09/21/2008 05:12 am ET Updated May 25, 2011

Google Goes Big for Geothermal

Google, Inc. announced plans to invest $10 million in an energy technology known as enhanced geothermal systems, or EGS. While conventional geothermal power plants generate electricity using ultra-hot steam stored in natural reservoirs one or two miles below the earth's surface, EGS can theoretically tap heat in dry rock by pumping cold water into artificial underground reservoirs. (Google produced this video to show how it works.)

While geothermal energy offers a renewable alternative to oil and natural gas, large-scale plants do not pass unscathed through the thicket of environmental woes. U.S. News & World Report's Kent Garber explains:

Though geothermal is largely carbon free, the required drilling can disturb the surrounding area. Most geothermal reserves are located on government land under the jurisdiction of the Interior Department, which requires lengthy environmental assessments before allowing new drilling.

But geothermal energy does have some significant advantages, not only over traditional fossil fuels but also over other renewable energies. For one thing, unlike wind and solar power, geothermal power is generated constantly--24 hours a day, seven days a week.

Awarded through Google's for-profit philanthropic arm,, the EGS investment is greater than 2008 funding for the federal geothermal program, which has taken big cuts in the last two years. Daddy Googlebucks will split the cash three ways, with $4 million going to the drilling company Potter Drilling and some $490,000 going to the geothermal lab at Southern Methodist University. The largest chunk, $6.25 million, goes to the Sausalito, California-based start-up AltaRock Energy, Inc., which announced an additional $20 million in funding today from Microsoft, Vulcan Capital, and the Silicon Valley venture capital firms Kleiner Perkins Caufield & Byers and Khosla Ventures--two big backers of alternative energy companies.

Fast fact: About 6 million people in the U.S. power their homes with energy produced with geothermal technology, according to the Geothermal Energy Association.

Share your thoughts and stories: Have you used a geothermal heat pump at home? What do you think about drilling for steam?

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