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ALTAROCK Energy is the second geothermal company to cancel its demonstration project, running hot on the heels of a project cancelled in Switzerland last week because it causes earthquakes.

AltaRock has removed its test drill from its demonstration site at Geysers, US, 160 km north of San Francisco. It’s not yet known whether or not the removal is related directly to the Swiss announcement.

Both projects rely on the same form of geothermal technology, which requires fracturing the bedrock so water can be injected into the hot rocks and withdrawn as steam to drive a turbine to generate energy. Fracturing the rocks can cause tremors as happened in Basel, Switzerland, in 2006. The Swiss project was permanently cancelled last week after a report found it could cause up to $0.5b worth of damage to local buildings.

AltaRock received $30m in venture capital for its project, from the likes of Google, and a $6m grant from the US Department of Energy (DoE). Whether the AltaRock disruption is permanent remains a mystery but the DoE remains buoyant. Despite so far investing some $440m in geothermal, not all geothermal energy projects require tampering with the geology to tap hot rock energy – in many places fluid flow and rock porosity is naturally adequate.   

“Geothermal energy holds enormous potential to heat our homes and power our economy while decreasing our carbon pollution,” says DoE spokesperson Stephanie Mueller.