The Geothermal Opportunity of The Gippsland Basin, Australia

The onshore portion of the Gippsland Basin covers about six thousand square kilometers of the state of Victoria, Australia, to the southeast of Melbourne. Most of that area is underlain by the highly productive Lower Tertiary Aquifer (LTA). Recent mapping by the Geological Survey of Victoria has confirmed that thick layers of brown coal within the Gippsland Basin sequence act as a thermal blanket to elevate the temperature of significant segments of the underlying LTA to as high as 75°C at less than 1,000 m depth. The hot aquifer was first identified by a government geologist in 1962, but in spite of some early uses of the hot water there has been little incentive to understand its full extent because of extensive local reserves of cheap natural gas and brown coal. The economic and environmental costs of those fossil energy sources are now on the rise, and the Gippsland Regional Aquatic Centre (GRAC), opened in 2020 in the town of Traralgon, became the first new user of the geothermal aquifer in several decades. The Latrobe City Council chose geothermal energy over natural gas to heat the GRAC based on cost, and the GRAC has now proven the potential of the aquifer as a source of cheap and reliable renewable heat—about AU$30 billion worth of heat at today’s natural gas price. The Latrobe Valley Authority and the University of Melbourne are working together to raise awareness of the economic potential of the aquifer and to identify other potential end users. We have recognized that geothermal sources in the same temperature range as the Gippsland Basin aquifer already provide sustainable, low emissions heat to a wide range of residential and industrial consumers in many other parts of the world. In most of those locations, the geothermal source is much deeper than in the Gippsland Basin. When compared to geothermal systems around the world, the natural hot water in the Gippsland Basin represents a truly world class geothermal energy resource that has, until now, been largely overlooked. Developing the Gippsland Basin geothermal resource could provide many socio-enviro-economic advantages to the region. It could deliver residential and industrial heat at a cheaper and less volatile price than natural gas; it could encourage the growth of new industries to re-employ skilled workers displaced from coal and power industry jobs; it could displace or avoid particulate pollution and greenhouse-gas emissions from fossil fuel combustion; and it could lead to a proper appraisal of the potential for geothermal power generation from much deeper, undrilled reservoirs in the Gippsland Basin. Importantly, geothermal energy with reinjection could provide all these advantages without putting additional pressure on regional aquifers.