Gem Energy Storage Center

Safe, Reliable and Emissions-Free Long Duration Energy Storage

As California moves towards its objective of achieving 100% carbon-free electricity by 2045, and addressing SB100 & City of Los Angeles decarbonization objectives, it will require large-scale, long-duration storage in order to more fully integrate increasing levels of renewable generation capacity. The Gem Energy Storage Center provides a cost-effective, emissions-free storage solution to integrate large amounts of renewable resources in the High Desert area (a designated renewable development zone). Located northeast of the Los Angeles basin, the project provides new, non-emitting capacity to serve emerging electrical needs and is deliverable to both the LADWP and CAISO grid (particularly as fossil plants continue to retire due to age and regulatory requirements). In addition, there are critical near-term drivers for long-duration storage, including the shutdown of Diablo Canyon Power Plant (DCPP) and other fossil-fired generation that is set to retire in Southern California. Advanced Compressed Air Energy Storage (or A-CAES) can provide the California grid with new flexibly sited, long duration and large-scale storage resources to help meet the evolving demand profile in California, without the use of fossil fuels.

About the project

Support 100% Net-Zero Carbon By 2045 (SB100 & LA100)

Stimulate Economic Growth and New Jobs

Improve Grid Reliability and Help Prevent Future Blackouts

Deploy Proven Technologies and Existing Workforce Skillsets

The Gem Energy Storage Center is a utility scale A-CAES facility that is under active development in Kern County, California, USA. The proposed facility will provide up to 500 megawatts (MW) of new electrical capacity, allowing California’s attractive and growing solar and wind resources to be directly converted into reliable, on-demand peaking capacity for the Los Angeles region and the broader California grid. This project will store excess generation from California solar and wind projects during periods of low customer demand by compressing air and storing it on the project site. During periods of higher customer demand or low supply, this high-pressure air is used to generate emissions-free electricity to meet real-time electrical load and enhance overall grid reliability. The project is designed to generate electricity for at least eight hours at full capacity.


  • Size: 500 MW / up to 4,000 megawatt hours (MWh) (8 hours duration)
  • Owner: Hydrostor
  • Location: Rosamond, Kern County, California, USA
  • Application: Renewables Integration, Fossil Fuel Generation Replacement, Transmission Optimization
  • Economic: 25-40 full-time equivalent jobs during operation, an estimated peak workforce of 700 jobs during construction, and over $500 million of regional direct and indirect economic impacts.
  • Project Design Life: 50+ years
  • In-Service: 2026



Driving economic growth: Provides diversified family wage job opportunities and generates significant regional economic development from both the construction and operation of the project. Delivers much greater direct and indirect economic benefits compared to lithium-ion battery projects. With a 50+ year lifetime, the operating facility will provide a stable revenue source for local communities. Additionally, A-CAES uses standard components and enable workers from the fossil-fuel industry to transfer existing skills while contributing to California’s clean energy future.


Achieving environmental objectives: Providing an emission-free alternative to meeting peak demand without the use of fossil fuels. Supports California’s objective of reducing GHG emissions 40% below 1990 levels by 2030. Key for enabling SB100 and LA100 objectives for 100% carbon-free renewable electricity by 2045.

Facilitating delivery of renewables: Deliver dispatchable capacity, using renewable energy generation in the High Desert area directly into the LA Basin. Reduces curtailment and enables further renewable asset growth in the High Desert Solar Resource Area and Tehachapi Wind Resource Area, while facilitating near-term delivery of solar and wind generation into either the Whirlwind Substation (CAISO delivery) or the planned Rosamond Switching Station (LADWP delivery).


Enabling firm capacity: Delivery of dispatchable electrical capacity into the Los Angeles Basin and broader California grid, while ensuring reliable long duration storage capacity well into the future as long duration storage becomes increasingly important to reliably serve load.

Delivering transmission system value: Maximize transmission system utilization by relieving transmission constraints on energy delivery, shaping wind and solar output to reduce the need for reserving transmission capacity, as well as improving local reliability for High Desert distribution system.

Offering low-cost expansion options post-COD: Options to cost-effectively expand either storage duration (i.e. MWh’s of storage) or capacity (i.e. MW’s of capacity) allowing for adjustment of the project’s configuration in the future as market and grid needs continue to evolve.

Supporting technological diversification: Offers technology diversity to the California grid to help enable future-proof grid resilience. Provides different generation characteristics relative to the other grid assets and storage technologies thereby supporting a more robust portfolio of clean energy resources.

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