Fraunhofer Research Institution for Energy Infrastructures and Geothermal Systems IEGGeothermally driven heat pump system combined with a borehole storage system for the energy efficient supply of cooling and heating
The use of geothermal heat has a high potential to shape the climate-neutral heat supply. While geothermal heat is available throughout the year, the head demand is subject to seasonality and in summer months given by the baseload heat demand for tap water. The use of geothermal heat in the summer period can either be limited or the geothermal hole can be designed solely for covering the baseload heat demand. Limiting the operation leads to reduced economical feasibility of such energy systems and by reducing the size of geothermal boreholes the full potential is not energetically exploited.
However, a reliable technological solution for a year-round and constant application of geothermal heat is the use of thermally driven absorption heat pumps (AHP). Similar to trigeneration systems combing CHP plants and AHP, sorption heat pumps can positively counteract the low utilization degrees of high-temperature grids in summer periods, known as district heating networks (DHN), and offer a primary energy friendly cooling generation. Further cooling can be provided with a higher electrical efficiency. Geothermal heat can serve as driving energy for an absorption chiller/heat pump connected to a high-temperature-/DHN. Depending on the size of the network pipeline-bound geothermal heat can thus be made available to a more distant site with heating and/or cooling needs.
