The feasibility of clean power generation from a novel dual-vertical-well enhanced geothermal system (EGS): A case study in the Gonghe Basin, China

Abstract

Recently, the first demonstration enhanced geothermal system (EGS) is being constructed at the Gonghe Basin, northwestern China, where manifests a massive potential source of geothermal energy for clean power generation within the hot dry rock (HDR). Based on the available geological data, a conceptual EGS with a novel dual-vertical-well is proposed to investigate the potential of clean power generation from the target geothermal reservoir in the Gonghe Basin. Particularly, the multiple interacting continua approach is employed to accurately delineate the transport of heat and fluid within the high-temperature fractured geothermal reservoir. The feasibility of power generation at depths between 2900 m and 3300 m is reasonably forecasted over the 30 years with a production rate of 40 kg/s. The results demonstrate that the proposed EGS can obtain an ascending production in the first 10 years, and a slight temperature drop by 7.7% in the following 20 years. In addition, the electric power ranges within 2.86–3.23 MW, and the electric energy efficiency ranges within 13.88–18.47 over the 30 years, showing a promising production performance. The levelized cost of energy (LCOE) for the proposed geothermal power system is estimated at 0.035 $/kWh, and the reduction in total greenhouse gas emissions is expected at 0.29–1.01 million tons. Thus, the spread of this proposed geothermal power plant is very important for realizing carbon neutrality by 2060 in China. The sensitivity analysis indicates that the injection temperature and injection rate are two key parameters that have significant effects on the production performance. For the proposed geothermal system in the Gonghe Basin, the suitable injection temperature and injection rate are recommended as 60 °C and 40 kg/s, respectively. This work also provides a guideline for the exploitation, reservoir stimulation, and flow test of future EGS development in the Gonghe Basin and other sites under similar conditions.