transportation network data to estimate VMT and estimate corresponding GHG emissions.
ABM2+ starts with a street-based active transportation network, a highway network, and a transit network. The resident transportation model, disaggregate models, and aggregate models are executed, and the resulting trip tables are summed up and used by an iterative traffic assignment process. The outputs – specifically, VMT by speed bin and vehicle classification – are then converted off-model to greenhouse gas emissions using Emission Factors (EMFAC) emissions factors.
EnergyPATHWAYS is a stock accounting tool from Evolved Energy that quantifies all energy infrastructure. The transportation portion of the model uses service demand projections, existing vehicle stock, and efficiency measures to estimate total emissions. The model can be made applicable to varying geographies across the nation by modifying the underlying parameters. In the context of California, it uses the 100% ZEV sales by 2035 goal and makes assumptions about adoption of EV technologies.
i In this model, decarbonization comes from
fuel shifts, not mode shifts. As such, many factors that are central to ABM2+, such as VMT, are not considered.
For the purposes of this chapter, the 2021 Regional Transportation Plan and SANDAG’s ABM2+ are discussed further. At the conclusion of this chapter, Appendix 3.A provides a summarized comparison between the two models. Appendix A of the report provides full technical
i For more information on the EER modeling assumptions, see Appendix A.
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77 documentation for the EnergyPATHWAYS model.
3.3.1 SANDAG Emissions Forecasts
As described above, SANDAG’s 2021 Regional Plan includes policy and transportation investment initiatives that are referred to as the 5 Big Moves, which aim to deliver an efficient and equitable transportation system that meets regional per capita GHG reduction targets assigned by the California Air Resources Board. However, these policies and actions are not sufficient on their own to meet the requirements of EO S-3-05 and EO B-55-18, as described in the emissions forecasts included in the 2021 Regional Plan Environmental Impact Report (EIR).
In order to reach deep decarbonization goals, additional efforts, such as the policies described in section 3.5 of this chapter, will be necessary both to rapidly electrify the surface transportation sector and to reduce VMT.
The 2021 Regional Plan EIR evaluates environmental impacts related to regional growth and land use change as well as the transportation network improvements and programs of the 5 Big Moves together because the per-capita CO
2 emissions from vehicles addressed by state targets
are influenced by the combined effects of both components. ABM2+ models the effect of the 5 Big Moves in conjunction with the rest of the 2021 Regional Plan through four forecast scenarios: Baseline Year 2016, interim years 2025 and 2035, and Horizon Year 2050.
Compared to existing conditions, the EIR shows that the regional growth, land use change, and transportation network improvements included in the 2021 Regional Plan would result in a reduction of GHG emissions across all sectors for all interim and horizon years. These reductions are summarized in Figure 3.1, which shows GHG impact of Passenger Cars and Light- Duty Vehicles with and without the SAFE Rule Impact (the Safer Affordable Fuel-Efficiency Vehicle Rule, also known as the SAFE Rule, which was adopted in 2019 and rescinded in 2021, set national fuel economy standards instead of California standards). Passenger Cars and Light- Duty Vehicles emissions are also forecasted to decrease for all interim and horizon years.
Heavy-Duty Trucks and Vehicles emissions are forecasted to remain the same from 2025 onward. Rail emissions are forecasted to increase between 2016 and 2050. Projected annual emissions in 2045 and 2050 (18 million MTCO
2e across all sectors and 7.5 million MTCO2e for
the Surface Transportation sector, including Passenger & Light-Duty with no SAFE Rule impact, Heavy-Duty & Trucks, and Rail) would be inconsistent with the levels of reductions required by EO S-3-05, EO B-30-15, and EO-B-55-18.i
i EO S-3-05 requires a reduction of GHG emissions to 80 percent below 1990 levels by 2050. EO B -30-15 requires a reduction of GHG emissions to 40 percent below 1990 levels by 2030. EO B -55-18 requires carbon neutrality across all sectors by 2045.
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78 Figure 3.1 Summary of 2016 Greenhouse Gas Inventory and Greenhouse Gas Projections, (SANDAG 2021 Regional Plan EIR Table X.3).
Per SB 375, specific GHG emissions reduction targets for the transportation sector are not yet established for Horizon Year 2050, but the target established for SANDAG for 2035 is to reduce per capita CO2 emissions from passenger cars and light-duty vehicles to 19 percent below 2005 levels. As shown in Table 3.3, implementation of the 2021 Regional Plan would reduce per capita CO2 emissions from this sub-sector of Surface Transportation to 20 percent below 2005 levels by 2035, and therefore would meet SB 375 targets.
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79 Table 3.3 SB 375 GHG reduction targets under the proposed plan from passenger vehicles and light -duty trucks, 2035, (2021 Regional Plan EIR Table 4.8-9).
Per Capita Reductions
from 2005 Levels
Per Capita Reduction under the Proposed Plan (On-Model Results Only) -19.30% Per Capita Reduction under the Proposed Plan (Off-Model Results Only) -3.03% CARB Adjustment Factor for EMFAC 2007–2014 1.70%
Induced Demand Adjustment Factor 0.20%
Per Capita Reductions -20.40%
CARB Target -19%
The EnergyPATHWAYS model shows that the region needs to reduce transportation GHGs by 25%-47% by 2030, 51%-82% by 2035, and 100%-109% by 2050 in order to reach the State’s emissions goals. SANDAG’s estimates show projected reductions of 27% by 2030, 34% by 2035, and 34% by 2050. Therefore, SANDAG’s policy landscape meets the low end of the range that has been modeled by the EnergyPATHWAYS model for the horizon year of 2030 (the “Electrification Delay” scenario), but does not meet the range of scenarios modeled after the 2030 horizon year. These gaps suggest that current policies do not put the region on track to meet State emissions reductions goals.
3.4 Decarbonization Strategies: Policy Pathways to Close the Emissions Gap Based on the regional policy context summarized above, including SANDAG’s 2021 Regional Plan, the County’s Electric Vehicle Roadmap, local jurisdiction policies and guiding documents, and the A2Z Gap Analysis, the San Diego region has a strong policy foundation for reducing emissions related to transportation through accelerated alternative vehicle and fuel technology improvements, and accelerated VMT reduction. The remainder of this section describes the ways in which the region’s jurisdictions can accelerate actions needed to achieve regional decarbonization of the transportation sector.
3.4.1 Accelerate Alternative Fuel and EV Adoption
Alternative fuels for transportation are those derived from sources other than petroleum.
Electricity is a cost-effective, secure, and powerful alternative fuel that has been the focus of decarbonization in the transportation sector, especially in passenger vehicles and transit vehicles. Within the 5 Big Moves and the 2021 Regional Plan more broadly, electrification is identified as a major factor in reaching regional GHG emissions reduction targets by:
● Establishing programs to incorporate EVs into Flexible Fleets and Transit Leap ● Including incentive programs that could increase the number of EVs and charging stations throughout the region and within Mobility Hub areas.
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80 Complete Corridors support alternatives to single occupancy driving, including modes such as transit, shared rides, and active transportation, and would help the San Diego region reach its 2030 decarbonization goals. The 2021 Regional Plan also supports electrification of the region’s transit buses and supports the state’s Innovative Clean Transit regulation. Per the plan documentation, it is likely that future high-speed rail projects will be powered by a combination of both diesel and electricity. In order to accelerate decarbonization through this strategy, SANDAG would need to adopt an aggressive implementation timeline for Complete Corridors and Transit Leap, focusing first on implementation in the parts of the region where transit will be most viable and well-utilized. While high-quality transit expansion is most efficient along corridors that are heavily populated and traveled, county-wide mass transit adoption will require transit infrastructure investments, such as BRT and rail, that reach rural and backcountry areas. Rather than only fulfilling current transit demand, SANDAG can craft a transit-for-all plan for a systemic adoption of public transit. Additionally, this plan should ensure that investments are located in a manner that does not contribute to habitat fragmentation.
The 5 Big Moves documentation also mentions several partnerships and policies that can assist with public charging and hydrogen fueling stations build-out. These include the CALeVIP San Diego County Incentive Project, which began providing rebates for placement of public level 2 and direct current fast charging stations in late 2020. The County is coordinating with SDG&E to manage the demands that EV charging places on the grid. SANDAG and SDG&E are also working to provide programs that install charging stations for workplaces, multi-unit dwelling communities, and medium- and heavy-duty vehicles. In order to accelerate decarbonization through this strategy, SANDAG and SDG&E would need to increase the levels of incentives and rapidly advance EV charging infrastructure installations, focusing first on Communities of Concern and then in places where transit is not yet viable.
In addition to the electrification-related components of the 5 Big Moves , the A2Z EV Gap Analysis articulates actions and policies to accelerate EV adoption in the San Diego region.
Although the main goal of the Gap Analysis was to identify needs in order to inform a long-term strategy, the report captured some initial solutions. These include:
● Decreasing the upfront costs of EV ownership through incentives, targeting both the new and secondary markets;
● Leveraging cooperative buying for medium- and heavy-duty fleets; ● Exploring alternatives to vehicle -purchase incentives, includin g low -emission zones, EV mandates, ordinances, or registration controls to enforce emissions standards; ● Streamlining permitting for charging infrastructure;
● Prioritizing infrastructure in communities of concern; ● Coordinating education campaigns for end use rs, property owners, and frontline salespeople; and
● Providing workforce training for commercial drivers and automotive maintenance workers.
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81 3.4.1.1 Downscaled Geographic EV Adoption Targets
The 2021 Regional Plan identifies an EV population target of 771,000 across the San Diego region by 2030, of which approximately 762,000 are light-duty vehicles or vehicles operated by Transportation Network Companies (TNCs). Based on the current distribution of registered EVs in the region, we identified which jurisdictions will need to accelerate adoption policies most aggressively to meet the stated goals. Table 3.4 shows the share of regional population within each San Diego regional jurisdiction, the share of total regional VMT, the current number of EVs, the current number of vehicles, and the proportion of EVs as a share of each jurisdiction’s vehicle population. Figure 3.2, following the table, shows the share of EVs as a proportion of all vehicles, by jurisdiction.
Table 3.4 Jurisdiction-level EV population, population share, and VMT share in the San Diego region.
Jurisdiction Total #
EVs
(2020)
Total #
Vehicles
(including
EVs) (2020)
Share % of
Total Vehicles
that are EVs
(2020)
Total Vehicle
Ownership
Share %
(2020)
Share of
Regional
Population
(2020)
Share of
Regional
VMT
(2012)
Unincorporated
San Diego County
7,838 473,689 1.7% 16.9% 15.4% 15%
Carlsbad 3,804 92,092 4.1% 3.3% 3.4% 4.5%
Chula Vista 2,708 205,797 1.3% 7.3% 8.1% 5.7%
Coronado 395 12,727 3.1% 0.5% 0.7% 1.0%
Del Mar 861 13,358 6.4% 0.5% 0.1% 0.3%
El Cajon 1,183 126,488 0.9% 4.5% 3.1% 2.9%
Encinitas 2,318 51,148 4.5% 1.8% 1.9% 2.1%
Escondido 2,222 139,093 1.6% 5.0% 4.5% 4.5%
Imperial Beach 128 17,299 0.7% 0.6% 0.8% [n.d.]i
La Mesa 967 54,751 1.8% 2.0% 1.8% 1.9%
Lemon Grove 145 20,861 0.7% 0.7% 0.8% 0.6%
National City 145 42,934 0.3% 1.5% 1.8% 1.7%
Oceanside 1,979 112,863 1.8% 4.0% 5.3% 4.3%
Poway 1,240 40,736 3.0% 1.5% 1.5% 1.9%
San Diego 25,337 1,179,150 2.1% 42.1% 42.6% 46.3%
San Marcos 1,876 73,657 2.5% 2.6% 2.9% 2.7%
Santee 544 44,691 1.2% 1.6% 1.7% 1.4%
Solana Beach 554 10,580 5.2% 0.4% 0.4% 0.6%
Vista 1,208 88,872 1.4% 3.2% 3.0% 2.6%
TOTAL 55,452 2,800,786 n/a 100% 100% 100%
Notes: 1. EV population and total vehicle population data from California Energy Commission (2020) .7 2.
Population data from American Community Survey 5-Year Estimates (2016-2020),8 extracted by jurisdiction.
Unincorporated San Diego County values calculated as the difference of all jurisdictions and the total county population. 3. VMT data from SANDAG ABM1 (2012).9 Total VMT is calculated using the Origin-Destination method at the TAZ level and then aggregated to the jurisdictional level, which may result in some double -counting of trips but overall reflects a reasonable proportional share of the County’s VMT.
i No VMT data were available for Imperial Beach at the time of the analysis.
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82 Figure 3.2 EV share of all vehicles, by jurisdiction in 2020. Darker colors represent higher shares of EVs. Source: California Energy Commission, 2020. Created by Fehr & Peers, 2022.
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83 To show where policy efforts can be focused to help accelerate EV ownership efforts, the countywide 2030 EV targets can be downscaled to the jurisdictional level. Table 3.5 shows the future target number of EVs based on three alternative methods of calculation:
● Based on population share
● Based on VMT share
● Based on vehicle ownership share
There is no perfect way to downscale EV targets to the local jurisdictional level. Basing the future target on population would follow the A2Z approach to determining the target number of EVs in the San Diego region as a proportion of California’s targets. However, this would produce an overestimated target in places where vehicle ownership rates are lower than average. Basing the future target on VMT would produce more aggressive targets in places where people drive longer distances. Basing the future target on vehicle ownership would reify the existing vehicle ownership patterns, which reflect the current inequities of EV ownership due to the cost of purchasing a vehicle as well as existing land use and travel behavior patterns.
These travel patterns may change in the future as a result of future land use development patterns, encouraging more transit-oriented development (discussed further in the section to follow). These downscaled targets are intended therefore to reflect a range of reasonable order of magnitude for each jurisdiction’s EV population in 2030.
To support the local acceleration of EV adoption towards the targets identified above, it will also be necessary to accelerate the rollout of EV charging infrastructure. The County and SANDAG can enhance the Plug-In San Diego Electric Vehicle Charging Map to provide improved modeling for charging infrastructure location suitability at a regional scale. i SANDAG and the
County can collaborate with local jurisdictions to encourage them to undertake a local EV Infrastructure Siting Plan, to identify more granular placement locations, and to support infrastructure investments in Communities of Concern.
i The Plug-In San Diego EV Charging Stations Map can be found at https://evcs.sandag.org/ , which includes methodological information about how the TAZs were analyzed to identify EV trip end percentiles.
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84 Table 3.5 Downscaled jurisdiction targets to meet regional A2Z EV goals of 762,000 passenger and TNC EVs across the San Diego region by 2030.
Jurisdiction Total # EVs
(2020)
Future Target # EVs
Based on
Population Share
Future Target # EVs
Based on VMT
Share
Future Target # EVs
Based on Vehicle
Ownership Share
Unincorporated
San Diego
County
7,838 117,392 113,940 128,875
Carlsbad 3,804 26,228 34,303 25,055
Chula Vista 2,708 61,616 43,693 55,990
Coronado 395 5,622 7,592 3,463
Del Mar 861 993 2,374 3,634
El Cajon 1,183 23,669 22,073 34,413
Encinitas 2,318 14,435 16,294 13,916
Escondido 2,222 34,477 34,574 37,843
Imperial Beach 128 6,266 [n.d.]i 4,706
La Mesa 967 13,802 14,152 14,896
Lemon Grove 145 6,130 4,315 5,676
National City 145 14,062 13,125 11,681
Oceanside 1,979 40,277 32,445 30,706
Poway 1,240 11,412 14,849 11,083
San Diego 25,337 324,276 352,920 320,807
San Marcos 1,876 22,058 20,537 20,040
Santee 544 13,160 10,958 12,159
Solana Beach 554 3,049 4,198 2,878
Vista 1,208 23,075 19,657 24,179
TOTAL 55,452 762,000 762,000 762,000
Note: Percentages from Table 3.4 multiplied by A2Z’s Countywide target of 762,000 passenger vehicles and TNC EV to determine jurisdictional targets.
3.4.1.2 Policy Opportunity Areas to Accelerate ZEV/EV Adoption Jurisdictions within the San Diego region have a great deal of room to strengthen policies related to transitioning to EV fleets and providing sufficient charging infrastructure. Based on the summary of efforts described in the Regional Policy Context section of this chapter, along with the findings from the A2Z Gap Analysis, there is a wide variety of policies and actions that have been informally or formally adopted by jurisdictions across the San Diego region, which range from more encouragement-based to more requirement-based. There is also variation in how these policies apply to different types of land use and development. The variety of policies and actions are summarized in Figure 3.3. Additionally, more information on local authority and local policy opportunities can be found in Chapter 8 and Appendix B of this report.
Policies shown on the left of Figure 3.3 will likely be insufficient to meet aggressive EV adoption goals, whereas policies shown on the right would be more effective at meeting aggressive EV adoption goals. Policies on the top of Figure 3.3 have a narrower application and policies on the
i No VMT data were available for Imperial Beach at the time of the analysis.
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85 bottom can be applied more broadly throughout the region. Thus, policies farther to the right and farther to the bottom are likely to be both the most effective and to have the broadest impact. For example, a policy requiring private parking lot owners to install EV chargers will be more effective than a policy that encourages them to do so (farther to the right) and a requirement in existing development as a retrofit will have a broader impact than a requirement on only new development (further to the bottom).
Figure 3.3 A spectrum of policy options to accelerate EV adoption. Policies that are more likely to be effective are further right and policies that are more likely to have a broad application are further down. Thus, policies in the bottom right are predicted to be the most effective and to have the broadest application of the policy measure shown where the top left is predicted to be the least effective and to have the narrowest application of the policy measures shown.
To accelerate decarbonization most effectively, regional jurisdictions can consider moving their own policies along the spectrum from more encouragement-based to more requirement-based and expanding the reach of requirements and ordinances to cover more land use contexts. To support the accelerated adoption of the strongest and most effective policies, jurisdictions in the region can offer more appealing incentives to developers for installing charging equipment, streamline development processes and infill benefits, and provide readily accessible information for property owners and vehicle owners.
Where collaboration across jurisdictions is required, the County or a Decarbonization Regional Steering Committee proposed in Chapter 7 can promote partnership across jurisdictions to Oct. 11, 2022
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86 support workforce development goals, share information and lessons learned, and support State-level advocacy to bring implementation funding to the San Diego region. Table 3.6 summarizes ways in which the County and other jurisdictions within the region can implement these actions and policies or partner to make progress.
3.4.1.3 Continue to Explore Alternative Fuels
For some transportation modes, the path to decarbonization may be a transition to renewable fuels such as hydrogen, natural gas, propane, and vegetable- and waste-derived oils, rather than a fully electrified fleet. Electricity-powered batteries currently do not have the capacity to support large elements of the regional transportation system such as shipping, long-haul trucking, and aviation. These elements may rely on alternative fuels other than electricity and on the development of technology and infrastructure to support them. Among the co-benefits of investing in alternative fuel production and transmission is the opportunity to transition workers out of gas and fossil fuel industries into new green jobs. A waste-to-energy fuel source would have the co-benefit of reduced waste in landfills. Though decarbonization of these transportation methods, such as aviation, shipping, and long-haul trucking, are outside of the scope of this analysis, they are worthy of additional study.
Many of these technologies are still under development. Until there is a clear pathway to deploying these alternative fuel options, the County and other jurisdictions can support these alternative fuels primarily through collaboration, investment, and partnership in research opportunities, and by participating in regional efforts to advance the field. Once technological solutions are available and commercially viable for these fuel sources, the Regional Decarbonization Framework and its implementation plans should be updated and should revisit the approach to planning, funding, and coordinating infrastructure build outs with utility operators.
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87 Table 3.6 Electrification strategies and implementation approach, including partnership opportunities across jurisdictions and with agencies.
Strategy Partnership
Opportunity
County & Local Jurisdiction Implementation Approach
Set Public EV Charger
Target
✔ Update 2019 EV Roadmap to include more aggressive targets; continue to partner with A2Z Collaborative to downscale jurisdictional targets on appropriate roadways; identify partnership opportunities with those jurisdictions that have made the least progress toward their targets to share information and successful implementation strategies
Set Fleet Adoption Target ✔ Update 2019 EV Roadmap to include more aggressive targets; identify partnership opportunities with those jurisdictions that have made the least progress toward their targets to share information and strategies to accelerate fleet transition Set-Aside Public Parking
Spots for Clean Vehicles
Adopt requirements in zoning codes that apply to clean air vehicles as defined by CalGreen
Encourage EV Charging
Infrastructure at
Development Projects
Encouragement through incentives can complement stronger policy requirements
Require New Development
to be “EV-Ready”
Adopt requirements in zoning codes that apply to clean air vehicles as defined by CalGreen; adopt ordinance that requires retrofitting
Require EV Charging
Infrastructure to be
Installed at Developments
Adopt requirements in zoning codes; adopt ordinance that requires retrofitting
Offer Consumer Incentives
to Purchase EVs
✔ Partner with SANDAG and SDAPCD to accelerate and increase the amount of incentives, reduce barriers to accessing incentives, and promote aggressively in CoCs
Provide Readily-Accessible
Information to Property
Owners and Vehicle
Owners
✔ Partner with A2Z to reach private entities, local governments, SDG&E, CCAs, and community groups to understand information gaps; partner with SANDAG to produce coordinated educational materials and aggressively promote
Train Workforce to
Support EV Ecosystem
✔ Partner with educational institutions to develop workforce training needs; increase funding to existing programs. Coordinate with SANDAG on workforce training on Electric Vehicle
Infrastructure Training Program (EVITP).
Collaborate to Share
Information Across Region
✔ Continue to partner with A2Z Collaborative
Engage in State-level
Advocacy to Bring
Implementation Funds to
San Diego County
✔ Continue to partner with A2Z Collaborative
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88 3.4.2 Accelerate Reduction of VMT
Current San Diego region actions and policies to reduce VMT are articulated in the 2021 Regional Plan across the 5 Big Moves and regional land use development policies. SANDAG is required to demonstrate how the region will reach targets by reducing VMT. As such, plans for the 5 Big Moves describe ways to influence behavior change and support denser land uses. To meet the targets, single occupancy vehicle trips need to be replaced with biking, walking, transit, and shared rides. The 2021 Regional Plan articulates the following strategies to reduce VMT:
● Complete Corridors support a greater variety of transportation options, and the initiative promises investments in infrastructure to make alternative transportation more attractive. Complete Corridors also explore congestion pricing as a tool for reducing demand and VMT during peak times.
● Flexible Fleets provide convenient and affordable alternatives to driving alone and help to reach communities with limited transit access.
● Transit Leap calls for a multimodal high-speed, high-capacity, high-frequency transit network that appeals to people who otherwise drive alone. In the 5 Big Moves, SANDAG states that public transit will “continue to be the most efficient way to move many people,” therefore reducing VMT.
● Mobility Hub areas are communities with a high concentration of people, destinations, and travel choices. Higher density Mobility Hub areas have a supportive mix of land uses that can help to encourage ridership and usage of the Transit Leap system. Mobility Hub areas in less dense areas may rely more on Flexible Fleets in order to connect residents to transit.
Table 3.7 provides details on VMT-reduction strategies that would support acceleration of VMT reduction within the San Diego region. The County, cities, and jurisdictions can only influence the zoning code within their jurisdictional boundaries, however they should all promote information sharing, evaluation to prove effectiveness of strategies, and inter-jurisdictional collaboration to encourage denser, more walkable, and more transit-oriented development.
SANDAG and the County can also initiate the exploration of cross-jurisdictional land use policies such as transfer of development rights to encourage densification in places where multi-modal investments are already underway, and also serve to preserve undeveloped and agricultural lands that can serve as carbon sinks.
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89 Table 3.7 VMT reduction policy strategies and County & local jurisdiction implementation approach. The figure also notes which VMT policy strategies also have electrification opportunities.
Policy Strategy Electrification
Opportunity
County & Local Jurisdiction Implementation
Approach
Expand geographic reach of bus and
rail services in areas where
development can support transit
use
✔ Identify corridors with land use patterns that can
support transit; partner with transit agencies to
fund additional miles of transit service
Invest additional transit service
hours in places where transit is
productive and high occupancy,
focused on infill locations
✔ Identify highest-performing transit corridors;
partner with transit agencies to fund additional
hours of transit service
Provide incentives and regulatory
relief to facilitate higher density
infill and transit-oriented
development
Modify zoning code along transit corridors to allow
denser development; streamline permitting
process for developments along transit corridors;
leverage parking reductions, density bonuses, and
other incentives to encourage development in
transit corridors.
Encourage local agencies to form partnerships with
each other to explore the potential for a legal
mechanism to transfer development rights from
undeveloped or agricultural lands within one
jurisdiction to infill areas in another jurisdiction.
Disincentivize development in rural
(or non-infill) areas that cannot
support efficient transit use or
multi-modal transportation options
Utilize transit opportunity areas, infill areas, and
VMT efficiency metrics to encourage compact
development and discourage exurban and very
rural development
In existing rural, non-infill, or
underserved transit areas, invest in
TNC partnerships to ensure
sufficient access to opportunities
✔ Identify limited-access areas that would benefit
from additional mobility resources; develop TNC
partnerships to support travel using higher-
occupancy vehicles
Incentivize high occupancy personal
vehicle use
Investigate opportunities to implement pricing
structures (cordon pricing, HOT lanes, etc.) that
incentivize high occupancy vehicles
Design walkable communities,
particularly in places where
compact development patterns are
already established
Adopt pedestrian-oriented design guidelines for all
new development; reduce or remove parking
minimums in walkable neighborhoods
Expand pedestrian and bicycle
facilities, using a network approach
to ensure destinations are served,
corridors and intersections are
Update county bicycle and pedestrian planning
documents; partner with SANDAG to accelerate
implementation of 2010 San Diego Regional
Bicycle Plan; develop Pedestrian Safety and/or
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90 equally comfortable and safe Vision Zero and/or Local Road Safety Plan Expand modal options including a
wide range of e-bikes, e-scooters,
bikeshare, micro transit, shuttles,
and TNC partnerships
✔ Partner with SANDAG to build out network of
Mobility Hub areas where shared vehicles and new
mobility services can be found. Could involve
coordination on e-bike incentive programs and
expansion of the County Pedal Ahead program.
Conduct programs to ensure people
of all abilities and ages are
comfortable using bicycle and
pedestrian facilities
Partner with mobility advocacy organizations to
fund expanded education programming;
implement periodic regular open streets events
throughout the region.
Encourage Transportation Demand
Management (TDM) programs that
incentivize some proportion of
telework, telemedicine, remote
learning and use of transit
Develop County TDM ordinance and
Transportation Management Organization (TMO)
to work with employers and service providers.
Expand broadband in places where
it is weak to allow more employees
to work from home and enable
substitution of other types of trips,
such as medical visits, with virtual
visits
Conduct broadband gap analysis; seek funding to
improve communications infrastructure in areas
that lag; require enhanced communication
technology in all new development through TDM
ordinance. Where relevant, coordinate with
SANDAG to build on the findings of the broadband
gap analysis completed in the Regional Digital
Equity Strategy and Action Plan (2021).
Restructure distribution centers to
enable more efficient delivery
patterns that enable short-haul
electrified freight vehicles and AV
delivery
✔ Conduct electrified freight study to understand
where opportunities for distribution efficiencies
exist; modify zoning code to encourage smaller
distribution centers in centralized locations close
to population centers. This could involve
coordination with SANDAG and the Port on
Regional MD/HD EV Blueprint development for
goods movement and transit, SANDAG’s
Sustainable Freight Implementation Strategy with
Imperial County, and the Port’s Maritime Clean Air
Strategy.
Address emissions from school-
related trips
✔ Coordinate with programs such as the California
Energy Commission’s School Bus Replacement
Program to replace diesel school buses in priority
communities with zero-emission vehicles.
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91 3.4.2.1 Geographic Opportunity Areas for VMT Reduction The above strategies are likely to be successful in different locations across the region. Transit- oriented strategies will be most successful in places where the density of population and development can support efficient transit vehicle use, or in “infill” locations where walking and biking strategies will likely be more effective. In non-infill locations, strategies related to trip reduction through TDM, partnerships with TNCs or County taxis that prioritize electrification and high-occupancy ridership, and enhancing broadband service may be more successful strategies to reduce VMT.
Figure 3.4 shows the SANDAG Mobility Hub areas overlaid on the transportation analysis zones (TAZ) in the San Diego region that meet the following definition of infill:
● Household density above 385 housing units/square mile (selected based on the U.S.
Census definition for urban area);
● Intersection density above 128 intersections/square mile (matches Frost (2018) average value for ‘Urban Places’);
10 and
● A Job Accessibility value of 12.73 (average value for local employment accessibility in Salon (2014)).11
Over time, additional areas may become well-suited for infill-oriented VMT reduction strategies as they meet higher population density thresholds. Figures 3.5 and 3.6 show that population density is anticipated to change from 2012 (Fig. 3.5) to 2035 (Fig. 3.6), creating more opportunity for future expansion of infill-oriented and transit-oriented strategies.
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92 Figure 3.4 Transportation analysis zones (TAZs) which meet the definition as an infill area (dark blue) and SANDAG Mobility Hub areas (light purple) . Source:
SANDAG Series 13 Base Year Model (2012). Created by Fehr & Peers, 2022.
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93 Figure 3.5 2012 population density (population per square mile) by TAZ. Darker colors represent denser areas. Source: SANDAG Series 13 B ase Year Model (2012). Created by Fehr & Peers, 2022.
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94 Figure 3.6 2035 Population Density (population per square mile) by TAZ. Darker colors represent denser areas. Source: SANDAG Series 13 B ase Year Model (2035). Created by Fehr & Peers, 2022.
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95 3.5 Key Actions
This chapter summarizes opportunities to accelerate EV adoption and VMT reduction based on existing countywide policies and patterns of vehicle ownership, travel behavior, and land use development in order to address the relevant gaps in EV purchase, EV charging infrastructure, and VMT reduction that create challenges in reaching deep regional decarbonization.
Recommended areas for accelerated action will help the region meet more aggressive decarbonization targets that have been established for California but are not yet satisfied by the guiding policies in the region.
Key actions that will accelerate decarbonization of the transportation sector are largely grouped into two categories: decarbonization of vehicles and reduction of VMT. In order to make progress towards deep decarbonization goals, the key actions that the region and local agencies can pursue over the next 10 years will require a mix of both strategies. Moving forward, it will be critical to share information and successful implementation strategies across jurisdictions, and advocate for funding and coordination at the state level.
Neither vehicle decarbonization nor any VMT reduction strategy are a silver bullet. To meet local and state transportation decarbonization targets, the County and local jurisdictions will need to pair vehicle decarbonization strategies with land use changes that reduce trip distance and car dependence. Strategies that simply focus on the shift to EV will not lower VMT, and some VMT reduction strategies may limit movement. Therefore, decision-makers must decide how to best phase in EV without encouraging additional driving, and how to best lower VMT without limiting access to destinations and opportunities.
The details provided in Table 3.8 (vehicle electrification policies) and Table 3.9 (VMT reduction policies) are intended to allow local jurisdictions to make effective comparisons between decarbonization investments, and thus enable policy prioritization. This comparison includes information on decarbonization potential, feasibility, co-benefits, trade-offs, and equity considerations for each policy. It identifies which actions are the highest priority to initiate, which geographic areas need more focus, where local jurisdictions have control, and where actions could benefit from regional coordination and collaboration. To further aid decision- making, Table 3.8 includes information about cost efficiency of electrification actions, and Table
3.9 includes quantifiable VMT reduction potential.
VMT reduction potential data has been adapted from the Handbook for Analyzing Greenhouse Gas Emission Reductions, Assessing Climate Vulnerabilities, and Advancing Health and Equity, a document assembled by the California Air Pollution Control Officers Association, Caltrans, and the Sacramento Metropolitan Air Quality Management District. 12 The Handbook includes a
range of measures that are frequently used to promote transit and alternative transportation, Oct. 11, 2022
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96 support use of alternatively fueled vehicles, or encourage land use planning practices that reduce vehicle trips and VMT. It is worth noting that when considering which measures are applicable for a jurisdiction or implementation area, the locational context should be incorporated into the decision-making process. Many VMT reduction strategies are best suited for denser landscapes, and the quantification methods and assumptions used in the handbook to determine strategy effectiveness may not be representative when applied to all geographies.
