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  • Eli is a contributing correspondent for Science magazine.
 

Dude, That's Deep

23 January 2007 (All day)
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A big answer to U.S. energy woes lies far below the surface of the ground, according to a new Massachusetts Institute of Technology (MIT) report. The 2-year study found that a reasonable investment in geothermal energy research could eventually yield enough power to fuel 25 million homes.

Drilling to tap earthly heat, which arises from radioactive sources and convective heat from Earth's core and mantle, was seen in the 1970's as a solution to U.S. dependence on foreign energy sources. Today, however, the fledgling industry provides less than 1% of U.S. energy needs. In part that's because the easiest way to get heat--by tapping active vents such as geysers or volcanoes--has been fairly expensive.

A better way, according to the MIT report, is to focus on deeper Earth resources. The study--funded by the U.S. Department of Energy (DOE)--touts a technology known as enhanced geothermal energy, whereby fluid is pumped through granite formations as much as 1500 meters below the surface, creating warm liquid to be converted to steam that can run turbines.

Technical challenges have called for further research in the past: Low-temperature heat can be hard to convert into electricity, for example. But the MIT team, which included academic researchers and industry officials, found promising trial efforts abroad. A drilling project in Soultz, France, for example, has exceeded by more than 100% company targets for recovery of steam using better imaging, cheaper drilling, and smarter use of pressurized fluids. "The panel did not uncover any major barriers or limitations to the technology," notes the report, which calls for some $20 million a year for 15 years in new research. That relatively modest investment by DOE, it says, could bolster research into drilling technology, plant designs, or even using CO2 to get underground heat--all elements of the enhanced strategy.

Charles Kezar, a former DOE official and professor at Lyndon State College in Lydonville, Vermont, says the report is "important" because it lays out for U.S. policymakers the promise of geothermal heat. Last year, DOE asked Congress to zero out geothermal research in favor of development and deployment of solar energy and biofuels. "This is an area of geothermal [energy] that hasn't been exploited yet," he says. The report "is telling developers you're missing a resource."

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