California Builder & Engineer

Dedicated to the people who make our built environment better and safer. We tell your stories and celebrate your successes.

Register with us and receive industry news and content only available to subscribers.


Indianapolis, IN, USA (HQ)

903 E. Ohio St., Indianapolis, IN 46202

Call: (317) 423-2325

Hydrostor Selects Kiewit to Advance Engineering for Willow Rock, the Largest Stand-Alone Energy Storage Project in California

ROSAMOND, CA — Hydrostor Inc. (Hydrostor), a long-duration energy storage solution provider, and Kiewit Engineering Group Inc. (Kiewit), have entered an agreement to advance Front-End Engineering and Design studies for the 500 MW Willow Rock Energy Storage Center (Willow Rock), which would be the largest stand-alone energy storage project in California.

This milestone demonstrates steady progress in the development of Hydrostor's Advanced Compressed Air Energy Storage (A-CAES) technology in North America. A-CAES (pronounced "case") uses commercially proven equipment and processes to provide affordable, large-scale, and emission-free long-duration energy storage (LDES). Willow Rock will be capable of storing enough energy to provide power for up to 400,000 homes over eight hours, turning California's growing solar and wind resources into on-demand peaking capacity, enabling the closure of emitting fossil fuel resources while maximizing transmission system utilization.

"Hydrostor continues to reach important milestones at Willow Rock, and we look forward to working with the world-class engineering and construction teams at Kiewit to advance this critical clean energy project," said Curtis VanWalleghem, Hydrostor's Chief Executive Officer. "Our global teams are paving the way towards achieving aggressive net-zero goals. Willow Rock will be capable of eliminating the equivalent of roughly 120,000 cars off the road every year over its 50-plus year project life."

"Kiewit remains committed to engaging in the clean energy transition and recognizes that LDES solutions like A-CAES are a critical component of grid modernization," said Kevin Needham, President of Kiewit Power Engineers. "We look forward to commencing work on Willow Rock, which has the potential to abate significant emissions and provide a reliable, sustainable energy source for many decades."

Your local Gomaco dealer
Terry Equipment
Your local Gomaco dealer
Terry Equipment
Your local Trimble Construction Division dealer
SITECH Southwest