Geothermal energy involves extracting the energy stored as heat in the earth. Although geothermal energy is present everywhere beneath the surface, it must be concentrated and close to the surface and energy consumers to be a cost-effective power source.
Resources in Western Australia
Western Australia’s geothermal resource falls into two categories – hydrothermal (from hot groundwater) and hot fractured rock.
Hot fractured rock processes involve pumping water into wells drilled deep underground to access heat from granite rocks. The steam created is used to drive turbines on an electricity generator.
Hydrothermal processes access existing groundwater resources that are generally shallower and cooler than hot fractured rock geothermal resources. The hot water can be used directly for applications such as heating and cooling buildings or industrial processes. If the temperature is high enough, it can be used to generate electricity.
Past studies, using data from petroleum exploration, have identified significant potential for geothermal energy in Western Australia. Further information is available from the Department of Mines and Petroleum.
Current use in Western Australia
Legislation to allow geothermal energy exploration and production was passed in 2007. Since then, the Department of Mines and Petroleum has released exploration acreage covering the entire state, and awarded over 40 exploration permits.
Exploration is concentrated in areas close to the electricity grid or where significant load growth is likely. The electricity generated could be used to power mining and industrial operations, as well as regional centres, ports and infrastructure.
The Western Australian Geothermal Centre of Excellence is focusing on large-scale direct heat applications (e.g. geothermal-powered air conditioning and desalination) in populated centres where there is shallow groundwater of moderate temperature.
Direct heat applications at relatively small-scale are already used to heat swimming pools around Perth. These include Challenge Stadium, Christchurch Grammar School, Claremont Pool and Craigie Leisure Centre.
Future use in Western Australia
Geothermal energy can be used to generate a reliable and constant low-emissions power supply, which is not possible with wind and solar technologies, which are considered intermittent energy sources. This makes it one of the most likely options to replace coal-fired power stations in the long-term.
Geothermal energy can be used to displace electricity used for large-scale heating and cooling applications. This helps to reduce the need for large amounts of investment in electricity generation and network infrastructure used only for a short period each year in which demand peaks. These peak periods generally occur during winter or summer, when electricity is used to control temperature.
Geothermal energy could also be used for industrial processes such as desalination.