Geothermal Energy and Heat Flow

The Geothermal Energy and Heat Flow Research Group investigates where and how geothermal energy can be used in Australia and elsewhere around the world.

Our research covers geoscientific exploration, numerical modelling, laboratory techniques, and applied economics. We also develop and apply novel tools and methods to quantify and interpret terrestrial heat flow, applied in fields as diverse as geothermal exploration, glacier studies, and ecosystem monitoring.

Closed-loop geothermal systems for low-emission alumina production

Conor Murray - murraycj@student.unimelb.edu.au

We are focused on using closed-loop geothermal systems to generate heat for the Bayer process and thus support the production of low-emission alumina. This process requires heat between 150 and 250˚C, presently provided in Australia by the burning of fossil fuels. As a large consumer of heat (around 3% of Australia’s total energy consumption is used in the Bayer process), it is critically important to transition to green alumina production.

Closed-loop geothermal systems operate essentially as a large underground pipe network, through which a working fluid passes to absorb heat via conduction. Above ground, the heat is removed, and the fluid reinjected. As such, the system can be constructed to reliably produce a set of desired output parameters (i.e., temperature, pressure, power) close to industrial sites or other end users.
However, as thermal conduction through rock is a slow process (relative to convection), conductive surface area must be maximised.

As a result, closed-loop systems are designed to be very large, several kilometres deep, with one or multiple long horizontal extensions. Drilling costs can therefore be a significant limiting factor in the viability of Closed-Loop Geothermal systems. Therefore, our work requires a multifaceted analysis, incorporating thermal modelling and economic forecasting of Closed-Loop systems, along with geological investigations into the subsurface of the study area.

CO2 plume geothermal systems for clean energy and storage

Mohammad Fathy - fathy@student.unimelb.edu.au

To help reduce rising CO₂ levels, carbon capture, utilisation, and storage (CCUS) technologies are becoming increasingly important. One promising approach within the geothermal sector is the CO₂ plume geothermal (CPG) system. This method offers a dual benefit: it can generate clean energy and store CO₂ underground. In a CPG system, CO₂ is injected deep below the Earth’s surface. As it travels through hot rock formations, it heats up. The heated CO₂ is then brought back to the surface, where it can be used to produce electricity or provide direct thermal energy.  In our research, we use a reservoir simulator (tNavigator) to compare energy output from conventional water, geothermal and CPG systems under various geological conditions.