Overview
- Willow Rock will use advanced compressed-air energy storage rated at 500 MW/4,000 MWh, delivering more than eight hours of discharge and enough capacity to serve over 400,000 homes for that period.
- Hydrostor targets a mid-2026 groundbreaking, and the CEC permit sets a deadline to begin construction by December 2030 unless an extension is granted.
- The project has grid interconnection, EPC contracts and union agreements in place, and it will tie into SCE’s Whirlwind Substation via a new 230‑kV, 19‑mile transmission line serving an 89‑acre site in Kern County.
- Financing steps include a conditional U.S. DOE loan guarantee of up to US$1.76 billion and US$200 million in commitments from Canada Growth Fund, Goldman Sachs and CPPIB, with the project cost reported at about US$1.5 billion.
- Hydrostor is finalizing offtake agreements, building on a 200 MW PPA signed with Central Coast Community Energy in 2022 that has since been slated for amendments and schedule adjustments in 2025.