Further, the effects of combining measure reductions are not always linear or complementary.
Decision-makers should be mindful of potential interactions among different measures, and should take care to avoid overestimating the VMT reduction potential of multiple strategies that target the same type of trip or the same population. Additionally, many of the strategies (for example, land use related strategies) are already accounted for in the SANDAG regional travel demand model, so additional reductions to VMT produced by the model are not appropriate.
Finally, Table 3.10 outlines possible next steps that jurisdictions can take toward reducing VMT and accelerating adoption of ZEVs based on local context. These next steps build on the actionable items listed in Table 3.8 and 3.9, while additionally considering the relevant goals, targets, and actions of each jurisdiction from Table 3.2 as well as the current EV uptake from Table 3.4. At a minimum, all local jurisdictions should review and evaluate their own progress on the following planning efforts and subsequently update existing efforts or initiate new efforts where needed. Examples may include updating or initiating the following:
● General Plan that prioritizes compact, mixed-use development around transit corridors, affordable housing, and transportation investments that support transit service; ● Bicycle and pedestrian plans that set active transportation modeshare goals, create a network of high-quality, safe facilities that offer access to destinations on par with vehicle access, in addition to standards and guidelines that embed a Complete Streets and Safe System approach into all roadway investments;
● Climate Action Plans that set municipal fleet electrification or decarbonization targets and public EV charger targets, establish incentives for retrofitting existing development with EV charging, and create climate adaptation strategies that hedge against climate risks that could make it difficult to achieve active transportation modeshare goals; ● Safe Routes to School Plans that identify opportunities to enable walking, biking, and bussing to school; or
● Municipal codes that include design guidelines to encourage pedestrian and bicycle connectivity, to establish transportation demand management ordinances that require employers to address commute trips and offer alternatives to single-occupancy vehicle travel, and, where appropriate, to channel transportation impact mitigation fee funds from development into VMT-reducing actions.
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97 Table 3.8 Key electrification actions and selected opportunities, co -benefits, consideration, trade-offs, context, and effectiveness.
Action Opportunities and Co-Benefits Considerations and Trade-offs Context [a] Strategy Effectiveness [b]
Strategies to Accelerate EV Infrastructure Buildout
Set and meet aggressive
public EV charging target.
Funding opportunities are available at
multiple geographic scales.
Building out an effective network of EV
charging infrastructure will have
significant impacts on the transmission
grid and its reliability, and deployment
costs (including upfront unit cost,
installation, operations, maintenance,
etc.) may be prohibitive. Additionally,
reliable charging in rural areas may be
complicated by unexpected power
outages.
Roll-out in densely
developed areas may
require fewer
infrastructure- and
utilities-related costs.
Public chargers will not
directly influence uptake,
but a built-out EV charging
network is critical for EV
uptake.
Require new
development to include
EV charging and require
existing development to
retrofit parking with EV
charging.
Beginning January 1, 2023, the CALGreen
building code will require EV charging spaces
and chargers for new multifamily residential
development and hotels/motels.
Requirements for new development present
the opportunity to coordinate with SDG&E
to optimize efforts in unincorporated areas.
Additional requirements for new
construction without incentives may
dampen development. Retrofits may be
cost-prohibitive for some.
Can be an effective
strategy in urban and
rural contexts.
Amendments to building
codes will require a longer
lead time, and will have an
indirect influence on EV
uptake. Retrofit
requirements may be more
costly but more immediate.
Increase dollar value of
incentives, provide
educational resources,
and streamline
permitting process for
landowners to install EV
charging in multi-family
developments.
SANDAG and the San Diego County Air
Pollution Control District have already
partnered with the California Electric Vehicle
Infrastructure Project on the San Diego
County Incentive Project.
Installation will require technical
assistance services for electricians as well
as local governments. Available funding is
limited.
Can be an effective
strategy in urban and
rural contexts, especially
in areas of high
development.
Residential charging
infrastructure is critical for
electrification but only
indirectly influences uptake.
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98 Action Opportunities and Co-Benefits Considerations and Trade-offs Context [a] Strategy Effectiveness [b]
Partner with educational
institutions to develop
programs to meet
workforce development
needs; increase funding
to existing programs;
require certification to
install and maintain EV
infrastructure.
Infrastructure construction can employ
California Certified Electricians with EVITP
Certification. This work can support new
green jobs creation, union job creation, and
jobs for and in marginalized communities.
Governments can facilitate partnerships
with industry and trade groups as well as
existing apprenticeship programs.
Electrification will necessitate a shift from
carbon-based jobs, potentially risking
temporary job displacement.
Can be an effective
strategy in urban and
rural contexts, with
potential for greater
opportunity near city
centers where workforce
may be located and
educational institutions
are present.
Does not directly influence
EV uptake but building out
the charging network relies
on a large and skilled
workforce.
Explore measures that
would allow private
parking lot owners to
build solar arrays and sell
electricity to EV owners
who use their lots.
Would not require new utility-owned
infrastructure and would reduce the need
for new infrastructure to support existing
and future building loads. Would not impose
a cost to ratepayers.
A predominantly solar renewable
strategy is not consistent with nighttime
EV charging, as it would require daytime
storage of solar-generated electricity at
the utility level, and nighttime release
from utility storage to EV batteries. If
large scale solar EV charging takes place
at a work destination, it may not be
feasible for employers to subsidize
employee charging.
Would be most effective
in densely populated
areas with a high number
of commercial and office
destinations with parking
lots.
Will not increase EV uptake
but can increase charging
supply. May be costly but
can help build long-term
energy resilience.
Construct commercial EV
charging hubs with
special rate sharing
agreements for small
fleets and small
businesses.
SDG&E’s ongoing “Power Your Drive”
program has a goal of installing charging
infrastructure to support approximately
3,000 medium- and heavy-duty EVs.
Installation will require technical
assistance services for electricians as well
as local governments. Available funding is
limited.
Would be most effective
in densely populated
areas with a high number
of commercial and/or
industrial destinations.
Commercial charging
infrastructure is critical for
electrification but only
indirectly influences uptake.
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99 Action Opportunities and Co-Benefits Considerations and Trade-offs Context [a] Strategy Effectiveness [b]
Strategies to Accelerate EV Uptake
Increase dollar value and
streamline consumer
vehicle purchase
incentives with
application to both new
and used vehicles, and
increase dollar value and
opportunities to retire
gas vehicles.
The San Diego County Air Pollution Control
District’s Clean Cars 4 All and Goods
Movement Emission Reduction Program
supports the acceleration of EV. 28% of the
California Energy Commission’s Clean
Transportation Program Funding is
dedicated to projects located in
disadvantaged and/or low-income
communities. Further incentives may reduce
barriers to access for priority communities.
Application processes could be
streamlined. Coordination on eligibility
requirements needs to be considered.
Funding should be identified to offset
potential losses from lowered gas tax
revenues.
Can be an effective
strategy in urban and
rural contexts, and
especially in
disadvantaged or low-
income communities.
Will directly accelerate EV
uptake.
Diversify types of small
EVs and ZEVs that are
eligible for consumer
purchase incentives.
Encouraging accelerated uptake of small
EVs, such as scooters, e-bikes, and
neighborhood electric vehicles (NEVs) as
well as other types of ZEVs, such as
hydrogen fuel cell vehicles, can better meet
diverse and specific travel needs. Emerging
EVs still require consumption of more
electricity than may be necessary to
complete a given trip. Replacement of
vehicle trips with small EVs can also help
achieve safety benefits for pedestrians and
bicyclists and encourage more compact,
walkable development patterns.
Requires additional funding streams. In
some cases, NEVs may not be allowed on
the local street network without enabling
legislation, ordinances, or adopted NEV
Plans.
Can be effective in urban
and rural contexts,
especially in
disadvantaged or low-
income communities
where a lower purchase
price is more attainable
and the rate of household
vehicle ownership is low.
Will directly accelerate EV
and ZEV uptake, particularly
for smaller vehicles.
Set and meet aggressive
(100%) fleet adoption
target.
EVs have the potential to improve fleet
efficiency and reduce vehicle operation and
maintenance costs. Explore cost-saving
opportunities by joining the Climate Mayor’s
Network EV purchasing collaborative.
Prioritizing implementation of new ZEV
school bus fleets can have VMT reduction
benefits as well as electrification benefits.
EVs still have well-to-wheel emissions.
Consideration must be given to the gas
and diesel vehicles that are discarded
when fleet upgrades are made. Programs
by pollution control districts and others
can help bear the financial and carbon
cost of retiring them.
Can be an effective
strategy in urban and
rural contexts.
Will directly accelerate EV
uptake.
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100
Action Opportunities and Co-Benefits Considerations and Trade-offs Context [a] Strategy Effectiveness [b]
Convert all-access
freeway or highway lanes
to HOV or HOT lanes that
permit electric, zero-
emission, and hybrid
vehicles.
HOV/HOT lane conversion can be completed
in support of SANDAG’s Complete Corridors
strategy.
HOV/HOT lane conversion may induce
driving and increase VMT over time by
adding capacity to the roadway system.
This can, to some extent, be mitigated if
HOV lanes require 3+ occupants and HOT
lanes price usage to reflect the true cost
of emissions as well as the time travel
benefits.
Would be applied to
highways and/or
freeways.
Does not directly influence
EV/ZEV uptake, but may
encourage a quicker
transition if EVs/ZEVs are
offered discounted access
into HOT lanes or a lower
occupancy threshold for
HOV lanes.
Note:
[a] Context in which the strategy or action will be the most impactful. [b] High-level assessment of how directly and how effectively this strategy will influence EV acceleration/uptake.
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101
Table 3.9 Key VMT actions and selected opportunities, co-benefits, consideration, trade-offs, context, and VMT/GHG reduction potential.
Action Opportunities and Co-Benefits Considerations and Trade-offs Context [a]
VMT & GHG
Reduction Potential [b]
Provide incentives and
regulatory relief to
facilitate higher density
infill and transit-
oriented development.
Areas that can support efficient transit
use or multi-modal transportation
options can prevent development into
natural lands. Land use policies can
facilitate the opportunity for affordable
housing opportunities and assist in
meeting the housing crisis. Opportunity
for community benefits agreements to
create opportunities for local workers
and develop amenities tailored to the
area.
Incentivizing infill and considering a regional
VMT methodology may curtail development
opportunities in more rural communities.
Therefore, in existing rural, non-infill, or
underserved transit areas, the County
should invest in TNC partnerships prioritizing
electric and high-occupancy vehicles to
ensure sufficient and continued access to
opportunities while reducing reliance on
single-occupancy, combustion-engine
vehicle trips.
Most effective in
densely developed
contexts.
Up to 31% of GHG emissions
from project-scale VMT in
urbanized areas.
Disincentivize
development in rural (or
non-infill) areas that
cannot support efficient
transit use or multi-
modal transportation
options.
Potential for electrification and high-
occupancy vehicles to be prioritized.
Prevents opportunity and necessary
infrastructure for the entirety of San Diego
County to shift to sustainable means.
N/A Captured in the estimate
above.
Partner with SANDAG to
build out a network of
Mobility Hub areas
where shared vehicles
and new mobility
services can be found.
Curtail urban sprawl, create
opportunities for affordable housing near
transit, and provide transportation
options for zero vehicle households.
Mobility Hub areas tend to concentrate
transit and mobility investments in areas
that are already transit-supporting.
Only effective in densely
developed contexts.
Up to 31% of GHG emissions
from project-level VMT in
urbanized areas.
Increase street
connectivity, update
county bicycle and
pedestrian planning
documents, and adopt
pedestrian- and bicycle-
oriented design
guidelines for all new
development.
Bikeable, walkable neighborhoods near
transit, jobs and amenities promote
healthier lifestyles and social outcomes,
in addition to reducing emissions and
providing cleaner air, especially in
frontline, working-class communities of
color. Improvements to pedestrian and
bicycle infrastructure can also improve
roadway safety and reduce injuries and
fatalities related to collisions.
May involve major expenses if building a
new street network or retrofitting an
existing street network to improve
connectivity is required.
Most effective in urban
or suburban contexts.
Up to 30% of GHG emissions
from vehicle travel in the
community, depending on the
extent of build-out.
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102
Action Opportunities and Co-Benefits Considerations and Trade-offs Context [a]
VMT & GHG
Reduction Potential [b]
Reduce or remove
parking minimums in
walkable neighborhoods
Parking lots can be converted into land
uses more urgently needed by a
community, potentially bringing higher
tax revenues.
Reducing parking supply without providing
alternative transportation modes will limit
mobility/access, and may harm local
businesses.
Only effective in densely
developed contexts.
Up to 13.7% of GHG emissions
from resident vehicles
accessing the site.
Expand BRT in transit-
supporting
communities.
Rail may not be presently feasible for
some geographies. In those cases, BRT
may be considered as a stepping stone to
rail investments in the future.
BRT has a higher operator to passenger ratio
than rail and would rely on costly battery
electric buses.
Most effective in
densely developed
contexts.
Up to 11.3% of GHG emission
from vehicle travel in the
plan/ community.
Expand geographic
reach and service hours
of bus and rail services
in areas where
development can
support transit use.
Significant public health benefits in
transit-focused pathways. Collaborate
with MTS and NCTD to develop pathways
for complete streets policies, smart
growth incentives, and optimize transit
options to create inclusive bikeable and
walkable neighborhoods. Emphasizing
public transit may result in less upkeep of
roads and less demand for parking in
urban areas.
By prioritizing transit development and
improvements only in areas that can already
support transit use, unincorporated regions,
tribal communities, and less dense areas are
not given the opportunity for transit-
oriented development.
Most effective in
densely developed
contexts.
Up to 4.6% of GHG emissions
from vehicle travel in the
plan/ community. Partner with school
districts to expand
bussing using an electric
or zero-emissions fleet,
and to implement
robust Safe Routes to
School programs for
students who live within
walking/biking distance.
This would also confer public health and
safety benefits by improving pedestrian
and bicycle safety of school-aged
children, and by reducing air pollution
near schools. CARB has piloted a Clean
Mobility in Schools program, funded by
California Cap & Trade dollars, to explore
ways to accelerate implementation of
these ideas.
The San Diego region has many school
districts, most of which do not have
dedicated staff tasked with addressing
school transportation emissions or
transportation safety. Additional staff
support and funding from regional and
municipal entities would likely be required
to implement this idea.
Safe Routes to School
programs are most
effective in urban and
suburban environments.
Bussing programs may
be effective in any
context.
Substantial variation exists in
school trips (as a share of all
trips, in trip length, and in
mode share). Some highly
successful bus programs have
been shown to reduce up to
63% of school-related VMT.
Investigate
opportunities to
implement pricing
structures (cordon
pricing, HOT lanes, road
use charge, etc.) that
incentivize high
occupancy vehicles.
Can help reduce the number of single
occupancy vehicles on the road and
alleviate traffic congestion by
encouraging active transportation
modes.
Historic lack of support from the San Diego
region. Must be designed in a way that does
not further transportation inequities—
should provide a discount, rebate, or
exception for low-income residents or
workers within the pricing zone.
Can be applied in urban
and rural contexts, but
most effective in high-
use corridors.
More research is needed;
substantial variation exists for
this strategy dependent on
context.
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Action Opportunities and Co-Benefits Considerations and Trade-offs Context [a]
VMT & GHG
Reduction Potential [b]
Implement on-street
market price public
parking.
Reduces illegal loading/standing in bus
stops and travel lanes, improving transit
times. Incentivizes shifts away from
single-occupancy vehicle modes by
increasing the total cost of driving to a
location.
Potential parking intrusion on nearby streets
without priced parking. Requires staffing
costs to monitor/enforce metered spaces.
Most effective in urban
contexts where
alternatives to driving
exist.
Up to 30% of GHG emissions
form vehicle travel in the
plan/community.
Consider the potential
of TNCs and taxis (as a
publicly regulated
alternative to TNCs),
integrated into the
transit system for the
Flexible Fleet strategy’s
offering of rideshare.
May be easier to incorporate taxis into
the NextOS and Flexible Fleets initiatives
because SANDAG would be able to access
taxi planning data and ensure systems
are designed to encourage safe driving.
San Diego County taxis are regulated
locally through MTS, creating an
opportunity to employ local regulations
and promotions to hasten electrification
of the fleet. Further, taxis are regulated
under the ADA and typically have fewer
deadheading miles than TNCs.
TNCs and taxis have the potential to increase
VMT for short trips that could have been
replaced by lower carbon initiatives such as
transit or walking. This strategy would be
most effective in reducing VMT if it
emphasized multiple occupancy trips, rather
than single occupancy.
TNCs and taxis would be
most beneficial as a
first-last mile
partnership with a
municipality or transit
agency in a densely
developed area.
More research is needed to
quantify the VMT reduction
potential of taxis and TNCs;
existing research shows
varying patterns depending
on context.
Encourage smart growth
and discourage new car-
dependent development
through transfer of
development rights.
Allows higher-density, lower-VMT
“receiving areas” to purchase additional
development rights from designated
“sending areas”. Land owners in
designated “sending areas” agree to
preserve the lands from which the
development rights were sold and keep
them as natural or agricultural lands that
sequester carbon.
Requires formal, legally-binding agreements
between “receiving areas” and “sending
areas” which are likely to be different
jurisdictions with different General Plans,
zoning codes, and appetites for denser
development.
Effective at a regional,
interjurisdictional scale
that include both
“receiving areas” that
can achieve VMT
reductions through
increased development,
and “sending areas”
with opportunities to
keep undeveloped land
as carbon sinks.
More research needed to
quantify the VMT reduction
potential, and associated GHG
reduction potential from
lands that remain as
undeveloped carbon sinks.
Likely to vary greatly
depending on the extent to
which such a regional
program is adopted and
implemented.
Note:
[a] Context in which the strategy or action will be the most impactful. [b] Information on VMT reduction potential sourced from the California Air Pollution Control Officers Association Handbook for Analyzing Greenhouse Gas Emission Reductions, Assessing Climate Vulnerabilities, and Advancing Health and Equity , 2021
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Table 3.10 Key Policy Actions by Jurisdiction/Agency
Jurisdiction/
Agency EV/ZEV Next Steps VMT Reduction Next Steps
SANDAG ● Continue to expand and increase the available incentives for EV and ZEV purchase, including for small EVs such as e-bikes, scooters, and NEVs. ● Provide technical assistance to jurisdictions who want to develop an NEV Plan to enable use of NEVs on the roadway network.
● Expand A2Z Collaborative to partner with private entities (such as vehicle manufacturers and land use developers) to accelerate EV and ZEV adoption and develop educational/marketing materials for EV/ZEV transition.
● Explore programs that would enable transfer of development rights across jurisdictions.
● Explore a VMT mitigation bank/exchange program to unlock developer investment in VMT-reducing actions.
● Conduct a regional travel pricing study to understand the opportunities to re-balance incentives via road pricing, parking pricing, and transit pricing.
MTS ● Look for opportunities to accelerate the transition of the bus fleet to fully electric before 2040.
● Develop a plan to implement EV charging at all MTS parking lots. ● Expand and streamline incentive programs (such as the Youth Opportunity Pilot) to reduce the cost of transit for those who are most likely to utilize transit, such as university students.
● Work with local jurisdictions to implement aggressive transit-oriented zoning within the ½-mile surrounding every trolley stop to maximize the impact of transit investments through high-density mixed-use development.
Unincorporated
San Diego County
● Build on the San Diego County Incentive Project. Increase dollar value of incentives to buy EV/ZEV and retire gas vehicles.
● Streamline consumer vehicle purchase incentives for both new and used vehicles and provide educational resources to increase EV/ZEV uptake. ● Provide technical assistance services for electricians and local governments.
● Set aggressive municipal fleet adoption and public EV charging targets and track uptake over time.
● Partner with SANDAG to build out Mobility Hub areas.
● Disincentivize development in non-infill areas that cannot support efficient transit use or multi-modal transportation options.
● Provide incentives and regulatory relief to facilitate higher density infill, and investigate opportunities to implement pricing structures that incentivize high occupancy vehicles.
Carlsbad ● Set aggressive municipal fleet adoption and public EV charging targets and track uptake over time.
● Work with other jurisdictions and agencies to identify procurement options to ensure progress of fleet adoption goals (such as the Climate Mayors network and EV purchasing collaborative).
● Expand 2011 CAP goals to accelerate the increase of ZEV miles. ● Adopt pedestrian- and bicycle-oriented design guidelines for all new development.
● Remove parking minimums in walkable neighborhoods.
● Provide incentives and regulatory relief to facilitate higher density infill and transit-oriented development.
● Implement transit-oriented zoning within ½-mile of all rail stations to maximize the impact of transit investments through high-density mixed- use development
Chula Vista ● Streamline the permitting process for landowners to install EV charging in multifamily developments.
● Partner with educational institutions to develop programs to meet workforce development needs.
● Expand on CAP goal of 40% alternatively-fueled municipal fleet vehicles by 2020, setting a new goal for a later horizon year and building upon the success of recent EV acquisitions.
● Partner with SANDAG to build out Mobility Hub areas.
● Reduce or remove parking minimums in walkable neighborhoods. ● Provide incentives and regulatory relief to facilitate higher density infill and transit-oriented development.
● Implement transit-oriented zoning within ½-mile of all trolley stations to maximize the impact of transit investments through high-density mixed- use development
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Jurisdiction/
Agency EV/ZEV Next Steps VMT Reduction Next Steps
Coronado ● Set aggressive public EV charging targets and track uptake over time. ● Monitor and report on municipal fleet transition to EV/ZEV; set updated targets that follow the recommendations of the City of Coronado Energy Roadmap (2012) establishing more ambitious fleet adoption goals. ● Adopt pedestrian- and bicycle-oriented design guidelines for all new development/redevelopment.
● Provide incentives and regulatory relief to facilitate higher density infill and transit-oriented development.
Del Mar ● Require new development to include EV charging and require existing development to retrofit parking with EV charging.
● Increase funding to existing programs to meet workforce development needs.
● Building on the CAP’s commitment to explore the potential for electrifying the municipal fleet, set an ambitious adoption goal.
● Increase street connectivity, update local bicycle and pedestrian planning documents, and adopt pedestrian- and bicycle-oriented design guidelines for all new development.
El Cajon ● Secure state and regional incentives to increase the dollar value of incentives for consumers to install EV chargers and purchase new or used EV.
● Develop an incentive program to retire gas vehicles.
● Partner with educational institutions to develop programs to meet workforce development needs.
● Follow the recommendations of the City of El Cajon Energy Roadmap (2013) and the city’s Sustainability Initiative (2020) and establish ambitious fleet adoption goals.
● Increase street connectivity, update local bicycle and pedestrian planning documents, and adopt pedestrian- and bicycle-oriented design guidelines for all new development.
● Implement transit-oriented zoning within ½-mile of all trolley stations to maximize the impact of transit investments through high-density mixed- use development
Encinitas ● Set aggressive fleet adoption and public EV charging targets and track uptake over time.
● Continue to make progress on transitioning all portions of the City’s municipal fleet.
● Identify funding to support City fleet conversion.
● Adopt pedestrian- and bicycle-oriented design guidelines for all new development.
● Provide incentives and regulatory relief to facilitate higher density infill and transit-oriented development.
● Implement transit-oriented zoning within ½-mile of rail station to maximize the impact of transit investments through high-density mixed-use development
Escondido ● Secure state and regional incentives to increase the dollar value of incentives for consumers to install EV chargers and purchase new or used EV.
● Develop an incentive program to retire gas vehicles.
● Partner with educational institutions to develop programs to meet workforce development needs.
● Work with other jurisdictions and agencies to identify procurement options to transition the municipal fleet.
● Work with NCTD to expand BRT by dedicating roadway to bus only lanes in areas where development can support transit use.
● Implement transit-oriented zoning within ½-mile of all rail stations to maximize the impact of transit investments through high-density mixed- use development
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Jurisdiction/
Agency EV/ZEV Next Steps VMT Reduction Next Steps
Imperial Beach ● Require new development to include EV charging and existing development to retrofit parking with EV charging.
● Secure state and regional incentives to increase the dollar value of incentives for consumers to install EV chargers and purchase new or used EV.
● Develop an incentive program to retire gas vehicles.
● Partner with educational institutions to develop programs to meet workforce development needs.
● Utilize fleet assessment and conversion plans to decide when to replace vehicles.
● Work with other jurisdictions and agencies to identify procurement options to transition the municipal fleet.
● Work with MTS to expand BRT by dedicating roadway to bus only lanes in areas where development can support transit use.
La Mesa ● Require new development to include EV charging and existing development to retrofit parking with EV charging.
● Secure state and regional incentives to increase the dollar value of incentives for consumers to install EV chargers and purchase new or used EV.
● Develop an incentive program to retire gas vehicles.
● Partner with educational institutions to develop programs to meet workforce development needs.
● Work with other jurisdictions and agencies to identify procurement options to transition the municipal fleet.
● Work with MTS to expand BRT by dedicating roadway to bus only lanes in areas where development can support transit use.
● Implement transit-oriented zoning within ½-mile of all trolley stations to maximize the impact of transit investments through high-density mixed- use development
Lemon Grove ● Partner with educational institutions to help develop programs to meet workforce development needs and increase funding to existing programs. ● Secure state and regional incentives to increase the dollar value of incentives for consumers to install EV chargers and purchase new or used EV.
● Follow the goals of the 2020 CAP and the recommendations of the City of Lemon Grove Energy Roadmap (2014) and establish ambitious municipal fleet adoption goals.
● Partner with SANDAG to build out Mobility Hub areas.
● Implement transit-oriented zoning within ½-mile of all trolley stations to maximize the impact of transit investments through high-density mixed- use development
● Work with MTS to expand BRT by dedicating roadway to bus only lanes in areas where development can support transit use.
National City ● Secure state and regional incentives to increase the dollar value of incentives for consumers to install EV chargers and purchase new or used EV.
● Develop an incentive program to retire gas vehicles.
● Partner with educational institutions to develop programs to meet workforce development needs.
● Set a municipal fleet adoption goal and work with other jurisdictions and agencies to identify procurement options.
● Partner with SANDAG to build out Mobility Hub areas.
● Implement transit-oriented zoning within ½-mile of all trolley stations to maximize the impact of transit investments through high-density mixed- use development
● Work with MTS to expand BRT by dedicating roadway to bus only lanes in areas where development can support transit use.
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Jurisdiction/
Agency EV/ZEV Next Steps VMT Reduction Next Steps
Oceanside ● Secure state and regional incentives to increase the dollar value of incentives for consumers to install EV chargers and purchase new or used EV.
● Develop an incentive program to retire gas vehicles.
● Partner with educational institutions to develop programs to meet workforce development needs.
● Follow the City’s Energy Climate Action Element (2019) to establish ambitious municipal fleet adoption goals.
● Partner with SANDAG to build out Mobility Hub areas.
● Work with NCTD to expand BRT by dedicating roadway to bus only lanes in areas where development can support transit use.
● Implement transit-oriented zoning within ½-mile of all rail stations to maximize the impact of transit investments through high-density mixed- use development
Poway ● Require new development to include EV charging and require existing development to retrofit parking with EV charging.
● Increase funding to existing programs to meet workforce development needs.
● Follow the recommendations of the City of Poway Energy Roadmap (2015) and establish ambitious municipal fleet adoption goals. ● Adopt a CAP that includes ZEV/EV acceleration strategies. ● Disincentivize development in areas that cannot support efficient transit use or multi-modal transportation options.
● Increase street connectivity and update bicycle and pedestrian planning documents.
● Adopt a CAP that includes VMT reduction strategies.
San Diego ● Set aggressive public EV charging targets and track uptake over time. ● Increase funding to existing programs to meet workforce development needs.
● Work with other jurisdictions and agencies to identify procurement options to transition the municipal fleet.
● Work with MTS to expand BRT by dedicating roadway to bus only lanes in areas where development can support transit use.
● Implement transit-oriented zoning within ½-mile of all trolley stations to maximize the impact of transit investments through high-density mixed- use development
● Reduce or remove parking minimums in walkable neighborhoods.
San Marcos ● Set aggressive public EV charging targets and track progress toward goal. ● Increase funding to existing programs to meet workforce development needs.
● Build on the City of San Marcos Energy Roadmap (2011) and the 2020 CAP to develop a low- and zero-emissions replacement/purchasing policy for official City vehicles and equipment.
● Identify and secure funding to purchase low- and ZEV fleet vehicles and equipment
● Work with NCTD to expand BRT by dedicating roadway to bus only lanes in areas where development can support transit use.
● Disincentivize development in non-infill areas that cannot support efficient transit use or multi-modal transportation options.
● Provide incentives and regulatory relief to facilitate higher density infill and transit-oriented development.
● Implement transit-oriented zoning within ½-mile of all rail stations to maximize the impact of transit investments through high-density mixed- use development
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Jurisdiction/
Agency EV/ZEV Next Steps VMT Reduction Next Steps
Santee ● Increase dollar value of local incentives and streamline the permitting process for landowners to install EV charging in multifamily developments.
● Partner with educational institutions to develop programs to meet workforce development needs.
● Increase dollar value and streamline the consumer vehicle purchase incentives at the local level.
● Build on the City of Santee Energy Roadmap (2011) and the Sustainable Santee Plan (2019) and establish a municipal fleet replacement goal with a percentage or number of vehicles.
● Update bicycle and pedestrian planning documents and adopt pedestrian- and bicycle-oriented design guidelines for all new development. ● Consider the potential of TNCs and taxis integrated into the transit system for rideshare.
● Implement transit-oriented zoning within ½-mile of trolley station to maximize the impact of transit investments through high-density mixed- use development
Solana Beach ● In the 2022 CAP update, set aggressive municipal fleet adoption and public EV charging targets and track uptake over time.
● Adopt a clean vehicle purchasing policy for new fleet vehicles.
● Partner with SANDAG to build out Mobility Hub areas.
● Work with NCTD to expand BRT by dedicating roadway to bus only lanes in areas where development can support transit use.
● Implement transit-oriented zoning within ½-mile of rail station to maximize the impact of transit investments through high-density mixed-use development
Vista ● Secure state and regional incentives to increase the dollar value of incentives for consumers to install EV chargers and purchase new or used EV.
● Develop an incentive program to retire gas vehicles.
● Partner with educational institutions to develop programs to meet workforce development needs.
● Work with other jurisdictions and agencies to identify procurement options to transition the municipal fleet.
● Increase street connectivity, particularly for people on foot and on bike. ● Work with NCTD to expand BRT by dedicating roadway to bus only lanes in areas where development can support transit use.
● Implement transit-oriented zoning within ½-mile of all rail stations to maximize the impact of transit investments through high-density mixed- use development
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3.6 Remaining Challenges and Gaps
Additional challenges and major gaps remain which will require collaboration, coordination, and advances to vehicle technology beyond what exists on the road today. In addition, outstanding questions regarding environmental externalities are important to consider as the County accelerates electrification as a key pathway to decarbonize the transportation sector.
3.6.1 Cross-Border Transportation and Tribal Jurisdictions The San Diego region’s location adjacent to the US-Mexico border creates opportunities and challenges for regional decarbonization. While Mexican border cities, such as Tijuana, are distinct political entities, transportation behavior on and around border crossings contributes to shared effects of carbon emissions. A major challenge of addressing these emissions is that there is limited jurisdictional control for directly influencing border crossings, as this authority lies with federal government bodies. Since cross-border traffic is a critical piece of regional decarbonization, though, it is important for local jurisdictions to coordinate with federal decision-makers on emissions-reducing regulations wherever possible. Similarly, local and state governments do not have authority over the 17 tribal governments in the San Diego region, yet reducing transportation emissions related to tribal jurisdictions are important for regional decarbonization.
