Powering Long Beach’s Future: The THUMS Borehole Battery™ Pilot Project
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Copyright © 2025 Philip C. Cruver
Geo2Watts is planning to launch the THUMS Borehole Battery™ pilot project in collaboration with California Resources Corporation (CRC) on the iconic THUMS Islands in Long Beach. This first-of-its-kind installation will demonstrate how idle oil and gas wells can be transformed into long-duration energy storage (LDES) assets, helping California move toward a resilient, low-carbon energy future.
The THUMS pilot uses Geo2Watts’ proprietary Borehole Battery™ technology, a breakthrough approach that converts deep subsurface wellbores into high-temperature thermal energy storage. Instead of relying on traditional batteries, the Borehole Battery™ stores energy as heat using a Reversible High-Temperature Heat Pump (RHTHP). During the day, when renewable electricity is abundant and inexpensive, the system runs in charging mode, using the compressor side of the RHTHP to heat pressurized water to approximately 200°C. This heat is circulated within a sealed, repurposed well using a closed-loop heat exchanger where the surrounding geology acts as a large natural thermal energy reservoir.
In the evening, when electricity prices in California can be six times higher, the system reverses. The stored heat drives the expander side of the RHTHP to generate AC power directly - no inverters or transformers required - delivering clean, dispatchable electricity to CRC’s operations. Each well can store roughly 1.3 MW of thermal energy, and wells placed only a few feet apart can be daisy-chained to build multi-megawatt power blocks rapidly and affordably.
Benefits for Stakeholders
CRC
CRC faces a major operational challenge: electricity costs are one of its largest expenses, with total demand in Long Beach reaching approximately 70 MW. By integrating Borehole Battery™ systems behind the meter, CRC can lower its electricity costs while increasing energy reliability for critical operations. The THUMS pilot also provides a scalable pathway to repurpose thousands of idle wells across CRC’s portfolio, turning liabilities into revenue-generating clean-energy assets.
City of Long Beach
Long Beach has long been at the forefront of innovation in coastal energy production. This project strengthens the city’s leadership by transforming legacy oilfield infrastructure into modern clean-energy storage. The Borehole Battery™ creates local jobs, supports responsible land use, and aligns with Long Beach’s climate and resilience goals without requiring new land acquisition or large above-ground installations.
Local Citizens
Residents benefit from cleaner air, reduced emissions, and the economic revitalization that comes from reusing existing industrial sites for sustainable purposes. Because the Borehole Battery™ is quiet, compact, and located entirely underground, it avoids the community impacts often associated with large-scale renewable projects. The pilot also helps insulate Long Beach from grid volatility and blackouts by providing reliable local power.
State of California
California has set an ambitious target of 1,000 MW of long-duration energy storage by 2028. Meeting this goal will require cost-effective, rapidly deployable solutions that minimize permitting delays and avoid transmission bottlenecks. The THUMS pilot showcases exactly that: a modular, scalable LDES technology that can be deployed in months rather than years by using existing wells and pre-installed grid infrastructure. With approximately 50,000 idle wells across the state, Borehole Batteries™ offer a uniquely California-ready pathway to achieving statewide LDES capacity at scale.
Turning Retiring Wells Into Investor-Ready Clean Assets
The THUMS project demonstrates how federal incentives under the Inflation Reduction Act (IRA) and the new One Big Beautiful Bill (OB3) make this model financially self-sustaining. By qualifying for a 50% Investment Tax Credit (ITC) under OB3, the Borehole Battery™ becomes an attractive, de-risked asset class for private investors. These tax benefits dramatically lower capital costs and improve project returns, enabling the private sector - not state or local governments - to fund the repurposing of end-of-life oil and gas wells. Instead of burdening taxpayers with the cost of retiring legacy infrastructure, IRA and OB3 incentives turn these sites into revenue-generating clean-energy assets, accelerating environmental remediation while catalyzing billions of dollars in private capital for California’s energy transition.
