Last month, a Spanish company opened a solar power plant in the Nevada desert that produces more power than any other solar installation in the country. But this 47-mile array is special for another reason: Instead of capturing the sun's light, it creates electricity from the sun's heat, at between a half to a third the cost of photovoltaic, or light-generated, energy. The arrays use mirrors to focus heat on fluid-filled pipes, which is funneled to a generator where it boils water into steam to power turbines. Scientists are working on making the systems even more efficient by experimenting with different fluids, such as molten salt, for the pipes.

Source: Matthew L. Wald, In the Desert, Harnessing the Power of the Sun by Capturing Heat Instead of Light. New York Times, July 16. Photo: Solar Two, a solar thermal power plant in Daggett, CA.