The Willow Rock Energy Storage Center
About the project
The Willow Rock Energy Storage Center is a long-duration energy storage facility under development in eastern Kern County, California. It will provide 500 MW of reliable energy storage and be capable of powering over 400,000 homes for eight hours.
Willow Rock Energy Storage Center
Project Highlights
A Project Built
for Impact
Serving the needs of Kern County.
500 MW
Storage capacity, enough to power approximately 400,000 homes for up to 8 hours.
2030
Expected commencement of operations, subject to approvals.
1,000+
Direct jobs expected to be supported during construction.
$500M+
Estimated in direct and indirect economic benefits to the regional economy during construction.
ABOUT THE PROJECT
Rethinking
Energy Storage
Built for Grid Reliability
The Willow Rock Energy Storage Center is an Advanced Compressed Air Energy Storage facility that will cost-effectively enhance grid reliability.
Project Updates
Latest Updates
See the latest updates from the Willow Rock Energy Storage Center project team here. Learn about recent community events, regulatory updates, and see communications from Hydrostor to the community
Update
FEB 25, 2026
Hatch and Hydrostor announce strategic execution partnership and equity agreement to deliver advanced compressed air energy storage
Update
Feb 12, 2026
Hydrostor’s Willow Rock Energy Storage Center Signs Offtake Agreement with California Community Power
Update
JAN 28, 2026
Hydrostor and Baker Hughes Deepen Strategic Collaboration to Advance Reliable, Resilient, and Sustainable Power Systems
Update
DEC 19, 2025
Hydrostor’s Willow Rock Energy Storage Center Obtains Final Approval for Power Plant License
The Technology
About
A-CAES
Advanced Compressed Air Energy Storage, or A-CAES, is an improvement on a technology that has been successfully deployed around the world for decades known as compressed air energy storage. Using a simple combination of air, water, and underground hard rock caverns, Hydrostor’s patented A-CAES technology allows the grid to draw on energy when it’s needed.
Long-Duration Storage
Hours of dispatchable power
24-7, 365 Reliability
When it's needed, where it's needed.
Emissions-free operations
No fuel combustion required
See how it works