Assessing the value of long duration energy storage in California

New analysis shows that long duration energy storage can deliver energy when California needs it most, at lower cost to consumers

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California is helping lead the country’s transition to clean energy, with over a third of the State’s electricity already coming from renewable sources. This share of renewable energy will only grow as the State works to meet California Senate Bill 100’s zero emissions resource target by 2045. To meet this target, California will need new, emissions-free, and cost-effective resources for ensuring grid reliability 24/7. Interest in long-duration energy storage (LDES) – which can store excess renewable energy during periods of low energy demand and release it when demand is high – has been growing as a potential solution.

Recently, the California Energy Commission (CEC) issued a grant to E3 and Form Energy to study the value that LDES could bring to meeting California’s electric decarbonization goals. This culminated in the most in-depth analysis of LDES’s role within the State thus far. Full findings were recently published in a white paper, Assessing the value of long duration energy storage in California, which are summarized below.

Overall, study findings demonstrate that LDES, including multi-day storage, will play an essential role in cost-effectively decarbonizing California’s electric grid – with between 5 to 37 GW of LDES anticipated to be needed by 2045, depending on the depth of decarbonization. LDES is shown to help reduce costs wasted on renewable curtailment, lower emissions from air pollutants, and mitigate land use impacts as a result of not needing to overbuild other resources across California.

Three of the study’s topline findings include:

  • Across various policy scenarios, LDES is part of California’s least-cost resource mix in 2045. Under an SB 100 scenario, deploying up to 5 GW of LDES can cost-effectively bring CO2 emissions down to 12 MMT by 2045. Under deeper decarbonization scenarios, the role for LDES increases dramatically, with up to 37 GW being part of a least-cost, 0 MMT portfolio that accounts for both in-state emissions and electric imports.
  • By 2045, 21 GW of LDES can cost-effectively substitute for all of California’s existing gas power plant capacity. Such a portfolio enables an electric grid with 0 MMT of in-state emissions at cost parity with a portfolio that retains existing gas power plants. Without LDES, the portfolio costs of using other resources to avoid existing gas power plants increases by up to 87%.
  • LDES can enable communities to meet local reliability area requirements with non-emitting resources, which can bring significant air pollution reduction benefits. In Form’s study of the Los Angeles Basin as an example area, 2 GW of LDES and 1.3 GW of 4-hour lithium-ion storage is found to be the least-cost substitute for gas power plants located in disadvantaged communities, lowering system costs by 3%. This is the first time that the benefits of LDES to local reliability and environmental justice have been studied in the State, creating a model for how other local reliability areas can be studied in the future.

 

Total Resource Capacity & Costs to Meet California’s 2045 SB 100 goals

Figure from E3 and Form Energy’s analysis of the California market demonstrating that LDES can cost-effectively substitute existing gas relative to the SB 100 baseline scenario

In addition to highlighting the role of LDES in California’s grid, the study demonstrates the need for modeling tools and approaches that are able to accurately capture the value of LDES during future portfolio planning. In particular, the study reinforces the importance of optimizing resource needs with hourly time resolution across a full year, evaluating multiple weather years, and reflecting the broad spectrum of LDES technologies becoming available, including multi-day storage. By using these methodologies, grid planners can proactively identify resources that electric markets may not yet be fully valuing. From there, policy initiatives can be designed to ensure these resources are able to rapidly proliferate and deliver savings to the electric grid.

To learn more about these results and further findings from our analysis for the California Energy Commission, please see the full white paper, Assessing the value of long duration energy storage in California, available at the link here.

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