First offtake deal signed for 500MW/4,000MWh ...
Compressed air is stored in hard rock caverns dug deep underground. Image: Hydrostor. The project will be built in California''s Kern County. Image: Hydrostor. Advanced compressed air energy storage (A-CAES) company Hydrostor has signed a power purchase agreement (PPA) for one of its flagship large-scale projects in California.