Steamy industry may clear the air / Geothermal energy producers try to develop more plants -- and more public awareness
Published 4:00 am, Sunday, January 14, 2007
2007-01-14 04:00:00 PDT Lake County -- The hill beneath Gary Snedaker's feet hides steam, heated by the energy of the Earth and trapped by solid rock. Starting in March, he plans to let a little out to generate power.
The steam, buried some 9,000 feet deep, will shoot up a series of wells, flow into thick pipes winding through a pine forest, pour into a turbine at 325 degrees and set the turbine's blades racing.
The Bottle Rock geothermal power plant will reopen this year after sitting dormant since 1990. The steam buried beneath this hill south of Clear Lake, on the edge of the Geysers geothermal field, will generate 20 megawatts of electricity at first, enough to power 15,000 homes. Snedaker, in charge of reviving the plant, says it could someday produce 50 megawatts.
Geothermal energy, which generates electricity from the Earth's natural heat, already supplies 5 percent of California's power. Government studies suggest the state could double its geothermal output in 10 years, using only the steam fields already discovered. More may lie hidden beneath mountains and deserts.
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Geothermal plants produce just a fraction of the greenhouse gases spewed by power plants burning coal. They also emit far less than plants using natural gas, considered a "clean" fossil fuel. And yet when policymakers talk about increasing reliance on renewable energy, they rarely mention geothermal power. It has been around for years and uses proven technology, but it remains something of an orphan in the renewable world.
"Everybody knows what a wind turbine is," said Snedaker, who is renovating the plant for its owner, US Renewables Group, a privately held company that buys renewable energy assets. "Everybody knows what a solar cell is. Even hydroelectric dams. People don't know what geothermal is."
California's small geothermal industry hopes to change that. Regulations now require that the state derive 20 percent of its electricity from renewable power sources by 2010. Geothermal plants can generate power levels comparable to conventional plants. Although they are expensive to build, their fuel is free.
And unlike solar cells or wind turbines, they run day and night in any weather.
"Solar's great," Snedaker said. "You should stick it on the roof of everyone who wants it. But you still need power at night."
Like any kind of energy, geothermal has its drawbacks.
It is not portable. The conditions needed for a geothermal plant exist only in specific places. And many of those places lie in relatively pristine landscapes whose few inhabitants don't always welcome power plants and transmission lines.
Most geothermal plants emit traces of toxic hydrogen sulfide gas, with its telltale rotten egg odor, although most of the sulfur can be removed with the proper technology. The hot water welling up from underground often contains small amounts of arsenic, nickel and silicates that build up within pipes and turbines and eventually must be sent to a landfill. And reinjecting the water underground, a step necessary to maintain power levels, can trigger frequent small earthquakes, depending on the location.
But given the looming threat of global warming, many environmentalists say geothermal energy can't be ignored. A typical geothermal plant produces just 5 percent as much carbon dioxide as a natural gas plant, 3 percent of a coal plant.
"Every form of electricity production has environmental impacts, but geothermal has magnitudes less than fossil fuel," said Sheryl Carter, director of the western energy program at the Natural Resources Defense Council.
California generates about 1,900 megawatts of geothermal power, enough to run 1.4 million homes. A report last year by the Western Governors' Association estimated the state could add 2,400 megawatts using existing technology and known geothermal fields. Other projections have been higher, with the California Energy Commission estimating 4,000 megawatts waiting to be tapped.
Those megawatts lie in areas with subterranean sources of steam or hot water. Some geothermal plants siphon steam from the ground and run it through a turbine to produce electricity. Others bring hot water from the ground, reduce the air pressure to convert the water to steam, then put it through a turbine. Future "hot dry rock" plants may inject water into hot underground areas that lack it, producing steam.
At the Geysers, the underground resource is steam.
The steam field, the largest discovered in America, lies beneath steep, forested hills at the border of Lake and Sonoma counties. The country's first geothermal plant started here in 1921, using its meager 250 kilowatts to power a resort and spa. But it soon ceased operations. Serious efforts to exploit the steam field's energy didn't get under way until the 1960s.
Power output passed 2,000 megawatts in 1989 but soon started to decline. The companies drilling into the field hadn't coordinated efforts and they tapped the same sources of steam, allowing pressure to decrease. What's more, they were re-injecting only about 20 percent of the condensed steam back into the ground, said Dennis Gilles, senior vice president for geothermal operations at Calpine Corp.
"That was drying out the teakettle," Gilles said.
Through the late 1990s, San Jose's Calpine started buying out the other companies working the Geysers, including Pacific Gas and Electric Co. and Unocal. Calpine runs 19 of the field's 21 facilities, spread over 30 square miles. To maintain pressure, Calpine brings in treated wastewater from Santa Rosa and Lake County, pumping 19 million gallons into the ground each day. The field now generates about 900 megawatts, Gilles said.
The Bottle Rock plant that U.S. Renewables has spent the last year renovating was built during the Geysers' 1980s heyday. But there, too, power output quickly declined. Built to generate 55 megawatts of electricity, the plant was producing 12 megawatts when its owner, the California Department of Water Resources, closed it in 1990.
It had run for just five years.
"There was still steam in the ground, but they would have had to drill for it and drilling is expensive," Snedaker said. "They lost money the entire time."
While too much drilling can lower steam production at a site, so can too little. Much like oil fields, geothermal fields require wells to be drilled over time to tap more pockets of steam or hot water. Drilling costs about $20,000 per day, Snedaker said. And that's if you can find a rig that isn't already working on an oil or natural gas well somewhere.
Managed properly, the Geysers should be able to continue producing electricity for the foreseeable future, Snedaker said.
"I can't see a day when the Geysers (field) isn't producing steam out of the ground," he said.
Still, the drilling necessary to tap and maintain a geothermal field troubles some people.
Calpine has for years wanted to build two geothermal plants near Medicine Lake, northeast of Mount Shasta. But those plans have been staunchly -- and so far successfully -- opposed by some local American Indian tribes.
They consider the area sacred and the thought of power plants there an insult. They also worry that wells could contaminate the local aquifer, which sits far above the hot, subterranean water the power plants would use.
"We're sacrificing one landscape after another to our rapacious needs," said Michelle Berditschevsky, environmental coordinator for the Pit River Tribe.
She doesn't consider geothermal energy a true renewable resource, since it requires water injection to maintain production. Rather, she views it as an extractive industry -- much like oil or natural gas -- that can harm the environment.
"It's not really an ecological industry," Berditschevsky said. "It's hard on air quality, on habitats."
Gilles said the wells, sheathed in concrete and metal, would not taint the ground water. Although the two proposed plants would together produce about 100 megawatts of power, the area could eventually generate another 400, he said.
"It's a sizable resource," he said.
Why hasn't geothermal power attracted the same attention recently lavished on solar power or wind? When natural gas and oil prices were low, geothermal appeared expensive and unnecessary. Now, when averaged over the lifespan of a plant, geothermal power prices can be competitive with other forms of electrical generation, according to California state figures.
Some within the industry also blame the lack of attention on geothermal power's location. Most all of the known geothermal resources are in the western continental states, Alaska and Hawaii, meaning politicians and entrepreneurs elsewhere don't have a reason to be interested.
"The potential, of course, is limited to the places where the resource exists," said Carter, with the Natural Resources Defense Council. "Perhaps that's why it's overlooked."