Long-duration energy storage developer Hydrostor has signed a 50-MW offtake agreement with California Community Power (CC Power) for the Willow Rock Energy Storage Center.
The 500-MW/4,000-MWh advanced compressed air energy storage (A-CAES) project can store energy for eight hours of continuous discharge to the grid, and will provide reliable capacity to the six community choice aggregator members of CC Power.
A rendering of the Willow Rock compressed-air LDES by Hydrostor.
“Hydrostor’s Willow Rock project brings much-needed grid benefits to California by providing reliable long-duration energy storage capacity using domestic content, off-the-shelf turbomachinery and only air and water to store energy,” said Alexander Morris, CC Power General Manager. “CC Power strives to advance California’s energy goals by contracting with novel, high-potential technologies and is excited to partner with Hydrostor on this innovative energy storage solution that improves reliability and diversifies California’s grid while supporting local employment and investment.”
The six CC Power members participating in the offtake agreement are CleanPowerSF, Peninsula Clean Energy, Redwood Coast Energy Authority, San Jose Clean Energy, Silicon Valley Clean Energy Authority and Valley Clean Energy Authority.
“Through this agreement with CC Power, we’re demonstrating how A‑CAES can be deployed at meaningful scale to meet emerging reliability needs while offering a cost‑competitive, infrastructure‑ready solution for utilities navigating rapid load growth,” added Jordan Cole, Hydrostor’s Chief Commercial Officer. “Willow Rock is a strong example of how our commercial strategy translates into real projects delivering significant value for customers and communities.”
The Willow Rock project received its California Energy Commission permit in December of last year, its franchise agreement from the Kern County Board of Supervisors earlier the same month, as well as a conditional letter of support from the Kern County Board of Supervisors in April of 2025. The project is expected to come online in 2030.
The Willow Rock Energy Storage Center is Hydrostor’s first utility-scale project being built in the United States, building on its operational project in Ontario, Canada. The company is developing another late-stage project in New South Wales, Australia, and has a 7-GW project pipeline globally, with projects in the United States, Australia, Canada and the UK.
