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The Geoscience Australia (GA) building located in Symonston, ACT utilises one of the largest GSHP systems in the southern hemisphere. It is based on a series of 210 geothermal heat pumps throughout the general office area of the building, which carry water through loops of pipe buried in 352 bore holes each 100 metres deep and 20cm in diameter. The system is one of the largest and longest operating of its type in Australia, providing an opportunity to examine the long term performance of a GSHP system. A 10-year building review conducted in 2007 estimated that the system had saved about $400,000 in electricity costs. When comparing energy performance in the annual 'Energy Use in the Australian Government Operations' reports, the GA building has maintained energy performance and targets that might normally be expected of a general office administration building. This is significant given the requirements to provide additional fresh air to laboratories and 24/7 temperature control to special storage areas. The energy savings can be attributed to the GSHP system and other energy efficient design principles used in the building.

The Geoscience Australia (GA) building located in Symonston, ACT utilises one of the largest GSHP systems in the southern hemisphere. It is based on a series of 210 geothermal heat pumps throughout the general office area of the building, which carry water through loops of pipe buried in 352 bore holes each 100 metres deep and 20cm in diameter. The system is one of the largest and longest operating of its type in Australia, providing an opportunity to examine the long term performance of a GSHP system. A 10-year building review conducted in 2007 estimated that the system had saved about $400,000 in electricity costs. When comparing energy performance in the annual 'Energy Use in the Australian Government Operations' reports, the GA building has maintained energy performance and targets that might normally be expected of a general office administration building. This is significant given the requirements to provide additional fresh air to laboratories and 24/7 temperature control to special storage areas. The energy savings can be attributed to the GSHP system and other energy efficient design principles used in the building.

The economic viability of geothermal energy depends on the depth that must be drilled to reach the required temperature. This depends on the geothermal gradient, which varies vertically and horizontally in the Earth's crust. Traditionally these variations in geothermal gradient have been interpreted in terms of thermal conduction. However, advection and convection influence the temperature distribution in some sedimentary basins. Convection can cause the temperature gradient to vary significantly with depth, such that temperature estimates derived from extrapolation of shallow temperature gradients could be misleading. We use borehole temperature measurements in the Perth Basin (Western Australia) and the Cooper Basin (South Australia and Queensland) to reveal spatial variations in the geothermal gradient, and consider whether these patterns are indicative of convection.

Currently it is difficult to assess the quality of Australian geothermal exploration targets, particularly for those with differing amounts of geological data. To rectify this, Geoscience Australia is developing a tool for evaluating geothermal potential across the continent and for identifying areas that warrant additional investigation. An important first step in the development of this tool is synthetic thermal modelling. Synthetic modelling has been used to perform a sensitivity analysis, determine the importance of different geothermal parameters and the values necessary to produce specific temperatures at depth. The results of this work are presented in this abastract.

This presentation was delivered at the Geothermal Energy Industry Roundtable at Parliament House in March 2007.

Within the Central Australian region, nominally constrained by 22.5oS 134oE and 31.5oS 144oE for this study, lie several systems of stacked basins beneath the extensive Mesozoic Eromanga Basin. Remnants of Proterozoic basins are largely inferred from gravity, unexplored, and are not everywhere differentiated from an extensive cover of the lower Palaeozoic Warburton Formation. This sequence is the central link between the contiguous Amadeus, Officer and Georgina Basins, and the Thomson Fold Belt. Since the Carboniferous, the region has largely experienced intracratonic sag and has accumulated continental sediments, including thick coal measures, with intermittent tectonism and uplift. In late Early Cretaceous, marine conditions briefly invaded this subsiding region, but continental sedimentation resumed in the Late Cretaceous. Tectonism occurred in the Tertiary with basin inversion and subsequent formation of the Great Artesian Basin. In the Cainozoic, the region is again in subsidence and accommodating fluvial and aeolian sediment slowly into the Eyre Basin. The preserved depocentres of the Carboniferous-Permian-Triassic Cooper, Pedirka-Simpson, and Galilee Basins are spatially separate, although all contain comparable, largely organically-mature continental coal measure sequences.

A compilation of extended abstracts as a record of proceedings of the 2nd Australian Geothermal Energy Conference, Brisbane, 11-13 November 2009

This record is the second in a series of heat flow determinations released by Geoscience Australia. Six new determinations, three from Western Australia and three from South Australia, are included in this record.

The geothermal industry has expanded rapidly in Australia, with 48 companies holding 385 license areas as of August 2009, with 10 listed on the ASX and with work programs excluding upscaling valued at ~AU$1.5B to 2013. Projects range from early to advanced exploration, proof-of-concept and pilot stages. Targets are for Hot Rock and Hot Sedimentary Aquifer resources, for the purposes of electricity generation or direct use applications. Ground source heat pump technology continues to struggle to attain the recognition it deserves.