Deep geothermal resources in China: Potential, distribution, exploitation, and utilization

Abstract

Deep geothermal resources mainly refer to the thermal energy stored in subsurface rocks and fluids therein at a depth of 3–10 km, which is a kind of renewable and sustainable clean energy unaffected by weather and seasonal changes. Large scale exploitation of the deep geothermal resources is of great significance to ensuring national energy security and achieving the “Carbon Peak and Carbon Neutrality”. Based on the latest terrestrial heat flow data, this paper estimated the potential of deep geothermal resources in the terrestrial areas of China, and the results show that the total amount of geothermal resources within 3–10 km under the Earth's surface in the terrestrial areas of China is 24.6 × 1015 GJ. In line with climate zones categorized, the geothermal resource proportion is 43.81% for severe cold regions, 29.19% for cold regions, 6.92% for mild regions, 13.82% for hot summer and cold winter regions, and 6.26% for hot summer and warm winter regions. Statistics according to the burial depth range reveal that the resources within depth ranges of 3–5 km, 5–7 km and 7–10 km under the Earth's surface are 4.3119 × 1015 GJ, 6.37674 × 1015 GJ and 13.89594 × 1015 GJ respectively, showing an increasing trend of geothermal potential with increasing burial depth. The deep geothermal resources are mainly of medium-to-high temperature reserves, and the energy supply strategy can be optimized by combining the climate conditions and population distribution, as well as considering power generation. In regions of cold or severe cold climate, the geothermal resources may be applied to geothermal power generation and district heating in combination; in regions of hot summer and cold winter or mild climates, the resources can be used for geothermal power generation combined with cooling and heating; in regions of hot summer and warm winter climates, the resources may be applied to geothermal power generation combined with cooling and industrial and agricultural utilization. Exploitation of deep geothermal resources also can be combined with carbon dioxide sequestration, multi-mineral resources extraction and energy storage to realize comprehensive exploitation and utilization of various energy resources. It is suggested that theoretical technology research should be combined with pilot tests and field demonstrations, and large-scale economic exploitation of deep geothermal resources should be arranged in a coordinated manner, following the principles of overall planning and step-by-step implementation.