International Geologiical Congress - Oslo 2008


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GET-02 Nature of geothermal systems based on geophysical, geochemical, petrological and tectonic studies


Geothermal Rifts (2) - The direct heat challenge


Xiaolin Wang, University of Western Australia (Australia)
Jan Florian Wellmann, University of Western Australia (Australia)
Klaus Regenauer-Lieb, University of Western Australia (Australia)
Hui Tong Chua, University of Western Australia (Australia)
Frank Horowitz, CSIRO (Australia)


Rifts, intraplate grabens, continental margins and sedimentary basins can contain thick sedimentary sequences that offer a unique low grade heat supply for geothermal use (see companion abstract). Many major cities, are built on such sedimentary basins, thus providing exploitable heat right where it can be used. By exploring for and utilizing low grade heat in a permeable sedimentary environment we address an overlooked opportunity for broadening the utilization of geothermal energy.
We suggest that geothermal groundwater convection in such basins provides a natural underground heat exchanger in such systems. There are challenges and opportunities. The main opportunity is that the drilling costs can be reduced substantially because the convection cells 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 the convective upwelling zones need to be accurately targeted and 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 desalination, heating and cooling, and dehumidification technologies.
Here we present some novel direct heat designs with the vision to provide geothermal zero-emission desalinated water, air conditioning and power to our cities.


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