In an effort to coordinate regional planning, SANDAG created the Borders Committee, which provides oversight for planning activities that impact the borders of the San Diego region as well as government-to-government relations with tribal nations in the San Diego region.
Membership includes representatives from Mexico, the County of San Diego, Orange County, Imperial County, Caltrans District 11, Southern California Association of Governments (SCAG), Southern California Tribal Chairmen’s Association, and several cities. The Borders Committee advises the SANDAG Board of Directors on major interregional planning policy-level matters, which are then forwarded to the SANDAG Board of Directors for action.
Another binational coordination effort is the California-Baja California 2021 Border Master Plan, developed by Caltrans in partnership with the U.S.-Mexico Joint Working Committee, the U.S. Federal Highway Administration, and Mexico’s Secretariat of Communications and Transportation. The Border Master Plan coordinates planning and delivery of land ports of entry and transportation infrastructure projects serving those ports of entry in the border region. The County and local jurisdictions can work to identify opportunities for efficiency in processing vehicles at ports of entry and advocate these plans to existing binational coordination efforts.
To achieve decarbonization, it will be important for regional jurisdictions to reinforce Oct. 11, 2022
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initiatives related to shared infrastructure, efficient transportation systems, and environmental planning. Outside of partnerships and direct authority over bi-national and tribal decisions, the County can further its active transportation work in the areas it has jurisdiction over. SANDAG’s Transit Leap and Mobility Hubs strategies can influence travel behavior of those proximate to its jurisdiction by continuing to make investments in complete streets, expanding high-quality transit options, and siting EV infrastructure in key areas. These strategies can support the communities that work and live around border crossings and tribal jurisdictions.
3.6.2 Freight and Trucking
The CARB Advanced Clean Truck Fleets rule requires that medium- and heavy-duty trucks must run on alternative fuels by 2045. However, current technology is insufficient to support electrification of or a shift to alternative fuels for long-haul freight and trucking. In support of this shift, SB 671 (2021) established the Clean Freight Corridor Efficiency Assessment, to be developed by the California Transportation Commission in coordination with other state agencies. The assessment will identify freight corridors throughout the state that would be priority candidates for the deployment of zero-emission medium- and heavy-duty vehicles by December 1, 2023. The bill also requires the state freight plan to include a description of needed infrastructure, projects, and operations for the deployment of zero-emission medium- and heavy-duty vehicles and the development of freight corridors identified in the assessment. Existing law requires the California Transportation Commission to allocate certain revenues deposited in the Trade Corridor Enhancement Account and certain federal funds for eligible infrastructure projects to mitigate emissions from trucks located on or along specified transportation corridors. This bill would make projects eligible for funding if they employ advanced and innovative technology to improve the flow of freight, environmental and community mitigation, or efforts to reduce environmental impacts of freight movement.13 The County might consider conducting a localized clean freight study to understand where opportunities for distribution efficiencies exist and modifying zoning code accordingly to encourage distribution centers in efficient locations. It can follow the lead of Los Angeles County, which set a goal of 25-50% of all medium-duty delivery trucks in the County to be electric, and 10-40% of heavy-duty regional drayage trucks to be zero-emission by 2028. The Los Angeles Cleantech Incubator, together with CARB, the Ports of Los Angeles and Long Beach, and the California Energy Commission, issued a request for information from medium- and heavy-duty truck manufacturers, EV supply equipment manufacturers, EV charging station networks, fleet operators, and fleet charging companies to influence the market and uptake of electrification and alternative fuels. Other zero-emission freight transportation pilot projects in Los Angeles County focus on seamless corridor approaches and last-mile solutions that respond to community needs as well as technology, business model, and educational challenges.
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Within the City of Los Angeles, a recently adopted maritime resolution calls on top importers to adopt 100% zero-emissions ships by 2030. While the technology does not currently exist for this shift, and while the City does not have enforcement power over internationally-regulated ships, the goal is to create green shipping corridors that can transition to zero-emissions corridors as technology improves. The City and the Port of Los Angeles hopes to exert influence on the shipping industry and on international regulators such as the International Maritime Organization to transition the industry to cleaner fuels. Local governments can incentivize clean cargo transportation through grants and special rates. San Diego and its port can build on the lessons from these initiatives to inform its own projects and policy recommendations and support the push to widespread zero-emission freight deployment.
3.6.3 Further Research
The following aspects of transportation decarbonization that are outside the scope of this framework but worthy of additional study by the County include:
● Environmental externalities of electrification, such as end-of-life waste, emissions associated with the extraction, processing, and distribution of the primary energy sources used for electricity production (e.g., “well-to-wheel emissions”), and roadway maintenance emissions associated with heavier vehicles; ● Lifestyle changes in the future that may not be reflected in today’s forecasts or assumptions, such as changing work from home patterns, home delivery of goods, and suburban migration that may be changing as a result of the COVID-19 pandemic; ● Policy response to pandemic conditions by transit agencies to match service to lower ridership levels, or to attempt to recover lost ridership; ● Transportation by and around local military bases; and ● Development and deployment of a metric that better captures travel efficiency, such as person-miles traveled (PMT) over VMT. Such a metric would encourage VMT reduction strategies that do not compromise people’s ability to travel, access opportunities, and move around the San Diego region in a way that meets their needs. The metric could be used in conjunction with VMT, which is required by the state to determine CEQA transportation impacts.
3.6.4 Cross-References
Transportation emissions are closely associated with other topics addressed in this Framework. For example, EV adoption is linked to emissions associated with electricity generation and VMT is heavily influenced by land use decisions and resulting development patterns. Collaboration between sectors and comprehensive approaches are necessary to achieve deep decarbonization. The table below summarizes how transportation decarbonization is linked to other chapters.
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Chapter Cross-Reference
Chapter 2: Geospatial Analysis of
Renewable Energy Production
Additional details on the emissions reductions implications of EV adoption relative to electricity sector decarbonization, and discussion of alternative fuels.
Chapter 4: Decarbonization of Buildings Information on the cost of fully electrifying (including EV charging) new buildings and assumptions for growth.
Chapter 5: Natural Climate Solutions and
Other Land Use Considerations
More information on how land use and transportation
decarbonization pathways are linked.
Chapter 6: Employment Impacts through
Decarbonization for the San Diego Region
More information about workforce development and new job opportunities related to EV and the charging network.
Chapter 7: Key Policy Considerations for
the San Diego Region
Additional details on region-wide policy and legal authority to implement strategies related to transportation sector
decarbonization.
Chapter 8: Local Policy Opportunity Additional details on local policy and legal authority to implement strategies related to transportation sector
decarbonization.
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Works Cited:
1. UC Davis.Decarbonizing California Transportation by 2045. https://www.ucdavis.edu/climate/news/decarbonizing-california-transportation-by-2045 (2021).
2. SANDAG. 2021 Regional Plan Programs and Policies - Electric Vehicles. https://sdforward.com/docs/default- source/final-2021-regional-plan/appendix-b---implementation-actions.pdf?sfvrsn=f4c1fd65_2 (2021).
3. SANDAG. 5 Big Moves. San Diego Forward https://www.sdforward.com/mobility -planning/5-big-moves (2021).
4. Black & Veatch Management Consulting. San Diego Regional Electric Vehicle Gap Analysis. h
ttps://www.sdge.com/si tes/default/files/2021-
07/FINAL%20San%20Diego%20Regional%20EV%20Gap%20Analysis%20%281%29.pdf (2021).
5. County of San Diego. County of San Diego Electric Vehicle Roadmap. https://www.sandiegocounty.gov/content/dam/sdc/sustainability/EV- Road map/EV-Roadmap-October-
2019.pdf (2019).
6. County of San Diego. County of San Diego Climate Action Plan - Final. https://www.sandiegocounty.gov/content/dam/sdc/pds/advance/cap/publicreviewdocuments/PostBOSDoc s/San%20Diego%20County%20Final%20CAP.pdf (2018).
7. California Energy Commission. Zero Emission Vehicle and Infrastructure Statistics https://www.energy.ca.gov/data-reports/energy-insights/zero-emission-vehicle-and-infrastructure-statistics (2020).
8. United States Census Bureau. American Community Survey. https://www.census.gov/programs -s urveys/acs (2015-2019).
9. SANDAG Activity Based Model. ABM1.
ht
tps://www.sandag.org/index.asp?subclassid=120&fuseaction=home.subclasshome (2012).
10. Frost, A. R. (2017). Quantifying the sustainability performance of urban form in California / by Alexander Rijiro Frost. San Diego State University.
11. Salon, D. (2015). Heterogeneity in the relationship between the built environment and driving: Focus on neighborhood type and travel purpose. Research in Transportation Economics, 52, 34–45. https://doi.org/10.1016/j.retrec.2015.10.008
12. California Air Pollution Control Officers Association. Handbook for Analyzing Greenhouse Gas Emission Reductions, Assessing Climate Vulnerabilities, and Advancing Health and Equity. https://www.airquality.org/ClimateChange/Documents/Final%20Handbook_AB434.pdf (2021).
13. SB-671 Transportation: Clean Freight Corridor Efficiency Assessment. https://leginfo.legislature.ca.gov/faces/billNavClient.xhtml?bill_id=202120220SB671 (2021).
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Appendix 3.A A table showing the comparison of SANDAG 2021 Regional Model (ABM2+) and EnergyPATHWAYS Model.
Model Fleet Mix Assumptions Fuel Mix Assumptions
Passenger Cars and Trucks Transit Vehicles Commercial Vehicles ZEV Adoption Rate (Passenger and Goods)
Speed
SANDAG 2021 Regional Model
(ABM2+)
5 classes for traffic
assignment:
- Drive-alone non-
transponder
- Drive-alone
transponder
- Shared-ride 2
- Shared-ride 3+
- Heavy Truck
Each class is broken down
by income or by weight
class for a total of 15
traffic assignment classes.
7 transit modes:
- Tier 1 Heavy Rail
- Commuter Rail
- Light Rail
- Streetcar
- Rapid Bus
- Express Bus
- Local Bus
Inputs vary by mode:
- Frequency of
service
- Travel time
- Fare
5 goods movement
modes:
- Truck
- Rail
- Pipeline
- Marine
- Air cargo
4 commercial truck
types:
- Light vehicle
- Medium truck
(<8.8 short tons)
- Medium truck
(>8.8 short tons)
- Heavy truck
(FHWA classes 7-
13)
Zero-Emission Vehicles (ZEV)
and Electric Vehicles (EV) in
general are handled off-model.
Growth forecasts are based off
EMFAC.
Between Model Year
(MY)2025-2050, required
percent of new Light-Duty
Vehicle (LDV) sales that must
be ZEVs in EMFAC2017:
- Plug-in Hybrid Vehicles
(PHEV): 7.32%
- Battery-Powered Electric
Vehicle (BEV): 4.06%
- Hydrogen Fuel-Cell Electric
Vehicle (FCEV): 14.89%
PHEV, BEV, FCEV are all
referred to as ZEVs.
Inputs that affect speed on
regional highway
networks:
- Posted speed
- Roadway capacity
- Functional
classification
- Roadway operation
(HOV lane, etc.)
- Congestion
- Origin/destination
- Intersection control
- Transportation mode
Evolved Energy Model
(EnergyPATHWAYS)
- Light car
- Light truck
- Motorcycle
- Buses
- Passenger Rail
- Medium truck
- Heavy truck
(divided into short
haul and long haul)
EMFAC growth forecasts.
Different assumptions by class:
more BEV for HD short haul
trucks, more FCEV for HD long
haul.
n/a
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Model VMT Accounting Resolution
Method Scale Conversion to GHG Spatial Temporal
SANDAG 2021 Regional Model
(ABM2+)
Accounting Methods for GHG
calculations using Vehicle Miles
Traveled (VMT):
- Internal-Internal: all VMT
included in analysis (VMT that
occurs from trips that start and
end in the SANDAG region)
- Internal-External or External
Internal: 50% of VMT included
in analysis (VMT associated
with trips with one trip end in
the SANDAG region and one
outside the SANDAG region)
- External-External: all VMT
excluded in analysis (VMT
associated with trips that start
and end outside of the SANDAG
region are not included).
- Total VMT
and GHG and
per-capita
VMT and
GHG.
VMT data tables are used
within EMFAC for
emissions calculations of
cold starts (trips) and
running emissions (VMT).
Calculations are adjusted
by transportation activity
data (VMT, speed
distribution) and vehicle
populations.
Emissions reductions
associated with various
ZEV policies are also
calculated outside of the
travel demand model.
Different resolution levels for
different steps of the model:
- Microanalysis zones: 23,002
Master Geographic Reference
Area (MGRAs) zones (roughly
equivalent to Census blocks)
- Traffic assignment demand
and skims: 4,996
Transportation Analysis Zones
- Transit assignment demand
and skims: 1,766 Transit Access
Points
Treatment of space is slightly
different for border crossing trips.
Transportation
behavior is
modeled every
half hour.
Evolved Energy Model
(EnergyPATHWAYS)
n/a n/a Electricity and fuel
emissions intensities are
determined by supply-side
optimization subject to
net-zero economy-wide
constraints.
Vehicle stock is modeled for
Southern California region (divide
from Northern California is along
Pacific Gas & Electric
Company/Southern California
Edison service boundary).
Number of households is used to
estimate vehicle stock.
Annual vehicle
stock.
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Model Analysis Years Input Data
Base
Year
Horizon
Year
Internal (SANDAG) Surveys Outside Data Sources
SANDAG 2021 Regional Model
(ABM2+)
2016 2050
- SANDAG Household Travel Behavior Survey (2016)
- Transit On-Board Survey (2015)
- SB 1 Transportation Network Company (TNC) Survey
(2019)
- Taxi Passenger Survey (2009)
- Parking Inventory Survey (2010)
- Parking Behavior Survey (2010)
- Border Crossing Survey (2011)
- Visitor Survey (2011)
- Establishment Survey (2012)
- Tijuana Airport Passenger Survey (2017)
- Commercial Vehicles Survey (2011)
- Vehicle Classification & Occupancy (2006)
- San Diego International Airport Air Passenger Survey
(2009)
- San Diego International Airport Passenger Forecasts (2013) - Decennial Census Summary File-1 tabulation (2010)
- Census Data for Transportation Planning (CTPP)
- Public Use Microdata Sample (PUMS)
- American Community Survey (2015-2017)
- Bicycle counts (2011)
- Jurisdiction annual traffic counts (2016)
- FasTrak Transponder ownership data (2012)
- Caltrans Performance Measurement System (PeMS) (2016) - Caltrans Highway Performance Monitoring System (HPMS) (2016)
Evolved Energy Model
(EnergyPATHWAYS)
n/a 2050
n/a - University of Virginia Population Projections
- California Air Resources Board vehicle service numbers (EMFAC)
- 2021 U.S. Annual Energy Outlook
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4. Decarbonization of Buildings
Philip Eash-Gates, Synapse Energy Economics, Inc.
Jason Frost, Synapse Energy Economics, Inc.
Shelley Kwok, Synapse Energy Economics, Inc.
Jackie Litynski, Synapse Energy Economics, Inc.
Kenji Takahashi, Synapse Energy Economics, Inc.
Asa Hopkins, PhD, Synapse Energy Economics, Inc.
Key Takeaways
● Reducing emissions from space heating and water heating due to fossil fuel combustion should be a primary policy focus for buildings within the Regional Decarbonization Framework. Other uses of fossil fuels in buildings—cooking, laundry, and process loads—will need to be addressed as well.
● Policies should support increasing adoption of efficient heat pump-based space and water heating systems in both new and existing buildings, with particular focus on assistance for communities of concern and rental buildings. ● Setting “electrification-ready” or “all-electric” standards for new construction and major renovations through building energy codes will reduce costs associated with transitioning away from fossil fuels.
● Some existing fossil fuel equipment systems will only turn over once by 2050. Near-term action is needed to guide building owners to replace end-of-life fossil fuel equipment with electric equipment.
● Low-carbon gaseous fuels can be used for hard-to-electrify end uses, though these fuels are not proven and scalable, necessitating research and piloting. ● The gas utility can mitigate its risk of not recovering its investment in assets (that is, its stranded cost risk) by minimizing unnecessary extensions or replacements of the pipeline system and by accelerating depreciation of existing utility assets. ● Improved data gathering is a low-cost, foundational action for future policy development.
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4.1 Introduction
San Diego County is the fifth most populous county in the United States1 and boasts a large and diverse building stock.2 The unique geography and varied climates within the San Diego region have helped create an architectural montage, with distinct attributes across the county’s 18 municipalities and unincorporated areas.3,4 Some local infrastructure also reflects the county’s 18 Native American tribal reservations5,6—the most in any U.S. county—and 16 military bases.7 While it is one of the county’s great assets, the building stock also contributes to emissions: on- site fossil fuel combustion comprised about 300,000 metric tons of carbon dioxide equivalent emissions in 2014, roughly 9 percent of the county’s total emissions.8 Decarbonizing existing and new buildings in the San Diego region represents a critical strategy within the Regional Decarbonization Framework. This chapter focuses on direct emissions from buildings resulting from fossil fuel combustion and how to eliminate those emissions by 2045. Chapter 2 and Appendix A address emissions from electricity generation.
Options for decarbonizing San Diego’s buildings include electrifying end uses that are responsible for direct emissions (primarily space and water heating) and using lower-carbon fuels (such as biomethane and hydrogen) for hard-to-electrify end uses of energy. These are the primary strategies for displacing the use of natural gas, the dominant combustion fuel used in buildings in the region.
i Demand reduction through traditional energy efficiency measures and programs, such as more efficient combustion equipment, improvements in building shells, and low-flow fixtures, is not sufficient to meet San Diego’s decarbonization objectives. Transitioning to efficient electric technologies such as heat pumps and induction cooking results in both substantially reduced energy demand and greater utilization of the increasingly renewable electric supply portfolio.
Pathways taking different approaches to building sector decarbonization incur similar relative costs, within the range of uncertainty. However, an electrification-based approach to decarbonizing buildings does not depend on technological innovation or deployment of novel technologies at previously unseen scales, making it generally lower risk.
All building decarbonization pathways cause a substantial transformation in the gas utility business due to changes in the amount and sources of gas sold. Electrification pathways in particular require fundamental changes in the gas utility business model because traditional pipeline gas sales would essentially conclude by mid-century. We conclude this chapter with an analysis of near-term steps that San Diego Gas & Electric (SDG&E), its regulators, and regional
i Natural gas is a fossil fuel predominantly composed of methane. Natural gas is a source of carbon dioxide when burned and is also a potent greenhouse gas when leaked into the atmosphere ( i.e., due to leaks in the supply chain, natural gas infrastructure, and appliances).
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policymakers could take to mitigate risks associated with this transition and thereby ease developing a long-term business transition plan.
4.2 Buildings in San Diego County
4.2.1 Residential Buildings
There are an estimated 1.3 million residential units across 0.9 million properties in San Diego County. These residences comprise approximately 1.7 billion square feet and grow at a rate of
0.9 percent per year.i Multifamily properties represent 9 percent of the total residential floor area, but are growing at a quicker rate than single-family: 2.2 percent per year compared to 0.7 percent. The relative sizes of the residential building stock vary considerably by municipality, as depicted in Figure 4.1. The City of San Diego and the unincorporated areas of the county represent 57 percent of the total. The City and County therefore have a large opportunity to reduce emissions in this sector through targeted policies, such as building energy codes.
Figure 4.1 Residential building stock floor area (million ft2) by municipality in the San Diego region, 2021. Source:
Synapse analysis of data provided by San Diego County Assessor's Office.
Figure 4.2 breaks down the building stock by type of residence and over time for each jurisdiction. These distinctions may affect how quickly and cost-effectively a community can
i Synapse analysis of data provided by San Diego County Assessor's Office.
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decarbonize its buildings. Strategies for addressing emissions for single-family homes and multifamily apartments differ due to distinct ownership/occupancy paradigms and types of end-use energy equipment in the residences. Additionally, for communities with the fastest relative growth rates—which have recently been Imperial Beach, National City, Chula Vista, San Marcos, and Santee—more stringent building energy codes can play an important role locally.
Figure 4.2 Residential building stock floor area (million ft2) by municipality in the San Diego region, 2017–2021.
Source: Synapse analysis of data provided by San Diego County Assessor's Office.
Figure 4.3 provides a breakdown of average pipeline gas usage for each major gas end use by residential customers under three investor-owned utilities, based on the latest Residential Appliance Saturation Study (RASS).9, i As shown in this figure, the average gas usage for water heating is 200 therms and accounts for the largest share (about 59 percent) of the total for major end uses in SDG&E’s jurisdiction. This share far exceeds the water heating usage share for Pacific Gas & Electric (PG&E), but mirrors the usage share for SoCalGas. On the other hand, the average residential gas usage for space heating in the SDG&E area accounts for about 29 percent. These gas end-use profiles show that SDG&E residential customers have the greatest opportunity for GHG savings in water heating. Lastly, a jurisdictional comparison of the total gas usage data in this figure shows that households in the San Diego region can more easily pursue
i Note that while this figure excludes minor end uses with low customer saturations such as spa and pool heat, secondary heating, and gas backup for solar water heaters, the average natural gas consumption among all gas customers is lower than the estimates shown in this figure because some customers do not use gas for all major end uses.
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building decarbonization because (1) their overall gas usage is lower and (2) electrifying water heating typically requires relatively lower-cost, lower-complexity upgrades than are needed for space heating.
Figure 4.3 Average annual natural gas usage (measured in therms) by end use and utility for households who use gas as the primary fuel for major end uses. Source: DNV GL Energy Insights (2021 ). 2019 California Residential Appliance Saturation Study (RASS).9
Figure 4.4 presents residential fuel-use breakdowns for space and water heating end uses in terms of the number of utility accounts in the San Diego region. Data for this analysis come from the 2019 RASS study. As shown in Figure 4.4, natural gas dominates both space and water heating, more so for water heating (about 83 percent) than for space heating (about 69 percent). Approximately 28 percent of total households use electric space heating, while electric water heating is used less than half as much: about 12 percent.
Figure 4.5 shows the breakdown of residential space heating equipment in terms of the number of utility accounts in SDG&E’s service area (which has a nearly perfect overlap with San Diego county). Electric heat pumps account for about 6.3 percent of all residential systems, up from 2 percent a decade earlier, as indicated by the 2009 RASS study. Central gas furnaces with ducts account for about 56 percent of the total systems. Three other heating systems that use ducts are central electric, LPG furnaces, and ducted air-source heat pumps (ASHPs). Together, the systems relying on ducts account for about 70 percent of the total residential space heaters.
Excluding ducted ASHPs, such systems account for 66 percent of the total. These represent the prime candidates for fuel switching to ducted ASHP technologies. The rest of the space heaters, including electric unit heater (13 percent) and other fossil heaters (about 13.6 percent), can be converted to heat pumps through the use of ductless minisplit heat pumps.
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Figure 4.4 Residential space and water heating by fuel type (% of customer accounts). Source: DNV GL Energy Insights (2021). 2019 California Residential Appliance Saturation Study (RASS). 9
Figure 4.5 Residential space heating system share by equipment type. Source: DNV GL Energy Insights (2021). 2019 California Residential Appliance Saturation Study (RASS).9
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4.2.2 Commercial Buildings
The commercial sector includes 158,000 building units across 36,000 properties in the county.
Together, these properties represent an estimated 554 million square feet and grow about 0.9 percent per year.i Figure 4.6 highlights the relative sizes of the commercial building stock in each area within the county. The City of San Diego, the unincorporated areas of the county, Chula Vista, Carlsbad, Escondido, and Oceanside have the largest total floor areas. Given the sizable stock of commercial buildings in the City of San Diego, its policies can have an outsized effect on reducing regional emissions. The City’s Building Energy Benchmarking Ordinance marks an important step toward managing energy use and emissions in large buildings. 10 The
ordinance lays the foundation for future innovative policies such as building performance standards, which establish mandatory energy or emissions targets that improve over time.ii The prominence of each commercial building type and the growth rate of the commercial building stock varies by location and over time, as shown in Figure 4.7. As with residential buildings, these distinctions influence the jurisdictions’ pathways to decarbonization. Some building types (e.g., hospitals and restaurants) are harder to retrofit with equipment that reduces carbon emissions, particularly from onsite combustion of fossil fuels, because they use specialized equipment or combined heat and power systems. Carlsbad, Imperial Beach, and San Marcos are experiencing higher rates of growth of commercial buildings.
i Synapse analysis of data provided by San Diego County Assessor's Office. ii The following resources provide additional information on building performance standards:
American Cities Climate Challenge. 2021. Building Performance Standards: A framework for Equitable Policies to Address Existing Buildings. Available at: https://www.usdn.org/uploads/cms/docume nts/bps-framework_july- 2021_final.pdf.
American Council for Energy-Efficient Economy. 2020. Mandatory Building Performance Standards: A Key Policy for Achieving Climate Goals. Available at: https://www.aceee.org/white-pa per/2020/06/mandatory-building- performance-standards-key-policy-achieving-climate-goals Carbon Neutral Cities Alliance. 2020. Existing Building Performance Standards Targets and Metrics Final Report.
Available at: http://carbonneutralcities.org/wp-con tent/uploads/2020/03/CNCA-Existing-Building-Perf-Standards- Targets-and-Metrics-Memo-Final-March2020.pdf
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Figure 4.6 Commercial building stock floor area (million ft2) by municipality in the San Diego region, 2021. Source:
Synapse analysis of data provided by San Diego County Assessor's Office.
Figure 4.7 Commercial building stock floor area (million ft2) by municipality in the San Diego region, 2017–2021.
Source: Synapse analysis of data provided by San Diego County Assessor's Office.
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4.2.3 Building emissions
GHG emissions from buildings primarily reflect fossil fuel combustion. Such onsite consumption provides services such as space heating, water heating, and cooking. Additionally, offsite generation of electricity, district heating, and district cooling utilize fossil-based fuels, and the associated emissions are attributable to buildings using these utilities. To identify strategies for reducing these emissions in the San Diego region, it is important to first understand the fuel use in local buildings—both how much of each fuel is used and what it is used for. Using data from SDG&E, the City of San Diego, the San Diego County Assessor’s Office, the U.S. Energy Information Administration, and prior energy studies,11,12,13,14 we estimated the fuel, energy, and emission profiles for buildings in the San Diego region. Figure 4.8 presents the results for each building type and across the total commercial building stock.
Figure 4.8 San Diego regional energy end-use profiles by commercial building type. Percentages are relative to total end-use energy within each building sector. Annual energy consumption, measured in metric million Br itish thermal units (MMBTU), for each building type is shown in blue at the top of the figure. Source: Synapse model.
Space heating and water heating are the two building end uses responsible for the most GHG emissions in the region. This reflects both that they require large amounts of energy—together they consume over a quarter of all energy used in commercial buildings in the county—and that they rely heavily on fossil fuels, specifically natural gas. Figure 4.9 provides a breakdown of the primary fuel used for space and water heating in commercial buildings. Due to the low GHG emissions associated with electricity generation in California, switching from fossil fuels to efficient electric technologies (such as heat pumps) for these end uses will immediately reduce emissions associated with space and water heating in commercial buildings. Additionally, end Oct. 11, 2022
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uses that rely on electricity will have fewer emissions over time as the electric grid incorporates more renewable generation. As climate change increases local temperatures, cooling demand in buildings will increase, partially offsetting the emissions reductions from a cleaner grid for this end use.i These facts together suggest that reducing emissions from space heating and water heating should be a primary policy focus within the RDF. The existing equipment within a building plays an important role in determining what strategies will work best when decarbonizing a building. A breakdown of existing equipment types for space and water heating is provided in Figure 4.10 for commercial buildings in the San Diego region.
Figure 4.9 San Diego region primary fuel used in commercial buildings (floor area, million ft2) by building type:
space heating (left) and water heating (right). Source: Synapse model.
i Cooling emissions will, however, trend toward zero as the electric grid approaches 100 percent decarbonization.
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Figure 4.10 San Diego region natural gas equipment system used in commercial buildings (floor area, million ft 2) by building type: space heating (left) and water heating (right). Source: Synapse model.
4.3 Technologies and Fuels for Decarbonizing Buildings
4.3.1 Space heating technologies
Electric heat pumps are energy-efficient heating and cooling systems that work for all climates.
Unlike fossil fuel-based heaters that generate heat by burning fuels, heat pumps provide space heating by extracting heat from outside and transferring it to the inside, using a vapor- compression refrigerant cycle that connects an outdoor compressor with an indoor heat exchanger. Heat pumps also work as an efficient air conditioner by reversing the heat transfer process to remove heat and moisture from indoor air. Because of this heat transfer process, heat pump efficiency levels typically exceed 250 percent (a coefficient of performance, or COP, of 2.5) for heating and 400 percent (COP of 4) for cooling. That means for one unit of energy input, a heat pump can provide 2.5 or more units of heating. By comparison, the most efficient gas combustion heaters provide 0.98 units of heating for one unit of energy input. Switching from natural gas heating to heat pumps will increase electricity demand in the winter. Notably, the electric grid in the San Diego region peaks in the summer and can accommodate additional winter load from electrification without substantial new investment in power transmission and distribution infrastructure.
Various types of heat pumps are available in the market. Heat pumps are primarily categorized by (a) the heat sources they draw from to heat buildings, (b) whether the systems heat air or water, and (c) how the extracted heat is distributed in the buildings. Primary heat pump Oct. 11, 2022
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technologies used for space heating include air-source heat pumps (ASHPs), ground-source heat pumps (GSHPs), water-source heat pumps (WSHPs), and air-to-water heat pump (AWHPs).
ASHPs are the most common heat pump system type used in the country. They move heat in the air between inside and outside. Because ASHPs use heat in the outdoor air, their performance (in terms of efficiency and capacity) degrades in cold temperatures. Thus, conventional ASHPs often have backup electric resistance heating strips for cold temperature operation. However, cold climate ASHPs that are now widely available in the market can provide comfortable heat even under freezing temperatures without a backup heater. i Notably,
the winter climate in the San Diego region is moderate compared to the rest of the state and much of the United States, and there is little need for backup heat in most of the region.ii ASHPs include ducted ASHPs, mini-split ductless heat pumps, packaged terminal heat pumps, and variable refrigerant flow (VRF) ASHPs. A short summary of these technologies is provided below.
● Ducted ASHPs are the most widely installed systems. Ducted ASHPs include split systems and packaged systems. Split heat pumps have an outdoor condenser and an air handling unit in the building to deliver heating or cooling through ducts similar to forced-air gas furnaces. Packaged heat pumps have all the components necessary for heating, cooling, and air circulation combined into a single system, usually mounted directly onto the building. They are typically installed on rooftops and thus are often called rooftop units (RTUs). Ducted ASHPs can be a suitable alternative to aging gas furnaces. Ducted ASHPs are installed in residential and small to medium commercial buildings.
● Mini-split ductless heat pumps are relatively new to the U.S. market, but have been gaining popularity over the past several years as new residential and small commercial heating systems across the country. Mini-split systems also have outdoor condensers, but use refrigerant pipes to deliver heating or cooling to each room where an indoor unit is installed. Because they use small refrigerant pipes and are relatively easy to install, they are suitable for heating system retrofits where ducts are not available. They also use variable speed compressors, which allow them to operate more efficiently and quietly than standard ducted ASHPs and to provide superior temperature controls.
i A field study in Vermont observed that cold climate ASHPs operated at 5° F with a COP of 1.6 and even at - 20° F at above 1 COP. See Cadmus (2017). Evaluation of Cold Climate Heat Pumps in Vermont . Prepared for the Vermont Public Service Department. Page 24. Available at:
https://publicservice.vermont.gov/sites/dps/files/documents/Energy_Efficiency/Reports/ Evaluation%20of%20Cold%20Climate%20Heat%20Pumps%20in%20Vermont.pdf . ii San Diego County spans four California climate zones. Most of the population live in Climate Zones 7 and 10, which are among the most moderate in the state. Climate Zone 14 is the coldest of the four and includes most of the eastern half of the county. Zone 14 experiences 2422 heating degree days in a typical climate year; by this metric it is less than half as cold as the northern and eastern parts of the state that comprise Climate Zone 16, with 5057 heating degree days per year.
