As the effects of climate change is further debated, a new gold rush is underway in Australia. But his time the search is not for gold, not copper, or oil, no - not even uranium, but close. This hive of exploration is centered around the search for Hot Rock, or Hot Granite three to five kilometres under the earth’s surface.

Harnessing the heat from Hot Dry Rock (HDR) or Hot Fractured Rock (HFR) consists of drilling two or more wells approximately three to five kilometres into the ground. A heat exchanger is then formed by hydraulic stimulation where the temperature of the granites is approximately 250 degree C. Water is then pumped down the injection well, where it is heated by the hot granite and returned to the surface via the production well. On the surface, this hot water is converted to electricity using a binary geothermal power plant.

Video 1: How to harness Hot Rock Geothermal Energy

The technology and concept is not new. The first concept of HDR was developed at Los Alamos in the 1970s and later demonstrated at the Fenton Hill site. The following EnviroVideo special shows the details of this site. France has the Soultz HDR project which is considered the most advanced HDR geothermal project in the world. In November 2007, they have installed the Geothermal loop and are working on the installation of the power plant.

Video 2: EnviroVideo Special - Hot Dry Rock Geothermal

HDR geothermal energy uses proven binary power plants and proven drilling techniques used everyday in the mining industry. Despite the many years of development on HDR overseas, HDR geothermal exploration in Australia was only kick started by South Australia’s and New South Wale’s recognition of HDR/HFR by granting Geothermal Exploration Licences (GELs) and the Government’s Renewable Energy (Electricity) Act 2000, early this decade.

Geodynamics, the pioneer of HFR in Australia, is undoubtedly the most advanced being the only company that has tested a geothermal flow from Hot Fractured Rock. On the days leading up to the 26th of April 2005, Habanero #2 produced over 10MW of thermal power. The following video from Geodynamics was filmed in the months later and demonstrates the progress Geodynamics has made.

Video 3: Geodynamic’s Promotional Video - May 2005

The most is known about the ASX listed companies exploring for Hot Rocks. Here is a list of these listed companies in order of listing date :

• Geodynamics, Listed on the 12th September 2002.
• Green Rock Energy, Listed 10th December 2003.
• Petratherm, Listed 27th July 2004.
• Geothermal Resources, Listed 21st March 2006.
• Eden Energy, Listed 6th June 2006.
• Torrens Energy, Listed 30th March 2007
• KUTh Energy, Listed 25th September 2007.
• Greenearth Energy, Expected to list 10th January 2008.