Hydrostor has signed a 50 MW / 400 MWh offtake agreement with California Community Power for the 500 MW/4,000 MWh Willow Rock advanced compressed air energy storage project in California. The agreement represents six community choice aggregators. Permitted in December 2025, the project is expected online in 2030 and marks company’s first U.S. utility-scale development.
PROJECT SNAPSHOT
| Field | Details |
|---|---|
| Project | Willow Rock Energy Storage Center |
| Developer | Hydrostor |
| Offtaker | California Community Power |
| Offtake Agreement | 50 MW / 400 MWh |
| Total Project Capacity | 500 MW / 4,000 MWh |
| Technology | Advanced Compressed Air Energy Storage (A-CAES) |
| Discharge Duration | Up to 8 hours |
| Permitting Authority | California Energy Commission |
| Local Franchise Approval | Kern County Board of Supervisors |
| Permit Secured | December 2025 |
| Expected Commercial Operation | 2030 |
Canada-based long-duration energy storage (LDES) developer, Hydrostor has signed a 50 MW / 400 MWh offtake agreement with California-based energy procurement authority, California Community Power (CC Power) for its Willow Rock Energy Storage Center project. The agreement has been executed representing six of CC Power’s community choice aggregator (CCA) members.
The Willow Rock project is a 500 MW / 4,000 MWh advanced compressed air energy storage (A-CAES) facility designed to deliver up to eight hours of continuous discharge to the California grid. It will provide long-duration capacity to the six CC Power members, includes CleanPowerSF, Peninsula Clean Energy, Redwood Coast Energy Authority, San Jose Clean Energy, Silicon Valley Clean Energy Authority and Valley Clean Energy Authority.
The Willow Rock project received a permit from the California Energy Commission (CEC) in December 2025. It also secured a franchise agreement from the Kern County Board of Supervisors during the same month and obtained conditional letter of support in April 2025. The facility is expected to come online in 2030.
Willow Rock represents company’s first utility-scale project under development in the United States. The company operates a commercial A-CAES facility in Ontario, Canada, and is advancing another late-stage project in New South Wales, Australia. Hydrostor has indicated a global project pipeline of approximately 7 GW across the United States, Australia, Canada, and the United Kingdom.
Alexander Morris, General Manager of CC Power, stated that the Willow Rock project is expected to provide long-duration energy storage capacity to the California grid using domestic content, standard turbomachinery, and air and water as storage mediums. He added that CC Power is procuring advanced technologies to enhance grid reliability and diversify resource portfolios while supporting local employment and investment.
Jordan Cole, Chief Commercial Officer of Hydrostor, said the agreement demonstrates the deployment of advanced compressed air energy storage (A-CAES) at utility scale to address reliability requirements and load growth. He noted that the Willow Rock project reflects company’s commercial strategy of developing infrastructure-ready storage assets for utilities and community choice aggregators.