As prices rise for fossil fuels and worries grow about their contribution to global warming, solar thermal plants are being viewed as a renewable power source with huge potential.

The technology involves covering acres of desert with mirrors that focus intense sunlight on a fluid, heating it enough to make steam. The steam turns a turbine and generates electricity. Some experts say that solar thermal plants could meet most of the galloping growth in power demand in Phoenix, Las Vegas and the rest of the southwestern United States.