Vincent Signorotti's power plant sits on the edge of the Salton Sea, surrounded by irrigated cropland in the middle of a scorched desert.

Beyond the lake, beyond the patch of green fields, the desert seems empty. But it holds all the energy Signorotti's plant will ever need. Energy that could play a key role in California's fight against global warming.

The plant runs on hot water, pumped from deep underground and flashed into steam to turn turbines. With 10 generators near the lakeshore, the facility produces enough electricity for 255,000 homes, and the company that owns it wants to expand. Other companies are drilling nearby, hoping to build their own geothermal plants.

"We're very lucky," said Signorotti, a vice president with CalEnergy Operating Corp., as he considered all the energy beneath his feet. "This is really the crown jewel of undeveloped renewable resources."