Performance analysis of shallow depth hydrothermal enhanced geothermal system for electricity generation

There is a large mismatch between potential estimates and developed geothermal resources in China due to high cost and risk for enhanced geothermal system (EGS) and scattered resources and low volume flow rate for hydrothermal system. Here we propose a shallow depth enhanced geothermal system (SDEGS), which can be implemented by fracturing the shallow depth hydrothermal system to create rich fractures in order to enhance permeability and volume flow rate. The mathematical models describing the continuity, momentum and energy equations in the artificial reservoir and surrounding rock, as well as the thermoelectric conversion equations of Organic Rankine cycle (ORC) are developed. From the simulation results we find that the artificial reservoir of SDEGS can provide stable heat output and outlet water temperature of respectively 59499.97 kW and 165 degrees Cfor almost 23 years. For ORC for generating electricity, the net work output and thermal efficiency are respectively 8053.6 kW and 13.54 %. SDEGS can reduce the hydraulic fracturing risk and cost due to existing rich natural fractures in hydrothermal system, thus broadening the application ranges of EGS.