Summaries of State 100% Clean Energy Plans

Below are links to the 100% clean energy plans and reports for twelve states, along with summaries of each report's objectives, information on how it was produced and organized, what its key conclusions/recommendations are, and key takeaways about the report.


2021 SB 100 Joint Agency Report: Achieving 100 Percent Clean Electricity in California: An Initial Assessment 

Authors: California Energy Commission, California Public Utilities Commission, California Air Resources Board 

Publishing Organizations: California Energy Commission, California Public Utilities Commission, California Air Resources Board

Date Published: March 2021

Number of Pages: 178 


Recording of CESA Webinar: 

Report Objective

In September 2018, California Governor Jerry Brown signed Senate Bill 100 (SB 100), which established a goal for California to achieve 100 percent carbon-free electricity by 2045. On the same day, Governor Brown issued Executive Order B-55-18, which committed California to achieve economy-wide carbon neutrality by 2045.

SB 100 directed the California Energy Commission (CEC), California Public Utilities Commission (CPUC), and California Air Resources Board (CARB) to produce a joint agency report examining pathways for California to achieve its goal of 100 percent carbon-free electricity by 2045. The report, 2021 SB 100 Joint Agency Report: Achieving 100 Percent Clean Electricity in California: An Initial Assessment, was released in March 2021. It provides an economic analysis of various pathways for California to achieve its carbon-free electricity goal based on a capacity expansion modeling approach and outlines the necessary technology portfolio mix. The report emphasizes that it includes preliminary findings and directional insights to inform further analytical and planning efforts and is not intended to be a comprehensive or prescriptive roadmap for California to implement SB 100. Further analysis on impacts, including reliability, land use, equity, labor, and other planning and implementation considerations will need to be conducted. Following this initial report, CEC, CPUC, and CARB will submit a joint policy report every four years to the state legislature.

How the Report Was Produced

CEC, CPUC, and CARB served as the three lead state agencies for the report and worked with consultants from Energy and Environmental Economics, Inc. (E3). The CEC’s Disadvantaged Communities Advisory Group and California’s balancing authorities also provided analytical and advisory support. Stakeholder engagement included three scoping workshops; two technical workshops; a year-long series of in-person and virtual sessions for the public to provide feedback on the report’s scope, process, and analysis; and public comment opportunities through the SB 100 docket. 

Report’s Organization and Recommendations

The report starts by discussing the context and motivation behind California’s 100 percent clean electricity goal, including the history of the state’s climate leadership, benefits of carbon-free clean electricity, and the existing and future state of California’s electric grid. It then provides an overview of the process of developing the report, including stakeholder outreach and engagement efforts, before articulating the statutory interpretation and definition of key terms, outlining the capacity expansion modeling approach, identifying results and key takeaways from the analysis, and proposing strategic next steps and recommendations for implementation.

A capacity expansion model developed by E3 known as the RESOLVE California model was used to ground the recommendations discussed in the report. The report considers three core scenarios and four study scenarios as part of its modeling analysis. The core scenarios are aligned with the 100 percent carbon-free electricity by 2045 goal outlined in SB 100, as interpreted by the joint agencies. The four study scenarios are “exploratory analyses” that examine a range of future possibilities, including expanded load coverage (i.e., high electrification demand and the addition of storage and system losses to loads), constraints with certain resources, development of zero-carbon firm resources, accelerated timelines, and a no-combustion condition. The study scenarios aim to provide additional insights into California's broader energy, climate, and health efforts.

The analysis excluded some zero-carbon technologies that had significant negative health or environmental effects, concerns over technology readiness and/or resource availability, or conflicts with existing state priorities and policies. For example, new in-state nuclear plants are prohibited under state law until a long-term waste management plan becomes available, new hydroelectric facilities are unlikely to be sited due to ecosystem impacts, new concentrating solar power has not proven to be economically competitive, biomethane has limited resource potential, and green hydrogen and natural gas or coal-fired generation with carbon capture and sequestration are not yet commercially viable. 

