| Abstract |
Hot Dry Rock is widely regarded as one of the most promising renewable clean energy sources, which is also expected to be the ultimate option of energy structure transformation. However, HDR exploitation is facing great difficulties, resulting in a low utilization rate with total installed capacity of 17.85 MWe at 52 projects in the world. The Enhanced Geothermal System (EGS) for HDR exploitation relies too much on the in-situ stress field and natural fracture characteristics of the thermal reservoir, leading to most reservoir quality failing their expectation. Most of the EGS projects in the world have some common shortcomings such as insufficient thermal reservoir volume, unstable fracture network, low flow rate with low temperature, significant water loss, and considerable risk induced seismic events, which fundamentally limit the large-scale commercialization of EGS. The proposal of the enhanced geothermal system based on excavation technology (EGS-E) inspires us to overcome the technical shortages and scale limitations of EGS. In this paper, EGS-E is illustrated more systematically and comprehensively in the aspects of the system composition, working principle and technical advantages. Based on mature mining technology, EGS-E replaces the conventional drilling and hydraulic fracturing technologies by the excavating, blasting and caving technologies, forming a unique reservoir reconstructing and two-stage heat exchange system. This novel system can overcome the restriction of geological conditions, providing customizable thermal reservoir volume, stable fracture network, sufficient flow rate with high temperature, little water loss as well as minimal risk of induced earthquakes. E-EGS may break through the existing dilemma, contributing a brand-new idea and scheme for the commercial exploitation of HDR utilization. |