A novel hybrid geo-solar thermal design for power generation in Australia

Abstract

This paper proposes a novel hybrid geo-solar thermal design for power generation in Australia. The low-grade geothermal heat, from shallow resources already flowing to the surface, will be used to off-load the recuperator duty in a supercritical carbon dioxide Brayton cycle for a concentrated solar thermal power plant. Hence, our design is limited to locations with reasonably high DNI at the vicinity of hot flowing wells. Winton in Queensland has been a case of interest where about 80 kg/s of water flows to the surface at a temperature of approximately 80 °C. Accordingly, a case study, pertinent to Winton, has been presented here. Our simulation of a geo-solar thermal power plant with this configuration has showed significant benefits compared to either solar thermal or geothermal plants in isolation. It is shown that the recuperator can be replaced by a less expensive shell and tube heat exchanger and a smaller, and hence less costly, recuperator while the overall efficiency gain is just under 5% compared to that of a solar thermal plant.