Exergoeconomic analysis of the super-long gravity heat pipe geothermal power system: A comparative study with typical single-well geothermal system

Abstract

Hot dry rock (HDR) energy is considered as a promising solution of energy shortage and environmental pollution, owing to its ubiquitous distribution and huge reserve. There are two technical routes to exploit the HDR energy: the enhanced geothermal system (EGS) and the single-well system. The novel technical scheme of super-long gravity heat pipe system (SLGHP) in a single-well has aroused widespread interest in the geothermal research and industry community. SLGHP outputs saturated vapor, which can directly drive the turbine to produce electricity, like the thermal power plants. In this study, a thermodynamic and economic model for SLGHP power generation system is established in the outset. A detailed comparison to a typical single-well downhole heat exchanger system (DHE) system is conducted to investigate its performance. Thermodynamic analysis shows that the SLGHP system has higher exergy efficiency compared to the DHE system. The economic analysis indicates that the levelized cost of energy (LCOE) of DHE is much higher than that of the SLGHP. This study unravels the generation performance of the two investigated single-well geothermal systems from the perspective of technology and economy, and the acquired knowledge gives in-depth information of the SLGHP geothermal power generation system.