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● Packaged terminal heat pumps (PTHP) are all-in-one systems (including compressor, condenser and evaporator coils, fans, etc.), installed on an exterior wall. They are often installed in hotels and small apartment units. Compared to other heat pump systems, PTHPs do not perform well and their operating temperatures are typically limited.
However, a few cold climate PTHP models recently have become available in the market.
15 ● Variable refrigerant flow (VRF) ASHPs can distribute heating and cooling to numerous indoor evaporator units through a main refrigerant line from a single outdoor system.16 Many VRFs can also provide heating and cooling simultaneously in different rooms by adding a heat recovery system, and thus benefit buildings with diversely loaded zones. 17 VRFs are generally suitable for medium to large commercial buildings, but especially for medium/high-rise multifamily buildings, office, schools, and lodging. 18 Compared with ASHP, GSHPs and WSHPs provide better performance in cold temperatures because they use heat reservoirs that have a higher temperature than ambient air during the winter.i GSHPs use underground rock or groundwater as a heat reservoir. WSHPs use a well, lake, aquifer, or other source (e.g., wastewater, cooling loop system, etc.) as a heat reservoir.
GSHPs need to drill holes or dig trenches in the ground to install a heat exchanging group loop and thus are considerably more expensive than other heat pump technologies; however, total lifecycle costs for GSHPs can sometimes be lower, due to high-efficiency operation.
AWHPs extract heat in the outdoor air and use water (or a mixture of water and glycol) as a heat transfer medium within the building instead of forced air. AWHPs are now widely available as heat pump water heaters for residential buildings. To date, their applications for space heating have been limited in the United States, although more systems are becoming commercially available in the early 2020s. For large commercial buildings with existing hot water heating systems (e.g., gas boilers), large-scale AWHPs can be a more energy-efficient alternative heating system or can provide supplemental heating.
GSHP, WSHPs, and even AWHPs can also produce temperatures high enough for a district heating energy system that circulates hot water. For example, Stanford University’s new district heating energy system includes three large-scale heat recovery chillers (a type of WSHPs) that extract heat from waste heat from the University’s cooling tower. 19 4.3.2 Heat pump performance
For our building energy analysis, we developed average annual coefficient of performance (COP) values for heat pumps separately for the residential and commercial buildings for a Central Case and for a Low Demand (high efficiency leading to low energy demand) case, as
i GSHPs and WSHPs also typically provide better cooling performance in hot temperatures because the heat reservoirs are generally lower temperature than ambient air during the summer.
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shown in Table 4.1 below.i We estimated these based on various data sources. These included our own calculation of COP values based on real-world heat pump performance data on residential-scale heat pumps in other states, combined with hourly temperatures in San Diego County.20-22 We also reviewed COP values in California and the US market as a whole.23, 24 For commercial buildings, we assumed that heat pumps are 20 percent more efficient than residential systems under the Central Case due to the availability of high-temperature heat sources, VRF’s high COP values due to simultaneous heating and cooling functions, and advanced technologies such as multi-stage compressors. Finally, we projected COP values through 2050 for the Central Case and for the Low Demand Case based on National Renewable Energy Laboratory’s COP forecasts in its Electrification Futures Study.25 Table 4.1 Synapse projection of COP values for heat pump space heating in the San Diego region. 2021 2030 2040 2050
Central Case
Residential 3.3 3.6 3.8 3.8
Commercial 3.9 4.4 4.5 4.6
Low Demand Case
Residential 3.3 3.8 4.4 5.0
Commercial 3.9 4.5 5.0 5.5
We also forecast total installed costs for heat pumps and gas space heaters for single-family and multifamily buildings, as shown in Table 4.2. Installation costs include equipment and labor, but exclude operation and maintenance. We reviewed numerous data sources and developed the current cost estimates primarily based on a 2019 study by E3 which analyzed residential building electrification in California.
26 We decided to use this data source for three main
reasons: (a) some cost estimates in this study aligned well with our knowledge of system installed costs and the cost estimates in other trusted data sources; (b) the study conducted a detailed bottom-up approach to estimate heat pump costs; and (c) the study provided cost estimates by climate zone, type of building, and building vintage. We selected cost estimates for coastal Los Angeles and downtown Los Angeles to develop cost estimates for the San Diego region, as these areas have the most similar climate. We then used various data sources to develop weighted average cost estimates for single-family and multifamily buildings in the San Diego region.
ii Next, we forecasted future total installed costs of these systems using data from
i See Section 4.4 of this chapter for a discussion of the modeled cases. ii We used the following sources to develop new construction and HVAC retrofit rates: Joint Center for Housing Studies of Harvard University. 2021. Improving America's Housing. Available at: https://www.jchs.harvard.edu/ sites/default/files/reports/files/harvard_jchs_improving_americas_housing_2021.pdf ; Statista. 2021. "Number of housing units in the United States from 1975 to 2020. Accessed September 27, 2021. Available at:
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NREL’s Electrification Future Study.25 Heat pump costs fall, in real terms, over the study period to reflect the increasing maturity of the technology along with technical and market advances as the equipment becomes much more widely adopted. (In contrast, gas furnace and boiler technology is largely mature and we project stable pricing.) Finally, we used the share of floor area between single-family and multifamily buildings (54 percent single-family and 46 percent multifamily) to develop per-unit costs for residential buildings on average, to align with how our decarbonization scenarios are defined. Equipment costs do not differ substantially between new construction and retrofits, provided that retrofits do not include changes in ductwork. i
Given San Diego’s mild winters and prevalence of air conditioning (approximately two-thirds of homes),9 we do not expect electric panel upgrades to be required to adopt efficient electric space or water heating in most homes. Panel upgrades may be required for electric vehicle charging, with the co-benefit of also increasing capacity for electric end uses in the home; these costs are not attributed to building sector costs. Due to the relatively small role of new construction in the overall pathway economic analysis, we did not account for new construction savings from avoiding the cost of installing gas piping or service lines to the street in the case of all-electric construction.
Table 4.2 Synapse projection of average total installed costs of residential HP and gas space heaters in San Diego ($2021).
2021 2030 2040 2050
Heat pump
Single-family $14,200 $13,142 $11,967 $10,791
Multifamily $10,900 $10,088 $9,186 $8,284
All residential $12,673 $11,728 $10,680 $9,631
Gas heater
Single-family $15,000 $15,000 $15,000 $15,000
Multifamily $11,400 $11,400 $11,400 $11,400
All residential $13,334 $13,334 $13,334 $13,334
Table 4.3 provides estimated building electrification costs for commercial buildings in the San Diego region. These include equipment and labor costs to convert existing fossil-based systems to electric systems as well as related building infrastructure changes. Energy efficiency retrofits, such as building envelope upgrades to reduce peak-load impact of electrification, are not included. Equipment maintenance and operation costs are also not included in these estimates.
We draw on data from a 2021 building electrification study for Los Angeles,27 heat pump cost
https://www.statista.com/statistics/240267/number-of-housing-units-in-the-united-states/; San Diego County’s tax assessor database. We also developed an estimate of HVAC retrofits by homes with ductless heaters (e.g., wall furnace, electric resistance heater etc.) in San Diego Country based on the 2019 RASS. i We assume that ducted systems are replaced with ducted, and ductless with ductless, to avoid such costs.
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trajectories from NREL’s Electrification Futures Study,25 and 2021 data on building characteristics from the San Diego County Tax Assessor’s Office. We adjusted these cost data to align with the local building stock. Our economic analysis in Section 4.3 below is based on costs to electrify space and water heating (and does not include other end uses, the cost to disconnect gas, or potential costs to upgrade electrical service).
Table 4.3 Estimated commercial building electrification costs for San Diego County ($2021).
Item Units 2021 2030 2035 2040 2045 2050
Space heat $/sqft $15.83 $13.79 $13.03 $12.28 $11.80 $11.33 Water heat $/sqft $0.65 $0.57 $0.53 $0.49 $0.46 $0.42
Cooking $/sqft kitchen $18.00 $18.00 $18.00 $18.00 $18.00 $18.00 Gas disconnection $/property $922 $922 $922 $922 $922 $922 Electrical upgrades $/property $32,975 $32,975 $32,975 $32,975 $32,975 $32,975 Other end uses, misc. $/sqft $1.75 $1.75 $1.75 $1.75 $1.75 $1.75 Source: Synapse model based on data from Jones (2021),26 Mai et al. (2018),46 and San Diego County Tax Assessor’s Office (2021). Values represent total gross costs, not incremental cost to fossil fuel systems.
4.3.3 Water heating technologies
Residential water heating is the largest gas-consuming end use in the San Diego region (Figure
4.3) and thus offers the largest GHG emissions savings opportunity through electrification.
Heat pump water heaters (HPWHs) have become widely available and very efficient. Their efficiency is measured using a Uniform Energy Factor (UEF) which presents an efficiency rating based on certain testing conditions.
i The majority of available products have UEFs above 3, and several products with a UEF of 4 are now available in the market.28 Electric resistance-based and combustion-based water heaters, whether tanked or tankless, cannot exceed a UEF of
0.99. The most popular HPWH technology is a hybrid HPWH which includes a heat pump, backup electric resistance coils, and hot water storage tanks. Hybrid HPWHs can be installed in many places, including garages, basements, back porches, and outdoor-vented closets. While siting details are beyond the scope of this policy document, these technologies’ performances vary with differences in air temperature and ventilation. Generally, garages are an optimal place for the best performance in warmer climates, while basements may be a better in cooler climates.
29, 30
Another HPWH technology is a split heat pump water heater with an outdoor compressor,
i UEF is comparable to coefficient of performance: it measures the ratio of the energy service output to the energy input. It is not exactly equal to the coefficient of performance for a water heater’s heating element because it incorporates heat losses from the water storage tank.
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sometimes called a “pure” HPWH because it does not need a backup resistance heater. As a split system, it offers more flexibility for placing the indoor unit within the living space. For example, Sanden produces a split HWPH that uses CO2 as a refrigerant. This split heat pump water heater has several advantages over hybrid models: it has a substantially higher capacity (approximately triple that of hybrid models) and efficiency (with a rated COP of 5), it only requires 13 Amp service, which could avoid upgrading an electrical panel, it can heat water to 175° F, and it can operate in ambient temperatures down to -20° F. 31, 32
Both hybrid and pure HPWHs can offer load flexibility and work as demand response resources by storing additional thermal energy when electricity rates are low to avoid energy usage during peak hours. A 2018 study by Ecotope, Inc. found that this HPWH load flexibility can yield 15-20 percent savings on customer bills and 35 percent marginal cost savings for utilities in California.
33 The demand flexibility of HPWHs can help mitigate grid impacts associated with electrification of water heating.
Several large-scale HPWHs (which are either AWHPs or WSHPs) are available for commercial buildings in the market (including large multifamily buildings), although to date such applications have been limited in the country. HPWH configurations for commercial buildings can be quite different from single-family homes because commercial buildings have a lot of variations in water use and building structures, and also because some buildings have unique opportunities to utilize different heat reservoirs. For example, HPWHs can be placed in a below- grade garage, if available, and take advantage of milder temperatures in the garage to produce hot water.
34 Mechanical rooms or laundry rooms can also be a suitable place for HPWHs installations if such those rooms are currently too hot or too humid, because HPWHs have the added benefit of cooling and dehumidifying the surrounding air. Further, HPWHs can be placed where they can utilize waste heat produced in certain commercial facilities such as spas, restaurant kitchens, or wastewater treatment facilities. Such HPWH applications provide space cooling benefits to the commercial facilities. Finally, large commercial and institutional buildings with a standard chiller system with a cooling tower could be a good candidate for installing HPWHs, more specifically heat recovery chillers. Heat recovery chillers can recover some of the waste heat from the electric chillers and produce hot water.35
4.3.4 Water heater performance
For our building energy analysis, we developed average annual COP values for HPWH separately for residential and commercial buildings for a Central Case and for a Low Demand Case, as shown in Table 4.4 below. We based these values on our assessment of a few different data sources. The primary source is the Natural Resource Defense Council and Ecotope’s analysis of HPWH performance in California, which estimated COP values in 16 California climate zones.29 Oct. 11, 2022
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We selected climate zones suitable for the San Diego region from this study and estimated average COP values for garage and vented-closet placement. We then adjusted the COP values upward to account for technology improvement, since the study was conducted using UEF ratings for HPWH products available at the time.
27 Finally, we developed our COP projections
and COP estimates for commercial systems loosely based on NREL’s COP forecasts for HWPH in its Electrification Futures Study.
25 NREL’s COP estimates for commercial systems are generally lower than residential systems, with the difference ranging from 0 percent to about 14 percent, depending on the years. However, we assume commercial systems perform at least as well as residential systems and better than NREL’s projections because some commercial buildings have access to unique heat reservoirs, unlike residential buildings.
Table 4.4 Synapse’ projection of COP values for heat pump water heating in the San Diego region, for central case and high efficiency (low demand) case.
2021 2030 2040 2050
Central Case
Residential 3.0 3.2 3.5 3.5
Commercial 3.0 3.2 3.5 3.5
Low Demand Case
Residential 3.0 3.3 3.6 4.0
Commercial 3.0 3.3 3.6 4.0
We also developed our forecasts of total installed costs for HPWHs and gas water heaters for single-family and multifamily buildings, as shown in Table 4.5 below. The installation costs include equipment and labor, but exclude operation and maintenance. We first developed the current cost estimates based on a literature review.36, 37 Next, we forecasted future total installed costs of these systems using data from NREL’s Electrification Future Study. Finally, we used the share of floor area between single-family and multifamily buildings (54 percent single- family and 46 percent multifamily) to develop per-unit costs for residential buildings on average, to align with how our decarbonization scenarios are defined. As with space heating, we do not find that costs differ substantially between new construction and retrofit applications. Cost data for water heating electrification for commercial buildings, including installing HPWHs, are provided in Table 4.3 above.
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Table 4.5 Synapse projection of total installed costs of residential HPWHs and gas water heaters in the San Diego region ($2021).
2021 2030 2040 2050
Heat pump water heater (HPWH)
Single-family $3,000 $2,500 $2,037 $1,852
Multifamily $2,125 $1,771 $1,443 $1,312
All residential $2,595 $2,162 $1,762 $1,602
Gas water heater
Single-family $1,650 $1,650 $1,650 $1,650
Multifamily $1,600 $1,600 $1,600 $1,600
All residential $1,627 $1,627 $1,627 $1,627
4.3.5 Cooking technologies
While cooking with fossil fuels contributes relatively few GHG emissions, this end use is among those which residents most directly see and engage with. Many people enjoy cooking with gas stovetops, especially when compared with older electric technologies. Consumers generally care less about a particular fuel for ovens, and almost every other cooking appliance (such as microwaves, toasters, and pressure cookers) is natively electric.
In the residential sector, cooking therefore matters less for direct GHG emissions and more for decarbonization pathway economics, as it shapes whether residents retain a gas connection for their home, even after switching fuels for water and space heating. Aside from restaurants or other food preparation businesses, most commercial buildings have no or very low cooking- related GHG emissions. However, cooking is a larger component of GHG emissions in the commercial sector than it is in residential, due to high energy use in commercial kitchens and lower relative demand for hot water and space heating in commercial buildings.
New electric cooking technologies, particularly cooktops that heat using induction, have the potential to upend customer devotion to cooking with gas. Induction cooking works by using magnetic fields to excite electric currents in the metal base of pots and pans used for cooking.
These electric currents quickly convert to heat. Directly heating the pan is faster, more responsive, and more efficient than older cooking technologies, with no waste heat lost into the room. Heat levels can be changed as fast or faster than with gas, and water commonly boils faster on an induction cooktop than a comparable gas one. The cooktop itself stays cool, which improves safety and makes cleanup easy. There are also no combustion emissions, so indoor and outdoor air quality is improved. Electric ovens are comparably priced competitors to gas ovens, and do not face technology-specific market or customer adoption barriers.
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and pans being incompatible with induction, and customer unfamiliarity with the new technology. Both electric cooktops and ovens (and combined systems) can require new electric circuits to be run to carry enough power, and they could even trigger the need for an electric panel upgrade (if the panel has not yet been upgraded to serve a fast electric vehicle charger and/or heat pump system).
4.3.6 Laundry
Electric dryers have a large market share today; in the Pacific census region, the U.S. Energy Information Administration found that two-thirds of homes that have dryers use an electric one.38 Aside from potential building-specific barriers stemming from electric-panel capacity and new circuits, there are no substantial barriers to residential adoption of electric dryers. There are also new, more efficient electric dryers that use heat pump technology. These pump heat into the drum, while the cool side of the heat pump condenses the water removed from the clothes. This eliminates the need for a vent, so heat pump dryers can be used very effectively in high-performance buildings with tight building envelopes. Heat pump dryers are gentler on clothes than traditional tumble dryers, but can also take a longer time to dry a load of laundry and are currently substantially more expensive than traditional dryers.
Commercial laundry systems face higher barriers to the adoption of electric options than do residential. Running many large electric dryers, as in a laundromat, could require substantial upgrades to a building’s electrical system if it is transitioning from gas equipment. The slower speed of heat pump dryers is also more of a challenge in throughput-limited commercial laundry systems than in residential applications.
4.3.7 Low-carbon fuels
One way to reduce the GHG emissions from buildings without changing building systems (or before changing those systems to non-emitting options) is to use fuel that does not release net greenhouse gases into the atmosphere. The two primary ways to generate such fuel are to process biological waste or separate hydrogen from various feedstocks.
4.3.7.1 Biomethane
Biomethane can replace natural gas in current applications, as methane is the primary component of fossil natural gas. Many microbes that digest organic matter in the absence of oxygen (“anaerobic” digestion) release a combination of carbon dioxide and methane, called syngas. Biological feedstock can also be gasified into syngas using high heat processes (called “pyrolysis”). The carbon dioxide can be removed (called “scrubbing” the gas), leaving pipeline- quality methane.
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Biomethane supply is currently very limited, and expected to remain well below the level of current fossil gas consumption. This constraint comes from both the lack of infrastructure to produce biomethane from biological feedstocks and the more fundamental limitation of the amount of feedstock biomass material that can be sustainably produced. Given limited supply, use in the building sector may not be prudent or economical because other sectors (such as industrial use) that have fewer low-carbon alternatives may require all available supply.
Processing for pipeline use must also compete with the option to combust the unprocessed (or less processed) fuels at their site of production to generate electricity and transport the resulting low-carbon energy to customers. There are also concerns about leakage of biomethane and recovered methane. Fugitive emissions can be high in certain production processes, including digestate storage and biogas upgrading. 39 Biomethane costs and emissions depend on the production pathway used. In general, though, biomethane has lower, but non-zero, GHG emissions (especially after leakage is considered), and costs range between $10 per MMBTU to over $50 per MMBTU. 40 For reference, fossil
natural gas currently costs less than $5 per MMBTU.
4.3.7.2 Hydrogen-based fuels
There are two primary methods used to produce low-carbon hydrogen. The first of these is electrolysis, which splits water into hydrogen and oxygen by running electricity through the water. If the electricity for this purpose is low-carbon, then the hydrogen is low-carbon. This is referred to as “green” hydrogen. The second method builds on today’s methods for making hydrogen, which rely on splitting methane into carbon dioxide and hydrogen using “steam reformation.” So-called “blue” hydrogen is low-carbon if the resulting carbon dioxide is captured and permanently sequestered. There are no fundamental physical limits to the amount of green hydrogen that can be produced, so this energy carrier holds promise to meet combustion energy needs not met by biomethane. Today, approximately 99 percent of hydrogen produced in the United States is produced directly from fossil fuels, and about 1 percent from electricity (although not all this electricity is low-carbon). 41 To play a significant
role in building decarbonization, green hydrogen production would need to increase spectacularly alongside associated increases in zero-carbon electricity generation beyond what was modeled for the RDF.
Hydrogen can be blended with natural gas up to the level of about 20 percent by volume, or 7 percent by energy, without requiring changes in pipeline or customer infrastructure. However, at higher hydrogen concentrations, some pipeline materials could be damaged and customer appliances might fail to work safely. Using pure hydrogen (or high-hydrogen blends) would therefore require a substantial infrastructure investment to replace pipes and ensure that all Oct. 11, 2022
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customer cooktops, furnaces, water heaters, etc., were upgraded before the gas were sent to their buildings. Because hydrogen-ready appliances are only just being tested today and pipeline systems would also need upgrading, this transition arguably represents a larger shift for customers than electrification would be.
One way to limit the need for infrastructure change to accommodate hydrogen would be to combine the hydrogen with carbon captured from a biological source or from direct air capture, to produce synthetic methane. When using biological sources, this fuel would face the same feedstock limits as biomethane. This means that for wholesale replacement of fossil natural gas with synthetic gas, the carbon would likely need to be captured from the air. Net lifecycle GHGs from these processes would depend on powering the air capture with zero-carbon sources of energy and limiting the leakage of the produced methane to low-enough levels so as to not fully counteract the climate benefits of the fuel.
One planning implication of using green hydrogen, especially paired with direct air capture, is the immense requirements for electricity to power the electrolysis and air capture processes.
The amount of electricity to produce these fuels and meet customer needs would dwarf the amount of electricity that would be required to directly meet customer needs with the generated electricity. As shown in Figure 4.11, meeting the same energy demand with green hydrogen as with heat pumps would require almost six times as much renewable energy generation.
While the ability to store and ship hydrogen and synthetic methane allows for distant generation not aligned with seasonal needs for heating, the added land use and cost associated with this electricity production warrant consideration. Overall, synthetic natural gas is expected to cost more than biomethane when using direct air capture: E3 recently estimated a cost of about $70 per MMBTU.
42 In the San Diego region’s context, with the region’s good year-round renewable electricity resource and lack of strong seasonal heating demand, these technologies face an even greater competitive challenge. In addition, industrial and heavy duty transportation end uses that are difficult to electrify would be the first users of low-carbon hydrogen or synthetic fuels, so supply for buildings would be a secondary market and could be limited.
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Figure 4.11 Comparison of efficiency of energy delivery between green hydrogen and heat pumps. Note that this figure does not include the added cost and efficiency loss from direct air capture and the manufacture of synthetic methane. Source: London Energy Transformation Initiative, 2021. “Hydrogen: A decarbonisation route for heat in buildings?,” Reproduced with permission. Available at: https://b80d7a04-1c28-45e2-b904- e0715cface93.filesusr.com/ugd/252d09_54035c0c27684afca52c7634709b86ec.pdf.
4.4 Pathways to Decarbonization of San Diego’s Buildings Synapse modeled three different trajectories to reach a carbon-free building sector in 2050.
These scenarios were designed to align with multi-sector analysis performed by Evolved Energy Research, as detailed in Chapter 1 and Appendix A.i
1. Central (High Electrification). This pathway assumes that over 95 percent of space heating and water heating equipment sales are fully electric by 2030 and 2032, respectively. In 2050, no residential water heating is served by gas and only 8 percent of residential space heating systems are unelectrified. SDG&E adds about 44,000 new gas customers by 2030, and about 2,000 after.
2. Low Demand (High Efficiency). In this scenario, space and water heating system sales and stock numbers match the trajectories from the Central Case. Heat pumps are assumed to perform at higher efficiencies, reducing electricity consumption and demand.
3. Partial Electrification. This case models an alternative approach, where less than half of space and water systems sales in 2030 are electric. In this case, a low-carbon gas to use as a natural gas alternative is required to achieve decarbonization within the study period. The scenario assumes a linear increase in the use of a low-carbon gas, ii starting
in 2030 and reaching 100 percent in 2045 and later years. SDG&E adds about 60,000 new gas customers by 2030, and about 34,000 more by 2050.
i The Evolved Energy Research (EER) model assumptions are described in Appendix A Table 1. ii Assumed to be a gas that reduces GHGs by 95 percent relative to fossil gas.
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Table 4.6 Some important differences between the three modeled scenarios.
Central Low Demand Partial Electrification
Electric space heat equipment sales
share in 2030
96% (84% heat
pump)
96% (84% heat
pump)
41% (17% heat pump)
Electric share of installed residential
HVAC systems in 2050
92% (75% heat
pump)
92% (75% heat
pump)
75% (54% heat pump)
New residential space heating heat
pump COP in 2050
3.51 5 3.51
Residential and commercial
electricity consumption from space
and water heating in 2050
4.6 TWh 4.2 TWh 4.3 TWh
We have not examined a reference case which fails to achieve zero emissions by 2045, which is in line with California’s statewide net-zero goal. GHG reductions are required by the state, so the relevant questions for policymakers and the public relate to which pathway to decarbonization to choose, not whether to decarbonize at all. Comparing the decarbonization cases to a “reference” or “business as usual” case that fails to reduce emissions would not provide useful insights.
We have also not modeled a scenario that reduces emissions from the building sector to zero (or net-zero) by 2035. Achieving such a target within the San Diego region’s building stock itself would require either extensive retirement and replacement of operating fossil fuel equipment, such as furnaces and water heaters, before the end of its useful life, or a rapid and extensive uptake of low- or zero-emission combustion fuels. Either approach would cost substantially more than replacing equipment with efficient electric options after a normal lifespan, as modeled here. It is likely that cost-effectively achieving a net-zero target for the buildings sector well in advance of 2045 or 2050 would require use of offsets from carbon removal or emission reductions in other sectors or locations. In the event that the San Diego region pursues this approach, it will be necessary to continue local emission reduction activities after 2035, such as those detailed in the scenarios considered here, to reduce dependence on offsets.
Early policy interventions—such as updating building energy codes to require “electrification- ready” or “all-electric” in all new construction and major renovations—can help achieve the high market penetration of electric space and water heating equipment, as in the Central and Low Demand scenarios. Harmonizing the region’s building codes to its decarbonization goals will reduce the overall costs of transitioning away from fossil fuels, aligning near-term investments to the 2050 vision. Further, building codes for new construction can help expedite the adoption of low-carbon technologies into the market, preparing the labor force and equipment distributors to supply these technologies to existing buildings as well.
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buildings and new construction. We use population growth projections for California to evaluate the rate of new construction in the San Diego region.43, i We estimate that 8 percent of the residential and commercial building stock will be new by 2030, increasing to 18 percent by 2050.
4.4.1 Central Scenario (High Electrification) Results
This case illustrates a decarbonization pathway centered on switching space and water heating systems from natural gas (and delivered fuels) to electricity, predominantly heat pumps. Figure
4.12 shows the breakdown in annual sales for space and water heating in the residential and commercial markets.
Figure 4.12 Sales of space and water heating equipment, by fuel and type, in the Central C ase through 2050.
Residential results are on the top and commercial results are on the bottom. Space heating results are on the left and water heating results are on the right. Sales for residential buildings are by unit; for commercial, they are denoted in floor space (million ft2).
i We assume 0.8 percent population growth during the period 2021–2030 and 0.6 percent population growth thereafter until 2050.
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Space heating systems are replaced at a slower rate than water heaters, so some gas space heating equipment remains in use in 2050 in the Central case, while gas water heating is effectively eliminated. Figure 4.13 shows the stock of space and water heating systems by fuel.i As building systems are electrified, the resulting on-site energy use and emissions change. Total site energy consumption falls, as shown in Figure 4.14, because electric heat pump technologies are much more efficient than combustion-based or resistive heating.
Figure 4.13 Stock of space and water heating systems, by fuel and type, in the Central Case through 2050.
Residential results are on the top and commercial results are on the bottom. Space heating results are on the left and water heating results are on the right. Stock for residential buildings is by number of units; for commercial, it is denoted in floor space (million ft
2). “Stock” is here defined as the total installed base of systems in buildings (not the equipment stocked for sale by distributors).
i By “stock” we mean the total installed base of systems in buildings (not the equipment stocked for sale by distributors).
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Figure 4.14 Total site energy consumption (measured in trillion British thermal units, TBTU) in the San Diego region for space and water heating in the Central Case through 2050 by building type and end use.
Natural gas use would decline to about 3 percent of current levels, with remaining use primarily for residential space heating, as shown in Figure 4.15.
On-site GHG emissions, which are currently dominated by natural gas combustion, would follow a trajectory closely aligned with the natural gas trajectory. Figure 4.16 shows on-site emissions by fuel. Remaining emissions in the natural gas sector could be reduced by using small amounts of low-carbon gas such as biomethane.
Electricity use for space and water heating, however, would increase substantially, as shown in Figure 4.17. Electric sector GHG emissions are set to decline to zero by 2045 as a result of California state electricity policy.
While this analysis shows more than a tripling in electricity use for space and water heating, this remains a relatively small part of SDG&E's total electric sales (Figure 4.17). SDG&E’s 2020 electric sales totaled slightly more than 14 terawatt hours (TWh). 44 This is because electricity is
used for many other purposes today, and those uses would continue. Additionally, the projected growth in electric vehicles will account for a greater impact on electricity demand.
Our analysis does not extend to an hourly look at load shapes from different end uses.
However, the increase in electric consumption shown here does not appear likely to drive a substantial increase in SDG&E’s peak electric demand. In 2020, SDG&E experienced a peak demand of about 4,600 megawatts (MW), driven by summer air conditioning load, while its winter peak loads were less than 3,000 MW.
44 This indicates there is substantial headroom for
winter heating load without driving new distribution system or transmission system peaks. To the extent that new water heating loads could add to the summer peak, rate design and control technologies can help shift these loads to off-peak hours.
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Figure 4.15 Total consumption of natural gas (in TBTU) in the San Diego region for space and water heating in the Central Case through 2050.
Figure 4.16 On-site GHG emissions (in million metric tons of carbon dioxide, MMT CO 2) in the San Diego region from space and water heating by fuel in the Central scenario, without use of low -carbon gas, through 2050.
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Figure 4.17 Consumption of electricity (measured in terawatt hours, TWh) for space and water heating in the Central scenario through 2050 by building type and end use. For context, SDG&E’s 2020 electric sales totaled slightly more than 14 TWh.
4.4.2 Low Demand Case Results
The primary difference between the Central and Low-Demand cases is that the latter assumes that electric equipment that replaces combustion-based space and water heating equipment is more efficient. This case has minimal changes in the sales and stock of natural gas equipment.
Thus, the most substantial difference between the Central Case and the Low Demand Case is that the Low Demand Case uses less electricity overall, with no difference in emissions or natural gas use. Figure 4.18 shows the electricity demand trajectory for space and water heating in this case, compared to the Central Case.
Figure 4.18 Total electricity consumption (in TWh) for space and water heating in the Low Demand scenario (blue) and the Central scenario (red).
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The use of higher-efficiency equipment results in lower electric supply costs (see below) and a lower demand for the construction of zero-carbon electric generators. This has implications for the electricity supply analysis presented in Chapter 2. The electric consumption reduction in this case in 2050 relative to the Central Case, about 330 gigawatt hours (GWh), is equivalent to avoiding the construction of about 124 MW of solar PV or 97 MW of onshore wind resources.
4.4.3 Partial Electrification Case Results
In the Partial Electrification case, electric technology market share is smaller and increases later than in the Central Case. Figure 4.19 shows the heat pump market shares for residential and commercial space and water heating used for this case.
Figure 4.19 Heat pump market shares of new system sales in the Partial Electrification (green) and Central (red) scenarios through 2050. Results for residential buildings are on the top and results for commercial buildings are on the bottom. Results for space heating heat pumps are on the left and for water heating heat pumps are on the right.
As a result of this slower uptake of electric options, the stock of natural gas systems remains higher throughout the study period, as shown in Figure 4.20. (Compare with Figure 4.13 above.) On-site pipeline gas use also remains higher through 2050, as shown in Figure 4.21.
