California regulators said this year that the state will need 1 gigawatt of long-duration storage by 2026. But the technologies that can cost-effectively meet that need have so far attracted more attention from white-paper authors than paying customers.

That changed on Thursday, when a coalition of eight Californian community-choice aggregators, led by Silicon Valley Clean Energy (SVCE), published a request for offers seeking 500 megawatts of long-duration storage capacity. In doing so, they beat the state's investor-owned utilities in making good on the California Public Utilities Commission's call to invest in this resource.

"We know that this is going to be needed in our future," SVCE CEO Girish Balachandran said in an interview. "As load-serving entities, we said, 'Let’s take the first step of moving this forward.'"

Indeed, the Joint CCA procurement appears to be the largest-ever effort to contract for long-duration storage.

"I haven’t seen anything this big...that’s focused on long duration," said Jin Noh, senior policy manager at the California Energy Storage Alliance.

8 hours or more by 2026

The lithium-ion batteries now being deployed at gigawatt scale typically deliver their full power for up to 4 hours. Beyond that, adding more discharge duration typically costs more than it's worth right now. But many grid analysts believe that, as wind and solar plants proliferate, cheap long-duration storage will play a valuable role in turning that intermittent generation into a round-the-clock resource.

The industry lacks a firm definition of what "long-duration" storage entails. Some alternative battery startups pitch their 4-hour storage products under the moniker. Cambridge-based startup Form Energy staked out the other end of the spectrum this year, winning a contract for a 150-hour-duration storage plant in Minnesota.

The Joint CCAs stipulated that eligible projects must provide at least 50 megawatts of power capacity with a minimum of 8 hours of discharge duration, and they have to come online by 2026. Bids can earn extra points for coming online sooner.

That deadline may seem far off. But most long-duration storage contenders are either new technologies or capital-intensive construction projects like pumped hydro. A few years of lead time is necessary to develop such projects and get them interconnected, said Monica Padilla, SVCE's director of power resources.

A firm path to market in six years is still a big step forward for the long-duration storage industry, which has struggled to find customers ready to pay for its products.

"Having 2026 as the deadline is helpful to create some urgency," Noh said. "That will help support this market segment overall."

Numerous companies responded to a request for information earlier this year, but the names are not publicly available. SVCE did confirm that the responses included multiple technologies, ranging from conventional lithium-ion to chemical flow batteries, compressed air, pumped hydro and emerging technologies such as thermal and gravity-based storage.

The Joint CCAs will serve as the scheduling coordinator, deciding when to tell the plants to charge and discharge, Padilla noted. That allows some latitude in what role the long-duration storage bids can play.

These projects will offer early field validation of the value that longer-duration storage assets can provide. Such data is needed because California could be investing a lot more money in this type of resource. A forthcoming study from Strategen Consulting found that 40 gigawatts of long-duration storage will be needed to meet California's goal of carbon-free electricity by 2045.