"It's great to see growth. It's finally happening. It was dead for a long time," said Shevenell, also a research hydrogeologist at the University of Nevada, Reno.

Paul Brophy, president of the Geothermal Research Council founded in 1970, said tens of thousands of acres of land under the supervision of the U.S. Bureau of Land Management have been leased for geothermal exploration and/or drilling. He has seen dramatic growth in interest from small and large investors — "even renewed interest from some large oil companies."

Gov. Jim Gibbons said 80 percent of the federal acres leased for geothermal projects in the nation are in Nevada, which issues an average of 60 drill permits annually for geothermal projects. That's why he is pressing state and U.S. officials to expedite the leasing process.

"When it takes eight to 13 months to get a geothermal drill permit approved and only 30 days to get an oil well drill approved, we have our work cut out for us," he said.

Yoram Bronicki, president of Reno-based geothermal developer Ormat Technologies, said the industry must do more to promote itself.

"I don't know if we have failed, but we certainly have not succeeded until now to capture the imagination of other people on the public relations level," he said. "Everybody else looks at the wind turbine as the staple of renewable energy."

Barry S. Andrews, senior vice president of Chevron Geothermal — the world's largest producer of geothermal energy, said it is a "critical time for us in the energy field."

"While geothermal has gotten more attention recently, it often seems to take a back seat to solar and wind," Andrews said. Chevron launched an international campaign to promote geothermal last year.

Dan Reicher, director of climate change for Google.org, said his company invested $10 million as part of a plan announced last year to develop "enhanced geothermal systems" technology to generate energy from rocks deep below the earth's surface.

"It is indeed the sleeping giant of renewable energy," said Reicher, a former assistant U.S. energy secretary. "Indeed, the giant is stirring."