Project Owner
Docket Number
500 MW
8684 Sweetser Road in Rosamond, Kern County, California
Project Status
Under Review
Project Type
Application for Certification
Project Description

The Gem Energy Storage Center (GESC) is proposed by GEM A-CAES LLC, a wholly owned subsidiary of Hydrostor, Inc. The project would be located at 8684 Sweetser Road in Rosamond, Kern County, California.

GESC would be a nominal 500-megawatt (MW), 4,000 MW-hour (MWh), advanced compressed air energy storage (A-CAES) facility capable of charging and discharging daily. GESC would compress air into a purpose-built underground cavern, using electricity from the grid, most likely off-peak, excess, or surplus electricity. The heat from the air compression process would be captured and stored in an aboveground thermal storage system. The compressed air would then be stored in the cavern under the pressure of a hydrostatic head created by an onsite, aboveground water reservoir. When electricity is needed by the grid, the compressed air would be released using the hydrostatic head pressure, re-heated using the stored thermal energy, and directed through aboveground turbine-generators to produce electricity.

GESC’s major equipment would consist of five all-electric air compressor trains, five 100-MW air-driven power turbine generators, heat exchangers, thermal heat storage, an underground compressed air storage cavern, an aboveground water reservoir, miscellaneous aboveground support facilities, and a 10.9-mile interconnection to the existing Southern California Edison (SCE) Whirlwind Substation.

Presiding Member: Kourtney Vaccaro, Commissioner

Associate Member: Andrew McAllister, Commissioner

Hearing Officer: Renee Webster-Hawkins/Susan Cochran

  • 12/2/2021 - Application for Certification (AFC) filed
  • 12/30/2021 - Staff's Data Adequacy Recommendation
  • 1/27/2022 - CEC Order concurring with the executive director’s recommendation and finding that the Gem filing is deficient

Power Plant Certification and Exemption Processes

As required by the Warren-Alquist Act, the Energy Commission monitors projects under its jurisdiction throughout construction, operation, and closure to ensure compliance with the conditions of certification imposed for approving the projects.


Project Manager

Leonidas Payne

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