Geothermal Energy

Geothermal viable, but in the wings

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HOT ROCK: November 24, 2011

THE challenge for the hot dry rock energy industry has been set out clearly by professor Tony Owen in his report on power generation options for the NSW Government.

Tapping earth's crust: Geodynamics imported the country biggest drilling rig for its Cooper Basin program in South Australia.

Theoretically, says Owen, HDR geothermal generation could provide large amounts of electricity for many years -- but, given that no power station has been built using the technology anywhere, the process is not yet sufficiently developed to be relied upon.

The upside, Owen adds, is that eastern seaboard electricity market signals as well as emissions trading, to be introduced by 2012, should provide an environment where the technology can be delivered, if it is both technically and commercially viable.

Owen's comments come as the efforts to make Australia the first country to commercially develop electricity production from heat mining are gathering pace: there are now 27 companies engaged in exploring 149 geothermal licence areas, with work programs totalling $656 million.

The heat source they are seeking to tap flows from radioactive decay in grantite formations three to 10km below the earth's crust. Australia is considered to have the best geology for this energy, including temperatures in rocks laid down 500 million year ago that are up to twice as hot as similar structures in another 70 countries where the concept is being examined.

Geophysicist Graeme Beardsmore from the Hot Dry Rocks Company says Australia's "unique geology" makes available granites that are the "hottest non-volcanic rocks in the world".

The heat is accessed via wells drilled in target rocks, then by circulating water. The water is brought to the surface under pressure and the heat transferred to another closed-cycle system connected to a power plant.

While the chief focus of geothermal activity is South Australia...