What is geothermal energy?

Geothermal energy is naturally occurring heat within the Earth. The two main sources are:

  • Hydrothermal systems – water circulates through fractures or pores in rocks in areas of high heat flow, such as in active volcanoes or where thick layers of sedimentary rocks cover hot basement rocks. In hydrothermal systems water can either naturally come to the surface or be pumped.
  • Hot rock systems – heat is trapped below an impermeable layer of rock then water is pumped from the surface into hot rock, where it is heated, and then returns to the surface.

Diagram geothermal

What can geothermal energy be used for?

Geothermal energy can be used to generate electricity, or for direct-use applications. Currently there are no geothermal power stations in NSW. This is partly because the current technology to produce electricity from geothermal energy requires groundwater temperatures over 100°C and there are few places in the state where readily accessible groundwater reaches these temperatures.

The geology of NSW is better suited to direct-use applications of geothermal energy including heating and cooling systems for buildings, heating swimming pools, and some agricultural and industrial uses. Typically, direct-use applications require water temperatures over 30°C.

Are there geothermal resources in NSW?

There are extensive areas of low temperature (<100°C) hydrothermal systems which can provide hot groundwater for heat extraction. Excess water may be put back into the system after use.

The central and eastern parts of NSW contain granites that have unusually high concentrations of the naturally occurring radioactive elements uranium (U), thorium (Th) and potassium (K). Although enriched in these elements compared to other rocks, the element concentrations are still relatively low (commonly ~0.002% U, ~0.01% Th and ~4% K) and they pose no health or environmental risk.

The radioactive decay of these elements over millions of years generates heat, which is trapped if the granites are surrounded by insulating sedimentary rocks. The resulting ‘hot rocks’ can be drilled and fractured to circulate and heat water which can then be used to generate electricity.

How is geothermal energy used in NSW?

NSW has a number of naturally occurring thermal springs that are heated by geothermal energy. Some
of these, such as the Lightning Ridge Bore Baths, Moree Plains Artesian Pools and Yarrangobilly Caves thermal pool, are used as recreational pools and are popular tourist destinations.

Diagram geothermal

What is the future of geothermal energy in NSW?

A number of direct-use applications of geothermal energy could be developed or further advanced in NSW. These include heating and cooling buildings; heating swimming pools; luxury spa developments at thermal pools; pre-heating water for industrial uses; and agricultural uses, such as greenhouses, fish farming, drying organic materials (e.g. grass and wool) and fermentation processes.

With current technology, NSW does not have the high temperature hydrothermal systems required for electricity production from geothermal energy sources. However, limited work has been done on assessing the hot rock potential of the state and, as technology continues to advance, geothermal power plants may be able to use lower temperature water to generate electricity.



a hole drilled into the ground to investigate the subsurface material


the ability to do ‘work’ or to ‘make something happen’. It can exist in different forms, such as thermal (heat), kinetic, electrical, chemical and potential (stored). Energy is measured in joules (J).

hydrothermal energy

power generated from heating fluids, such as water. Steam is produced from the heated fluids and can power a generator, producing electricity.


the movement of electricity along transmission lines once it leaves the power station

For further information
Geological Survey of New South Wales
+61 (0)2 4931 6666
+61 (0)2 4931 6700
PO Box 344, Hunter Region Mail Centre NSW 2310
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