New way of storing energy, with underground water columns and compressed air, to be tested in coastal California

Rendering shows surface installations at Hydrostor's planned
compressed-air storage project. (Image from Hydrostar)

Several local governments in California have agreed to "buy power from what would be the world’s largest compressed-air energy storage project," reports Sammy Roth of the Los Angeles Times. "The innovative technology could help California — and other states and nations — transition from planet-warming fossil fuels to renewable energy, without causing blackouts."

Roth explains the process: "The developer, Hydrostor, will drill three shafts thousands of feet below ground, and send down miners to dig out a series of rows and columns. When the project is ready to go in 2028, the underground caverns will have a collective volume equivalent to two football fields about 100 yards high. . . . When electricity is cheap — such as sunny afternoons when California has more solar power than it needs — Hydrostor will use that low-cost energy to push air down into the caverns. . . . When Hydrostor’s customer, Central Coast Community Energy, needs to draw on the stored power — on a cloudy January day, for instance — the company will open a valve and funnel the high-pressure air through a turbine, generating electricity."

Robert Shaw, chief operating officer of CCCE, told Roth, “This new technology is a critical component of that. That’s how we get to 100 percent renewables.” It remains to be proven, but Aaron Marks, a senior analyst at energy research firm Wood Mackenzie, told Roth, "That’s not a strike against the technology.” Also, the project needs a permit from the California Energy Commission, and Defenders of Wildlife says it "could significantly impact several special-status species," including the burrowing owl, desert tortoise, Swainson’s hawk and the Joshua tree," Roth reports. "When asked about environmental concerns, Hydrostor told Roth in an an email that "recent habitat surveys will 'allow for further review by the dedicated agencies,' and that the company 'has a rigorous biological survey program planned for spring and summer 2023.'"

CCCE is "a government-run 'community choice' agency that supplies electricity to 450,000 homes and businesses in five counties, saw advantages to the technology: "Unlike lithium-ion batteries, which degrade over time and must be replaced, compressed air caverns can bank power for decades without loss of efficiency. They can also supply the grid for longer than a four-hour battery. The 200 megawatts under contract to Central Coast — part of Hydrostor’s 500-megawatt project — will provide eight hours of backup power."