It’s still an “if current plans work out” kind of story. But John Fialka of ClimateWire reports in Scientific American that by 2021, the second-largest city in America may have a futuristic climate-change-fighting source of electrical power. Southern California Edison Co. has chosen AES of Arlington, Va., to design a gigantic storage battery to hold and deliver backup electrical power to western areas of Los Angeles for times of peak demand — usually on midsummer afternoons, when air conditioners blast and people come home from work and turn on appliances.

The array, to be built in Long Beach, involves 18,000 lithium-ion battery modules, each as big as the ones that power the Nissan Leaf. The huge battery will be capable of holding and delivering 100 megawatts of power an hour for four hours. (One hundred MW is about a tenth of the power delivered by a nuclear power plant.) It will get that power overnight, when power is cheap, from traditional sources such as natural gas, and during the morning, from even cheaper solar sources.

“The technology seems mature,” Fialka writes. “AES has spent nine years working with manufacturers of electric-car batteries. It has learned how to assemble and control ever-bigger constellations of these lithium-ion batteries. . . . The parent company owns and operates power plants in 17 countries around the world.”

Unfortunately, the article notes, “the timing is terrible.” The Long Beach plant won’t be completed for five years — and Southern California already needs more power. Officials say there could be up to 14 days of scheduled blackouts this summer because of a leak earlier this year at a major storage facility for natural gas.