To represent potential scaling of low-carbon gaseous fuels in this case, we have increased the amount of biomethane and synthetic natural gas distributed using the pipeline gas system from zero in 2030 to 19.4 TBTU in 2045. This is enough to fully replace fossil gas in 2045. As pipeline gas use continues to fall after 2045, we assume all of the gas supplied is low-carbon gas. If we optimistically assume that this gas has emissions equal to 5 percent of fossil natural gas emissions, then the emissions trajectory for this case is as shown in Figure 4.22. For the Oct. 11, 2022
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purposes of cost estimation in the following section, we assumed that this low-carbon gas has an average cost of $30 per MMBTU.i This cost reflects the limited quantity of fuel required and thus the ability of biomethane to meet some or all of the demand.
Figure 4.20 Space and water heating stock in the Partial Electrification scenario through 2050. Residential results are on the top and commercial results are on the bottom. Space heating results are on the left and water heating results are on the right. Sales are denoted in floor space (million ft2).
i We also assumed that fossil gas would have the Henry Hub spot price projected by the Annual Energy Outlook 2021 published by the U.S. Energy Information Administration.
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Figure 4.21 Pipeline gas consumption (in TBTU) in the Partial Electrification (green) and Central (red) scenarios.
Figure 4.22 Onsite GHG emissions in the Partial Electrification scenario (in million metric tons of carbon dioxide, MMT CO2), reflecting increasing use of low-carbon fuels in place of pipeline gas starting in 2030 and complete replacement of fossil gas with low-carbon fuels in 2045 and later.
4.4.4 Capital and Energy Costs
Each decarbonization scenario considered here results in substantial changes in household and business spending on heating systems, water heaters, and the fuel and electricity to operate those systems. Space heating heat pumps displace the need to pay for separate air conditioning and furnace systems, thus offering substantial cost savings on purchasing other equipment.
Heat pump water heaters are more expensive upfront than traditional electric resistance or gas storage water heaters, but cost less to operate.
Maintaining delivery infrastructure and procuring low- to zero carbon energy sources to reliably meet demand drive fuel and electricity costs.
Table 4.7 shows the present value of estimated capital and energy costs between 2021 and 2050 for each case, using a 3 percent real discount rate. Interestingly, the three scenarios have almost indistinguishable present value costs—well within the margin of error of the numerous cost assumptions they incorporate. As expected, the Partial Electrification case has lower building system capital costs (because it depends on mature technologies), but fuel costs are higher as a result of the need for low-carbon gas fuel. If low carbon gas became available at scale and at costs well below $30 per MMBTU, this case would be distinctly less expensive than shown here. Similarly, if low carbon gases are not available or only available at scale at costs above $30 per MMBTU, the high electrification cases would be comparatively less expensive.
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11 cents per additional kWh).45 Maintenance costs for space heating and water heating equipment in buildings are not included within the estimated scenario costs. Heat pumps typically have higher maintenance costs than natural gas space and water heating equipment.
However, the cost of maintenance is small—ranging from 2 to 8 percent of the total lifecycle cost of the equipment46, 47—and would not change the overall economics of the decarbonization scenarios.
The costs presented here are only the marginal costs associated with the electric and pipeline gas systems under a case in which those systems continue operating at the current scale and with the same regulatory treatment. Therefore, these costs do not reflect the potential to reduce gas system costs in the electrification cases, which are discussed in the following section; they also do not include the cost of gas piping in new construction. Additionally, the scenario costs include neither health and safety upgrades that may be needed at the time of equipment replacement, which are societal costs. The ways in which costs are spread among customers is a matter of public policy and are not considered here. These considerations may include incentives, weatherization and utility demand-side management programs, rate design, and tax policy.
Table 4.7 Present value capital and energy costs under three decarbonization scenarios (in billions of $2021).
Central Low Demand Partial Electrification
Capital costs
Res. space heating $12.8 $12.8 $11.7
Res. water heating $2.9 $2.9 $2.7
Comm. space heating $7.4 $7.4 $7.4
Comm. water heating $0.5 $0.5 $0.4
Electric upgrades $0.6 $0.6 $0.4
Energy costs
Electricity $6.3 $6.1 $4.8
Pipeline gas $2.0 $2.0 $5.2
Total $32.4 $32.2 $32.7
4.4.5 Health, Environmental, Equity, and Economic Co-Benefits Equitable policymaking for building decarbonization can help address existing social disparities in the San Diego region. Populations of concern for building decarbonization include communities with lower incomes, communities of color, and areas with high pollution exposure. Low-income households already face high energy cost burdens; due to capital limitations that may prohibit electrification, they are also at risk of being left to bear otherwise stranded costs for existing natural gas systems. Communities of color have higher rates of housing rental
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redlining in the San Diego region.49 For these reasons, residents in areas with high pollution exposure are at heightened risk for adverse health impacts associated with combustion of fossil fuels in buildings. Building decarbonization across these communities of concern can create resilient and reliable buildings, reduce energy costs to occupants, improve residents’ wellbeing, alleviate impacts of climate change, and create high-quality jobs.
Re
ducing use of fossil fuels in buildings not only decreases greenhouse gas emissions, but also reduces indoor and outdoor air pollutants that contribute to and exacerbate a variety of negative health and environmental impacts.
50, 51 This includes a range of pollutants: nitrogen
oxides (NOX), carbon monoxide (CO), methane (CH4), nitrous oxide (N2O), volatile organic compounds (VOC), trace amounts of sulfur dioxide (SO2), and particulate matter (PM). Further, these combustion byproducts include precursors of ground-level ozone or photochemical smog.
As a result, decarbonization of building heating and water heating would provide additional co- be
nefits for air quality.
Suc
h reductions in indoor and outdoor air pollution would improve health outcomes in the San Diego region. The associated benefits include lower rates of mortality, cardiovascular disease, respiratory disease, emergency room visits, restricted physical activity, and lost work. Recent work underscores this need, showing the prevalence of unvented combustion in communities of concern in California and negative health impacts that this can cause. 52 Replacing existing gas heating equipment with heat pumps will also add cooling to houses that do not already have cooling equipment. Thus, space heating electrification could reduce heat- related illness in the region, an increasing risk due to climate change. According to the 2019 RASS, approximately one-third of households in the SDG&E service territory do not have air conditioners
9 and policies to replace fossil fuel-based space heating systems can target these households to offer both heating and cooling effects in an equitable way.
The barriers to retrofitting existing housing in communities of concern can be substantial, necessitating policies and programs to help ensure equitable access to decarbonization technologies among residents in the San Diego region. Without targeted action by policymakers and community leaders, historical inequities in access to energy efficiency, renewable energy, and other decarbonization technologies are likely to persist.53 Initiatives should be developed in conjunction with local communities of concern and tailored to those communities’ needs and circumstances.
54 Investing in retrofits for these communities can reduce energy costs for residents, improve pollution exposure, and provide an opportunity to address deferred maintenance and other safety issues. Further, building decarbonization initiatives can create jobs through paired investments in workforce development and training programs that target Oct. 11, 2022
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residents of frontline communities where building investments are most needed.i
4.5 Gas Utility and Rate Impacts
4.5.1 Introduction to Utility Finance and Economics
No matter which pathway is pursued, decarbonizing the San Diego region’s buildings will transform the business of the gas utility, SDG&E. In any scenario, SDG&E will transport much less gas to homes and businesses than it does today. This section focuses on the economics and business model of the gas utility portion of SDG&E. SDG&E as an enterprise also has the ability to coordinate its electric utility planning with changes on the gas side.
Planning for decreased gas system utilization can reduce the financial impact of SDG&E’s transformation on ratepayers, and particularly on low-income households. Increased planning would also decrease the risk of supply issues in the gas and electric utilities. In doing so, SDG&E can better help the region achieve its deep decarbonization goals. This analysis focuses on the utility as a business because of the nature of the relationship between a regulated utility and the residents for whom it provides services. The financial health of the region’s monopoly electric utility, as well as the safety of its electric and gas systems, are important to both residents and the utility’s investors.
SDG&E, like all investor-owned regulated utilities in the United States, is allowed to earn a rate of return based on the amount of capital it has invested in transmission and distribution assets that serve its customers. Under cost of service ratemaking, which is the standard approach across the United States, the utility’s rates are designed to recover the company’s “revenue requirement”—the amount of money it must collect from customers each year to pay for that year’s depreciation of its assets, cover operating costs, and leave a “just and reasonable” return on invested capital for its bondholders and shareholders. Gas rates are composed of the delivery rate, which covers the cost of the local transmission and distribution systems, and the supply rate, which covers the cost of the commodity fuel that flows through the pipes. SDG&E does not make any profit on the supply rate – it simply passes fuel costs through as an operating expense.
Changes in how pipeline gas is used in the San Diego region will cause substantial change in how this business model functions. If the utility maintains its full gas system and invests in that system as it has historically done, while gas sales fall, it will need to raise the rates it charges per unit of gas to recover its full revenue requirement. If it doesn’t raise rates sufficiently, its returns to investors will fall. However, as the gas utility raises rates, more customers may
i Employment impacts are addressed in Chapter 6 of this report.
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choose to use electricity instead of gas, to lower their energy bills. At the same time, greater utilization of the electric system, if achieved without creating new peak-related costs, would allow electric rates to decline. Combined, these rate effects would create an accelerating departure from the gas system, as continued electrification would accelerate the rate differential.
Delivery rate increases could be mitigated by retaining a larger amount of pipeline gas sales.
However, meeting the region’s emissions reduction goals with such quantities would require the remaining sales be low-carbon fuel, which is much more expensive than fossil natural gas.
As a result, the supply portion of gas rates would increase substantially.
Low-income customers and tenants are particularly vulnerable to accelerating gas rate increases because these households have the least ability to invest in changes in their home’s water and space heating systems to mitigate rate changes. A clear transition path for the gas utility would allow for improved opportunities to transition low-income households and tenants to all-electric homes while mitigating the financial burden on these households. The gas utility’s transition path is also particularly important to the utility employees and contractors who install and maintain the gas pipeline infrastructure. In all scenarios considered in this analysis, the gas system continues to have some role, and associated maintenance, for many years.
Nonetheless, having a clear plan would allow the utility and policymakers to support retraining for employees and help them find comparable jobs in the construction, electric, and renewable energy sectors.
i Understanding the dynamics and timing of rate increases and gas customer economics is essential to managing the equitable and just transition from the gas system into a decarbonized future.
4.5.2 Scenario Results without Mitigation
To investigate the impact of changes in gas sales and the number of gas customers as residents and businesses decarbonize their buildings, we modeled SDG&E’s gas utility revenue requirements (in total and per customer), rate base, and rates in both the Central and Partial Electrification cases.
ii In both cases, we did not apply any of the mitigating actions that we detail below. In that way, these results present a bookend case, with higher rates and more assets at risk than would be experienced in reality. We have also not modeled the impact of electrification on electric rates and bills (which will also be strongly impacted by transportation electrification).
Because we assumed no mitigating actions, SDG&E’s total revenue requirements (other than
i More information about on job retraining is covered in Chapter 6 of the report. ii The Low Demand Case differs from the Central Case only in its electric demand, so we have not addressed it separately here.
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the cost of fuel) and rate base are not affected by the scenario. In both cases, we assume that SDG&E continues to add new customers through 2036 (albeit at a declining rate) and continues to replace aging assets at the current pace. It maintains the full extent of its gas pipeline system. Figure 4.23 shows the resulting revenue requirement for the regulated gas delivery business (that is, not including the cost of fuel), while Figure 4.24 shows the utility’s rate base. i In both cases, we have adjusted to real 2020 dollars to eliminate the effect of underlying inflation.
Where the scenarios differ are in three further aspects: the cost of fuel, the number of customers, and the amount of fuel delivered. As shown in Figure 4.25, adding the cost of fuel to the delivery revenue requirement (dashed yellow line) results in the Partial Electrification (green) and High Electrification (red) trajectories.
ii
Figure 4.23 Gas utility revenue requirement (in million 2020$) for delivery services through 2050 in both the Central and Partial Electrification scenarios.
i Rate base is the amount of unrecovered assets on which the utility earns its return for shareholders. It generally equals the undepreciated (remaining) value of the utility plant in service, adjusted by the tax treatment of depreciation.
ii The fossil gas prices used here reflect projections from the U.S. Energy Information Administration’s 2021 Annual Energy Outlook and do not reflect the recent increase in gas prices seen this winter. The change in prices observed recently, if sustained into the future, would increase costs.
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Figure 4.24 Gas utility rate base (million 2020$) through 2050 in both the Central and Partial Electrification scenarios.
Figure 4.25 Gas utility revenue (million 2020$), including fuel costs, for the Central (red) and Partial Electrification (green) scenarios. The delivery revenues only are the same for both scenarios and are shown in the dashed yellow line. The difference between the dashed line and the solid lines reflects the fuel costs.
To estimate the trajectory for delivered gas rates in each case, we divided the total revenue requirement by the total sales of pipeline gas in each case. This results in the forward rate curves shown in Figure 4.26. While the Partial Electrification case has lower rates than the Central Case, it still shows rates that far exceed today’s average gas rates of just over $1 per therm. Both cases have rates that exceed $2 per therm by the 2030s (2033 in the Central Case Oct. 11, 2022
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and 2038 in the Partial Electrification case). These higher per-unit rates could encourage customers to choose to heat with electricity, absent policy intervention to change the relative costs of fuels.i
However, customers do not pay rates–they pay bills. Therefore, it is necessary to multiply the rates by the average consumption per customer to evaluate the impact of each scenario on the total annual energy costs of the customers who remain connected to the gas system. Figure
4.27 shows the resulting energy bills.
Figure 4.26 Forward gas rate curves (measured in 2020$ revenue per therm) for the Central (red) and Partial Electrification (green) scenarios.
i This analysis uses the total revenue requirement divided by total sales as a proxy for rate impacts. We do not distinguish between rate classes, and we do not distinguish between the monthly customer charge and the marginal rate for consumption, which each send different signals that shape customer behavior. Rate designs that shift more costs into the monthly customer charge would strengthen gas in marginal competition with electricity for each end use, while simultaneously giving customers a stronger incentive to fully disconnect from the gas network.
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Figure 4.27 Average annual customer bills (2020$ per customer) for gas customers in the Central (red) and Partial Electrification (green) scenarios. This can be compared to the increase in electric utility bills from a home switching from gas to all-electric (blue dashed).
These bills illustrate the challenge facing SDG&E and its stakeholders as it plans a path forward:
in both cases, the cost of gas service per customer increases substantially. While gas customer bills in the Partial Electrification scenario are lower than in the Central Case, in both cases they rise to far exceed the bills for equivalent service provided with all electric appliances (Figure
4.27, dashed blue line).i Low-income households are particularly vulnerable to the increasing gas bills because they will struggle more to invest in electric space and water heating. This energy burden becomes increasingly impactful as the annual all-electric home bill remains relatively constant and the gas bills in both the Central and Partial Electrification cases continue to rise.
Our analysis indicates that, absent policy intervention or mitigating actions, the level of electrification in 2050 in the Partial Electrification case is not a stable equilibrium. The customer savings from switching to electricity will continue to increase as more customers electrify, which will in turn drive further electrification. While some households will face barriers to electrification, the increasing savings will overcome more and more of those barriers.
4.5.3 Mitigation Approaches
SDG&E, its owners, and its regulators have numerous options to evolve the utility’s practices and business model to mitigate the rate trajectories that would result from decarbonization.
i The exact customer economics depend on rate design for both gas and electric utilities. Figure 4 .27 reflects the relevant per-customer costs of service (accounting for the fact that building electrification will not drive changes in electric transmission and distribution costs), as a proxy for the costs that would be assigned to each customer under a reasonable rate design.
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The objectives of these approaches would be to more equitably share the cost of the existing gas system between today’s customers and future customers, as well as to limit the risk to residents and investors that the utility will leave substantial stranded assets. Stranded assets are investments that the utility made but which are retired before their full asset value has been recovered (see Figure 4.28 for an illustration of stranded assets).
The cost of stranded assets could be passed to utility investors, which would risk the financial viability of the company. This is not optimal because San Diego residents require SDG&E to be a viable enterprise to continue to provide electric service (at least), and financial difficulties threaten service to any remaining gas customers. Safety of the electric and gas systems could also decline in such a case. The value of some stranded assets could instead be recovered from electric ratepayers or from taxpayers. Both approaches would require changes in fundamental approaches to utility ratemaking. One option would be securitization, wherein stranded assets are bought out by a public bond-backed entity with a lower cost of capital (thus lowering the total funds to be recovered), and then the bond is paid back over an appropriate timeframe using electric ratepayer funds or tax revenues. California is using securitization to address electric utility costs associated with wildfire risk reduction. i
To limit the risk from and the amount of stranded assets whose fate must be resolved in groundbreaking ways, utility financial and infrastructure practices could be changed in the near term.
ii These approaches would have different effects on the utility’s annual revenue requirements. In some cases, stranded cost risks are mitigated by recovering funds sooner, while there is still extensive use of the gas system. In other cases, actions mitigate risks by reducing the size of the total investment at risk. Some actions do not change the total size of the investment or stranded cost risk, but they can mitigate rate impacts and thereby buy breathing room to use rates to recover invested capital. In each case below, we change one aspect of the utility’s action or accounting to illustrate the impact of each change. In reality, the utility’s management, along with its investors, regulators, and other stakeholders, would develop a portfolio of actions to best achieve their objectives.
i See, for detail, California Assembly Bill 1054 (passed 2019) and California Public Utilities Code, Sec. 8386.3. ii One resource to learn more about the options discussed here, and others, is Managing the Transition: Proactive Solutions for Stranded Gas Asset Risk in California by Bilich, Colvin, and O’Connor (2019) for the Environmental Defense Fund (available at
https://www.edf.org/sites/default/files/documents/Managing_the_Transition_new.pdf ) While the analysis in this report differs somewhat from that study, the general conclusions and analysis are compatible.
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Figure 4.28 Illustration of the amount of stranded asset risk when an asset is no longer used and useful, before the end of its planned lifetime. Source: Bilich, Colvin, and O’Connor (2019). “Managing the Transition: Proactive Solutions for Stranded Gas Asset Risk in California.” Environmental Defense Fund. Reproduced with permission.
4.5.4 Accelerated depreciation
Depreciation is the process by which a utility under cost of service regulation recovers the costs of its investment in assets over the lifetime of the assets. Gas utility assets are generally depreciated over their expected engineering lifetime—as many as 70 years for new plastic pipes, for example. However, for intergenerational fairness, this approach assumes that the pipes will carry roughly the same amount of gas each year throughout their lifetimes. As the gas sales trajectories shown in this chapter illustrate, this assumption no longer holds. Accelerating the recovery of the invested capital in the gas system (e.g., so that it would fully recover by 2045) would reduce stranded cost risk, at the cost of higher gas rates in the near term.
Regardless of the treatment of depreciation, long-term gas rates would still rise with falling sales, as long as operations and maintenance costs of the system do not fall along with sales (in inflation-adjusted terms).
Figure 4.29 shows the approximate revenue requirement trajectory for SDG&E under an accelerated depreciation scenario (Figure 4.29, blue solid line), compared with the traditional depreciation approach (Figure 4.29, red dashed line).
i This scenario was developed by setting
the minimum depreciation rate for any asset type to 4 percent (equivalent to a 25-year depreciation period if there were no removal cost). Revenue requirements, and therefore rates,
i These results are the same for the Central and Partial Electrification cases.
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are higher in the near term with accelerated depreciation, as expected.
Figure 4.30 shows SDG&E’s projected rate base with and without accelerated depreciation. The rate base rises and then falls in the accelerated depreciation case, as the utility continues to make its historical pattern of capital investments. However, the value of rate base at risk in the gas utility transition is reduced substantially—by more than $1.4 billion in 2050.
Figure 4.29 Gas utility revenue requirement (million 2020$) with and without accelerated depreciation (blue, solid line and red, dashed line, respectively).
Figure 4.30 Gas utility rate base (million 2020$) with and without accelerated depreciation (blue, solid line and red, dashed line, respectively).
One minor, but impactful, change to depreciation practice could be eliminating recovery of funds to cover gas asset removal upon retirement. Standard depreciation practice recovers not just the amount invested in the pipe, but also the net cost of removal of the pipe at end of life.
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Because this action is expected to occur far in the future (when inflation will have raised the cost of removal), the removal cost can approach, or even exceed, the value of the asset itself.
As a result, depreciation costs can be almost twice as large as they would otherwise be. If policymakers decide that gas pipes could be retired and abandoned in place without removal (or that removal costs would be borne by future taxpayers), regulatory financial calculations could adjust, lowering gas rate pressures and creating room for accelerated depreciation or other approaches.
4.5.5 Limiting capital investment
Another approach to limiting stranded cost risk is to limit the total amount of assets the utility has invested. Because past investments have already been made, the point of impact here has to do with the rate of new asset investment. SDG&E invests in assets for two primary purposes:
(1) to extend pipes to serve new customers, and (2) to replace old or damaged assets.
Addressing these two drivers would require policy changes tailored to each.
First, investment in pipes to reach new customers would be shaped by whether new customers demand gas service. If new construction is all electric, there would be no such investment.
Other approaches, such as requiring customers that require a line extension to cover the full cost themselves, could also limit shareholder and other shared risk from these assets. The Central Case includes continued, but slowing, expansion of gas service to new customers (about 44,000 by 2030 and about 2,000 after). Figure 4.31 shows the impact of not expanding gas line investments to reach these new customers on the baseline trajectory of SDG&E’s rate base.
Forgoing these additions reduces the utility’s rate base by about $400 million in 2050.
Figure 4.31 Gas utility rate base (million 2020$) with and without new customer additions (red and blue lines, respectively).
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Second, most of SDG&E’s capital investments relate to replacing old assets with equivalent new ones. These replacements occur both reactively (to address actual leaks or damage to pipes) and proactively by SDG&E to improve pipeline safety and reduce leaks. We have not assessed the necessity of SDG&E’s pipeline replacements. However, to indicate the potential ratepayer impact of slowing the pace of these replacements (which could correspond to targeting replacement only to the most urgent locations), we modeled a reduction in the pace of these replacements by a factor of three. The results are shown in Figure 4.32. This figure also shows the combined effect of eliminating new gas lines and reducing investment in existing asset replacement by a factor of three. Together, these changes would reduce the utility’s rate base at risk in 2050 by $1.15 billion.
Figure 4.32 Gas utility rate base (million 2020$) with Central Case findings (red line), reduced pipeline and service replacement rate (blue line), and combination of reduced replacements and no new customer additions (purple line).
4.5.6 Targeted system retirements
One way to reduce the need for new capital investment, while also reducing operation and maintenance costs, would be to retire gas system assets instead of replacing them, as seen in Figure 4.33. By targeting all buildings served by a particular gas system asset for electrification, that gas asset can be retired. Targeted retirement likely represents a more cost-effective way to manage the gas transition than replacing assets in the face of declining sales.
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Figure 4.33 Illustration of the gas infrastructure implications of targeted vs. untargeted electrification. Source: Asa et al., 2020. “The Challenge of Retail Gas in California’s Low-Carbon Future: Technology Options, Customer Costs, and Public Health Benefits of Reducing Natural Gas Use.” E3 for the California Energy Commission.
However, the pace of natural system replacements in the San Diego region is much slower than the pace at which the system might be abandoned, particularly under a High Electrification decarbonization pathway. SDG&E currently replaces an average of about 33 miles of distribution main pipes per year. We estimate that SDG&E also replaces about 1,400 service lines each year.i If the customers served by these mains and services were electrified rather than the repiped, it would decrease the utility’s stranded cost risk by reducing its new investments.
While targeting electrification to the areas of pipe replacement would reduce stranded cost risk by limiting new capital investment, it does not eliminate the issue. Targeted electrification and pipeline retirement should also reduce operation and maintenance costs since there are fewer miles of pipe to maintain, which could allow for either lower rates and thus a stronger competitive position vs. electricity (thus allowing departures and sales reductions to be more measured and planned) or for more room in constant gas rates to recover asset value otherwise left stranded.
Figure 4.34 illustrates the impact on the utility’s revenue requirements for gas distribution service (not fuel supply) in the Central Case if targeted electrification and mains retirement substituted for mains replacement and if customers due for new service lines were electrified instead. As modeled, both transitions in utility practice would ramp in over the next decade. In this example, we have also modeled no new customer additions. In this case, the utility’s rate
i Services are the small pipes that connect customers to the distribution mains.
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base in 2050 would be about $1.4 billion less than in the unmitigated case (Figure 4.32).
Targeted electrification, which would involve retiring distribution mains not due for replacement, would create stranded costs that would need to be addressed in some fashion.
Targeting electrification toward communities of concern could limit the risk that these populations face from increasing gas rates.
Figure 4.34 Gas utility delivery revenue requirement (without fuel costs, million 2020$) in the Central case (red) compared with a case where electrification is targeted to allow the utility to avoid rebuilding or replacing aging distribution mains (blue). The targeted electrification results also include no new customer additions.
4.6 Key Policy Actions
Taking actions immediately represents the best way to put San Diego’s buildings on a course for decarbonization by mid-century. This timeframe is driven by the long lifetime of building components such as HVAC systems and water heaters, along with the relatively nascent state of the market for efficient low-carbon technologies that can reduce direct emissions from the region’s buildings. By taking action that changes markets swiftly, local policymakers will reduce the future costs of early equipment replacement and stranded assets. While the end state for the region’s buildings remains unknown, the initial steps policymakers can take are common across all pathways and are “low regret” policy choices. These include:
Equity: Leading with communities of concern as part of the market transformation can mitigate risks of communities being left behind and avoid social costs of helping them transition later.
Investments in building energy efficiency and decarbonization provide an opportunity to simultaneously address deferred maintenance and existing health and safety issues in existing buildings, which are more common in buildings occupied by low-income families and communities of color. Financial support—such as incentive programs, grants, and low-interest Oct. 11, 2022
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loans—will facilitate decarbonization of low-income housing and buildings for which owners face financial hardship. Paired investments in workforce development and job training programs that target residents can simultaneously create good-paying jobs.
Electrification: Increasing adoption of efficient heat pump-based space and water heating systems in both new and existing buildings, with particular focus on assistance for communities of concern and rental buildings, is a key first step. Approaches can focus on early replacement or end-of-life replacement based on the condition of existing space heating, water heating, and cooling systems.i Market forces alone cannot ensure a timely transition away from fossil fuel combustion in buildings. Examples of strategies to achieve broader electrification include building codes and ordinances to require electrification or “electrification readiness,” appliance replacement incentives, subsidized building retrofit programs, and building emissions performance standards. Building shell improvements, such as insulation and air sealing, can help reduce electric system demand peaks and manage system costs associated with building electrification. Other uses of fossil fuels in buildings—cooking, laundry, and process loads—will need to be addressed and can typically be electrified as well. Policymakers can look to examples of building electrification efforts across the country, as cataloged by various organizations including the American Council for an Energy-Efficient Economy, the Building Electrification Institute, the New Buildings Institute, the Institute for Market Transformation, and more.
Statewide building codes: The region can benefit from state-level action by working with state regulators and actively participating in the California Energy Commission’s stakeholder process to support building energy efficiency standards (Title 24) that prioritize building decarbonization. Efficient construction will be more costly in some circumstances; however, high-performance buildings have lower utility costs, which can result in equal or lower monthly costs when considering rent or mortgage and utilities. Further, all-electric buildings save substantial gas hookup and plumbing costs. See Chapter 8 for a discussion of the local authority to establish building codes. Where local jurisdictions do not have authority, collective participation in state rulemaking processes may be useful.
Local building codes: Setting local “electrification-ready” or “all-electric” standards for new construction and major renovations through building energy codes would reduce costs associated with transitioning away from fossil fuels. Policymakers can benefit from lessons learned in the adoption of all-electric reach codes or ordinances—which are local codes or ordinances that go beyond state or federal requirements—in the cities of Carlsbad, Encinitas, and Solana Beach. Local jurisdictions have authority to mandate electrification or expressly prohibit natural gas plumbing in buildings if all statutory requirements are met. For more information on local authority, see Chapter 8 of this report.
Existing buildings: Programs and policies must target eliminating combustion of fossil fuels in existing buildings, which turn over slowly and will continue to generate emissions for decades if left unchecked. Approximately 80 percent of the buildings that will exist in 2050 in the region
i The end of life of an existing air conditioning system provides an opportunity to replace it with a heat pump and simultaneously eliminate existing fossil fuel heating equipment.
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have already been built. Energy efficiency improvements can reduce emissions associated with electricity use in existing buildings; however, this opportunity decreases as electricity generation approaches 100 percent carbon-free. Therefore, electrification should also be a focus for existing buildings. Market barriers to electrifying the existing building stock include initial cost hurdles, consumer preferences and awareness, and workforce development needs.
An integrated strategy for existing buildings should include:
• Education and outreach to
inform residents and building owners and catalyze local action. Public resources should inform the community of local and regional decarbonization initiatives and guide building owners to financial support, technical assistance, and decarbonization programs. Building owners may need assistance planning for future conversion of combustion equipment away from fossil fuels; planning and education efforts should focus on end-of-life equipment replacement. See also the paragraphs below on education and outreach.
• Financial incentives and financing fo
r building electrification and energy efficiency
retrofits. Low-income homeowners and building owners facing financial hardship may need extra support. Point-of-sale discounts can support the transition to efficient electric equipment. By expanding property assessed clean energy (PACE) financing options in the region and providing utility-meter-tied financing, local agencies can ensure building owners are not burdened with repayment of costs beyond the duration of ownership.
Local, regional, or state revolving loan funds may provide lower interest loans than traditional private financing for building retrofits.
• Mandatory energy information disclosure suc
h as (1) disclosure of energy use data and
equipment systems at the time of sale or lease, or (2) mandatory energy reporting for large buildings like the City of San Diego’s Building Energy Benchmarking Ordinance. • Energy audits to identify energy and emissions reduction opportunities for buildings.
Programs to defray the cost of audits could be funded publicly or through ratepayer’s bills.
• Mandatory emission reduction requirements suc
h as building performance standards or
prescribed fuel switching. These requirements can be aligned to the emission reduction goals of individual jurisdictions or the overall Regional Decarbonization Framework. • Local government leadership, s
uch as setting aggressive targets for the decarbonization of publicly owned buildings. Local leadership can showcase the commitment of public entities to climate action, provide an early market signal to contractors and equipment suppliers, and create case studies for others to follow. State and federal agencies that own buildings in the San Diego Region may already fall under governmental commitments to early decarbonization and can be partners for local government. i
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Gas pipelines: Utilities and regulators can mitigate stranded cost risk by minimizing unnecessary extensions or replacements of the gas pipeline system and by aligning depreciation of existing utility assets with their utilization lifetimes.
Geographic targeting: Focusing electrification and targeting retirement of gas pipeline segments (e.g., in neighborhood clusters) can help optimize available resources and reduce ratepayer burden for maintaining the gas distribution network.
Regional coordination: Accomplishing deep decarbonization of the buildings sector requires action by a diverse set of stakeholders in the region. Regional coordination, such as through existing or new governance structures, may help to sustain progress over time. For more discussion of this, see Chapter 7 of this report.
Low-carbon fuels: Research and pilot production and use of low-carbon gaseous fuels can prepare the region to decarbonize hard-to-electrify end uses in buildings.
Co-benefits: When evaluating prospective policies and programs, consider the full range of benefits created by building decarbonization, such as improved environmental and human health and equitable job creation.
Education: Inform building owners of the financial risks of installing new fossil fuel equipment, which may need to be replaced before the end of its useful life to meet regional decarbonization targets and may expose building occupants to high future gas rates. Teach owners about the co-benefits of eliminating fossil fuel combustion in buildings. Building owners with harder-to-decarbonize end uses may need resources and technical assistance to achieve full decarbonization. Expand building operator certification programs, with specific curriculum for building decarbonization and carbon-intensive end uses.
Outreach: Leverage the existing Regional Energy Network and community choice aggregation platform to promote building electrification through outreach, engagement, and direct enrollment. Look to building electrification initiatives among the following California providers for guidance: Central Coast Community Energy, East Bay Community Energy, MCE, Peninsula Clean Energy, Redwood Coast Energy Authority, Silicon Valley Clean Energy, Sonoma Clean Power, and Valley Clean Energy.
