Maximising the potential of deep geothermal energy: Thermal output increase by large-scale heat pumps

Due to the high share of the heating market in Europés final energy consumption, it is mandatory to intensify the decarbonisation in this sector. Large-scale heat pumps could significantly contribute to different areas of application, like the supply of existing heating networks or the utilisation of industrial waste heat, by using various energy sources like geothermal, air or running water. However, there are still open research questions regarding the technical aspects like fluid selection or part load behaviour as well as economic aspects. This study investigates the potential of maximising the thermal capacity of existing geothermal heating plants by integrating large-scale heat pumps. To consider a realistic performance of the heat pump, experimental results are implemented into a techno-economic model. Annual simulations are carried out based on real data for a district heating network and the geothermal source. The experimental investigations of a high-temperature heat pump show the high impact of temperature lift, temperature glides and part load operation on the COP. Additionally, this investigated part load behaviour is implemented in the techno-economic model. For the techno-economic analyses, the levelized costs of heat (LCOH) are calculated. For a base scenario, 68 €/MWh are estimated. Additionally, sensitivity analyses were conducted to quantify the influence of selected geological, design and economic parameters on the LCOH. The electricity price shows the most significant impact, with a potential reduction of the LCOH of 39 %. In general, the study points out the great potential of integrating large-scale heat pumps into geothermal energy systems and district heating networks to extend the renewable system's thermal capacity efficiently and cost-effectively.