Publication Name: PESA's Eastern Australasian Basin Symposium II
Authors: R.R. Hillis, M. Hand, S. Mildren, J. Morton, P. Reid and S. Reynolds
Date Published: December 2004
Number of Pages: 26
Reference Type: Book Section
Abstract:
Hot dry rock (HDR) geothermal energy is obtained by circulating water between injection and production wellsthrough hot subsurface rocks. The recovered hot water should be around 250?C for efficient electricity generation. South Australia has become a focus for HDR developments due to its exceptionally hot subsurface rocks. Geothermal Exploration Licences have been issued in South Australia following modifications to petroleum legislation. New South Wales has issued geothermal licences after modifications to mining legislation. Renewable Energy Certificates, mandated by the Commonwealth Government, increase the competitiveness of electricity generated from renewable sources such as geothermal energy.
Previous HDR projects have focussed on areas of known high geothermal gradient, based, for example, on experience from petroleum wells such as the European Soultz-sous-Forets site and Geodynamics' Habanero-1 well in the Cooper Basin. An alternative strategy is to explore for the highest geothermal gradients closest to electricity markets. MNGI/Petratherm holds Geothermal Exploration Licences within the exceptionally hot South Australian Heat Flow Anomaly and will target buried thermally anomalous granites and radiogenic iron oxides therein. Simple thermal calculations indicate that under suitable circumstances temperatures of250?C may be attained at depths <4 km within the licences. The thermal conductivity of the cover rocks is as important a factor as the heat-generating potential of the basement. There exists a continuum of geothermal energy sources from hot, shallow, high-permeability aquifers to deeper, tighter aquifers, to hot fractured basement, to basement hot dry rocks. Indeed end-member HDR-type targets may be relatively rare and commercial HDR exploration may also target conventional geothermal resources.