Deep Geothermal Project Suspended in California After Setbacks

A $17 million renewable energy project designed to tap into the earth’s heat more than 2 miles deep has been suspended because of difficulty drilling through rock formations. The project, run by AltaRock Energy and partially funded by Google, was designed to drill down to about 12,000 feet, fracture rock at the bottom of the hole, and then circulate water to create steam. But the company reported that it had encountered “anomalies” in the rock that had prevented it from drilling deeper than 4,000 feet. State and federal officials and residents at the Geysers site, not far from San Francisco, also are concerned that the fracturing process could set off local earthquakes, as happened with a similar project in Switzerland. The U.S. Energy Department had allowed AltaRock to drill in California but not to fracture rock at great depth pending a review. AltaRock said it is suspending drilling and did not say when it intends to resume activity. Renewable energy advocates are hopeful that deep geothermal power may one day prove to be a potent source of steam-generated electricity.