Steve Lowe gazed into a gaping pit in the heart of the California desert, careful not to let the blistering wind send him toppling over the edge.

The pit was a bustling iron mine once, churning out ore that was shipped by rail to a nearby Kaiser Steel plant. When steel manufacturing declined, Los Angeles County tried to turn the abandoned mine into a massive landfill. Conservationists hope the area will someday become part of Joshua Tree National Park, which surrounds it on three sides.

With backing from NextEra Energy — the world’s largest operator of solar and wind farms — he’s working to fill two mining pits with billions of gallons of water, creating a gigantic “pumped storage” plant that he says would help California get more of its power from renewable sources, and less from fossil fuels.

Lowe’s project, known as Eagle Mountain, is no outlier. Across the country, companies are scrambling to build similar facilities to complement solar and wind farms.

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