Geothermal could power millions of U.S. homes, Study says.

• Author: Herro, Alana
• Position: EYE ON EARTH

Geothermal power, a renewable energy source that has been largely ignored in the United States, could supply a significant share of the country's future energy needs, according to a recent Massachusetts Institute of Technology (MIT) study. The study notes that by investing some $1 billion over 15 years--less than the cost of building a single clean-coal power plant--geothermal energy could power an estimated 25 million U.S. homes by 2050.

"Heat mining can be economical in the short term," said Jefferson Tester, a professor of chemical engineering at MIT and the head of the 18-member panel that prepared the report. The 400-page assessment, sponsored by the U.S. Department of Energy, is considered the broadest review of geothermal energy in 30 years. It is based on a global analysis of existing geothermal systems, an assessment of U.S. geothermal resources, and continuing improvements in the technologies of deep drilling and reservoir stimulation.

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Most commercial geothermal production in the United States today occurs in isolated reaches of the West, where higher-grade heat sources lie closer to the surface. But the report notes that subsurface "hot rocks" (areas of the Earth's hard rock crust that store thermal energy) are present across the nation, offering the potential for more widespread use of the renewable resource. By drilling wells into hot rock regions and connecting them to water, geothermal developers would be able to generate large amounts of steam that could be used to power electric...