As the geothermal industry seeks approval for hundreds of new projects in the West, it brings with it a promise most wind and solar developers have been unable to make: more power using less land.
Geothermal plants use wells to pump searing hot steam and water to the surface in order to drive turbines that generate electricity.
But unlike wind and solar farms that threaten to carve up vast areas of public lands -- potentially compromising sensitive species and disrupting picturesque landscapes -- most of the geothermal energy footprint is hidden miles underground.
"Out of the renewable technologies, geothermal is a very compact way to generate energy," said Robert McDonald, a scientist with the Nature Conservancy's Emerging Strategies Division. "But it is one that's often missed in the discussion of renewables."
A McDonald-led study released last summer found that future geothermal developments will be less than half as land-intensive as solar thermal plants and about one-tenth as land-intensive as wind farms.
In addition, "binary cycle" designs used in most new geothermal plants utilize air cooling technologies to condense and recycle water withdrawn from underground reservoirs, alleviating fears about depletion of water resources.
"Water is always a concern in the West," said Charles Benjamin, director of the Nevada office for the environmental group Western Resource Advocates. "But the [geothermal] industry has been successfully developing projects since the 1980s and has been doing it in an environmentally sensitive way."
Striking the right balance
Indeed, one of the challenges to implementing a new energy policy built around renewable resources is that harnessing wind, solar and biomass requires large amounts of land, according to McDonald's study.
Coal-fired and nuclear power, while carrying their own environmental risks, typically use less land over their lifetimes than renewables, with the exception of geothermal.
Yet even if coal- and gas-fired electricity remain part of the U.S. power supply, at least 50 million acres of new land is expected to be consumed to meet rising energy needs by 2030. Meeting that demand without adding significant amounts of carbon dioxide to the atmosphere will take a mix of aggressive energy efficiency measures and the careful siting of renewable energy, McDonald said.
Much of the responsibility for planning and siting such projects will fall to federal agencies like the Bureau of Land Management and Forest Service, which together oversee several hundred million acres of public lands.
But while BLM works to clear an ever-expanding number of renewable energy projects, especially in the West, some fear regulators will overlook threats to sensitive landscapes and species that inhabit them.
"There is no dispute that we need to transition off of fossil fuels," said Ileene Anderson, the public lands desert director for the Center for Biological Diversity in a recent op-ed in the New York Times. "But renewable energy projects can be even more land-intensive than the fossil fuel projects they replace."
Ace in the hole?
In Nevada, land and water conservation was a big selling point during the fast-track permitting of the Blue Mountain geothermal plant in the northwest part of the state, said Paul Mitchell, a manager of investor relations at Nevada Geothermal Power Inc.
"There's minimal impact," Mitchell said of the 50-megawatt plant that occupies about 640 acres of BLM land. By contrast, the 150-megawatt Spring Valley Wind project under development in eastern Nevada would take up more than 8,000 acres.
And Blue Mountain's environmental credentials helped qualify it for a $57.9 million federal stimulus grant -- the first geothermal project to receive such an award -- after coming online four months ahead of schedule in October.
A portion of the plant's output is used to recycle the water it pumps out of the ground to be condensed and reinjected into the reservoir, Mitchell said.
"It's a cyclical system," he said of the plant's binary cycle design. "What we bring up, we put back down."
Of all of the fast-tracked renewable projects under review at BLM, Blue Mountain was the only one that did not require a full environmental impact statement, said Ray Brady, manager of BLM's energy policy team in Washington, D.C.
But while small compared to wind farms and solar arrays, some geothermal projects beyond the remote Nevada desert have faced opposition from local residents and conservation groups concerned about the technology's safety record and visual impacts.
A geothermal project in central Oregon, for example, has drawn the ire of some environmentalists because of its proximity to the Newberry National Volcanic Monument and its potential impacts to area groundwater.
The $86 million project by AltaRock Energy Inc., which includes Davenport Power LLC and several universities as partners, is supported by a $25 million stimulus grant from the Energy Department and will seek to demonstrate what are known as "enhanced geothermal systems," or EGS.
"There are places in Oregon where that is appropriate," said Asante Riverwind, forest organizer for the Sierra Club's Eastern Oregon chapter. "But right on the edge of the Newberry Monument is not the right place to try an experimental technology."
Riverwind said he is concerned that successful commercialization of the AltaRock project could attract several more developers to the Newberry area hoping to tap the volcano's heat.
A separate EGS project by AltaRock in Northern California generated fears among area residents that the technology could generate small earthquakes, though the DOE-funded project was discontinued before operators could begin fracturing the rock.
Similarities between the AltaRock project and an EGS demonstration in Switzerland that caused damaging tremors prompted DOE and BLM officials to conduct a separate safety review of its seismic potential.
Long a fledgling industry compared to other renewable sectors like wind and hydropower, the geothermal industry is poised to expand in 2010, in part because of major new government incentives and growing interest among investors.
"Things have been difficult for many of the renewable technologies, but we're seeing growth," said Karl Gawell, executive director of the Geothermal Energy Association, during a presentation to investors last week in New York City.
The industry added 178 megawatts of capacity in 2009, up from just 50 megawatts added the year before, he said. Currently, 144 geothermal plants are under development in the United States, many of which will utilize part of a $338 million Energy Department stimulus program announced in October.
And while U.S. geothermal plants currently produce just over 3,000 megawatts of electricity -- far less than the 28,200 megawatts of installed wind capacity and 9,183 megawatts of solar power -- Gawell noted that geothermal can operate around the clock, generating three times as much energy as its intermittent counterparts.
"I think five years from now, we're going to be in a totally different place," he said. "You're going to see an industry that reflects the type of sustained, dynamic growth that we see in the wind industry today. You're at the front end of the curve here."
But major challenges remain.
Obtaining financing for drilling projects, for example, remains difficult because of the inherent uncertainty surrounding geothermal finds. Exploration and drilling alone account for about half of a project's capital costs and such activities require their own permits, all of which adds risk for investors.
"One of the biggest risks in geothermal is confirming the resource," said Gawell, "not just whether it's there, but what is its character. If we're not sure whether we have [a] 10-megawatt or 100-megawatt resource, that sort of uncertainty is a huge problem."
A recent report from the Icelandic bank Islandsbanki estimates it would take $26 billion to fund all of the geothermal projects in the U.S. permitting pipeline. If built, those projects would represent a doubling of U.S. geothermal capacity over the next five years.
"The wind is at the back of geothermal, so to speak," said Paul Leggett, a vice president of investment banking at Morgan Stanley, citing both the government stimulus and rising favorability on Wall Street toward sustainable energy. "We see more and more of the pieces of this puzzle coming together."