AltaRock Energy -- a geothermal startup backed with more than $30 million from Vulcan Ventures, Google, Kleiner Perkins and others -- has suspended drilling of a test well north of San Francisco due to "geological anomalies." The suspension of the project is a serious setback for the company, which has offices in Seattle and Sausalito, Calif. And it comes just three months after an in-depth report in The New York Times indicated that process could trigger earthquakes.

But the company, with 20 patent filings on engineered geothermal systems, said it is pushing forward.

"We believe EGS is a clean, renewable energy alternative capable of reducing our economy’s dependence on fossil fuels and creating a more sustainable future, and this technology is the best way of tapping this non-carbon based source of power,” the company said in a statement.

PeHub reports that the project was already behind schedule, and points to a fascinating story in The New York Times which noted that a similar geothermal project in Basel, Switzerland caused a series of earthquakes in 2006.

The Times also reported that residents of Lake and Sonoma counties in California have been protesting geothermal projects in the area. And they noted that AltaRock failed to mention the Basel earthquake in a report it was required to file before commencing drilling.

Last year, I asked AltaRock about the possible threat of earthquakes from a technology that fractures rock miles below the earth's surface, creating man made reservoirs underground.

At the time, CEO Don O'Shei said locating a facility near a fault line might not be the best choice.

"There are so many places to do it, why bother taking the risk?" he said. In fact, the Times reported that AltaRock chose the area north of San Francisco in part because it did not have a history of large earthquakes.