Enhanced or "hot rock" geothermal power production usually works by pumping water into fissures in hot rocks deep underground, A shaft is drilled into the fissures and some ot the resulting super-heated water comes to the surface where it is used to drive a turbine.

One problem with this technique is the amount of water needed since much of it remains underground.

In 2000, a Los Alamos National Laboratory physicist, Donald Brown, proposed replacing water with supercritical carbon dioxide, a pressurized form that is part gas, part liquid. Subsequent modelling at the Lawrence Berkeley laboratory has shown that using carbon dioxide would produce 50% more heat than using water because the carbon dioxide will flow more freely than water through cracks in the rock.

As well as being more efficient, using carbon dioxide would sequester much of the gas.

A Salt Lake City-based geothermal developer, GreenFire Energy, has now announced plans to build a two-megawatt carbon dioxide-based demonstration plant near the Arizona-New Mexico border. The company proposes to commence drilling in 2010 and says that the location could yield enough heat to generate up to 800 megawatts of power and, in the process, could absorb much of the carbon dioxide generated by the six large coal-fired power plants in the region.

(Adapted from sources including Technology Review)

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General Electric and Google have announced that they will collaborate to develop smart-grid technologies with a particular focus on plug-in hybrid vehicles and enhanced, "hot rock" geothermal systems.

Smart-grid technology lets utilities more efficiently manage electricity on the grid while smart meters and displays in homes and businesses allow consumers better understand and control home energy use.

The deal combines each company’s strengths: GE will make the hardware — from turbines to metering switches, and Google will make the software.

For example, electric cars will require more power generation capacity, which GE will provide, and the intelligence needed by the grid to tap the electricity stored in charged car batteries when they’re parked at night would come from Google.

In the geothermal area, Google will create visualization software while GE will work on power conversion technology. Google recently invested in a number of enhanced geothermal projects, while GE does not yet have a large investment this area.

GE, however, does have a large investment in wind energy, expecting revenues of more than $7 billion from wind power this year. Google will work on software to manage the grid so that power generated from wind, wherever it may be blowing at a particular time, will be available where it is most needed.

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Power can be produced from the geothermal energy in hot rocks. This is being trialled in South Australia.

How It Works

Geodynamics believes that its hot fractured rock project in South Australia has the potential to produce almost twice the energy of all of the oil reserves of the United States. It could produce enough energy to supply all of Australia’s power needs for 70 years with no greenhouse gas emissions and at about the same price as coal-fired power.

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