Geothermal explosion rocks green energy hopes

New scientist

13:08 28 April 2009 by Rachel Nowak

The bid to produce green power on a commercial scale using heat mined from subterranean rocks – or "hot rocks" – has suffered a major setback, with the breach of a four-kilometre-deep well on Friday in the Cooper Basin in South Australia.

Mining heat from subterranean rocks could one day provide continuous, affordable energy anywhere on Earth, and Geodynamics, the Brisbane-based company that operates the South Australia well, is widely tipped as being closest to making the technology cost effective.

Geodynamics holds the rights to a potential power supply of up to 10 gigawatts trapped in a 1000-square kilometre slab of hot granite deep under the town of Innamincka in South Australia.

The company was in the final stages of commissioning a demonstration one-megawatt power plant for Innamincka when the rupture occurred, and steam started to escape from the well.

Drilling deep wells into hot rocks and circulating water to mine heat is technically challenging, and the cause of the breach is still unknown.

"We've mobilised a team from the US to investigate," a company spokesperson says.