California is moving ahead with plans to procure two gigawatts of long-duration energy storage as part of a wider effort to install 10.6 GW of long-lead time (LLT) clean energy resources.

The long-term plan includes up to a gigawatt of geothermal and 7.6 GW of offshore wind, along with a gigawatt of 12-hour storage capacity and another gigawatt with “multi-day discharge capacity”, Energy Storage News reports. Contracting will begin in 2026, and the storage resources are meant to be in place between 2031 and 2037, Utility Dive writes, citing a fact sheet from the California Public Utilities Commission (CPUC).

“The resources were strategically selected for their ability to support California’s greenhouse gas emissions reduction goals, scale up the technologies to reduce costs, enhance the diversity of the California resource mix, and enable their more effective integration into the grid,” Energy Storage News states. “The regulator wants to establish competition across a broad range of resource categories, encourage competition where possible, and maximize opportunities to reduce costs over time through a series of solicitations.”

In earlier consultations, some California stakeholders opposed including lithium-ion batteries in the definition of long-duration energy storage (LDES), the news story adds. “The California PUC took this into account and selected technologies that energy providers are not procuring in large enough quantities to create scale and lower costs.” As well, eligibility of pumped storage is limited to installations up to 500 MW that received state funding before January 1, 2023.

Last month, Microgrid Knowledge reported that LDES was beginning to emerge as a practical option for microgrids in California, based on a series of tests in military applications and on Indigenous lands. “Most LDES technologies are scalable, have modular designs, and use relatively inexpensive and abundant materials,” wrote reporter Lisa Cohn. “They’re also less likely than lithium ion to catch fire.”