Geothermal energy is a renewable resource that will be part of the world’s transition to clean power production. Different technologies can be utilised to extract heat or produce geothermal-based electricity. The Geological Survey of NSW has identified several regions across the state where there are higher than average geothermal gradients. These regions in the southern Sydney Basin are investigated with the aim of determining if the high temperatures might be related to subsurface rocks with relatively high concentrations of radiogenic isotopes that might create a ‘hot dry rock’ play. Rock properties are tested that would be required to generate a geothermal resource. Existing and potential engineering technologies (i.e. geothermal-based electricity, heating and cooling applications accompanied by heat pumps, geothermal-hybrid systems, and mine-based geothermal technologies) are also further reviewed. Overall this study provides insights into future opportunities and challenges to harnessing geothermal energy in NSW.