Thermo-economic analysis of an enhanced gekothermal system for power generation based on organic Rankine cycle

Abstract

Abstract The enhanced geothermal system (EGS) has been regarded as a promising means to exploit the abundant and low-carbon hot dry rock geothermal resources. In this work, two-stage EGSs with/without one-stage recuperative cycle for power generation based on organic Rankine cycle (ORC) were proposed, and their thermo-economic performance was evaluated, comparing to the one-stage EGS-ORC. The recuperative cycle improved the thermal performance of two-stage EGS and it had the highest thermal efficiency of 16.48%. Intermediate pressure and steam extraction ratio were important parameters that impacted the thermal performance of the two-stage EGS. The higher thermal efficiency was achieved at the intermediate pressure of 0.22 MPa and steam extraction ratio of 0.1. The two-stage EGS with one-stage recuperative cycle also had the lowest levelized cost of energy (LCOE) of $0.1895 kWh−1. According to the sensitivity analysis, the temperature of hot water and prices of electricity had the greatest impact on LCOE. The LCOE could be as low as $0.1704 kWh−1 if the temperature of hot water was 165.33 C. On the other hand, if the temperature of hot water was 149.58°C, the LCOE would be increased to $0.2179 kWh−1. The results from this study could provide the possible strategies to improve the overall thermo-economic performance of EGS-ORC.