Donna Charpied remembers a day last February, when she and her husband, Larry, visited entrepreneur Arthur Lowe in his Palm Desert, Calif., office to talk about renewable energy projects proposed for the Mojave Desert. The Charpieds farm jojoba near the town of Desert Center, southeast of Joshua Tree National Park, and Lowe had long been their ally in the fight against a landfill on the park's southern boundary at Eagle Mountain, where two open pits remain from an old mining operation. But Lowe had a plan of his own for those pits: A system of reservoirs and turbines that could help integrate renewable energy into the electrical grid.

"We told him, 'We love you, but we hate your project,' " Charpied says. And then Lowe showed the Charpieds the map he had brought them over to see: A lease was pending for a seven-acre solar plant right next to their property. "He said, 'Jesus — that's your place right there, and they're going to build right on top of it!' "

Lowe died shortly after that meeting, at 72. But the $1.4 billion Eagle Mountain Pumped Hydroelectric Storage project he'd shepherded since 1990 may have a brighter future than ever. An optimistic U.S. Department of Energy report proposes ramping up wind power from 30 gigawatts to 300 by 2030; another predicts adding nearly a gigawatt of solar. All of that energy is what grid managers call "intermittent" — you can't always predict when you're going to get it, or how much you're going to get. To balance an unpredictable supply with demand, grid operators need to store that energy so they can deploy it when people need it most.

Pumped hydro is one way to do that. At night, when the wind spins turbines in Wyoming but Nevada's air conditioners are quiet, pumped hydro can pull amps off the grid and use them to hoist water from one reservoir to another, 500 to 1,500 feet up. On the next hot, calm afternoon, the water cascades down again, spinning a turbine and generating electricity just as it's been done since Westinghouse harnessed Niagara Falls at the end of the 19th century.

Some gets lost along the way; the 40 pumped-hydro plants currently operating in the U.S. generate 70 to 80 percent as much electricity as they use. "You tell people about it and they say, 'That's crazy! It doesn't make any sense!' " says Steve Lowe, who took over as president of the Eagle Crest Energy Co. after his father's death. But since all that off-peak energy would go to waste, "it's better to capture 80 percent of it than to continue throwing it all away."

Other storage methods exist in various stages: Special batteries can store a few megawatts; compressed-air storage can bank hundreds. But pumped hydro is "the oldest and the cheapest," says Lowe, and the most flexible and powerful, capable of caching up to 1,500 megawatts for use at any time.

The Federal Energy Regulatory Commission (FERC) has license applications or letters of intent pending for roughly 40 more plants, the majority in the West, where the need to balance wildly fluctuating, gigawatt-sized wind resources is most urgent. Lowe was converted when he learned that pumped hydro could replace expensive gas-burning "peaker" plants that use ocean water for cooling and send coastal air-quality plummeting.

Yet pumped hydro is hardly environ-mentally benign, and as with wind and solar power, it's prompted some battles. An 800-megawatt pumped storage project in Grand County, Utah, has attracted the ire of the Southern Utah Wilderness Alliance, even though the utility, Utah Independent Power, only has a license to study the site. In southeastern Oregon, public opposition to pumped hydro at pristine Lake Abert moved an Idaho company to drop the project last June.

Conservationists like Charpied worry about losing wilderness to the projects and their new transmission towers. But mostly they worry about water: Filling the two Eagle Mountain reservoirs, for example, will require 8,000 acre-feet, or 2.6 billion gallons, of groundwater every year for three years — a significant strain on a desert aquifer that yields, at best, 12,000 acre-feet per year.

And while in some ways the site is ideal — not least because it exploits the scar left behind by Kaiser Steel, which mined iron ore there until 1982 — Eagle Mountain provokes the same conflicts that have stalled Kaiser Mine Reclamation Co.'s plan to dump 20,000 tons of Los Angeles County's trash in those pits. In an August letter to FERC, Kaiser's lawyers detailed the many ways in which the pumped-hydro project could degrade habitat for desert tortoise, desert bighorn sheep and migratory birds — the very creatures that mired Kaiser's landfill in lawsuits. 

There is, of course, a difference between a garbage dump and a project that could help transition the country off fossil-fueled electricity, sacrificing a small local habitat for our global one. Charpied, however, is not convinced. "It's a mosquito bite on the ass of a rhinoceros," she says. "All this renewable energy in the desert is going to have just about that much of an effect."

Judith Lewis is an HCN contributing editor and writes from Venice, California.