Board sends conditional support to California Energy Commission for Willow Rock long‑duration storage project

The Kern County Board of Supervisors on April 29 authorized the chair to send a conditional letter of support to the California Energy Commission (CEC) for the Willow Rock Energy Storage Center, a proposed 500‑megawatt, 4,000‑megawatt‑hour compressed‑air energy storage project north of Rosamond.

Planning staff and the applicant described the project as long‑duration energy storage that stores energy using compressed air in a deep cavern (staff said the cavern would be roughly 3,000 feet deep and the size of a football field) and releases it during peak demand. The project would require construction of a large on‑site operation, up to 700 construction workers at peak and about 19 miles of high‑capacity transmission lines to the Willowspring substation.

Planning staff recommended a conditional position of support tied to seven mitigation measures the county wants the CEC to require. Key county requests described in staff’s presentation included: acquisition and placement of an urban search‑and‑rescue vehicle located in eastern Kern (estimated applicant cost cited in the staff report: $1.9 million), funding to support expanded emergency response capacity during construction, traffic‑management and road‑repair/maintenance commitments for heavy hauling of rock (an estimated 1.6 million cubic yards to be removed over 3–4 years), limits on road closures (county asked that closures not exceed 10 minutes and not occur during Willow Springs Raceway high‑traffic days), provisions to ensure sales tax is realized in unincorporated Kern County and a 50% local‑hire goal.

Representatives of HydroStore (the applicant) told the board the project team had been coordinating with county staff and supports the proposed conditions. Numerous local governments, education and business groups filed or delivered letters of support; speakers from economic‑development and community groups told the board the project would generate construction and permanent jobs, local tax revenue and other downstream economic benefits. Several Rosamond residents raised visual and environmental concerns about construction and transmission‑line routing.

Following presentations and public comment, the board voted unanimously to adopt a conditional position of support and authorized the chair to sign the letter to the California Energy Commission that lists the county’s requested conditions. Planning staff said the CEC had just released the project’s preliminary staff assessment (PSA) ahead of an expected public workshop in late May or early June and that the county’s docketed support letter would be the first from the Board of Supervisors.