Thermoeconomic analysis of a CO2 plume geothermal and supercritical CO2 Brayton combined cycle using solar energy as auxiliary heat source.

This study presents an investigation of a CO 2 plume geothermal and supercritical CO 2 Brayton (CPG-sCO 2) combined cycle using solar energy as auxiliary heat source. This combined cycle may help solve the problems of CO 2 sequestration and geothermal energy utilization simultaneously. The CPG production is heated by a solar power generation system with solar tower and molten salt. Then a recompression sCO 2 cycle utilizes geothermal energy and solar energy directly. A solution procedure is performed to analyze the thermoeconomic performance of the CPG-sCO 2 combined cycle. Results show that the combined cycle has an optimal main compressor inlet pressure and split ratio for maximum combined cycle efficiency. It can achieve 19.57% by genetic algorithm (GA) optimization, which is 5.65% and 4.07% higher than CPG systems with indirect sCO 2 cycle and organic Rankine cycle, respectively. Moreover, it indicates that the combined cycle efficiency and total capital cost have opposite variation trends with the increase of parameters, including main compressor inlet pressure (p 5), split ratio (sr), well distance (d 8,11) and injection temperature (T 8). Based on multi-objective GA optimization and optimal solution selection, it is concluded that the most thermoeconomic CPG-sCO 2 combined cycle has a combined cycle efficiency of 18.09% and a total capital cost of $5.959 × 107, respectively. Findings suggest that the CPG-sCO 2 combined cycle has potential to combine CO 2 sequestration with geothermal energy utilization. • A CPG-sCO 2 combined cycle with auxiliary solar energy source was studied. • This combined cycle coupled CO 2 sequestration with geothermal energy utilization. • The CPG-sCO 2 combined cycle had a maximum efficiency of 19.57%. • Its efficiency is 5.65% and 4.07% higher than CPG with indirect sCO 2 cycle and ORC. • Most thermoeconomic combined cycle had η cc of 18.09% and C cur,cc of $5.959 × 107. [ABSTRACT FROM AUTHOR]