PROCEEDINGS, Thirty-Fourth Workshop on Geothermal Reservoir Engineering Stanford University, Stanford, California, February 9-11, 2009 SGP-TR-187 DIRECT HEAT GEOTHERMAL APPLICATIONS IN THE PERTH BASIN OF WESTERN AUSTRALIA Klaus Regenauer-Lieb, Hui Tong Chua, Xiaolin Wang, Franklin G. Horowitz, J. Florian Wellmann Western Australian Geothermal Centre of Excellence c/o School of Earth and Environment The University of Western Australia 35 Stirling Avenue Crawley, W.A., 6009, Australia e-mail: klaus@cyllene.uwa.edu.au ABSTRACT Sedimentary basins offer an ideal target to push forward new technologies of direct heat use. The natural temperature, porosity and permeability of these sedimentary basins may be sufficient to provide usable geothermal power without the requirement of stimulation. A new technology has emerged in which natural hot water motions are targeted. This technology is particularly suited for direct use of heat from extremely deep sedimentary basins such as the Perth Basin (>10 km thick sedimentary sequences). The main opportunity offered by sedimentatry basins is that the drilling costs can be reduced substantially because heat, salinity and topography driven upwellings exist that provide natural transfer of heat to shallower levels. Through this effect geothermal power may in the future become more competitive even in areas with normal or only slightly elevated regional heat flow. The main challenges are that natural convective upwelling zones need to be accurately targeted. The second challenge is that new methods need to be devised to harness the use of low- grade heat; shallow geothermal sources may not reach the temperatures necessary for efficient electricity generation but are ideally suited for direct heat-driven applications, such as desalination, heating and cooling, and dehumidification technologies. We are presenting our methods for improved targeting in the Perth Basin and introduce two direct heat use technologies: geothermal air conditioning via sorption chillers and geothermal desalination. The technologies are not new in their basic principle. However, their engineering art has advanced significantly and their potential for incorporation into geothermal systems is a perfect match. INTRODUCTION Sedimentary Basins in Australia Sedimentary basins offer an ideal target to push forward new technologies of direct heat use. Sedimentary basins occupy a large proportion of the Australian landmass (Figure 1). The Great Artesian Basin (comprising amongst others the Eromanga and Surat Basin), for instance, is one of the world's largest artesian groundwater basins, underlying one fifth of the Australian continental landmass. Groundwater comes out at wellheads at temperatures up to 100 °C. The natural temperature, porosity and permeability of these sedimentary basins may be sufficient to provide usable geothermal power without the requirement of stimulation. A new technology has emerged in which natural hot water motions are targeted. This technology is particularly suited for direct use of heat from extremely deep sedimentary basins such as the Perth Basin (>10 km thick sedimentary sequences). Figure 1: A large portion of the Australian landmass is covered by sedimentary basins. http://www.ga.gov.au/image_cache/GA11 137.pdf THE PERTH BASIN OPPORTUNITY The Western Australian State Government announced a new $2.3million WA Geothermal Centre of Excellence focussing on direct heat use (e.g. geothermally powered air conditioning and