Gem Energy Storage Project

Clean, Safe, and Reliable Energy Storage – Using only Water, Gravity, and Air

As California moves towards the objective of achieving 100% carbon-free electricity by 2045, and addressing SB100 objectives, it will require bulk-scale, long-duration storage in order to integrate increasing renewables and allow for a fully decarbonized grid. The Gem Energy Storage Project provides a cost-effective, emissions-free storage option to integrate large amounts of renewable resources in the High Desert area (a designated renewable development zone). Located immediately northeast of the Los Angeles basin, the project facilitates new, non-emitting capacity to serve emerging electrical capacity needs in the LA area (particularly as fossil plants continue to retire due to age and regulatory reasons). In addition, there are critical near-term drivers for long-duration storage, including the shutdown of Diablo Canyon Power Plant (DCPP). Advanced Compressed Air Energy Storage (or A-CAES) can provide the California grid a flexibly sited long duration and large-scale storage resource to meet the evolving demand profile in California, without the use of fossil fuels.

About the project

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

Stimulate Economic 


Improve Transmission Optimization and Grid Reliability

Enable Proven Technology and Existing Skills

The Gem Energy Storage Project is a full scale A-CAES facility that is under advanced stage 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 translated into reliable on-demand peaking capacity for the LA region. This project will directly integrate intermittent renewable generation in a critical renewable development zone and facilitates the closure of emitting fossil fuel generating stations.


  • Size: 500 MW / up to 6,000 megawatt hours (MWh) (12 hours duration)
  • Owner:  Self-Developed – Hydrostor, Meridiam, & Partners
  • Location: Rosamond, Kern County, California, USA (Northeast of LA Basin)
  • Application: Renewables Integration, Fossil Fuel Generation Replacement, Transmission Optimization
  • In-Service: Phase 1 – Early 2024 / Phase 2 – 2026
  • Lifetime: 50+ years



Driving economic growth: Provides diversified high paying 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 government. Additionally, A-CAES uses standard components and enables workers from the fossil-fuel industry to transfer existing skills while contributing to our 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’s objective of 100% carbon-free electricity by 2045. 

Facilitating delivery of renewablesDeliver 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 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 LA Basin, while ensuring reliable extended storage durations 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 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 circumstances and grid needs continue to evolve.

Supporting technological diversificationOffers technology diversity to the California grid to help enable future-proof grid resilience.  Provides different value streams relative to the other grid assets and storage approaches, supporting a portfolio of clean energy technologies.


Leading compressed air energy storage company with differentiated long duration storage technology that can be flexibly sited. 

Visit Main Website HERE

International infrastructure fund and global developer with experience across multiple sectors, specializing in sustainable infrastructure and energy transition projects. 

Visit Main Website HERE

Rosamond image by SkiDragon – Own work, CC BY-SA 3.0.