The Energy Debates: Solar Farms

By Charles Q. Choi, Special to LiveScience
posted: 08 December 2008 08:25 am ET

Editor's Note: "The Energy Debates" is a LiveScience series about the pros, cons, policy debates, myths and facts related to various alternative energy ideas. We invite you to join the debate by commenting directly on each article.

The Facts

The amount of energy from the sun that falls on Earth is staggering. Averaged over the entire surface of the planet, roughly each square yard collects nearly as much energy each year as you’d get from burning a barrel of oil. Solar farms seek to harness this energy for megawatts of power.

There are two ways solar power is used to generate electricity. Solar thermal plants — also known as concentrating solar power systems — focus sunlight with mirrors, heating water and producing steam that drives electric turbines, while photovoltaic cells directly convert sunlight to electricity.

Altogether, solar currently makes up less than 1 percent of U.S. energy, according to the Solar Energy Industries Association. The nation now has just two large-scale solar thermal systems — one 354-megawatt set of facilities has run continuously in the Mojave Desert in California for about 20 years, and another 64-megawatt plant came online in Nevada last year. When it comes to solar photovoltaics, the largest system in the nation so far is the 14-megawatt plant at Nellis Air Force Base in Nevada.