By Cheryl Katz | Grist

The twin smokestacks of the Moss Landing Power Plant tower over Monterey Bay. Visible for miles along this picturesque stretch of the Northern California coast, the 500-foot-tall pillars crown what was once California’s largest electric power station — a behemoth natural gas-fired generator. Today, as California steadily moves to decarbonize its economy, those stacks are idle and the plant is largely mothballed. Instead, the site is about to begin a new life as the world’s largest battery, storing excess energy when solar panels and wind farms are producing electricity and feeding it back into the grid when they’re not.

Inside a cavernous turbine building, a 300-megawatt lithium-ion battery is currently being readied for operation, with another 100-megawatt battery to come online in 2021. Together, they will be able to discharge enough electricity to power roughly 300,000 California homes for four hours during evenings, heatwaves, and other times when energy demand outstrips supply, according to project developer Vistra Energy.