Geothermal energy company Ormat Technologies recently acquired full ownership of a Guatemalan power plant -- the latest in a long list of the company's holdings in the Western United States and around the world. Since the beginning of the year, the company has announced several new deals, a sign that this form of alternative energy is experiencing a revival.
Geothermal energy uses the heat under the Earth's surface, usually in the form of hot water or steam, to power turbines above the earth's surface. The process is much like solar thermal energy, but the source of the heat is the main difference.
The exploration process for this subterranean heat is very similar to the techniques used in the oil and gas industry, according to Hezy Ram, Ormat Technologies' executive vice president for business development.
Since oil companies are obligated to share geological data with the U.S. Geological Service, he said, geothermal companies like Ormat can take advantage of the work the oil industry has already done to identify sources of geothermal energy.
"Most of the time, there is what we call a 'surface manifestation,'" Ram said; for example, a melted area in an otherwise snow-covered surface.
Once the company identifies a heat "well," it drills, extracts the super-heated water or steam, and then returns the cooled water back underground, where the heat of the earth's core reheats it, Ram explained.
"We reinject everything we take out ... as far as we can tell, these (sites) will last for perpetuity," he added.
The first geothermal plant, still in operation today, Ram said, was established in the Tuscany region of Italy in 1904.
"Modern direct-use projects (on the Tuscany site) have expanded to 1120 gigawatt hours per year," according to California's Geothermal Education Office, which also recounted ancient usage of the hot springs for baths. "The fumaroles at the Campi Flegrei near Naples are said to have been so impressive they became the model for Dante's Inferno," the office said via its Web site.
Geothermal energy has experienced somewhat of a revival in the past year thanks to the Energy Policy Act of 2005, according to Ted J. Clutter of the Geothermal Resources Council.
"A wave of geothermal power plants were built nationwide during the late 1980s and early 1990s, but interest cooled with rock-bottom prices for natural gas followed by utility deregulation that forced electric utilities to seek the lowest-cost power options," he wrote in a recent article for U.S. Energy Policy.
"With recent power shortages in the (Western United States), however, interest in geothermal power production resurged with ... (mandates) for utilities to provide a portion of their electricity from alternative power sources," Clutter said.
The Energy Policy Act of 2005 includes a Renewable Energy Production Tax Credit of 1.9 cents per kilowatt hour for geothermal plants that go online by the end of 2007, according to Clutter. This tax credit will be paid out to the qualifying facilities over a 10-year period from their "placed-in-service" date, Clutter wrote.
So what sets geothermal apart from other forms of alternative energy, such as solar and wind? For one thing, in comparison with solar energy, geothermal presents more attractive prices. Ram said Ormat recently signed a deal with the Southern California Edison utility to provide electricity at 6.2 cents per kilowatt hour for the next five to six years, and that an Ormat project in Nevada will produce electricity for between 5 cents and 6 cents per kilowatt hour.
Solar, on the other hand, can cost as much as 11 cents per kilowatt hour if not subsidized by state or local governments.
Furthermore, unlike with wind and solar power, geothermal plants are what Ram called a "24/7 facility." Geothermal production isn't limited only to daylight hours or windy days, meaning it can be a baseload source of power, available all the time, Ram said.
Solar and wind-powered facilities also can't control the voltage they produce, while "our plants never go down," Ram said.
"It think that's why geothermal is the alternative energy of choice for all utilities," he added.
Of course, geothermal is not likely to replace fossil fuels as a primary energy source, Ram said. "It would be pretentious to think that," he said. However, he continued, geothermal can make a substantial contribution to the world's efforts to reduce fossil fuel dependency.
California currently gets 5 percent of its energy from geothermal plants -- not an insignificant figure, considering the state's economy surpasses most countries in size, Ram said.
The Philippines get 15 percent of their energy from geothermal, the Big Island of Hawaii is 25 percent geothermal and Nevada cities like Reno and Sparks are "basically (completely) geothermal," he said.
"We and our competitors produce 3,000 megawatts of electricity per year," Ram said. "This number could be (doubled) or even tripled in years to come."
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