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 policy scenario. 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.

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

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.