“High above the sand and sagebrush of southeastern California, a transmission line runs along Interstate 10, connecting solar farms in the Sonoran Desert to Los Angeles. From daybreak to nightfall, that line crackles with electricity as photovoltaic panels soak up the sun. It goes quiet just as millions of people turn on their lights.

When the sun sets, that line goes empty,” said Steve Lowe, president of Eagle Crest Energy Co. “We want to do something about it.”

Eagle Crest is partnering with NextEra Energy, Inc., the U.S.’s biggest clean energy developer, to build a 1.3 gigawatt, pumped-hydro facility near a sun-baked crossroads named Desert Center. The $2 billion project, already approved by federal regulators, could stockpile enough electricity to power nearly 1 million homes.

It will utilize two pits left over from a defunct iron-ore mine dug into the side of a mountain. During the day—when solar power floods the grid—pumps will move water to the upper pit, ready for release at night. Lowe estimates it will take six years to build.”

Read more: Bloomberg | May 24, 2017