California Taps Compressed Air to Power Clean Energy Future

DENVER, CO – February 12, 2026 – In a significant move to bolster California’s increasingly strained power grid, a coalition of community-led energy providers has signed a major agreement to purchase power from a first-of-its-kind energy storage facility that uses compressed air and water.

Hydrostor, a global developer of long duration energy storage (LDES), announced that its Willow Rock Energy Storage Center has secured a 50-megawatt (MW) offtake agreement with California Community Power (CC Power). The deal, made on behalf of six of CC Power's member community choice aggregators (CCAs), marks a critical milestone for the 500 MW / 4,000 MWh project in Kern County and a vote of confidence in advanced compressed air energy storage (A-CAES) technology as a key to unlocking a zero-carbon grid.

A New Pillar for California's Grid

The Willow Rock project is poised to become a cornerstone of California's ambitious energy strategy. The state, which aims for 100% clean electricity by 2045, faces a monumental challenge: ensuring grid reliability while integrating vast amounts of intermittent renewable energy like solar and wind. State energy agencies project a need for up to 55 gigawatts of long-duration storage by 2045—a more than 150-fold increase from what has been deployed since 2010.

Willow Rock directly addresses this need. With its ability to deliver 500 MW of power for eight continuous hours, the facility is designed to solve the "duck curve" dilemma—the steep drop in solar generation as the sun sets, which coincides with a rise in evening electricity demand. While 4-hour lithium-ion batteries have been instrumental in short-term grid balancing, experts agree that 8-hour-plus storage is essential for a deeply decarbonized system.

“Hydrostor’s Willow Rock project brings much-needed grid benefits to California by providing reliable long-duration energy storage capacity," said Alexander Morris, CC Power’s General Manager, in a statement. He highlighted the project's use of "domestic content, off-the-shelf turbomachinery, and only air and water to store energy."

Beyond Batteries: The Mechanics of Compressed Air

Hydrostor’s A-CAES technology offers a compelling alternative to both chemical batteries and traditional pumped-hydro storage. The process is elegantly simple in concept: it uses electricity from the grid—ideally cheap, abundant renewable power—to run a compressor that forces air into a purpose-built underground cavern, displacing water to maintain constant pressure. The heat generated during compression, which is wasted in older CAES designs, is captured and stored in a thermal management system.

When the grid needs power, the process reverses. The compressed air is released, reheated with the captured thermal energy to boost efficiency, and expanded through a turbine to generate electricity. This system boasts a projected lifespan of over 50 years with no degradation in capacity, a stark contrast to lithium-ion batteries which have a shorter operational life and lose storage capacity over time. Unlike pumped hydro, which requires specific mountain geography, A-CAES technology offers greater siting flexibility, allowing projects like Willow Rock to be strategically placed near grid connection points in energy hubs like Kern County.

“We’re pleased to have signed this agreement with CC Power on behalf of its members, whose forward-thinking procurement activities are leading the way to ensure a future-proof and resilient grid," noted Hydrostor President Jon Norman. He emphasized that the grid is being "underpinned by cost-effective and reliable long duration energy storage."

The Power of Community Choice

The agreement is also a powerful demonstration of the growing influence of Community Choice Aggregators in shaping California's energy landscape. CC Power, a joint powers authority, allows its nine member CCAs to combine their purchasing power to invest in large-scale, innovative projects that might be out of reach for a single entity.

The six members participating in the Willow Rock agreement—CleanPowerSF, Peninsula Clean Energy, Redwood Coast Energy Authority, San Jose Clean Energy, Silicon Valley Clean Energy Authority, and Valley Clean Energy Authority—collectively represent over 3 million customers. By acting together, they are not only securing a source of clean, reliable capacity to meet state mandates but also driving the commercialization of novel technologies essential for the energy transition.

"CC Power strives to advance California’s energy goals by contracting with novel, high-potential technologies and is excited to partner with Hydrostor on this innovative energy storage solution," Morris added.

Powering the Future: From AI to Grid Resilience

The urgency for projects like Willow Rock is being amplified by an unexpected and voracious new source of electricity demand: artificial intelligence and data centers. Global data center electricity consumption is on track to nearly triple by 2035, with AI being the primary driver. In the U.S. alone, data centers could consume nearly 10% of the nation's electricity by 2030.

This constant, 24/7 power demand threatens to stall decarbonization efforts if met with fossil fuels. Long-duration storage is seen as the critical link that allows intermittent renewables to provide the firm, round-the-clock power that data centers require. Hydrostor executives have explicitly pointed to this trend as a key market driver for their technology.

"This agreement marks an important milestone for Hydrostor as we continue scaling advanced long‑duration storage in key markets...all of which are anticipating growing electricity demand, including from AI and data centers,” Norman stated.

The Path to 2030: Hurdles and Milestones

With a planned online date of 2030, the Willow Rock project has a clear but challenging path ahead. It has already achieved major regulatory victories, securing its final permit from the California Energy Commission in late 2025 and agreements with Kern County. The project also has a conditional commitment for a massive loan guarantee of up to $1.76 billion from the U.S. Department of Energy's Clean Energy Financing Program, a crucial step toward financial viability.

However, challenges remain. The project has secured significant offtake agreements, including a 200 MW contract with Central Coast Community Energy and this new 50 MW deal with CC Power, but it must still contract for its remaining capacity to secure final financing and break ground. The complexities of permitting and grid interconnection in California have also been noted as potential sources of delay for large-scale energy projects.

Even so, the Willow Rock center represents a landmark for Hydrostor's global ambitions. It is the company's first utility-scale project in the U.S., building on experience from an operational facility in Canada and paving the way for a 7-gigawatt global pipeline that spans Australia, Canada, and the UK. For California, it represents a tangible step toward a resilient, reliable, and renewably powered future.