A newly discovered deep geothermal hotspot in Utah is generating excitement – but whether it ever generates much electricity is another matter entirely.
Utility-scale geothermal has grown in recent years in the United States, but not nearly as fast as other renewable sources, like wind and solar. A U.S. Energy Information Administration report in November 2011 found that over the previous three years, wind power production increased 121 percent and solar grew 111 percent. Geothermal’s 10 percent gain paled in comparison.
There’s an irony to this relative failure of geothermal: Unlike solar and wind, it can provide steady baseload power that can be easily integrated into the grid without some of the same challenges that come with intermittent sources like solar and wind. According to the EIA, a number of issue have nevertheless stood in the way of geothermal assuming a larger role:
- Location. Geothermal plants can be very site-specific, and have generally been limited to areas with accessible deposits of high temperature ground water.
- Transmission access. Lack of access to transmission lines, especially in western states where the geothermal resources are highest, limits growth.
- Completion lead times. Completing a geothermal power generating project takes four to eight years, longer than completion timelines for solar or wind.
- Risk. Even in well-characterized resource areas, there is significant exploration and production risk, which can result in high development costs. Development is often undertaken incrementally at a site to mitigate this risk and control costs.
Still, despite its challenges and limitations, scientists in Utah are hopeful that the discovery of a vast geothermal resource deep under the Black Rock Desert basin south of Delta will actually lead to new power generation.
The first thing that gives them hope is the quality and quantity of the resource. They say:
Using the drilling results, a reservoir modeling team at the University of Utah estimates a basin-wide power density of about 3 to 10 MWe/km2 (megawatts of power per square kilometer), depending on reservoir temperature and permeability. Given the large area of this basin, the power potential is conservatively estimated to be hundreds of megawatts, and preliminary economic modeling suggests a cost of electricity of about 10c per kilowatt-hour over the life of a geothermal power project.
Further, one of the hurdles the EIA cites as common to geothermal, a lack of access to transmission lines, might not be a big issue with this discovery. According to the Utah scientists, the Black Rock Desert basin “is especially attractive for geothermal development because of the existing nearby infrastructure ─ it is next to a large coal-fired power plant, a 300 MWe wind farm, and a major electrical transmission line to California.”
And make no mistake, this would be a very green source of energy: “The modeling assumes air-cooled binary power generation with all produced water injected back to the reservoir so that there would be no emissions or consumption of water.”
In undertaking the Black Rock Desert basin study, the researchers, from the Utah Geological Survey, knew that oil exploration decades ago had found very hot temperatures 3 kilometers below the surface.
To find out how extensive that underground reservoir might be, the researchers in 2011 and this year drilled nine temperature gradient holes up to nearly 1,000 feet deep around the basin, “testing a concept that geothermal resources might exist beneath young sedimentary basins.” The temperature gradient data was impressive, implying temperatures of 150-200 C (300-500 F) at depths of 3-4 km (10,000-13,000 feet) beneath the basin.
And there might be more of this sort of thing hidden underground in the West.
“There are other potentially hot basins across the Basin and Range province that need to be investigated using this exploration model,” Rick Allis, UGS Director and joint lead scientist of the sedimentary basin geothermal research project, said in a statement. “We have identified the Steptoe Valley and Mary’s River-Toano basins in northeast Nevada as obvious geothermal targets. There may also be hot basins across the western U.S. that have similar unrecognized geothermal energy potential.”
What might it take to exploit these great geothermal resources? Like all renewables trying to gain ground against well established and historically supported fossil fuel industries, the geothermal industry says it needs help.
The Geothermal Energy Association reported earlier this year that while U.S. government policy has helped foster geothermal projects abroad, thanks to programs created by the U.S. Trade and Development Agency, U.S. Agency for International Development and the Export-Import Bank of the United States, domestically the uncertainty about the ending of federal tax credits for renewable energy was stifling growth.
“It is encouraging to see such widespread geothermal growth, as this baseload energy source has the potential to replace coal and other non-renewable power sources in countries around the world,” said Karl Gawell, executive dDirector of industry group. ”Worldwide, national policies are propelling growth in the strongest markets, but growth in the United States is still hindered by uncertainty about the direction of government policy.”
“Federal tax credits for geothermal in the U.S expire at the end of 2013, making it difficult for many projects with long lead times to move forward in this unpredictable economic climate,” Gawell went on. “The way to ensure constant and steady industry growth domestically is for Washington to extend renewable energy tax incentives and promote policies consistent with industry needs for sustained growth and technology advancement.”