Geothermal power search holds promise, threat (earthquakes)

[Kadie]

Geothermal power search holds promise, threat

David R. Baker,David Perlman, Chronicle Staff Writers

Sunday, August 16, 2009

On a high ridge in the Mayacamas Mountains, a drill slowly bores into the earth to test a new way to generate electricity.

The test, by a Bay Area company called AltaRock Energy, could give the world another source of renewable energy, a valuable weapon in the fight against global warming. It could also trigger earthquakes in a corner of California that already shakes most every day, a prospect that is jangling the nerves of some nearby homeowners.

AltaRock has chosen this ridge to try a new form of geothermal power, using the heat of the Earth to produce energy. The surrounding hills - in an area known as The Geysers, about 70 miles north of San Francisco - hold more than a dozen older geothermal plants that tap underground pockets of steam to turn turbines and generate electricity.

But AltaRock will drill below the steam pockets, burrowing into deep rocks hotter than 500 degrees Fahrenheit. The company, based in Sausalito, will fracture those rocks with high-pressure water, creating a network of cracks. AltaRock will then pump more water into the cracks, using the rocks to heat the water and create steam. Geologists monitoring the $17 million project say it will create earthquakes, but most will be too small to notice.

more...
http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2009/08/16/MN5N18UU3J.DTL&type=green&tsp=1




A rig more than 170 feet high will drill down more than 2 miles in a test to produce a new type of geothermal energy.

Photo: Brant Ward / The Chronicle