Information gathering: Improve existing data collection practices to inform future policies and programs. Local governments can begin identifying the fuel type for space heating and water heating systems and the capacity of electrical panels. This information can be collected through building permits and other administrative processes and can be mapped to existing property databases. Further, building energy benchmarking practices can lay the foundation for building performance standards, which establish mandatory energy or emissions targets that improve over time. Cities can expand on the example of the City of San Diego’s building energy benchmarking ordinance and lead by example by disclosing energy information for public
emissions in local buildings.
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buildings.55 Finally, collecting equity-related metrics is foundational to designing equitable initiatives and monitoring progress.
Embodied carbon: Targeting embodied carbon (the carbon intensity of building materials) in buildings through zoning or building codes can complement policies focused on operational carbon from energy use in buildings. Local policymakers can consider adopting “buy clean” policies such as Marin County’s Low Carbon Concrete Code i or work with state regulators to
build on existing statewide legislation, including the Buy Clean California Act.
i See, for details, Marin County Code Chapter 19.07 Added To Marin County Code Title 19 , available at https://www.marincounty.org/-/m edia/files/departments/cd/planning/sustainability/lo w-carbon- concrete/12172019-update/low-carbon-concrete-code.pdf?la=en.
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Works Cited:
1. U.S. Census Bureau. 2021. County Population Totals: 2010-2019. Available at:
https://www.census.gov/data/tables/time-series/demo/popest/2010s-counties- total.html#par_textimage_242301767.
2. U.S. Census Bureau. 2021. 2019 County Business Patterns. Availabl e at: https://www.census.gov/programs- surveys/cbp.html. Synapse review of property data provided by San Diego County Assessor's Office
3. The City of San Diego. 2007. San Diego Modernism Historic Context Statement. Available at:
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4. Sutro, Dirk. 2002. San Diego Architecture from Mission to Modern: Guide to the Buildings, Planning, People, and Spaces That Shape the Region. American Institute of Architects | San Diego. Sunbelt Publications.
5. University of San Diego. 2021. Indian Reservations in San Diego County. Available at:
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8. County of San Diego. 2018. Greenhouse Gas Emissions Inventory, Projections, and Reduction Targets. Available at:
https://www.sandiegocounty.gov/content/dam/sdc/pds/advance/cap/publicreviewdocuments/CAPfilespublicr eview/Chapter%202%20Greenhouse%20Gas%20Emissions%20Inventory%2 C%20Projections%20and%20Reduct ion%20Target.pdf.
9. DNV GL Energy Insights. 2021. 2019 California Residential Appliance Saturation Study (RASS). Available at:
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10. City of San Diego. Building Energy Benchmarking. Accessed September 23, 2021. https://www.sandiego.gov/sustainability/energy-and-water-efficiency/benchmark.
11. City of San Diego. Building Energy Benchmarking. Accessed September 23, 2021. https://www.sandiego.gov/sustainability/energy-and-water-efficiency/benchmark.
12. U.S. Energy Information Administration (EIA). 2013. Commercial Buildings Energy Consumption Survey (CBECS), 2012. Available at: https://www.eia.gov/consumption/commercial/data/2012/. EIA Form 176, Years 2005 – 2019; Form 861 and 861S, Years 2005–2019 and Year 2020 early release.
13. Mahone, A., et al. 2018. Deep Decarbonization in a High Renewables Future. Prepared by Energy and Environmental Economics for the California Energy Commission. Availa ble at:
https://www.energy.ca.gov/publications/2018/deep-decarbonization-high-renewables-future-updated-results- california-pathways.
14. Itron, Inc. 2014. California Commercial Saturation Survey Report. Prepared for California Public Utilities Commission. Available at:
http://capabilities.itron.com/wo024/Docs/California%20Commercial%20Saturation%20Study_Report_Final.pdf
15. Armstrong, S., et al. 2019. A Zero Emissions All-Electric Multifamily Construction Guide. Redwood Energy.
Available at: https://fossilfreebuildings.org/ElectricMFGuide.pdf.
16. Mitsubishi . n.d., City Multi Brochure (CM11WD-I), p. 83, Available at:
https://www.mitsubishielectric.com.au/assets/LEG/MEE10K026_CM11WD_I_w.pdf.
17. Northeast Energy Efficiency Partnership (NEEP). 2019. Variable Refrigerant Flow (VRF) Market Strategies Report. Available at:
https://neep.org/sites/default/files/resources/NEEP_VRF%20Market%20Strategies%20Report_final5.pdf.
18. Bonneville Power Administration. 2018. HVAC Technology Guide. Page 106. Available at:
https://www.bpa.gov/EE/Utility/Momentum-Savings/Documents/2018_BPA_HVAC_Technology_Guide.pdf.
19. Stagner, J.C. n.d. Stanford University’s “fourth generation” district energy system. Available at:
https://sustainable.stanford.edu/sites/default/files/IDEA_Sta gner_Stanford_fourth_Gen_DistrictEnergy.pdf.
20. Northwest Energy Efficiency Alliance. 2014. Final Summary Report for the Ductless Heat Pump Impact and Process Evaluation. Available at: https://neea.org/resources/final-summary-report-for-the-ductless-heat-pump- impact-and-process-evaluation;
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21.Cadmus. 2016, Ductless Mini-Split Heat Pump Impact Evaluation. Available at:
http://www.ripuc.ri.gov/eventsactions/docket/4755-TRM-DMSHP%20Evaluation%20Report%2012-30-2016.pdf
22. Schoenbauer, B. 2018. "Cold-Climate Air-Source Heat Pumps." Center for Energy and Environment. Available at:
http://www.duluthenergydesign.com/Content/Documents/GeneralInfo/PresentationMaterials/2018/Day1/ccA SHPs.pdf.
23. Mahone, A. et al. 2019. Residential Building Electrification in California - Consumer economics, greenhouse gases and grid impacts. Energy and Environmental Economics. Available at: https://www.ethree.com/wp - content/uploads/2019/04/E3_Residential_Building_Electrification_in_California_April_2019.pdf.
24. Air Conditioning, Heating, and Refrigeration Institute. 2021. Directory of Certified Product Performance.
Available at: https://www.ahridirectory.org/Search/SearchHome.
25. Mai, T. T. et al. 2017. Electrification Futures Study: End-Use Electric Technology Cost and Performance Projections through 2050. National Renewable Energy Laboratory. Availabl e at:
https://www.nrel.gov/analysis/electrification-futures.html.
26. E3. 2019. Residential Building Electrification in California - Consumer economics, greenhouse gases and grid impacts. Available at: https://www.ethree.com/wp-
content/uploads/2019/04/E3_Residential_Building_Electrification_in_California_April_2019.pdf.
27. Jones, Betony. 2021. Los Angeles Building Decarbonization: Community Concerns, Employment Impacts, Opportunities. Inclusive Economics.
28. U.S. EPA. 2021. “ENERGY STAR Certified Water Heaters.” Available at:
https://www.energystar.gov/productfinder/product/certified-water-heaters/
29. Delforge, Pierre and Swanson C. 2016. “Very Cool: Heat Pump Water Heaters Save Energy and Money.” NRDC.
Accessed September 27, 2021. Available at: https://www.nrdc.org/experts/pierre -delforge/very-cool-heat- pump-water-heaters-save-energy-and-money;
30. Hopkins, Asa S., et al. 2018. Decarbonization of Heating Energy Use in California Buildings – Technology, Markets, Impacts, and Policy Solutions, page 21. Available at: https://www.synapse - energy.com/sites/default/files/Decarbonization-Heating-CA-Buildings-17-092-1.pdf.
31. Armstrong, S., et al. 2019; Bruce Sullivan. 2017. “CO2 Takes Heat Pump Water Heaters to the Next Level.” Accessed September 27, 2021. Available at: https://zeroenergyproject.org/2017/05/22/co2-take s-heat-pump-
water-heaters-next-level/
32. Steven Groves. 2018. “Mitigating the Parasitic Effect of Heat Pump Water Heaters on Home Heating Systems in Cold Climates” Fortis BC. Presentation at the 2018 ACEEE Hot Water Forum, March 21, 2018.
33. Carew, Nick. Et al. 2018. Heat Pump Water Heater Electric Load Shifting: A Modeling Study. Ecotope, Inc.
Available at: https://ecotope-publications-
database.ecotope.com/2018_001_HPWHLoadShiftingModelingStudy.pdf.
34. Ecotope. 2015. RCC Pilot Project: Multifamily Heat Pump Water Heaters in Below Grade Parking Garages in the Pacific Northwest.
35. Alan Meier et al. 2018. University of California Strategies for Decarbonization: Replacing Natural Gas, p. 76.
Available at http://dms.hvacpartners.com/docs/1001/Public/0A/04-581025-01.pdf.
36. Gartman, M., S. Armstrong. 2020. “Heat Pumps for Hot Water: Installed Costs in New Homes”. Rocky Mountain Institute and Redwood Energy. Available at: https://rmi.org/insight/heat -pump-hot-water-cost/
37. Jones, B.. 2021. Los Angeles Building Decarbonization: Community Concerns, Employment Impacts, Opportunities. Inclusive Economics. Available at:
https://drive.google.com/file/d/117bFbCLccCdu316IJAIHkRyoLMhQTQd3/view.
38. U.S. Energy Information Administration. 2015. “Table HC3.8 Appliances in homes in the South and West regions, 2015” Residential Energy Consumption Survey (RECS). Available at:
https://www.eia.gov/consumption/residential/data/2015/hc/php/hc3.8.php
39. IEA Bioenergy. 2017. Methane emissions from Biogas Plants. Available at:
https://task37.ieabioenergy.com/files/daten-
redaktion/download/Technical%20Brochures/IEABioenergy_Task%2037_methane_emiss ions_2Psummary.pdf.
40. E3, 2018. Deep Decarbonization in a High Renewables Future: Updated Results from the California PATHWAYS Model. Prepared for the California Energy Commission. Available at https://www.energy.ca.gov/publications/2018/deep-de
carbonization-high-renewables-future-updated-results-
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california-pathways
41. U.S. Department of Energy, Office of Fossil Energy. 2020. Hydrogen strategy: enabling a low-carbon economy.
Available at:
https://www.energy.gov/sites/prod/files/2020/07/f76/USDOE_FE_Hydrogen_Strategy_July2020.pdf
42. E3. 2021. Maryland Building Decarbonization Study Final Report. Available at:
https://mde.maryland.gov/programs/Air/ClimateChange/MCCC/Documents/MWG_Buildings%20Ad%20Hoc%2 0Group/Maryland%20Buildings%20Analysis%20Slide%20Report.pdf.
43. University of Virginia Weldon Cooper Center, Demographics Research Group. (2018). National Population Projections.
44. San Diego Gas & Electric Company. FERC FINANCIAL REPORT FERC FORM No. 1: Annual Report of Major Electric Utilities, Licensees and Others and Supplemental Form 3-Q: Quarterly Financial Report for end of 2020/Q4.
45. San Diego Gas & Electric. 2020. Attachment A to the 2020 Integrated Resource Plan. https://www.sdge.com/sites/default/files/regulatory/Attachment%20A_Cost%20Table%20%281%29_0.pdf
46. Mai, T. T. et al. 2018. Electrification Futures Study: Scenarios of electric technology adoption and power consumption for the United States. National Renewable Energy Laboratory. Available at:
https://www.nrel.gov/docs/fy18osti/71500.pdf.
47. Jadun, Paige, Colin McMillan, Daniel Steinberg, Matteo Muratori, Laura Vimmerstedt, and Trieu Mai. 2017. Electrification Futures Study: End-Use Electric Technology Cost and Performance Projections through 2050. Golden, CO: National Renewable Energy Laboratory. NREL/TP -6A20-70485. https://www.nrel.gov/docs/fy18osti/70485.pdf.
48. U.S. Census Bureau. 2022. ACS 1-Year Estimates 1-Year Estimates-Public Use Microdata Sample, 2019. Available at: https://data.census.gov/mdat.
49. Nelson, R.K., Winling, L., Marciano, R., Connolly, N. and Ayers, E.L., 2020. Mapping inequality: Redlining in new deal America. American Panorama: An Atlas of United States History. University of Richmond: Digital Scholarship Lab.
50. Lin, W., Brunekreef, B. and U. Gehring. 2013. Meta-analysis of the effects of indoor nitrogen dioxide and gas cooking on asthma and wheeze in children. International journal of epidemiology, 42(6), pp.1724- 1737.
51. Buonocore, J.J., Salimifard, P., Michanowicz, D.R. and J.G. Allen. 2021. A decade of the US energy mix transitioning away from coal: historical reconstruction of the reductions in the public health burden of energy.
Environmental Research Letters, 16(5), p.054030.
52. Holm, S.M., Balmes, J., Gillette, D., Hartin, K., Seto, E., Lindeman, D., Polanco, D. and E. Fong. 2018. Cooking behaviors are related to household particulate matter exposure in children with asthma in the urban East Bay Area of Northern California. PloS one.
53. Fournier, E.D., Cudd, R., Federico, F., Pincetl, S., Iles, A. and D. Mulvaney. 2020. On energy sufficiency and the need for new policies to combat growing inequities in the residential energy sector. Elementa: Science of the Anthropocene, 8.
54. USDN. 2019. Facilitating Power, and Movement Strategy Center —From Community Engagement to Ownership:
Tools for the Field with Case Studies of Four Municipal Community-Driven Environmental & Racial Equity Committees. Available at:
https://www.usdn.org/uploads/cms/documents/community_engagement_to_ownership_ - _tools_and_case_studies_final.pdf
55. City of San Diego. 2022. Building Energy Benchmarking. Available at:
https://www.sandiego.gov/sustainability/energy-and-water-efficiency/benchmark.
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5. Natural Climate Solutions and Other Land Use
Considerations
Elise Hanson, UC San Diego
Emily Leslie, Montara Mountain Energy
Key Takeaways
● Natural climate solutions (NCSs) are an important component of decarbonization because they involve natural sequestration and medium to long-term storage of carbon dioxide (CO2) in lands, but NCSs alone cannot sequester enough CO2 in the San Diego region to offset current levels of regional emissions.
● To contribute to reaching California's net zero goals, natural and working lands (NWLs) need to act as stronger net sinks through investments in bolstering NCSs and minimizing carbon emissions from the land and land use activities. To accurately account for net carbon land use emissions, local data need to be collected and integrated into regional carbon calculations.
● Avoiding land use change by protecting NWLs represents the most effective and inexpensive NCS policy in the San Diego region, except where other decarbonization actions necessitate land use change (such as siting renewable energy infrastructure).
This report estimates that annual sequestration in NWLs may be up to 2 million metric tons (MMT) of CO
2 under ideal circumstances and that there may be up to 58 MMT of CO2 stored in vegetation, woody debris, leaf litter, and soils, some of which would be released with land use change.
● Other important regional NCSs considered here may be less effective and/or more expensive; these include carbon farming, wetland protection and expansion, and urban forestry and greening. Wildfire management is important for reducing emissions and numerous other economic, ecological, and social reasons. Large-scale habitat restoration and reforestation, which were not considered in this report, are expensive and may not be effective for decarbonization in the local context. While generally less cost-effective, these NCSs can still be important options with co-benefits.
● NCSs include co-benefits such as ecosystem services that provide economic, social, and public health benefits (e.g., ecosystems can reduce storm surge damages; urban trees provide shade that leads to energy savings and reduced heat island effects). These co- benefits may help justify the cost of NCSs, even in circumstances where carbon sequestration and storage may be relatively low.
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5.1 Introduction
5.1.1 San Diego region’s ecology
The San Diego region and the larger California Floristic Province are generally considered “biodiversity hotspots,” characterized by high levels of endemism (where a species exists nowhere else) and habitat intactness while facing threats of extinction or biodiversity loss.1–3 San Diego county is widely regarded as the most biodiverse county in the nation, in large part due to its high diversity of native plants, bees, birds, reptiles, and mammals.2,4–7 The region is largely shrub-dominated, having cool, wet winters with warm, dry summers, and having highly fragmented habitats near urban and suburban development (Figure 5.1; Table 5.1).2,8 The San Diego region is also home to over 70 species that are listed as either threatened or endangered at the state or federal level and over 100 more species that are considered to be at-risk.9 Further, the San Diego region contains areas that are considered refugia – areas that are relatively protected from stressors that can negatively affect species or ecosystem survival such as fire, climate change, water stress, and recreational impacts. 10 These regions will be
increasingly important for maintaining ecosystem functioning and for protecting ecosystem services, like carbon storage,
10,11 thus highlighting the importance of land use planning at the ecosystem level across the entire region.12,13
Table 5.1 Area (acres) and percent of total area in the San Diego county boundary per vegetation category, calculated in QGIS 3.16 from Figure 5.1.
Regionwide total
Vegetation Classification Subcategory Area (acres) Percent Agriculture and Working Lands (including row crops, orchards, vineyards, pastures, fields, etc.) 136985.26 5.02
Desert/Dune Community 47065.45 1.73
Disturbed 29627.94 1.09
Forest 85489.40 3.13
Grasslands (not used for grazing or pasture, includes native and non- native) 146750.91 5.38 Marshes and Wetlands 6248.76 0.23
Meadows and Vernal Pools 15115.86 0.55
Riparian and Bottomland Habitat 71195.26 2.61
Scrub and Chaparral 1607073.92 58.93
Settlement 381509.95 13.99
Unvegetated Habitat (includes open water, bays, and unvegetated freshwater) 31452.74 1.15 Woodland 168479.01 6.18
TOTAL 2726994.44 100%
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Figure 5.1 Vegetation categories within the San Diego County boundary. All data from SanGIS ( SanGIS.org). See Appendix 5.A for information on shapefiles, geospatial layers, vegetation type classifications, and other data source information.
5.1.2 Natural climate solutions (NCSs)
Land use contributes both negative and positive emissions in the San Diego region. Negative emissions refer to greenhouse gases (GHGs) being absorbed and positive emissions refer to GHG being emitted. The emissions are generally net negative, meaning that most lands absorb more carbon dioxide than they emit every year and act as carbon sinks (Figure 5.2).12,14,15 Land management practices and natural resource uses can maintain, increase, or decrease negative emissions and therefore affect the associated capacity of the land as a carbon sink accordingly.
Actions that maintain or increase negative emissions and bolster carbon sinks in natural and working lands are commonly known as natural climate solutions (NCSs). Natural lands refer to lands relatively unchanged by humans and include wildlands, preserves, and restored habitats.
Working lands refer to lands that are worked by humans to produce a good and include all agricultural lands, like orchards, plant nurseries, row crops, and pasture lands. Most agencies account for these areas under a single natural and working lands (NWLs) categorization encompassing all lands that are not urbanized or developed beyond agricultural purposes, Oct. 11, 2022
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although these two types of land typically have divergent carbon emission profiles and different carbon management practices.12,16,17
Figure 5.2 Total 2019 NWL carbon dioxide equivalent (CO2e) net emissions per land use and land use change sector and for total forestry and total agricultural sectors in the United States. Negative values are net negative emissions, or sequestration, and positive values are net positive emissions. Data are from the 2021 EPA report of national greenhouse gas emissions, tables 5-1 and 6-1.15 *The “existing settlements” sector includes urban trees, which offer large sequestration gains. Without urban trees, existing settleme nts would have net positive emissions.
NCSs will play a significant role in removing and storing atmospheric carbon dioxide (CO2) in the future.i One study suggests that global terrestrial and coastal lands and associated NCSs could contribute up to 30% of the global mitigation needed by 2050 to keep warming to 1.5 degrees Celcius.18 This finding, along with others, demonstrate the importance of maintaining and enhancing ecosystem carbon sequestration. These findings also underscore the need for mitigation and negative emissions technologies to offset natural and anthropogenic emissions.
12,16,18–20
Globally, nationally, and in California, most of the natural mitigation will occur through reforestation, afforestation, forest management, agroforestry, and other tree-based solutions. ii;
i The California State Budget, 2022-2023 includes funding for “nature-based solutions” to, among other things, increase carbon sequestration and storage in California’s natural and working lands. See https://www.ebudget.ca.gov/FullBudgetSummary.pdf for more information (accessed 7/11/22). ii While reforestation involves planting trees in areas that were once forested, afforestation refers to planting in areas that did not historically contain forests or large numbers of trees. Agroforestry is the practice of incorporating trees into agricultural and working lands. Examples of agroforestry may include planting trees in fields and growing “shade-grown” crops, planting trees in pasture and grazing lands, or planting trees and shrubs Oct. 11, 2022
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12,18,21,22 The San Diego region is shrub-dominated2 (Figure 5.1), so there are fewer tree-based NCSs beyond restoring riparian areas and increasing the urban tree canopy cover.12,17 Instead, local NCSs such as non-forest management of shrublands and shrubland restoration may be important, despite not being as prominent at the global level.12 These non-forest management strategies warrant further research but are not considered in this report largely because there are few studies and data on the effectiveness of non-forest management.
There are two major considerations for land use and NCSs in the RDF: maintaining or increasing annual GHG sequestration in NWLs and protecting carbon stored naturally by decreasing or maintaining potential GHG emissions from the land and coastal ecosystems. This analysis focuses on net carbon dioxide equivalent (CO
2e) emissions of NCSs and land use, though there
are numerous co-benefits associated with land use management and NCSs including, but not limited to: biodiversity and endemism conservation, ecological resilience, and ecosystem services.
5.1.2.1 Sequestration
Carbon sequestration is the flow of CO2 from the atmosphere into soils, biomass, geological formations, etc. Natural and working lands can sequester CO2 through photosynthesis and can sequester methane (CH4) and nitrous oxide (N2O) through bacterial metabolic reactions.23–25 Despite some CH4 and N2O sequestration, NWLs tend to emit more than they sequester, and thus generally represent CH4 and N2O sources rather than sinks.24,26–28 On average, NWLs absorb more CO2e than they emit because they can collectively absorb large enough quantities of CO2 to counteract the climate warming effects of CH4 and N2O emissions and result in a net decrease of GHGs.20,24
Annual carbon sequestration rates vary by prevailing climate, levels of disturbance, and dominant plant species,
29 however, landscapes with older, larger plants generally have higher sequestration rates.29,30 As such, forests tend to have higher sequestration rates than grasslands, for instance, with forests sequestering up to twice as much carbon as grasslands.20,21,24 While the focus is often on the volume of trees planted, the International Panel on Climate Change’s most recent report highlights the scientific consensus that land managers should avoid afforestation in lands like grasslands or savannas that historically have low tree densities. Afforestation in these areas replaces native and adaptive vegetation with ill- adapted trees and is therefore more vulnerable to emitting its stored carbon and provides fewer co-benefits.20,31 Further, the report, along with numerous studies, emphasizes that the type of tree matters20,32 and that non-forest ecosystem protection and restoration are also critical.20
around crops and agricultural lands to provide windbreaks.
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5.1.2.2 Storage
NWLs hold large quantities of carbon in soils and both living and dead biomass.21,24 Carbon storage is defined as an accumulated stock of CO2 stored as carbohydrates and other carbon- containing molecules. Carbon storage in plant tissues occurs when net primary production (NPP) is positive (i.e., when carbon sequestration occurs in the form of plant growth). Primary production is the process by which photosynthetic organisms create sugar and oxygen via sunlight, water and CO
2. NPP is the sugar creation minus the CO2 released through respiration.
When NPP is positive, the plant sequesters more CO2 through sugar production than it releases through respiration.13–15 As plants grow, they store carbon in their tissues in both aboveground (stems, leaves, trunks, etc.) and belowground (roots) biomass. The fate of that carbon is highly dependent on local conditions, although generally some belowground biomass becomes soil carbon, for example as root tissues die and decompose. Additionally, the complex soil ecology and fungal ecology interact with plant sugar production and also contribute to soil carbon storage. Aboveground biomass can store carbon in the system as dead/downed woody debris.
This storage is especially important in low humidity systems where decomposition rates are lower, as they are in Southern California, however there is a trade-off to this storage because it increases fire fuel.
Despite the fact that natural systems are adept at storing carbon on average and in the long- term, total carbon storage contributions vary significantly by ecosystem type in the San Diego region. For instance, though forests and woodlands store and sequester more carbon globally than any other habitat type, they play a smaller role in Southern California. This reflects primarily the relative lack of forests in the San Diego region (Figure 5.1, Table 5.1), and secondarily that existing trees and forests grow more slowly in the majority of Southern California than in more humid regions.
13,17,22
Shrubs and other woody, non-tree plants dominate the San Diego region, as nearly 60% of the region is classified as scrub or chaparral habitats (Table 5.1), which are locally important for carbon storage2,12,30 and nitrogen storage.33 Scrub habitats, including coastal sage scrub (CSS) and chaparral, are somewhat unique in that they continue to provide high sequestration rates and storage even when they are invaded by non-native grasses, which are themselves inefficient carbon storage systems.33 Further, because Southern Californian scrub-dominated ecosystems have longer historic fire regimes (i.e., fires occur less frequently) than forest- dominated ecosystems or more northerly regions,34–37 San Diego’s scrub ecosystems have low carbon “turnover” from their dead, woody tissues to the atmosphere and therefore store that carbon for a longer time period.
33 Though marsh and wetland ecosystems are slow to sequester carbon on an annual basis, they Oct. 11, 2022
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hold large quantities in stable reserves38,39 and can even transport carbon to the deep ocean, thereby storing it for millennia or longer.40 For the San Diego region and California as a whole, salt marshes, salt pans, mudflats, and eelgrass (or seagrass) beds are the crucial “blue carbon” ecosystems that store disproportionately high amounts of carbon for long time periods.39,41,42
5.1.2.3 Avoiding land use and land use change emissions Avoided emissions refer to emissions that would have come from NWLs if not for some land use protection or land use change prevention. In California, the majority of avoidable emissions come from large crown wildfires in forests and from changing land use from forests, shrub, wetlands, grasslands, and agricultural lands (roughly in that order) to human-made environments.
12,13,43 In the case of wildfires, centuries of fire suppression have left areas with excess downed woody debris on the forest floor, which fuels faster, hotter fires.36 Additionally, pest and noxious weed invasions have fueled large, destructive fires by creating larger pools of downed woody debris and swaths of dead non-native grasses or excessively flammable leaf litter from non-native plants.36,44 Further, worsening droughts stress plants and therefore reduce the likelihood that an otherwise healthy forest or scrub ecosystem will withstand a wildfire or rebound quickly after one. This effect is magnified in an invaded forest or scrub habitat.12,36,44 For example, the combination of drought and non-native weed and insect species invasions fueled San Diego’s 2003 and 2007 super fires, where large quantities of dead pine trees, oak trees, and annual grasses fueled historic fires and permanently altered ecosystems, changing previously forested lands to scrub-dominated lands.35,44 In the case of land use change, rapid development has fragmented the San Diego region’s natural ecosystems and has created large expanses of settled and built up areas that provide little carbon sequestration value or other ecosystem services.
2,8,13,15
Beyond preventing “avoidable” emissions through land use and management practices, some emissions will be nearly or completely unavoidable. For instance, if there are not large-scale wetland management practices implemented in the region, there will be future emissions generated from lost wetlands as sea levels rise. As seawater inundates intertidal zones, marshes, bogs, and wetlands, the associated plants will die and a portion of the carbon stored in the sediment and biomass will be emitted.
42 These emissions will be unavoidable,45,46 but
they can be mitigated through restoring upland habitats and allow for wetland migration, which may result in net zero emissions from wetland loss due to sea level rise.17,42,47,48
5.1.2.4 Other considerations (co-benefits)
NWLs provide numerous societal benefits beyond carbon sequestration and storage as a result of natural ecosystem processes. These are called ecosystem services or nature-based solutions, and include air and water quality improvements, reduced impacts from natural disasters, Oct. 11, 2022
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increased food and fiber production, groundwater recharging, soil stabilization and erosion control, and improved public health through better air quality or increased outdoor recreation opportunities. The majority of the proposed methods to increase carbon storage and sequestration naturally have such co-benefits.17,20–22,49 The California Air Resources Board (CARB) reports that each NCS considered here improves water quality and/or increases water quantity; protects biodiversity, habitats, and ecosystem health; and improves public health and/or community resilience to climate change. Additionally, protecting NWLs from land use change improves air quality, as does urban forestry and chaparral restoration. 49 While this report focuses on the carbon storage and sequestration aspects of NCSs, future work should characterize, quantify, and value the additional ecosystem services and co-benefits to understand the full impacts of these actions and where they could be implemented to deliver benefits to people most efficiently and equitably. The full understanding of NCS co-benefits will be especially important as the San Diego region prepares for a more uncertain climate and plans mitigation policies to address the possibility of longer and/or more severe droughts, more frequent and/or severe wildfires, and other natural disasters and changing baseline climatic realities.
50 The rest of the chapter will focus on describing and providing quantifications of four NCSs that the San Diego region could implement that would sequester atmospheric carbon dioxide, maintain or increase carbon storage, and provide co-benefits. These four NCSs are: protection of natural lands from land use change; carbon farming; protection of blue carbon habitats; and urban forestry and greening. The chapter also describes some additional NCSs without quantifying their benefits, which merit further study.
5.1.3 Land Use Change and Regional Growth, Development, and Sectoral Decarbonization There are considerable trade-offs between preventing land use change and development that are not explicitly considered in the RDF, but that warrant further research and consideration.
Namely, the development for regional decarbonization outlined in this report’s pathways will generally necessitate some degree of land use change.
5.1.3.1 Renewable energy production and land use change Given the current technological availability of low-carbon energy production, Chapter 2 of this report finds that electricity supply decarbonization will require land use change in every investigated scenario to build renewable energy generation facilities and transmission infrastructure. This is true even of scenarios that do not allow the region to independently produce sufficient renewable energy by 2050 to meet the projected demand (Table 2.5). From an NCS perspective, the scenario that prioritizes protecting lands with high sequestration falls Oct. 11, 2022
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short of reaching 2050 regional energy demand and would require relatively expensive investments in developing urban renewable energy resources and significant energy imports from outside of the region. Even by avoiding lands with high sequestration potential, the scenario would still impact regional sequestration to some degree. This scenario underscores the fact that, under the current technological landscape and grid interconnections, there will be trade-offs between producing low-carbon energy and maintaining existing natural carbon sequestration in NWLs. Decision-makers will need to weigh the inherent trade-offs between reducing ongoing energy emissions and preventing the land use change’s one-time emissions and lost ongoing sequestration potential.
5.1.3.1 Transportation and land use change
Chapter 3 of this report shows that a decarbonized transportation sector will also require land use change, some of which may be in NWLs. Land use change may be required to update, expand, and improve public transit; build electric vehicle charging infrastructure; improve and/or expand regional bikeability and walkability; and to otherwise better connect communities to reduce vehicle miles traveled. As with decarbonizing energy, decarbonizing the transportation sector, which is the largest regional GHG emitter, may require some trade-offs between reducing emissions and enhancing NCSs.
5.1.3.1 Development, housing, and land use change
As cities, towns, villages, and communities in the San Diego region continue to grow, land use change will be necessary to build housing, public buildings, businesses, and critical infrastructure, among other building types. This is especially true as the region plans for housing development to address the regional housing shortage and as the region addresses housing equity and access for low-income residents. Reports have explicitly examined land use change and housing in the San Diego region, including the Climate Action Campaign’s “Solving Sprawl” report.
51 This chapter’s findings supports that report’s findings that community- centered growth that focuses on expanding or enhancing existing community footprints will, by definition, have fewer disruptions to NWLs than creating new communities in current natural or working lands. Although the RDF does not explicitly consider housing, this report acknowledges that housing is an important component of continued development, economic stability, social justice, and sustainability in the region. This chapter, along with other resources like the Solving Sprawl report, can offer decision-makers tools to understand the trade-offs of housing, transportation, renewable energy, and land use change and the accompanying loss of NCSs associated with development in NWLs. This chapter highlights the negative emissions potential of the region’s NWLs to provide decision-makers with information on the trade-offs of preventing or allowing land use change. These trade-offs, as well as emissions accounting from Oct. 11, 2022
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other regional studies, should be carefully considered.
