Australia has considerable hot rock geothermal energy potential located near the centre of the country.Enhanced geothermal system (EGS) technology has been proposed for accessing these vast resources to generate electricity.Queensland Geothermal Energy Centre of Excellence (QGECE) is developing technologies on power conversion, advanced heat exchanger and cooling system, reservoir simulation, and power transmission based on the site conditions.All these technologies focus on improving the efficiency of EGS power plants and making them more cost competitive with fossil fuel power plants.Carbon capture combined with geothermal energy extraction is one of the major research areas of the QGECE.Carbon dioxide generated from the recovering of fossil fuels can find a second life as a working fluid to help transfer geothermal heat from kilometers underground in EGS power plants.By sequestering CO2 in geothermal reservoirs, the carbon dioxide is captured, kept out of the atmosphere and used for the working fluid of the plant.Ultimately, the viability of the concept depends on economics, and the preferred design will be one that is economically optimized.Atrens et al (2011) conducted economic optimization on a CO2-based EGS power plant.They found that the economic viability of the concept depends strongly on the price associated with CO2.Price for CO2 represents the cost of supplying CO2 at the boundary of the power plant and could be estimated as market price for CO2 emissions minus per-tonne costs of sequestration and transport of the CO2 to the geothermal site.Figure 1 shows the LCoE (levelised cost of electricity) versus CO2 cost for the two scenarios.Expenses associated with procuring CO2 dramatically increase the LCoE, but income from CO2 disposal makes the concept much more economically feasible.