SCIENCE

Take a Look at the World’s Largest Solar Thermal Farm

When completed in 2013, this series of 170,000 mirrors will power 140,000 California homes

November 2012

When completed in late 2013, the $2.2 billion Ivanpah Solar Electric Generating System will power 140,000 California homes. Gilles Mingasson

The Mojave Desert is blooming. Construction crews are erecting mirrors —each measuring 70 square feet—at a rate of 500 per day across some 3,500 acres. When completed in late 2013, the $2.2 billion Ivanpah Solar Electric Generating System—the largest of its type in the world—will power 140,000 California homes.

Unlike photovoltaic technology, which converts solar radiation directly into electricity, the Ivanpah facility generates heat. More than 170,000 mirrors will gather tremendous amounts of sunlight and focus it on three towers filled with water, raising temperatures to more than 1,000 degrees Fahrenheit and producing steam that spins turbines that generate electricity. The Oakland-based company BrightSource Energy, which is overseeing construction by the Bechtel corporation, says that using sunlight instead of fossil fuels to power the turbines will reduce carbon emissions by more than 400,000 tons annually. The desert region—thanks to its elevation and clear, dry air—receives reliable sunlight 330 to 350 days per year.

Not everyone thinks the solar plant represents a brighter future. Environmentalists warn that the construction threatens the desert ecosystem, while the heated plumes of air from the towers could singe migrating birds.

But more than 75 percent of Californians say they support using desert lands for renewable energy production. And come next year, when Ivanpah flips the on switch, it will nearly double the amount of solar thermal energy produced in the United States.