Feasibility analysis of a medium- to low-temperature enhanced geothermal combined with heat pump system (MLEGHP) for heating application in severely cold regions: a case study in Shenyang, Northeastern China

Ground-source heat pumps (GSHPs) have been widely applied in China in recent years. However, for heating-dominant buildings in cold regions, more heat from the ground is extracted than rejected, which leads to an annual decrease in heat source temperature and degradation of GSHP heating performance. In this study, a novel medium- to low-temperature enhanced geothermal combined with heat pump system (MLEGHP) is proposed for winter heating. Taking Shenyang city as an example, we technologically and economically investigate the applicability of this novel MLEGHP system in heating-dominated regions over a 30-year period. According to real geological data, hydraulic fracturing simulation, reservoir simulation, heating performance assessment, and economic analysis are conducted successively. Results indicate that the MLEGHP system can continuously work efficiently without performance deterioration and strengthen heating reliability during long-term operation in cold regions. Despite the high initial investment, the heat production and payback period of the system are considerable for large-scale projects. Thus, the MLEGHP system is a potential solution for the underground thermal imbalance of GSHP systems and for winter heating in cold regions.