Coastal Geothermal Energy Initiative – an Approach to Quantifying the Geothermal Energy Potential of Queensland, Australia

Abstract

Globally, geothermal energy is utilised within active volcanic regions. The state of Queensland in Australia has few areas of recent volcanic activity, but has large volumes of identified hot granites at 3 to 5 kilometres depth, most of which are located in the far south-west of the state, beneath the Cooper and Eromanga basins. This is potentially a vast source of thermal energy that can be tapped by Engineered Geothermal System technology for power generation purposes. However, their distance from potential markets and the existing national electricity grid, prevent economic viability of the resources in the near term. The Queensland Government designed the Coastal Geothermal Energy Initiative program to investigate additional sources of hot rocks close to major population centres and existing infrastructure. The program targeted a variety of geological settings along the state’s north and east coasts in a structured drilling and heat flow investigation program to collect new, pre-competitive geoscientific datasets for geothermal energy. The new datasets indicate moderate to high heat flow values, between 67.0 and 113.0 mW/m2, across the Millungera, Surat, Hillsborough and Maryborough basins. Using the newly established heat flow data, modelled temperatures of 187–240°C are estimated at 5 km depths. Monte Carlo simulations predict a cumulative total stored heat in-place of 1,280,000 PJ at 90% probability for the basins. The estimated stored heat is sufficient to generate electricity to meet the state’s forecast demand over the next decade. Detailed exploration programs are required to refine geothermal energy potential across the highlighted basins.