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Squeezing Energy from A Rock

New geothermal approaches bring massive resources within reach.

Fortnightly Magazine - December 2008

single 280-kW module supplied by UTC, but Karl hopes it will grow to 20 MW as Quantum expands the Jay oil field.

Beyond resource locations where water naturally is present, another method of production involves enhanced geothermal system (EGS) technology, which involves pumping water into hot, dry rock to tap the energy potential. A landmark Massachusetts Institute of Technology study commissioned by the Department of Energy (DOE) concluded 100,000 MW of EGS capacity could be developed by 2050 in the United States, but the technology still is in development. “In 10 years EGS might come online, and the geothermal market could grow even faster,” Gawell says.

Mapping the Magma

One prerequisite to any geo-thermal project is knowing the parameters of the heat reservoir. With geographically limited, decades-old and spotty mapping of U.S. geothermal resources, developers can find it difficult to locate the most promising spot to drill. “One of the biggest problems in the industry is a lack of basic resource assessment. I wish someone knew what the U.S. geothermal potential was at 150 degrees,” says Gawell. “The DOE has done resource assessments for solar, wind and biomass, but it has almost refused to do geothermal because of statutory authority. The USGS used to do it, but now Interior has authority.” The net result is insufficient data in many regions.

“If you look at the best geothermal resource map we have now, Kentucky looks cold; but that’s because the number of data points we have in Kentucky is zero,” Gawell laments.

Among utilities charting geothermal reserve potential is Pineville, La.-based Cleco Corp., which recently entered into a cooperative research and development agreement with the U.S. Army Engineer Research & Development Center to study the potential for geothermal energy in Louisiana. “We don’t have an expectation for how much geothermal power we might be able to generate, or know yet how much we plan to spend to do it,” says Robbyn Cooper, a Cleco spokesperson. “We’re just being prudent in evaluating the resource.” While Louisiana has no RPS mandates now, the project could prove to help fill any future requirements, she notes.

Once resources are mapped adequately, that information will be combined with data about accessible transmission capacity to identify the best potential sites for geothermal development. BLM already has conducted some of this work, but more progress is needed. Toward that end, the California Geothermal Energy Collaborative, supported by the California Energy Commission, is trying to pull disparate sources together to yield a new generation geothermal database map of California, which then could be used as a template for other states and regions.

“For a developer to get financing, he has to go to the backer and say, ‘Here is the resource and this is its magnitude,’” he says. “Transmission line location also will be an integral part of it. We’re hoping to have one region of California complete by 2009.”

Such efforts are expected to support geothermal development by better quantifying its potential—particularly for utilities facing RPS requirements. Plus, investments in U.S. geothermal energy might become more popular among non-energy companies