Australian Geodynamics wins $90M to make hot-rock power a reality

Screen shot 2009-11-06 at 11.26.11 AM Geodynamics, a company that draws emissions-free power from hot fractured rocks beneath the earth’s surface, has just won $90 million from Australia’s Renewable Energy Demonstration Program.

The Hot Fractured Rock (HFR) technique is basically the extraction of the earth’s heat from broken granite over three kilometers deep in the planet’s crust. The rocks are astoundingly hot — making it sustainable to siphon off some of the heat for electricity (assuming the earth’s core doesn’t cool down anytime soon).

Geodynamics’ process is largely based on previously developed technologies. The oil industry, for one, has made drilling to these depths something of an art form. And standard geothermal power systems provided the theoretic background for HFR.

The simplest HFR power stations would use one injection well and two production wells. Water is pumped under high pressure (in very stout pipes) into the heat exchanger 3 kilometers or more under the earth’s surface. The water is then heated beyond its normal boiling point while remaining a liquid due to the pressure and the pipe. At 200 degrees centigrade, it is piped back to the surface into another heat exchanger.

At this point, the superheated water is introduced to liquids with low boiling points — similar to what is used in air conditioners and refrigerators. These liquids quickly turn to gas and expand violently, driving turbines that churn out electricity.

This is a closed-loop system with two loops. The water and low-boiling-point liquids never leave the system and are recycled over and over.

The benefit of HFR over wind and solar technologies is that the rocks used are always hot –24 hours a day — so the electricity isn’t intermittent. With Australia already making enormous investments in transmission infrastructure, it wants to have a reliable source of renewable power. Geodynamics has received $235 million in government grants total to be disbursed over the life of one of its installations in the southern part of the country. The last installment is slated for 2013.

The only reason the company’s technology can’t go global is that Australia is unique in its supply of hot rock beneath the ground. However, the U.S. southwest may be a viable candidate, considering how successful traditional geothermal developments have been.

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