Clean power was on the rise in the U.S., even before President Obama’s carbon rules aimed to accelerate the trend

Jay Owen Resource Efficiency

Kevin Smith has spent his career building power plants, but the billion-dollar Crescent Dunes complex he’s completing in the high desert halfway between Las Vegas and Reno, Nev., is no ordinary power plant. “This is the cold tank,” Smith says, pointing at a massive steel silo that will hold 70 million lb. of 550°F molten salt. “Not really cold,” he blandly observes.

It’s a comparative thing. Crescent Dunes is a solar thermal plant, powered by 360,000 mirrors that look like a vast glass crop circle carved into a lonely landscape of sagebrush and tumbleweed. The mirrors will redirect the sun’s rays to heat the salt up to 1,050°F, temperatures so extreme that the plant had to be designed by rocket …