Report Key Conclusions

  • California’s goal of 100 percent carbon-free electricity is technically achievable.
  • Achieving 100 percent carbon-free electricity will yield numerous benefits by improving public health, promoting energy equity, and advancing a clean energy economy.
  • Achieving California’s goals will require record-setting, sustained increases in capacity additions, resource build rates, and resource costs, with significant economic, labor, regulatory, policy, technology, and land use implications.
  • Implementing SB 100 will require a robust technology portfolio mix, including transportation electrification, building decarbonization, energy efficiency, load flexibility, and research and innovation.
  • Increasing technological and geographical resource diversity will reduce costs.
  • Natural gas will likely remain an economic option for reliability needs, but advancements in zero-carbon resources and storage will reduce the need for natural gas capacity.
  • Demand remains a significant driver of future resource needs, while demand flexibility will reduce total resource costs, as would cost-competitive zero-carbon firm resources.
  • Emerging technologies that will benefit from innovation may contribute significantly to California meeting its carbon-free electricity goals if/once development and implementation barriers are addressed include offshore wind, energy storage, hydrogen, and load flexibility.
  • Further analysis on specific impacts, including reliability, local impacts, and equity considerations, is needed.
  • It is technically feasible for California to reach 100 percent carbon-free electricity sooner than 2045, but it would require more gas retirements, increased geothermal resources, and decreased selection of solar and storage resources, which would yield increased overall resource costs.

Action Items

The report makes 13 specific recommendations for future research, engagement, and policy development. 

  • Areas for Further Study in the 2025 SB 100 Report
    • “Perform a comprehensive reliability assessment as the next step in the modeling process.”
    • “Continue to assess the role and impacts of emerging technologies and non-generation resources.”
    • “Analyze projected land-use impacts of scenarios and opportunities to reduce environmental impacts.”
    • “Define and include social costs and non-energy benefits in future analyses.”
    • “Continue to study opportunities and impacts related to achieving the 100 percent clean electricity target before 2045.”
  • Process and Engagement for SB 100 Reports
    • “Convene an annual joint agency SB 100 workshop in years between reports.”
    • “Align future SB 100 planning with findings and outcomes from relevant state efforts.”
    • “Consult with advisory groups to guide equitable planning and implementation.”
    • “Retain and expand upon best practices for community outreach and accessibility.”
  • Supporting Achievement of the 100 Percent Target
    • “Continue state support for research and innovation in clean energy technologies.”
    • “Continue to prioritize energy efficiency and load flexibility to minimize total implementation costs.”
    • “Identify and address bottlenecks in project permitting and development.”
    • “Promote workforce development programs that focus on high-quality job creation.”

Notable Takeaways

While California has the full complement of renewable energy resources, including wind, geothermal, biomass, and the potential for ocean energy sources, solar power has dominated development in the past decade. California now gets 20 percent of its electricity from solar, including from over 1.25 million customer-sited rooftop systems. On some days, solar can provide over half of peak demand. Given the low cost of solar PV, California has the potential for much more.

However, solar has caused serious changes to grid operations. As the sun sets before demand drops on hot days, other resources must rapidly respond to meet evening peak demand. This so-called “duck curve” creates a number of complications, including a large afternoon ramp, a growing amount of curtailments of renewable resources, and a lack of revenues for capacity resources.

As a result of the primary role of solar, the Joint Agency Report includes strategies to manage very high levels of solar power. Already virtually all new utility-scale solar is being developed with battery storage. The report anticipates a need for deploying 2.0 GW of storage for each 2.8 GW of solar PV added each year. But the report also calls for expanding non-storage strategies, such as greater resource diversity, more integration with the Western power grid, and greater use of demand flexibility.

The figure below shows the unprecedented pace of renewable energy capacity additions that California will need in order to achieve carbon-free electricity based on various timelines, including the 100 percent carbon-free electricity by 2045 goal outlined in SB 100.