Single well geothermal heating systems: Technical and economic assessment of two widely-used configurations

Abstract

Benefiting from the closed wellbore space, the single well geothermal heating system (SWGHS) could avoid a large number of environmental problems compared to conventional geothermal systems. Combined with heat pump, this technology is attracting growing interest for the development of district heating based on medium-depth geothermal resources. Efforts of the scientific community and of business operators now focus on the technical optimization and commercial viability of the different SWGHS concepts already available. Here, we numerically investigate the heat extraction performance of a butted- and a vertical-well SWGHS possibly operational in a geothermal prospect area in Xi’an, central China. We addressed the performance of the two systems in terms of outlet temperature, heat production rate, heating area, and economic benefits. Sensitivity analysis suggests that large circulation rates and low inlet temperatures have beneficial effects on both thermal efficiency and economic benefits of the project. Our integrated technical and economic analysis suggests that the butted-well SWGHS configuration is particularly suitable for long-run, large-scale applications, compared to the vertical-well design. This work can provide valuable references for the applications of SWGHS, which is of criterial importance for reaching carbon peaking and carbon neutrality goals.