Monday, 31 May

RESEARCH TO UNLOCK THE GEOTHERMAL SECRETS OF QUEENSLAND

The Queensland Government expects 250 MWe to be generated from geothermal energy in Queensland by 2020. The Geothermal Energy Bill was tabled with the Queensland Parliament on 19th May 2010. Following the passage of the bill, a significant increase is expected to occur in geothermal exploration activities through the State.

The geology program of the QGECE is focussed on better understanding of the Queensland geothermal resource. In a new project, the QGECE PhD student Alex Middleton and his supervisors Drs Tonguc Uysal and Masimo Gasparon are aiming to develop a new exploration method for hot rock geothermal resources.

This pioneering study is starting from the premise that any deep geothermal resource is bound to produce some alterations at the surface through its interaction with the deeply-circulating surface fluids. QGECE's Dr Tonguç Uysal tells me that "the analysis of near-surface mineral alterations and geochemistry is a well-established method in mineral exploration but has not been used yet in exploring hot rock geothermal resources." QGECE is one of the few groups in the world working in this area. We all know that those granite types highly enriched in elements (uranium, thorium and potassium) whose radioactive decay produces a significant heat source can offer substantial geothermal energy potential if they are insulated beneath thick sedimentary succession. The interesting thing is that, in spite of such insulating layers (which are essential to preservation of the radiogenically generated heat), there would still be relatively short instances in the geological past in which the radiogenic granite would interact with deeply circulating sub-surface waters. Water interacting with such granites would pick up their geochemical fingerprints and carry them to shallow sedimentary rocks along fault and fracture zones. It is exactly the detection of these fingerprints that the QGECE research is aimed at. Drs Uysal and Gasparon and their students are developing techniques to identify and quantify these fingerprints and use them to estimate the potential subsurface geothermal resource.

One of the outcomes of the project will be more precise knowledge on where hot geothermal resources are likely to be found in Queensland without having to drill deep exploration holes. Obviously, the existence of such knowledge would substantially increase the chances of success in future geothermal projects and would increase the commercial viability of geothermal electricity. The QGECE PhD student Alex Middleton is planning to analyse samples from the Galilee Basin, Innot Hot Springs region, Hodgkinson Province, Styx Basin, Maryborough Basin and North d'Aguillar Block, Wandilla Province. The above map of Queensland shows some of the target areas.The granites in these areas were generated between the Late Devonian to Triassic representing a geologic time span from 370 to 230 million years ago . The preliminary research indicates significant promise of hot rock geothermal energy in these areas. As readers of this blog would remember from past postings, the Galilee Basin is of special interest to the QGECE as it directly overlies the Drummond Basin, which is known to harbour Devonian-Carboniferous granitic igneous rocks abundant in uranium and thorium, providing a significant potential for hot rock geothermal systems. Similar expectations apply to the other target areas.

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