5.2 Natural and Working Lands – Ecological Carbon Dioxide Sequestration and Storage
5.2.1 Introduction
NWLs are, on average, carbon sinks and globally recognized for their ability to sequester and store CO2 in plant biomass and soils.14,20 The current level of global net negative emissions from NWLs is insufficient to offset anthropogenic emissions and are thus unable to reduce total atmospheric CO
2 until positive emissions are drastically reduced. However, NWLs represent an important tool for reaching net zero emissions globally, nationally, and locally.12,17,21,22,43 The NCSs for NWLs are to protect current NWLs from land use change to settlements or barren landscapes, to enhance lands’ ability to sequester and store carbon through land management, and to restore degraded or lost NWLs to their natural states.21,22,43 Protecting current NWLs from changing to less photosynthetically productive lands (i.e. settlements or barren landscapes) is consistently the least expensive NCS and is highly effective.21,22 This section will focus on the NCS of protecting existing carbon pools and carbon sequestration potential in NWLs through preventing land use change.
Land use change is a global problem that leads to net emissions as more productive carbon sequestering lands, like forests or grasslands, are turned into less productive lands, like settlements or high emissions agriculture.14,20,24 The loss of NWLs that currently hold carbon and that sequester carbon annually is twofold: there is a one-time loss of carbon that is stored in soil and biomass and there is the lost sequestration potential of that given land area.14 Net zero emissions scenarios rely heavily on preventing land use change that would result in net emissions (e.g. urban expansion, land conversion to croplands) and promoting land use change that would result in net sequestration (e.g. reforestation). 12,19,21,24
Nevertheless, it is important to discuss other common NCSs, even if they are not applicable to the San Diego region or if they were not analyzed here. While forest management and other land management techniques are effective tools in California and in the United States, 17,22,43
they are less important in Southern California, which is shrub dominated and has few forests that would benefit from forest management on a large enough scale (Figure 5.1). 17 Similarly,
reforestation efforts are costly and ecologically inappropriate in most of the San Diego region.17,22,43 While other restoration efforts are also expensive, some efforts – like restoring riparian zones, wetlands, savannas, or woodlands– are generally less expensive than reforestation and can contribute significantly to negative emissions in the San Diego Oct. 11, 2022
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region.17,22,52 Riparian restoration is considered in the agriculture and carbon farming section and blue carbon restoration is discussed in the blue carbon section, while other restoration efforts are discussed briefly in Section 5.6 of this report. This section will focus on the negative emissions benefits of protecting existing carbon pools and carbon sequestration potential in natural and working lands through preventing land use change.
Among the NCSs listed above, preventing land use change is relatively inexpensive. National estimates for the U.S. suggest that over 60 million metric tons (MMT) of CO2e can be sequestered in 2025 for marginal abatement costs of $10 or less per metric ton (MT) of CO2e simply through avoiding conversion of forest and grasslands.22 Comparatively, reforestation, which has the highest potential for sequestering and storing carbon of any NCSs that are considered at the global, national, or State level, is relatively expensive (estimates range from $16 to 100 per MT of CO2e and likely drastically underestimate costs for the San Diego region).12,20,22,29 In the United States, this is largely due to the high costs of collecting seeds, raising seedlings in nurseries, and planting saplings in reforestable areas. When additional costs, such as maintenance and program evaluation, are considered, the costs increase further.
53 Costs vary by prevailing climatic conditions, infrastructure, workforce, and species, and are likely to be higher in Southern California than in the Southeastern United States or Northern California, where conditions, infrastructure, and species are more amenable to reforestation.12,53
In the San Diego region, land use change occurs through both natural processes, such as ecosystem succession after fires or pest invasions,
34,36,44 and through settlement expansion,
such as urban and transportation expansion.2,8,54 This section investigates the current approximate carbon storage and sequestration in the San Diego region using geospatially explicit vegetation data types from SANDAG’s GIS portal i (see Appendix 5.A for more
information on geospatial source data). It additionally considers approximate carbon storage and sequestration in eelgrass beds in the San Diego Bay based on published survey results of total coverage, rather than on geospatially explicit data.
This analysis is not peer-reviewed nor is it a comprehensive analysis of the region’s carbon accounting in natural and working lands. Instead, it is intended to illustrate the following points:
1) the region’s NWLs are, on average, carbon sinks – meaning that they naturally capture and store CO
2; 2) land use change in these NWLs will release stored carbon while simultaneously eliminating future sequestration in those areas; 3) land use decisions affect the carbon cost- benefit calculations of NWLs and, therefore, decision-makers should be aware of the broad carbon implications of the region’s NWLs.
i SanGIS.org
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5.2.2 Methods
All analyses, calculations, and data manipulation were done in QGIS 3.16 and Microsoft Excel.
Carbon storage and sequestration values were taken from the literature (see Appendix 5.A for sources). Whenever possible, local data were chosen. If local data were not available, then California, Pacific Coast, Western U.S., U.S., and global data were used, in that order. When there were multiple estimates or when there was a range of possible values in the same geographic area, the most conservative value was chosen. All carbon storage values were converted to metric tonnes of CO
2 equivalent or carbon per hectare (MT CO2e ha-1 or C ha-1) and all carbon sequestration values were converted to metric tonnes of CO2 equivalent per hectare per year (MT CO2e ha-1 yr-1) if the data were not already reported as such. Total carbon storage and sequestration values for the entire region were converted into millions of metric tonnes (MMT) (See Appendix 5.A for methods details).
The total estimated eelgrass of 1,693 acres (685 ha) from the San Diego Bay were also included.
55 Mission Bay eelgrass beds were not included because restoration and data collecting efforts are ongoing and not yet comprehensive, though more comprehensive data will be available in the near future and should be integrated into blue carbon and negative emission calculations.56–59 Marine eelgrass beds were also not included because they are in State waters and are outside of the jurisdiction of San Diego regional governments and agencies.
5.2.3 Results
The biodiverse and ecologically rich natural landscapes in the San Diego region have significant potential for both carbon storage and for annual carbon sequestration (Table 5.2). This analysis shows that there are approximately 58 MMT of carbon stored in San Diego’s biomass and soils.
Scrub ecosystems, including chaparral and coastal sage scrub, contribute most significantly to regional carbon storage, due in large part to their abundance and their local adaptations (Figure
5.1). Per hectare, coastal wetlands store the most carbon of any system. They are followed by tree-dominated systems, like woodlands, forests, and riparian areas. Wetlands are one of the least abundant systems in the region, though tree-dominated systems also have relatively low coverage. This is all readily visible in Figure 5.3, which shows the highest carbon storage per hectare values as darker areas and the lowest carbon storage value as lighter areas.
In addition to storage, the region also has high sequestration values and may be able to sequester up to 2.25 MMT of carbon per year. An important caveat to this value is that it relies on several assumptions that may not reflect the biological realities, and this caveat is especially important in the scrub category because it is the dominant ecosystem type in the region (see Section 5.2.4 for more discussion of assumptions, caveats, and drawbacks). The largest Oct. 11, 2022
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sequestration potential is in scrublands, forests, woodlands, and riparian zones. However, settlements show some high sequestration potential because of urban trees (Table 5.2). Per polygon, forests and woodlands have the highest annual sequestration rates per hectare (Figure 5.4 – darker areas have the highest rates, lighter areas have the lowest rates).
Interestingly, disturbed wetlands have net positive emissions,42,48,60 so the associated polygons have negative sequestration values (Figure 5.4 – light gray polygons). Importantly, these areas remain significant repositories of carbon stored deeper in the soil, despite having shifted to become net emitters due to disturbance (Figure 5.3).
Table 5.2 Total carbon storage (MMT CO2e) and sequestration (MMT CO2e yr-1) in the San Diego region by land use category and for all land uses throughout the region.
Notes:
* Includes row crops, orchards, vineyards, fields and pastures, dairies, plant nurseries, chicken ranches, and general agriculture.
** Includes urban and developed areas.
*** Includes disturbed wetlands and other habitats.
**** Includes unvegetated areas.
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Figure 5.3 Total stored carbon (MT CO2e ha-1) estimates for the San Diego region. Darker colors represent larger carbon stock estimates and lighter colors represent lower stock estimates. Regionwide storage totals per vegetation category were calculated from these values a nd are in Table 5.2. Note that eelgrass beds were not included because they were not included in the SanGIS shapefiles. However, eelgrass beds are prevalent in both Mission and San Diego bays and are important blue carbon habitats.
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Figure 5.4 Annual sequestration rate (MT CO2e ha-1 yr-1) estimates for the San Diego region. Darker colors represent higher rates, lighter colors represent lower rates, and light gray represents either zero sequestration or net positive emissions (which is represented as a negative value here). Regionwide sequestration totals per vegetation category were calculated from these values and are in Table 5.2. Note that eelgrass beds were not included because they were not included in the SanGIS shapefiles. However, eelgrass beds are prevalent in both Mission and San Diego bays and are important blue carbon habitats that provide carbon sequestration and storage.
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5.2.4 Discussion
San Diego’s NWLs represent two important NCSs. First, the lands provide stable, long-term carbon storage for the region and keep CO2 out of the atmosphere. Second, the lands provide annual net negative emissions by sequestering atmospheric carbon in plant tissues and soils, thereby removing some of the region’s anthropogenic emissions. This analysis is not comprehensive and is meant to illustrate that regional lands are currently producing NCSs at little to no cost and that these lands should be valued for their natural carbon sequestration and storage abilities.
Further, this analysis demonstrates that there are climate and emissions costs that would be incurred with land use change in the region. Figure 5.3 shows that land use change throughout most of the region will result in large one-time emissions of carbon that is currently stored in biomass and soils. While positive emissions from land use change are not explicitly accounted for in any of the Climate Action Plans,
i such accounting can be an important metric to help
decision-makers understand the inherent emissions trade-offs involved in land use change.
Additionally, Figure 5.4 shows that land use change throughout most of the region will have long-term sequestration consequences, as those lands will sequester less carbon each year after usage changes. This accounting can also elucidate trade-offs because the lost sequestration would need to be replaced with other NWL sequestration to maintain an equilibrium in the NCSs in NWLs. Alternatively, technological solutions could compensate for NWL sequestration loss, though this would be costly and potentially difficult to implement. 16,18
The exception to this rule of thumb is if the land use change is a change from less photosynthetically productive lands to more productive lands, as would be the case in chaparral or woodland restoration on degraded, retired, or disturbed lands, for instance (See Figure 5.2 for an illustration of land use change that results in greater sequestration).
There are some caveats and drawbacks to this analysis. First, local data were unavailable for some vegetation classes and the values used may not accurately reflect local conditions or circumstances. As a result, this analysis made assumptions that generalized carbon storage and sequestration potential. Importantly, the analysis assumes that all scrub and chaparral habitats store and sequester a uniform amount of carbon, regardless of the vegetation class within scrub and chaparral. Without more accurate values based on local data collection, this assumption was used as a starting point. Local data will become more important in the future as droughts and other phenomena affect the San Diego region. Additionally, this analysis assumed that all scrub habitats were intact (i.e., not invaded), which will inflate the storage and sequestration values. Luo et al. (2007)
30 show that chaparral in one part of the San Diego region
i Personal communication Scott Anders, September 2021.
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is a strong sink in normal years but an emitter during years of severe droughts, while Wheeler et al. (2016)33 show that invaded chaparral in the San Diego region stores and sequesters less carbon than an intact habitat. These studies highlight both the uncertainties in carbon accounting and the importance of localized data. Second, soil carbon estimates were not universally included in the literature, or it was not clear whether soil carbon had been included in some stated values, so this analysis does not universally include soil carbon estimates.
Excluding soil carbon would underestimate the total stored carbon, but it is unlikely to affect the carbon sequestration rates because the majority of measured soil carbon is relatively shallow, where much of the long-term soil carbon storage is in deeper soil layers. 61 Third, the
full extent of eelgrass and other marine, beach, and intertidal plants and algae were not included in the vegetation classification shapefiles or were not included in enough detail to make determinations. Thus, their carbon storage and sequestration potentials are underrepresented, despite the fact that they are important contributors to negative emissions in the region and store large quantities of carbon.38,41,56 Fourth, this analysis was done at a coarser scale than other regional and localized analyses that are forthcoming.i Those more detailed analyses should be considered more accurate because they will better reflect plant biomass and soil carbon estimates as well as carbon sequestration potential. Finally, any NWL carbon accounting analyses would benefit from research done by local institutions and organizations like WildCoast, the Climate Action Alliance, San Diego State University, and the Scripps Institution of Oceanography. When local data become available, they should immediately be incorporated into all land use analyses.
5.2.5 Policy implications
This analysis illustrates that an ounce of prevention is worth a pound of cure – protecting a hectare of NWLs will prevent emissions and will continue to sequester carbon in a low to no cost manner. As such, NWLs contribute to negative emissions in the region and thus mitigate some anthropogenic emissions. Meanwhile, losing NWLs would require expensive restoration, mitigation, or negative emissions technology investments to capture the one-time emissions of stored carbon and to continue to sequester the carbon that those lands would have sequestered naturally.
Further, this analysis illustrates that local efforts to characterize the carbon storage and sequestration capacity of NWLs in the San Diego region should be supported by local governments, jurisdictions, and agencies because current policies are generally not informed by the most localized carbon cycling data. Similarly, this analysis shows that there will be emissions trade-offs associated with land use change in the region. Thus, regional governments should
i Personal communication Drs. Megan Jennings and Matthew Costa, 2021 an d information from the Climate Action Alliance detailed here: https://www.climatesciencealliance.org/carbon -sequestration Oct. 11, 2022
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include emissions from lost biomass and soils as well as the lost carbon sequestration potential when deciding land use policies and decarbonization pathways to better understand the carbon-related trade-offs of land use decisions. Additional effort should price these emissions and lost sequestration potential to properly incentivize natural and working land protection and to understand the extent of regional net negative emissions.
5.2.6 Policy recommendations:
● Support infill development and natural growth in rural communities that minimize loss of carbon sequestration potential and co-benefits from NWLs. Disincentivize sprawl growth in NWLs and sprawl growth that cannot support efficient transit use or multi- modal transportation options.
● Support studies to accurately measure and report local carbon stocks and sequestration rates.
● Consider incorporating the costs of CO
2 emissions from land use change and the lost CO2
sequestration potential into land use planning decisions. ● Consider quantifying co-benefits, like ecosystem services, for incorporation into land use planning decisions.
5.3 Agricultural and Working Lands
5.3.1 Introduction
Nationally, agriculture is a net GHG emitter because agricultural activities result in net positive emissions of methane, nitrous oxide, and CO
2 (Figure 5.2).14,15,24 However, agriculture is a
relatively small source of regional emissions62 and is the only sector capable of switching from net positive to net negative emissions, all while producing agricultural goods.12,15 In this way, the NCSs associated with farming, ranching, and other agricultural activities can support decarbonization and continue to provide jobs, livelihoods, food, and other agricultural goods to the region and beyond.
Many NCSs focus on ways to both reduce CO2 emissions and enhance sequestration potential,21,22,24 where methane and nitrous oxide management are more nuanced and difficult.25,26 This is also true for agricultural emissions; however, manure and fertilizer management can reduce methane and nitrous oxide emissions, respectively.21,52 This report focuses on the CO2 implications of agricultural climate solutions, sometimes referred to as “carbon farming” or “climate farming,” though it will note important considerations for methane and nitrous oxide when applicable. NCSs in existing agriculture increase annual sequestration, decrease emissions, or do both simultaneously. Examples of increasing sequestration include adding compost to soils, planting cover crops, planting trees in or around Oct. 11, 2022
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farms or pastures, planting perennial plants rather than annuals, preventing the premature loss of existing orchard trees, engaging in whole orchard recycling, or adding biochar to soils.
Examples of preventing emissions include cover cropping, practicing no or low-till agriculture, planting perennial plants rather than annuals, planting trees, or utilizing on-farm compost.12,20,21,52
Agriculture and working lands are economically and socially important to the San Diego region and there are NCSs available today that may be able to turn agricultural carbon sources into carbon sinks and thus contribute to regional decarbonization goals.52,63 Agriculture is thus a unique industry because it can counteract climate change and simultaneously provide food, nursery plants, and other agricultural goods for regional consumption.15,63,64 In implementing these NCSs, it will be critical to accurately assess costs and benefits and to help farmers, farm laborers, and farming communities to facilitate an equitable and mutually beneficial transition to climate farming techniques, for example through programs and projects that provide financial and/or educational assistance.
There are significant uncertainties in GHG accounting in agricultural lands because of the inherently complex and highly heterogeneous soil gas interchanges. These depend on factors beyond human control, such as weather and existing soil gas composition, and on land management and farming practices, like the type and amount of inputs on any given day, species selection, tillage regime, and land use history. 12,27 The majority of agricultural climate
discussions in the United States rely on the Department of Agriculture’s (USDA) COMET planner.
i Discussions that focus on California tend to use a California-specific COMET planner tool,ii with additional help from CARB and the California Department of Food and Agriculture (CDFA). This tool is important, though it should be used carefully because there are some caveats to the data. First, the data behind the estimates represent 10-year averages and the values should be considered highly uncertain beyond that timeframe and should be updated or validated.
12,65 Second, the models that use the field data are simple relative to the biochemical interactions in soils. Given that soils are highly dynamic systems, there are concerns that the COMET planner overestimates the amount of carbon that will be stored and may simultaneously underestimate the potential nitrous oxide emissions.12,27 Further, the report “Getting to Neutral: Options for Negative Carbon Emissions in California” notes that the models underlying the COMET planner also likely overestimate how much carbon is stored in deeper, and thus longer term, soil storage.12 Thus, the “Getting to Neutral” report, and others, emphasize the importance of longer term monitoring of local demonstration farms where climate farming practices have been implemented.12,52
i http://comet-planner.com/
ii http://www.comet-planner-cdfahsp.com/
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5.3.2 Discussion
While localized carbon flux data, which would be ideal for calculating climate farming impacts, is unavailable, Dr. Puja Batra produced a report52 for the unincorporated San Diego region to recommend policies for the County of San Diego regarding climate farming and transforming agricultural lands from sources to sinks using California-specific COMET planner data. That report focused on compost applications in orchards, rangelands, and row crop fields. It also discussed riparian restoration and preventing the removal of orchard trees due to increasing marginal costs of watering and losses due to fire.
Compost application is estimated to yield the highest carbon sequestration benefits of any investigated carbon farming techniques, according to Batra, 52 resulting in 227,170 MT of CO2e
sequestered annually. However, the report notes that there are potential problems of nitrogen leaching into surface water and groundwater if the application rate is too high or if the nitrogen levels in the compost are too high.52 Repeated application of compost may result in eutrophication52 and/or net GHG emissions from the soil,12,27,43 so compost application for the sake of carbon sequestration will need to be coupled with monitoring. Regardless of carbon sequestration potential, compost application may offer co-benefits in reduced application of synthetic fertilizers, which could reduce NOx emissions;22 improved manure management, which could reduce CH4 and NOx emissions;12,22,52 and increased soil water retention.20,22,52 Batra also investigated riparian restoration as a means of sequestering carbon in the region’s agricultural and working lands. The unincorporated County has nearly 7,000 miles of freshwater and riparian systems,
52 which are typically dominated by shrubs and trees and have higher carbon sequestration potential than forb and grass-dominated systems.2,6,24 Restoring riparian ecosystems typically involves planting native trees and shrubs, which is estimated to result in approximately 2 MT of CO
2e sequestration per acre per year.52,65 Batra estimated restoration of about 25% of riparian habitats and 35 feet of buffer zones around them would result in approximately 7,230 MTCO
2e per year.52
Finally, Batra considered the emissions from recent orchard tree removals and the lost sequestration value of those trees. The unincorporated County lost approximately one million orchard trees from 2000 to 2015. Many of the trees were removed because rising marginal costs of inputs like water forced farmers to choose between paying higher water costs or removing some of their orchard trees.
52 Trees are particularly good at sequestering carbon
because of their size and at storing carbon because they deposit carbon deep in the soil and store carbon in biomass,
12,20,21,29 so removing these orchard trees has two carbon related impacts. First, it releases stored soil carbon and begins the process of releasing the biomass carbon. Second, it reduces the orchard’s annual sequestration potential because the removed Oct. 11, 2022
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tree is no longer able to sequester carbon.52 Batra estimated that the cumulative total lost orchard trees in this period released 243,468 MT of CO2e and lost the ability to store 131,657 MT of CO2e during that 15 year period. All told, the loss of stored carbon in orchard trees in the unincorporated County is estimated to be more than 375,000 MT CO2e.52 This analysis highlights the importance of retaining existing carbon pools, however it also speaks to the financial difficulties that farmers face when input prices increase.
Beyond Batra’s report, other carbon farming methods to consider should include cover cropping, improved species selection, and restoration of degraded, abandoned, or marginal agricultural lands.12,20–22 Importantly, each of these techniques has co-benefits for the farmers, ranchers, and land owners, including increased soil water retention, more shade for livestock, and/or increased agricultural yields. The techniques also have co-benefits for the surrounding ecosystems like improved or increased habitat and/or increased biodiversity.20–22,66 Restoration of degraded, abandoned, or marginal agricultural lands is likely to offer the greatest co-benefits for the San Diego region in large part because planting trees and shrubs in grasslands or fields leads to large belowground and aboveground carbon storage gains as well as improved biodiversity, soil health, water quality and quantity, and air quality outcomes.12,20–22,24 Additionally, given that much of the region’s agricultural output and acreage consists of livestock grazing, rangelands, and pasturelands,2,67 planting trees in or around grasslands used for grazing or pasture, which is a form of agroforestry, is likely to improve regional carbon sequestration while offering numerous co-benefits to farmers and ranchers, like shade for livestock, in addition to the restoration co-benefits listed above.52,65 Finally, restoration of degraded, abandoned, or marginal agricultural lands may offer a source of revenue for farmers if they are paid for their restoration and carbon sequestration enhancement efforts.i Addressing methane and nitrous oxide emissions is generally more difficult because there are generally fewer carbon farming solutions for these sources, despite the fact that they contribute more warming potential (per metric ton) to the atmosphere than CO
2.13,14,21,24,52
Methane in the San Diego region is primarily emitted from landfills, livestock manure, enteric fermentation, and wastewater, though there are also some methane emissions from natural decomposition in wetlands and wetland loss.12,17,20,24,47 Of these, only livestock manure and enteric fermentation are directly applicable to the region’s agricultural emissions. Batra did not account for the agricultural methane that is prevented from entering landfills because avoided methane emissions are covered by regional climate action plans and would constitute double counting.
52,68,69 This would also be the case for the City of San Diego’s wastewater
i For example, the USDA’s Natural Resource Conservation Service has provided funding in the past for numerous carbon farming, restoration, and land management projects across the country, so federal funds could be available for the region’s carbon farming projects (for more information, see:
https://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/newsroom/releases/?cid=NRCSEPRD1829258 ).
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emissions.68,69 There are, however, some manure and enteric fermentation management techniques that are distinct from those already captured in Climate Action Plans for the region.
These include on-site anaerobic manure digestion,70 methane capture or digestion from enteric fermentation, methane reduction from enteric fermentation.12,52,66,71,72 The opportunities to reduce methane and nitrous oxide emissions in the region’s agriculture sector require further study, but they may provide important GHG emissions reductions.
Two demonstration projects hosted by the Resource Conservation District of Greater San Diego County67,73 and several independent agricultural operations in San Diego Region74 offer examples of carbon farming and monitoring. These projects are providing data on carbon farming techniques and will continue to provide insights into the carbon sequestration benefits as well as the capital costs associated with the new techniques, processes, and monitoring.
Projects like these will be critical for understanding the long-term costs and benefits of carbon farming and may help create a local market for carbon offsets or other incentive programs.74 A final caveat to this analysis is that agricultural lands can contribute to negative emissions and reduce regional emissions by diverting some of the waste that would have otherwise gone to landfills. For instance, Senate Bill (SB) 1383i (Box 5.1) will result in larger quantities of compost and mulch that are produced as organic materials from homes and businesses are diverted from landfills. Farms can potentially utilize some of the compost and mulch produced by SB 1383, though transporting and utilizing compost and mulch will come with challenges and costs.
While these potential emissions reductions from organics being diverted from landfills are important, they should be considered within the waste and landfill sector’s emissions accounting, not in agricultural accounting. The negative emissions of off-site compost additions to working lands (or beyond) are also important considerations, but require careful accounting to only incorporate the additional negative emissions from the off-site compost additions to avoid double counting and overinflating the value of the climate farming technique. Further study of integrating the compost and mulch produced by SB 1383 with climate farming will be important to both proper carbon accounting and to accurately incentivize utilizing off-site compost.
i https://leginfo.legislature.ca.gov/faces/billNavClient.xhtml?bill_id=201520160SB1383 Oct. 11, 2022
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Box 5.1 – Senate Bill 1383
In 2016, the California State Legislature passed SB 1383, or California’s Short-Lived Climate Pollutant Reduction Strategy, which sets Statewide targets to reduce organic waste disposal by 75% from 2014 levels by 2025 and to rescue at least 20% of currently disposed surplus edible food for human consumption by 2025. SB 1383 focuses on landfills because organic waste in landfills emits 20% of the State’s methane gas, with the San Diego region’s landfills producing emissions.i Methane is a more powerful greenhouse gas than carbon dioxide, despite its shorter lifetime in the atmosphere. Organic waste like food scraps, yard trimmings, paper, and cardboard make up half of what Californians dispose of in landfills.
SB 1383 also requires jurisdictions to procure recovered organic waste products – such as renewable natural gas, compost, and mulch – to drive markets for those goods. Compost and mulch application to agricultural and working lands are carbon farming techniques with economically and ecologically important co-benefits like increased soil water holding capacity and improved food nutrition content.
The County of San Diego’s Department of Public Work (DPW) Solid Waste Planning & Recycling section leads local efforts by chairing the regional Integrated Waste Management Technical Advisory Committee and Subcommittees, as well as coordinating regional food recovery and organic materials processing capacity planning. For the unincorporated County areas, DPW Solid Waste Planning & Recycling works with franchise waste and recycling haulers to provide organics collection services to residents and businesses. DPW Solid Waste Planning & Recycling also provides technical assistance, education and outreach materials on reducing and managing organic waste, free composting workshops and subsidized bin sales, and free indoor collection containers (while supplies last).
However, transporting compost and mulch from facilities to farms incurs costs from fuel, equipment, and labor. These costs may be prohibitive, especially for small farms which have different economic realities than large farms and agriculture operations. The San Diego region has thousands of farms that are 10 acres or fewer,ii so regional incentive structures will need to account for the differing economics of the region’s farms to ensure efficient and equitable access to this carbon farming option.
5.3.3 Policy implications
First, localized data from farms, orchards, pastures, and rangelands will be crucial to understanding the carbon storage benefits of different carbon farming techniques. There are significant uncertainties associated with the USDA and CDFA’s data that underlie the COMET planner tools,12,65 largely because soil systems are complex and nuanced and because soil carbon storage is highly dependent on local conditions.12,27,29 Thus, improved data for local agricultural productions would enhance the region’s understanding of agricultural carbon fluxes and would better inform carbon farming techniques and policies.
i SANDAG. Appendix X: 2016 Greenhouse Gas Emissions Inventory and Projections for the San Diego Region. https://sdforward.com/docs/default-source/2021-regional-plan/appendix-x---2016-greenhouse-gas-emissions- inventory-and-projections-for-the-san-diego-region.pdf?sfvrsn=8444fd65_2 (2021). ii For more information, see: https://www.sandiegocounty.gov/content/dam/sdc/lueg/docs/State -of-the-F ood- System-for-the-San-Diego-Region-November-2019.pdf
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Second, cost data should be collected and incorporated into carbon farming analyses. Many carbon farming techniques have high costs because they require additional or specialized machinery. For example, no-till agriculture prevents soil carbon losses from tilling but requires specialized machinery for seeding. Conversely, compost application requires a much smaller investment into a tractor attachment and is therefore cheaper for the farmer while still offering climate farming benefits.
52 Further, data collection can be costly and there is little economic incentive for farmers to independently engage in regular soil testing to track carbon storage.74 Thus, cost-effectiveness and/or cost-benefit analyses of carbon farming should incorporate the costs of the associated new equipment investments, soil testing, and marginal operating and management expenses to inform incentivizing or otherwise reducing the costs of carbon farming.
Third, climate farming should be voluntary, incentivized, and responsive to on-the-ground conditions and farmer feedback. Investments in climate farming are not without costs and farmers facing difficult financial decisions should not be required to engage in additional practices that would incur additional financial costs, like purchasing new equipment or hiring additional staff, and opportunity costs, like spending time on training or searching for equipment, employees, or technical help. Instead, the region should actively assist farmers who are able and willing to engage in climate farming to reduce the financial and time burdens associated with new techniques to maximize engagement and minimize costs to the farmer.
Additionally, incentives can be structured based on the lessons learned by programs that currently help farmers engage in climate farming. Regional climate farming efforts should incorporate feedback from ongoing work by collaboratives, non-profits, and extension services.
Finally, stakeholder input generally agreed that the region’s incentive structures are not set up to incentivize carbon farming in the region. As Batra notes, farmers in unincorporated San Diego County face myriad economic challenges, including tree losses from climate change and the increasing prices of water.
52,74 There seems to be high agreement that local farmers need financial assistance to address their carbon emissions and allow them to engage in carbon farming, while not providing assistance would place an undue burden on farmers and farming communities in the region. Policies addressing carbon farming will need to focus on incorporating farmers’ experiences, concerns, and cost data as well as accurately characterizing the co-benefits – like healthier soils, higher yields, and better soil water and nutrient retention, which reduce water and fertilizer needs and may additionally provide ecosystem services – to maximize carbon storage potential in an equitable manner.
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5.3.4 Policy recommendations:
● Support incentivized climate farming in the region to promote agriculture’s unique ability among regional sectors to produce goods and negative emissions. ● Study local carbon farming techniques to better understand carbon storage and sequestration potential, costs, associated ecosystem services, and economic benefits. ● Consider incentivizing tree planting in and around agricultural lands and additionally incentivizing farmers to retain existing trees.
● Engage farmers and other stakeholders to create carbon farming policies that are equitable, just, and beneficial to farmers and farming communities. ● Support farmers and other stakeholders who are already engaged in climate farming to foster community knowledge sharing for carbon farming.
5.4 Blue Carbon and Sea Level Rise
5.4.1 Introduction
Blue carbon generally refers to the carbon storage and sequestration potential in vegetated coastal ecosystems, like eelgrass beds, marshes, wetlands, and mangrove forests, but it sometimes specifically refers to restoring vegetated coastal ecosystems to improve carbon sequestration and storage.20,39 Coastal ecosystems are known for their many ecosystem services, including economically valuable services such as storm surge reduction, wave action and wind buffering, commercially important fish nursery habitats, and air and water quality improvements.
20,66 These have historically been important reasons to protect and restore blue carbon and coastal ecosystems, but many coastal ecosystems are now being protected because they also collectively store disproportionately higher levels of carbon per unit area than most ecosystems, and can do so on the order of millennia.
38,41,75
The San Diego region historically contained over half of the Southern Californian Bight’s blue carbon habitats (~11,000 hectares), much of which was in the Mission and San Diego Bays.
Since mapping efforts began around 1850, it is estimated that the San Diego region has lost approximately 69% of its historic wetlands through conversion to non-wetland systems like urban development.
76 Wetlands throughout the region are susceptible to land use change, sea level rise, and invasive species, all of which would reduce or eliminate annual carbon sequestration and would emit CO
2 and methane currently stored in the soils.17,20,47,48 As with terrestrial carbon storage and sequestration, the primary methods of maintaining or enhancing blue carbon are through the protection of existing wetland ecosystems and restoration of degraded or lost wetland ecosystems.
