When the world’s largest solar thermal power plant—in Ivanpah, California—opened earlier this year, it was greeted with skepticism. The power plant is undeniably impressive. A collection of 300,000 mirrors, each the size of a garage door, focus sunlight on three 140-meter towers, generating high temperatures. That heat produces steam that drives the same kind of turbines used in fossil-fuel power plants. That heat can be stored (such as by heating up molten salts) and used when the sun goes down far more cheaply than it costs to store electricity in batteries (see “World’s Largest Solar Thermal Power Delivers Power for the First Time”).
But many experts—even some who invested in the plant—say it might be the last of its kind. David Crane, CEO of NRG Energy, one of three companies, including BrightSource Energy and Google, that funded the plant, says the economics looked good when the plant was first proposed six years ago. Since then, the price of conventional photovoltaic solar panels has plummeted. “Now we’re banking on solar photovoltaics,” he told a crowd of researchers and entrepreneurs at a conference earlier this year.
The allure of solar thermal technology is simple. Unlike conventional solar panels, it can generate power even when the sun isn’t shining. But in practice, it’s far more expensive than both fossil fuel power and electricity from solar panels. And that reality has sent researchers scrambling to find ways to make the technology more competitive. . . .