by Kimberly N. Chase
- USA -
In an unmarked meadow by the side of the road at The Geysers, the 30-square-mile steam field about 70 miles north of San Francisco, California, the air smells like sulfur. Clouds of steam drift up from fumaroles, or open holes of rapidly boiling brown water, and waft across the landscape carrying the smell of rotten eggs.
These well-hidden hot springs offer an excellent way to comprehend the massive strength of the energy that lies just below the Earth’s surface. Located on the Pacific’s Ring of Fire and over the fault between the Pacific and North American tectonic plates, here the Earth’s latent heat bubbles up from beneath California’s earthly crust - a perfect place for a power plant.
Funding for geothermal development has been scarce in recent years, but Obama’s stimulus plan has dedicated $380 million to the renewable source. Research groups from companies, universities and national labs are now able to apply for funding from the Department of Energy (DOE) and get to work on the tough challenges that stand between the light switch in the kitchen and the energy inside the Earth’s core.
“It is our hope that the government investment in awards with the Recovery Act funding will be a catalyst that moves the technology forward enough that the financial community and venture capitalists embrace geothermal and other renewables and move them into mainstream,” says Ed Wall, Geothermal Technologies Program Manager at the DOE.
Geothermal energy now generates more than 3,100 megawatts of energy in the U.S., and experts estimate up to 6,400 megawatts of new geothermal power plant capacity under development in 12 states. The DOE hopes that R&D success will result in a total of 100,000 megawatts available by 2050, or enough to power 40 million homes, Wall says.
“We think the teams that come together around these financial opportunity announcements are the teams that can significantly move it forward,” Wall adds.
At The Geysers, the most active geothermal field in the country, ground water is heated by hot rock deep beneath the surface, creating a natural bed of steam under extremely high pressure. Calpine, the biggest geothermal producer in North America, pipes the steam to 15 plants where it turns turbines and generates electricity.
Because it runs 24/7, The Geysers is an important source of base-load, or constant intensity power, for the region. Its plentiful steam is an iconic example of traditional geothermal power, which extracts heat from existing steam beds. But its natural hydration is waning, and Calpine is already injecting wastewater from nearby Santa Rosa into the hot rock to produce more steam.
While the U.S. Geological Survey estimates there are 30,000 MW of undiscovered hydrothermal resources in the US, far more potential lies in the hot dry rock miles below the surface.
Traditional geothermal energy of the variety Calpine produces is likely to be surpassed in the next decade by enhanced geothermal systems, or EGS – a set of new techniques that will allow the extraction of energy from far deeper inside the Earth’s crust. Injected into the thermal area, the water or gas heats up as it passes through the fractures in the rock, then comes up and out of other nearby holes in order to be extracted and generate power. Where water is scarce, researchers are looking at the use of carbon dioxide to convey heat to the surface, with carbon sequestration as a secondary benefit.
Many technical hurdles remain until EGS reaches its full potential, but researchers are striving to find new ways to mine heat in areas that don’t have easily accessible thermal resources. “We’re looking for reservoir creation techniques in different geologic formations and in different environments than have been attempted before,” Wall says.
A 2007 MIT report highlights geothermal as a potentially substantial power source since the energy can be found below the surface in most of the U.S. Heat is more accessible in the West, where it can be found just 5,000 feet below the surface, whereas drilling would have to be much deeper in Eastern areas.
The government funded extensive research in geothermal energy in the 1970s and early 1980s, but when oil prices fell, so did market enthusiasm, leading research on renewables to stagnate. Today, concerns about climate change and energy security are bringing it back to the table.
Funding for geothermal energy from the DOE increased from $19.3 million in FY 2008 to $42 million in 2009 and $44 million in 2010. But the bigger difference is more likely to come from the considerably larger allotment in stimulus funding.
Funding from the American Recovery and Reinvestment Act stimulus awarded in October 2009 includes $98.1 million for 24 projects using innovative exploration to find new hydrothermal resources, $20.7 million for 11 projects in low temperature, co-produced and geopressured geothermal production, $51.4 million for the demonstration of EGS in different geological environments, $105.2 million for research and development of new EGS technologies, and $33.7 million for five projects in international geothermal data, developments, collections and maintenance.
“It probably is enough as long as it doesn’t stop there,” says Earth Sciences professor Roland Horne of Stanford University.
Understandably, drilling miles into the ground comes with significant challenges. For EGS to work, companies must improve drilling technology and reduce its cost, then learn to increase the permeability of the rock miles below the surface in order to create a reservoir of heat stored in hot water and steam. But drilling can cost millions, and there is no guarantee that the creation of a reservoir will be successful.
“We know how to drill a hole; what we don’t know how to do is drill a hole cheaply,” says Doug Blankenship, Geothermal Research Manager at the Sandia National Laboratory.
In addition to the cost of generating the energy, transmission of power from the plant to the end user is a challenge because geothermal resources are often in remote areas. And like wind and solar, geothermal lends itself to placement in areas where much of the land is government-owned.
“Federal land policies that encourage leases to be made available for geothermal development can be very important,” says Donna Attanasio, a Washington, D.C.-based lawyer specializing in energy markets and regulatory law. The Department of the Interior, Bureau of Land Management has sought in recent years to make it easier for developers of renewable resources to use its lands, she explains.
Another important aspect of geothermal energy is the ability to use it on a smaller scale to take advantage of the earth’s ambient temperature of about 60 degrees. The American Recovery and Reinvestment Act includes $61.9 million for the demonstration of ground source heat pumps, which use the ground temperature to make heating and cooling more efficient and are especially applicable to large buildings like academic institutions, local government offices and commercial buildings.
“They are significantly more energy efficient and they have significantly less impact on the environment than conventional systems,” says Michael Lucas, partner at Alfa Tech Cambridge, a project and construction management company with offices in San Francisco. Lucas worked on the new campus of Ohlone College in Newark, CA, a LEED Platinum-certified building that uses a ground source heat pump. But EGS is still the holy grail of geothermal energy.
“That’s the home run,” Wall says. The rest of the world agrees - European EGS projects can be found in Soultz-sous-Forets, France and Landau, Germany.
There are more than twenty EGS projects in Australia, which has never used traditional geothermal and is jumping straight into hot, dry rock. In the last few years, several new companies proposing to use EGS have sprung up in the U.S., including AltaRock, which won funding from Google. AltaRock's project at The Geysers was recently canceled because of complications due to the rock formations in the drilling path and concerns about seismic risk.
“People are going to be watching very carefully as the first few projects get started,” says Stanford Professor Roland Horne. “I think the challenge will be to stick with it through the early problems that are likely to occur, because it’s a new technology.”
About the Author
Kimberly N. Chase is a freelance journalist specializing in environmental features for print and television. She graduated in 2005 from Stanford's MA program in journalism and worked as a crime reporter in California before spending two years in Mexico City. She is now enjoying working on some of the same issues stateside.