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The San Diego region has lost eelgrass beds, salt marshes, mudflats, coastal riparian zones, and other intertidal zones39,48,76 and is expected to continue to lose these habitats into the future.42,46,60 Of these lost ecosystems, only some will be ecologically eligible for restoration,17,48 which highlights the importance of both protecting existing ecosystems and restoring degraded or lost ecosystems wherever possible.
Wetland degradation or destruction imposes two significant costs that warrant protecting them from damage. First, the one-time releases of stored CO
2 and methane will be significant
because wetlands have a higher density of carbon storage per unit area than other regional ecosystems.
38,39,41 These positive emissions would be costly to offset, where preventing these emissions is less costly. Second, wetland restoration is expensive,12,21,22 costing at least as much as comparable non-forest restoration while yielding less annual sequestration.12,77 Despite these costs, there are strong economic reasons to restore lost or degraded wetlands, including substantial ecosystem services and preventing CO2 emissions from degraded wetlands. An estimate by The Nature Conservancy of California found that wetland restoration in California would result in over $1 billion of avoided climate-related damages due to ecosystem services provided by expanded wetlands.17 This further highlights the importance of existing wetlands, which currently provide those services at no cost, and supports the need to study and invest in wetland restoration in the region. While healthy wetlands contribute meaningfully to negative emissions, degraded or inundated wetlands are predicted to emit more CO2 than they sequester. This could occur through sea level rise (SLR), land use change, or other natural or anthropogenic impacts. Wetland restoration and wetland migration, which is natural or anthropogenic land use change of upland ecosystems to wetlands as sea water inundation occurs, can mitigate some wetland loss and associated carbon emissions. 42,47,48
Given the inevitability of SLR and of other impacts of climate change,78 restoring wetland and other blue carbon habitats will be important to blue carbon’s ongoing contributions regional negative emissions and to critical ecosystem services that can bolster coastal climate resilience.45,78,79
This analysis focused on wetlands and the potential loss of blue carbon habitats with SLR because regional wetlands are well mapped and the loss of wetlands with sea level rise is well studied. However, eelgrass habitats will also be affected by sea level rise, that eelgrass beds are critical blue carbon habitats, and that further study of eelgrass beds is critical to understanding regional NCSs (See Box 5.2).
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Box 5.2 – Eelgrass
Eelgrass, which is also known as seagrass, grows in populations called eelgrass beds. Eelgrass beds are areas of shallow coastal and bay habitats where the dominant vegetation is Zostera marina or Z. pacifica, are important blue carbon habitats.38,41,80 As with marshes, they sequester carbon as they grow and are capable of storing carbon in their immediate surroundings as tissue and as compounds deposited into sediments.38,81 Eelgrass is slightly less efficient at sequestering and storing carbon than marshes and other wetlands, but they play an important role in sequestering carbon and offer many unique co-benefits, like creating habitat for marine life, reducing turbidity, and improving water quality.38,80
Beyond the traditional carbon sequestration that plants provide, eelgrass beds offer two additional decarbonization benefits that are unique. First, eelgrass utilizes dissolved carbon in the water for photosynthesis. This dissolved carbon acidifies the water and is the primary driver behind the phenomenon of ocean acidification that causes ecological harm, perhaps most famously in leading to coral bleaching events. As such, eelgrass beds reduce the acidity of their immediate surroundings, which may offer some ecological benefits to other species and/or may facilitate additional drawdown of atmospheric CO2.81–83 Second, eelgrass is capable of transporting some of its sequestered carbon to the deep ocean.40 This means that restoring and protecting eelgrass beds will ensure that, on average, some fraction of the sequestered carbon will be locked away in the deep ocean for thousands to tens of thousands of years.40 Thus, eelgrass beds can offer some of the only NCSs that are essentially permanent.
Eelgrass beds are also unique because they may potentially benefit from more CO2 in the water. The excess CO2 from the atmosphere dissolves into the ocean and forms a weak acid which creates the “ocean acidification” phenomenon where global ocean pH has shifted to be more acidic.84 While most marine plants, algae, and animals are reacting negatively to ocean acidification, there is some evidence that eelgrasses are potentially limited by carbon availability (in the form of dissolved CO2) and that their growth, and thus their carbon sequestration and storage potential, may increase with increasing ocean acidity because there is more carbon available for photosynthesis.82
Although eelgrass beds are submerged, they require sunlight to penetrate strongly enough through the water column to fuel photosynthesis and will thus be impacted by sea level rise. Studies by Merkel & Associates, Inc. have shown that water depth is a primary factor that limits eelgrass distribution in the region’s bays and inland water systems.55,57 This suggests that SLR may make some current eelgrass beds too deep for eelgrass, while SLR may simultaneously create new eelgrass habitat out of newly submerged marsh, wetland, or upland habitats. Overall, the impacts of sea level rise on eelgrass are less certain and should be monitored to understand the impacts.
The San Diego region has coastal and inland bay eelgrass beds, but the former is in state waters and are outside of the jurisdictional boundaries of San Diego governments. The Port of San Diego and the Navy have jurisdiction over the eelgrass beds in the San Diego Bay and the City of San Diego has jurisdiction over the eelgrass beds in Mission Bay.55,57
Eelgrass surveys and assessments for both the San Diego and Mission Bays have occurred for several decades. These surveys estimated changes over time to eelgrass bed distribution and found that eelgrass cover has changed significantly over time, with population blinking in and out.55,57,85 This suggests that newer data will be important for understanding the current extent of eelgrass beds and the associated NCSs. To this end, the Port of San Diego was awarded a $150,000 federal grant to study the San Diego Bay’s eelgrass beds and the associated carbon sequestration in the San Diego Bay.86 This study will be invaluable in helping regional agencies and authorities understand the negative emissions of eelgrass beds and the impacts of water conditions on eelgrass beds.
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5.4.3 Results
The 1 foot of sea level rise that is anticipated to occur between 2030 and 2050 is projected to result in a loss or ecosystem change of nearly 800 hectares of blue carbon habitats throughout the region, an area approximately 1.4 times the size of downtown San Diego (Table 5.3, Figure
5.5).88 One foot of sea level rise will endanger approximately 180,112 MT CO2e that is currently stored in marsh and wetland plants and soils. Some of this would be emitted directly into the atmosphere.42 Additionally, if all 800 hectares of susceptible blue carbon habitats are lost (i.e., if they do not change to eelgrass beds or other habitats that could sequester carbon), then the lost habitats would have been able to sequester approximately 1,715 MT CO 2e per year (Table
5.3). To offset these one-time emissions and to sequester the CO2 that would have been sequestered, a comparable level of new wetlands, marshes, and riparian habitats would need to be restored prior to wetland inundation. However, such restoration efforts would merely allow the region to break even by sequestering as much as is being emitted from blue carbon habitats.
Figure 5.5 Some blue carbon habitats will be affected or lost under 1 foot of sea level rise in the San Diego region.
Blue areas in the map show blue carbon habitats that will be affected by 1 foot of sea level rise, which are quantified by ecosystem category in Table 5.3. Insets show more detail of four of the regions with affected blue carbon habitats.
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Table 5.3 Total blue carbon habitat area (hectares) affected by 1 foot of sea level rise, annual carbon sequestration (maximum amount of carbon dioxide equivalent sequestration in metric tonnes per year that may be lost), and long-term storage (maximum amount of carbon dioxide equivalent in metric tonnes that may be emitted upon habitat type change) per blue carbon vegetation class.
Vegetation
classification
Total area affected by 1
foot of SLR (hectares)
Maximum lost annual
sequestration potential (MT
CO2e yr-1)
Endangered carbon
storage (MT CO2e)
Freshwater marsh 20 28 3,020
Mudflats/Saltpans 22 44 5,082
Riparian scrub 14 60.2 1,400
Salt marsh/estuary 726 1,582.68 170,610
Total terrestrial blue
carbon ecosystems 782 1,714.88 180,112
5.4.4 Discussion
As in the case of regional land use change in forests and non-forest terrestrial ecosystems, protecting wetlands, marshes, mudflats, and riparian habitats from loss is the first-best option because doing so both protects existing stored carbon stocks and ensures ongoing annual sequestration. Protecting existing blue carbon habitats is especially important because they hold larger quantities of carbon per unit area and for longer periods of time than San Diego’s forest and non-forest ecosystems.38,56,60,77 Restoring lost or degraded blue carbon habitats and enhancing existing blue carbon habitats will also be important because failing to do so may result in greater carbon losses with SLR or other impacts.
Protecting, restoring, and enhancing blue carbon habitats can take many forms and will be specific to each system. For example, the Kendall-Frost marsh in the northeast corner of Mission Bay can be expanded such that it reconnects with Rose Creek, which would provide sediment and freshwater inputs, both of which would naturally protect the marsh from some of the effects of sea level rise.
89 The active restoration of lost marsh habitat in the northeast area and other areas of Mission Bay would thus serve to both increase carbon storage and sequestration in Mission Bay while improving habitat quality and resilience.89–91 Jurisdictions that utilize this NCS should utilize the most recent and localized data possible for their systems to maximize the systems’ sequestration and storage potential.
Unlike regional land use change, which can generally be planned for and can thereby be reasonably prevented, blue carbon ecosystem loss is inevitable given current estimations of sea level rise and the dearth of options to prevent sea water inundation and flooding in low-lying areas and ecosystems.
20,42,46 Restoring or enhancing NCSs in other ecosystems to offset the anticipated losses of blue carbon ecosystems will be expensive and likely impractical, given the challenges of large-scale habitat restoration.
12,17,53 Therefore, expanding existing blue carbon
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habitats to enable wetland migration and protecting existing blue carbon habitats from land use change will be important NCSs in the region.
5.4.5 Policy implications
Wetland, marsh, and mudflat losses will significantly impact the ability of the region’s NCSs to contribute to negative emissions. Local carbon sequestration and storage data for marshes, wetlands, and eelgrass from organizations like the Scripps Institution of Oceanographyi (pers. comm., Dr. Matthew Costa, July 22, 2021) and from the Port of San Diego are forthcoming,86, 91 which will improve the analysis of anticipated impacts from sea level rise. Nevertheless, the unique threats of sea level rise and the eventual emissions from blue carbon and other low- lying ecosystems should be accounted for in decarbonization plans, even if data are imperfect.
5.4.6 Policy recommendations:
● Protect existing carbon storage pools and annual sequestration in blue carbon ecosystems from anthropogenic land use change.
● Collaborate with organizations and governments to study the feasibility and costs of wetland migration, wetland restoration, and carbon sequestration enhancement in existing wetlands. Collaborate regionally and inter-jurisdictionally to implement blue carbon restoration where feasible and possible.
● Collaborate with organizations and governments to study local blue carbon values to improve blue carbon accounting in the region.
5.5 Urban Forestry and Greening
5.5.1 Introduction
Urban forestry refers to managing trees that were planted or maintained in some manner within urban or suburban boundaries.92–94 Urban greening refers to establishing any plants in urban or suburban areas, including trees. Trees are often planted in urban settings because they provide ecosystem services like reducing air pollution, providing shade that cools buildings, reducing urban stormwater runoff, increasing aesthetic value, reducing noise, and other services.17,92,93 However, urban trees are also being recognized for their contributions to negative CO2 emissions because their growth reduces atmospheric CO2.17,95,96 Urban forestry and urban greening provide the only NCSs for urban areas and settlements, so it is critical for such areas to have urban trees to sequester carbon in lieu of natural landscapes. These trees also provide co-benefits like ecosystem services that were lost to land use change and can provide these and other co-benefits to communities, including those disproportionately
i Personal communication with Dr. Matthew Costa, July 22, 2021.
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affected by poor air quality, high temperatures, and little shade or green space.17,92 There are, however, some important caveats to urban forestry in particular that are worth consideration in the San Diego region. First, trees in urban, suburban, and highly developed areas are more stressed than trees in natural landscapes and thus have shorter lifespans on average. However, they can still sequester and store carbon throughout their lifetimes, which can be more than 40 years.
97 These shorter lived urban trees will require more frequent replacement than naturally occurring trees in natural landscapes, which will need to be factored into planning. Second, if urban trees require large inputs that rely in some sense on fossil-fuels, like water pumped by carbon-based energy or synthetic fertilizers, then urban forests may not sequester enough carbon to offset their maintenance-related emissions.97 Third, the species of tree planted has large implications for carbon sequestration, life expectancy, water and maintenance needs, and potential co-benefits, highlighting the importance of careful tree selection based on local conditions and needs. Generally, native trees and shrubs should be prioritized, but drought tolerant non-native trees can also be successfully and appropriately utilized. Invasive trees should not be planted. i; 97–99 Fifth, as trees
reach the end of their lives, they will need to be replaced for the urban forest to continue to provide services. Thus, tree planting goals may be too low as urban forests age and die. 100
Finally, urban greening often focuses on trees because of their ability to provide unique services like shading and subsequent cooling, but regional greening should also include planting native or non-native, drought tolerant shrubs and plants. These plants can offer aesthetic value, air pollution mitigation, water quality improvements, improved habitat and biodiversity, and carbon storage while generally requiring fewer inputs than trees. 17,92,101
5.5.2 Discussion
In a 2003 San Diego regional analysis, the non-profit American Forests produced a report of the tree cover in the City of San Diego and 22 surrounding cities and communities and found that, collectively, these urban forests stored 640,846 MT of carbon and sequestered 4,864 MT of carbon annually.92 Despite the significant sequestration and storage values, the study region lost 29% of its tree cover from 1985 to 2002.92 While California as a whole has steadily gained tree cover and urban carbon sequestration since 1990,95,102 the San Diego region has not seen similar gains and thus has the potential to create substantial negative emissions through expanding urban tree cover.17,92,100
i For a more detailed discussion of utilizing native species in regional landscaping, urban greening, and urban forestry, see the report “San Diego County Native Landscape Program: Program Recommendations by the San Diego County Biodiversity Working Group,” (2022) available here:
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A 2021 national report by American Forests projected carbon storage and sequestration based on anticipated tree plantings and assuming a 1% die back rate of existing trees using current carbon storage and sequestration values, recognizing that there will be climate-related feedbacks to tree growth and life expectancy in response to localized climate change.100 The report found that the San Diego region is expected to increase its urban tree carbon storage by approximately 6 MMT of carbon and to increase its annual sequestration rate by 0.32 MMT of carbon per year from 2010-2060 through urban tree expansion alone.100 The report also noted that the San Diego region is expected to see an increase in avoided emissions as urban trees are expected to reduce electricity use for cooling, though, importantly, there will be increased emissions with urban expansion and overall avoided emissions will be reduced through the loss of natural lands.
100
An analysis by The Nature Conservancy of California found that the San Diego region had 111,763 acres of urban land that was suitable for urban forestry or other greening.17,103 At an average sequestration rate of approximately 18 MT of CO2e per acre per year,17,99 the report estimates that fully foresting the San Diego region’s urban areas would result in over 2 MMT CO
2e of annual sequestration.17,103 This roughly equals the estimated annual sequestration in Section 5.2, though it is important to note that the costs associated with planting such an extensive urban forest in the region would be significant. This is due to both the upfront costs of purchasing saplings, trees, or seeds in addition to the labor to initially plant that many trees and the ongoing marginal costs of maintaining an urban tree, which are higher than maintaining a tree in NWLs.
i Additionally, as the region’s climate changes, hotter, drier conditions may increase the water input costs and/or the urban tree mortality rate, which would decrease the sequestration potential. This further underscores the importance of species selection during urban greening planning and implementation.
Though these estimates from The Nature Conservancy are rough because they are not based on extensive field data, estimates still highlight the importance of greening the region’s urban areas as an NCS. As cities and municipalities throughout the region set and achieve tree planting goals, it will be important to account for accurate, localized carbon stock and sequestration values based on species, tree age, tree health, and growing conditions.
Additionally, it will be important for jurisdictions to account for both the electricity savings due to trees’ cooling effects and to account for the emissions from inputs like watering, tree care, fertilizers, and other inputs.
5.5.3 Policy Implications
Urban forestry is an important NCS for urban and developed areas because it can sequester and
i See Fargione et al., 202153 for a discussion of some of the costs of producing and planting a large number of trees.
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store carbon in an environment that is otherwise unable to provide negative emissions, replacing some of the natural sequestration and storage that was lost with development.92 Their numerous co-benefits and their ability to increase equity and improve social welfare through air and water quality improvements, cooling effects, aesthetic improvements, and more are also important reasons to increase urban canopy cover and urban tree distribution.101,104 However, as an NCS, urban trees pale in comparison to natural systems, so the first best choice from a decarbonization perspective is to protect and enhance natural systems that more efficiently generate negative emissions, rather than expand urban areas and try to offset the damage with urban foresting and greening. 12,17,21,29,100
There are ways to increase urban tree carbon sequestration and storage potential and maximize their ability to sequester and store CO
2. First, governments can choose tree species
and adjust tree management practices to maximize carbon benefits. Ideally, species would be large, long-lived, low-maintenance trees with low water requirements that are well-suited for the local climate and are not invasive.
97 This choice could increase the lifespan of the tree, increase the lifetime of carbon storage, and reduce total carbon-intensive inputs, like water, during the tree’s lifetime. Second, governments can integrate tree planning into public land maintenance and work with private landowners to plan tree locations to maximize cooling effects on structures or surfaces.
97 These locations need to be carefully balanced with providing defensible space in areas prone to fire. Third, governments can empower and encourage local communities to collect data on trees in their areas to inexpensively improve overall urban tree data.
92 These data can inform distribution, size, and species urban forest information that can aid decision-makers in crafting urban forestry policies that will increase carbon storage and sequestration while providing local co-benefits equitably. Fourth, there are funding opportunities from the State that the region can utilize and there are initiatives in other regions and states that the San Diego region can imitate. For example, CARB has provided funding in the past for urban tree planting and funding available for such efforts should be utilized by regional authorities when possible.
105 Additionally, Washington State’s investments in urban forestry can serve as an example to local jurisdictions for structuring funding and implementation plans.106 Finally, local efforts by non-profits, community organizations, and private companies to plant trees in communities can be promoted, and supported to foster urban forestry, greening, and regional collaboration.
5.5.4 Policy recommendations:
● Plant trees that maximize lifetime net negative emissions and net carbon storage. ● Plan tree planting locations in public spaces to maximize co-benefits like shade and provide information and education to private landowners to assist in tree planting location choices on private land.
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● Governments and agencies can collect data on urban forests and actively support non- profits and community members to also collect data.
● Where feasible and in alignment with community and land management needs, goals, and visions, protect existing trees from dying to extend carbon sequestration and storage.
5.6 Additional Natural Climate Solutions
There are other NCSs that are applicable to the region but that were not investigated in this report, due to either a lack of local data or their limited applicability in terms of negative emissions and/or geographic extent. Nevertheless, they may be relevant to some areas, may become more important in the future, or more data and research may elucidate their negative emissions value in the future.
5.6.1 Tree planting in public, non-urban lands
There are ongoing restoration efforts throughout the region that focus on planting native trees in areas that have lost them. Tree planting in the region is occurring on tribal, private, state, federal, and local lands, though there are no comprehensive datasets detailing these efforts.
Some data are being collected, but they may not yet be complete or publicly available. As an example, the County of San Diego’s Department of Parks and Recreation (DPR) has instituted two tree-centered NCS programs in County-owned and managed public lands. First, DPR has a program to protect and preserve old, large trees during prolonged drought periods. 107 Under
the conditions associated with severe and/or prolonged droughts, trees become more susceptible to death or disease, and losing older trees has disproportionately large impacts on carbon sequestration and storage. In general, older trees are larger and thus have higher annual sequestration rates, storing more carbon in any given year and in their lifetimes.108 By protecting these trees, DPR has an outsized impact on the negative emissions where those trees are. Second, DPR has a tree planting program that is working to plant trees in County parks and preserves to increase negative emissions.i This program has the goal to plant at least 3,500 trees a year and to replace every dead or dying tree with three new trees. In this way, the program will mitigate tree loss and strengthen carbon sequestration into the future.
Additionally, this program provides an excellent model for NCSs in the region because of its focus on planting native species.109,110 Native species are more resilient because they have
i This tree planting program is a part of the County’s 2018 CAP. Although the CAP was not formally approved, t he tree planting program has continued to increase negative emissions, offer co -benefits to the unincorporated areas, and meet or exceed goals. This program was analyzed in Chapter 9’s CAP analysis and is one of the few examples of how NCSs were incorporated into CAP planning. More details on CAP contributions to regional decarbonization commitments can be found in Chapter 8 section 8.8.
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evolved to live in the region and may be less susceptible to drought, more adapted to seasonal resource availability, and better able to provide co-benefits like biodiversity or habitat for other native species.32,97,109
As more data on tree planting and restoration efforts on public, private, and tribal lands become available, they can be integrated into negative emissions estimates and can facilitate decision-making, which may include incentives to engage in or continue such NCSs.
5.6.2 Non-forest management
Despite the fact that the region is dominated by chaparral, coastal sage scrub, and other shrub habitats, there are few resources available for non-forest management, which is management of shrub-dominated habitats, savannahs, woodlands, or other non-forest ecosystems.
Conversely, forest management, which includes actions like thinning or prescribed burns to manage forest health and minimize large wildfire risk, is well studied. As such, non-forest management practices were not investigated in this chapter. However, there are many agencies and jurisdictions in the region that are managing non-forest ecosystems and the associated changes to carbon storage or sequestration resulting from this management should be studied and accounted for in regional NCSs.
Among the non-forest management techniques that could be researched and investigated are habitat restoration and invasive species management, with a focus on removing non-native, annual grasses and forbs. Local studies have demonstrated that chaparral systems that are invaded by non-native, annual grasses have diminished sequestration and storage potential. 30 As such, managing these grasses and other non-native plant species can enhance regional NCSs.
Further, non-native, annual plant species invasions are correlated with increased fire risk and increased fire intensity because they provide fuel between shrubs and that may lead to a larger fire footprint and/or hotter fires.37,111 Frequent and/or hot wildfires can contribute to ecosystem shifts and habitat loss, both of which may reduce a landscape’s overall carbon storage capacity and/or its annual sequestration potential.34,37,44 Finally, non-forest management techniques that minimize invasive plant species cover can also help chaparral and scrub ecosystems rebound after a wildfire and resume carbon sequestration faster. 34,37 A large
soil seedbank of non-native species can hinder native seedling growth, so managing for invasive species can assist in ecological resilience.37
5.6.3 Fire management
Beyond the reduced wildfire frequency and/or intensity resulting from managing invasive plant species, other fire management techniques can prevent or minimize carbon emissions from wildfires. Given that nearly every contemporary wildfire in the San Diego region has been Oct. 11, 2022
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ignited by a human-related source,35 preventing anthropogenic ignitions is critical to reducing the frequency and overall impacts of wildfires. Some wildfire prevention and management strategies include road, infrastructure, or home hardening, which can minimize sparks from vehicle or infrastructure ignition sources that can start wildfires and simultaneously minimize property damage and/or loss.112–114 These management techniques are ongoing in the region, with opportunities to expand them through education campaigns and to better understand the NCSs associated with reducing wildfire intensity and/or frequency in the San Diego region.
5.7 Regional Natural Climate Solutions Policy Recommendations and Conclusions
As the County of San Diego and other governments in the San Diego region plan for decarbonization to meet their emissions and climate goals, NCSs will be an important part of the regional carbon accounting. NCSs and NWLs contribute to decarbonization through sequestering atmospheric carbon annually and through storing atmospheric CO 2 in plant tissues
for the medium to long-term. However, NWLs can also contribute to regional emissions when they are lost or damaged due to development, natural disasters like wildfires, or climate change induced ecosystem changes like sea level rise. General policy recommendations for carbon sequestration and storage through NCSs follow.
5.7.1 Sequestration
The simplest, cheapest, most effective regional policy to contribute to NCSs is to prevent land use change and allow NWLs to continue to sequester carbon naturally. The San Diego region has a large quantity of conserved lands and has plans to conserve more, 54 so continuing to
protect conserved lands and expanding protections to additional areas will provide annual carbon sequestration and low to no cost negative emissions of more than 2 million tons of CO2e stored annually. Other NCSs like reforestation, forest management, or other restoration techniques, are typically highly effective at removing CO2, but they are almost universally more expensive than protecting existing carbons sinks.21,22 Regional governments and agencies can contribute to regional net negative emissions through preventing land use change among their NWLs. In addition to continuing conservation and preservation efforts, governments can research or partner with research groups to better characterize the carbon sequestration potential in the region’s NWLs. Doing so will allow for better carbon accounting, reduce uncertainties, and inform better management policies and practices to maximize NCSs.
Regional governments can research and incentivize carbon farming techniques like compost application, riparian restoration, and orchard tree retention. Additional research should investigate how rangeland tree planting, no-till agriculture, crop choice, manure management, Oct. 11, 2022
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and grazing/livestock feed management affect agricultural emissions. Carbon farming is widely considered to be the best way to transform the agricultural sector from a carbon source to a carbon sink and will likely be important for the San Diego region’s decarbonization efforts.12,22,43,52
Wetlands, marshes, and other blue carbon ecosystems contribute less to annual sequestration than tree and shrub-dominated ecosystems, but nevertheless play an important role in total carbon sequestration. Protecting these systems from land use change and restoring them will contribute to continuing sequestration in the near-term. Restoration of surrounding habitats may allow blue carbon habitats to migrate as sea level rise inundates coastal areas, thereby allowing blue carbon systems to continue to sequester carbon in the medium and long-term.
Last, local governments should continue to increase the urban tree canopy and other greenery cover because these trees and shrubs turn settlement areas into carbon sinks (Table 5.2).
Additionally, governments can select tree species and location selections to maximize carbon sequestration rates, minimize inputs like water, and maximize co-benefits. The latter will be especially important as governments pursue environmental justice policies that aim to provide public goods to disadvantaged and low-income communities.
There are additional NCSs to increase sequestration rates that were not investigated here but which are important to consider. For example, while forest management is not widely applicable in the region, non-forest management of chaparral and scrub ecosystems may improve regional sequestration rates and data gaps should be filled to better understand effectiveness and cost.
5.7.2 Storage
As with carbon sequestration, the simplest and cheapest way to maintain the naturally stored carbon is to protect NWLs from land use change. By protecting existing carbon storage, the region can prevent large one-time emissions from land use change. Beyond protecting lands from intentional land use change, governments can research carbon storage values in the region to characterize the magnitude of stored carbon. Such efforts would elucidate the role of NWLs and help the region understand long-term land use carbon accounting under different development strategies.
Similarly, blue carbon ecosystems are particularly adept at storing large quantities of carbon and are therefore disproportionately vulnerable to generating large emissions if they are lost.
Wetlands, marshes, and other coastal systems should be actively protected from land use change and should be restored and enhanced when possible. Such efforts would both increase coastal carbon storage and prepare for loss due to sea level rise. Improved understanding of Oct. 11, 2022
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blue carbon ecosystems would provide similar relevant information as for other land uses in the region, and it would similarly inform emissions under different development and restoration strategies.
Agricultural lands hold carbon primarily in trees, like orchard trees, and in soils. Some carbon farming techniques, like composting and riparian restoration, are likely to increase stored carbon in agricultural lands. These techniques, and other carbon farming techniques, will have variable effects by locality, and should thus be researched and better characterized. Regardless of carbon farming, agricultural lands store more carbon than barren landscapes or settlements that do not have urban trees. As such, preventing land use change can also be an important measure for active, productive agricultural lands.
Urban trees and vegetation lead to the only carbon storage that occurs in settlements and urban areas. These trees, shrubs, and other green spaces are not as efficient at storing carbon as the native ecosystems that were historically present, however, they still provide medium- term carbon storage and should be protected and expanded. There are important opportunities for communities to invest in maintenance of existing trees so overall mortality is reduced.
Carbon storage and other ecosystem services are highest with mature trees, and it will take newly planted trees significant time to provide the carbon and ecosystem services of the older trees they replace. However, some mortality is inevitable, and as urban trees die, they should be replaced with appropriate species to maximize total carbon storage and carbon storage longevity while also minimizing lifetime inputs, like water. 97 Finally, some NCSs that can protect or enhance carbon storage were not included here but are still important to consider. For instance, wildfire prevention via educational programs and infrastructure hardening will reduce wildfire emissions and will allow natural systems to regenerate after wildfires and recover the emitted carbon as plants regrow. 34 5.7.3 Future research, alignment, and uncertainty
This chapter has identified ways that natural, working, and urban lands are contributing to regional decarbonization. It has also highlighted areas for future research and work. Primary among these are that more regional and localized data can be incorporated into future decision making to better account for regional NCSs. Additionally, regional governments should quantify the full breadth of co-benefits and ecosystem services provided by NWLs, carbon farming, blue carbon, and urban forestry. A wide array of co-benefits should be considered, quantified, and maximized in addition to carbon sequestration and storage, including: water savings; groundwater recharge; air and water quality regulation; soil stabilization and erosion control; soil fertility and maintenance; protection of people and property from storm surges, inland flooding, and other natural hazards; pollination and pest regulation; livestock fodder Oct. 11, 2022
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production; recreation opportunities and resulting benefits to physical and mental health; biodiversity protection; and wildfire risk reduction. A key consideration for these co-benefits is who benefits and who may be left behind. While carbon sequestration benefits the world equally wherever it occurs, most other ecosystem services are highly context dependent– their value varies spatially based on the path of their delivery and the location and activity of the people who need them. NCS programs should be designed with this in mind to ensure an equitable distribution of benefits to all people, especially the most vulnerable.
Further, the RDF has shown that the San Diego region can align with State and federal initiatives and programs to improve regional decarbonization outcomes, fund regional projects, foster collaboration inside and beyond the San Diego region to better facilitate information sharing and learning. Regional alignment can and should include decarbonization specific initiatives, like SB 1383, and can also extend to initiatives that will improve land management and indirectly contribute to NCSs. Examples of State and federal initiatives include the State’s 30x30 initiative (which aims to protect and conserve 30% of the State’s terrestrial and marine spaces by 2030, as laid out in California Executive Order N-82-20) 115 and the national “America
the Beautiful” initiative (Presidential Executive Order 14008), which includes a “goal of conserving at least 30 percent of our lands and waters by 2030” 116 that will be driven by locally-
designed conservation strategies.117 These initiatives are aligned with this chapter’s findings that protecting natural and working lands have important carbon sequestration and storage benefits, in addition to the myriad other benefits. Regional participation in and alignment with these collaborative efforts will be important both to producing local decarbonization outcomes and to sharing insights and knowledge with other regions for their benefit.
This report’s analyses have some important uncertainties. These primarily stem from unavailability of localized carbon storage and sequestration data. This is problematic because local climate, prevailing fire regimes, ecosystem composition, and environmental stressors like drought have significant impacts on any given local NCS effectiveness. Regional governments should utilize the most recent and localized data possible when estimating NCSs’ contributions to decarbonization. Data on local chaparral and blue carbon storage and sequestration are forthcoming.
i These data will be critical to understanding valuing regional land contributions to negative emissions and long-term carbon storage.
i Personal communication with Zachary Plopper, Dr. Meagan Jennings, and Dr. Matthew Costa, 2021.
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Acknowledgements: The authors wish to thank Dr. Megan Jennings from SDSU, Dr. Matthew Costa from the Scripps Institution of Oceanography, Zachary Plopper from the Surfrider Foundation, Dr. Heather Henter from the UC San Diego Natural Reserve System for their guidance and expertise on local ecosystem functioning and ongoing carbon sequestration accounting efforts; Michael Wonsidler and Caitlin Lelles from the County of San Diego’s Department of Public Works; Allison Wood, Anna Van, and Anna Lowe from SANDAG for guidance on regional efforts to map carbon sequestration; Dick Cameron, Brian Cohen, and Dr.
Joe Fargione from The Nature Conservancy for advice on maps, framing, and sources; and Jeffrey Myers from UC San Diego School of Global Policy and Strategy, Dr. Becky Chaplin- Kramer from the Natural Capital Project, and Alex Cagle for reviewing and offering invaluable edits and comments.
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