Hot Rocks in Australia - National Outlook

Barry A. Goldstein¹, Anthony (Tony) J. Hill¹, Anthony R. Budd², Fiona Holgate², and Michael Malavazos^1
1Petroleum & Geothermal Group, Primary Industries & Resources - South Australia, Adelaide, SA, Australia
²Onshore Energy & Minerals Division, Geoscience Australia, Canberra, ACT, Australia

Fear of climate change plus vast, hot rock resources at drillable depths are stimulating geothermal exploration, proof-of-concept and demonstration projects in Australia.

Since the grant of the first Geothermal Exploration Licence (GEL) in Australia (in 2001), 29 companies have joined the hunt for renewable and emissions-free geothermal energy resources in 206 licence application areas covering 187,000 km² across Australia. Roughly 80% of these projects are located in South Australia.

The associated work programs correspond to an investment of more than $630 million, and that tally excludes deployment projects assumed in the Energy Supply Association of Australia’s scenario for 6.8% (~ 5.5 GWe) of Australia's base-load power coming from geothermal resources by 2030.

Australia’s geothermal resources fall into two categories: hydrothermal (from relatively hot groundwater in deep sedimentary basins) and hot rock. Geologic factors that limit the extent of hot rock plays can be generalised as:
● source rocks in the form of radiogenic, high heat-flow basement rocks;
● traps defined by favourable juxtaposition of low (thermal) conductivity insulating rocks to radiogenic heat producing basement rocks;
● heat-exchange reservoirs under favorable stress conditions within insulating and basement rocks; and
● a practical depth-range limited by drilling and completion technologies (defining a base) and necessary heat exchange efficiency (defining a top).

Government grants are focused on reducing critical, sector-wide uncertainties and equate to roughly 25% of the private sector’s field efforts to date. A national hot rock resource assessment and a road-map for the commercialisation of Australian hot rock plays are expected to be published in 2008.

The poster will provide a synopsis of investment frameworks and geothermal energy projects both underway and planned in Australia.

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas