A regenerative Enhanced Geothermal System for heat and electricity production as well as energy storage

Enhanced Geothermal Systems (EGSs) evolved from hot dry rock (HDR) can play a crucial role in fulfilling the energy demands while boosting the transition toward carbon neutrality. This study proposed an innovative conception of EGS to integrate heat and electricity production and the storage of surplus renewable energy. Employing engineering data from the GeneSys project, Germany, a geothermal facility is numerically simulated by adopting two horizontal wells. In order to investigate the evolution of fluid and heat transmissivity during fracturing, production, and storage procedures through multiple hydraulic fractures while incorporating stress superposition effects, we performed coupled thermo-hydro-mechanical (THM) modeling with improved simu-lators, namely FLAC3Dplus and TOUGH2MP-TMVOC. By critically optimizing the thermal production, the electric potential caused by reservoir temperature decreases from 7.17 MW to 5.08 MW during 30 years, and the Lev-elized cost of electricity (LCOE) of proposed EGS is estimated at 5.46 c$/kWh; thus indicating remarkable development feasibility from an economic perspective. Finally, we have inspected several schemes for energy storage on the thermal-depleted reservoir to extend the life of geothermal power plant and make surplus energy useable efficiently. The results revealed that the EGS project could indeed be regenerative as formation tem-perature rises with energy storage/recovery cycles.

Automated summary

This study proposed an innovative concept of Enhanced Geothermal Systems (EGS) that integrates heat and electricity production with the storage of surplus renewable energy. Numerical simulations and coupled thermo-hydro-mechanical (THM) modeling were performed to investigate the evolution of fluid and heat transmissivity and optimize thermal production. The results showed a decrease in electric potential and the Levelized Cost of Electricity (LCOE), indicating the economic feasibility of the proposed EGS, and suggested several schemes for energy storage to extend the life of geothermal power plants.