Australia's efforts to become the first country to commercially develop electricity production from heat mining continue to gather pace.

The Australian Geothermal Energy Group has told a Federal Parliament committee investigating the potential of non-fossil fuel industry that more than a half billion dollars is expected to be outlayed in the next five years to test deep-buried heat reservoirs across South Australia, Victoria and Queensland.

The exploration and development effort underway since 2002 has seen $100 million spent to date and has attracted $27 million in Federal Government grants as well as a promise of a further $50 million in support if the Labor Party wins the forthcoming federal election.

Geothermal energy is the natural heat found within the Earth.

To be viable for conversion to usable energy, hot granite rocks need to have an efficient insulation in the form of sedimentary material and there needs to be an adequate water supply for high pressure injection in to fractures in the rock.

Geoscience Australia has suggested that the first five kilometres of the surface of the continent has enough contained heat to supply this country's electricity needs at current demand levels for 22,000 years.

Geothermal energy can produce baseload power 24 hours a day, seven days a week, with no greenhouse gas emissions.

Development of geothermal power is characterised by high exploration costs and competitive production costs, with connection to market by high voltage transmission lines a key factor for a resource that is mostly located in remote areas.

AGEG reports that there are now 27 companies engaged in 149 licences across Australia, with work programs worth a total of $656 million.

Of this, $526 million is designated for expenditure in South Australia on 125 licence areas covering 54,000 square kilometres.

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