| Title | Advancements in heat pump technology for shallow and deep geothermal sources: three case studies from Germany |
|---|---|
| Authors | Arianna Passamonti, Simon Höckenkamp, Christopher Schifflechner, Paola Bombarda |
| Year | 2026 |
| Conference | World Geothermal Congress |
| Keywords | |
| Abstract | Geothermal heat can be harnessed in various ways, depending on the temperature of the heat source. The geothermal heat pump (GHP) technology is particularly effective when utilized with medium to low-temperature geothermal heat sources, to produce the required temperature and power lifts. In the study the current state of research on the field of heat pump technology is presented, focusing especially on the integration between GHPs and geothermal sources. Three case studies from Germany are investigated: two large-scale high-temperature heat pumps (HTHPs) at the location of Bochum, Germany, one for shallow and one for deep geothermal application, and a concept of a novel reversible Organic Rankine Cycle (ORC) and HTHP system. The 500 kWth heat pump for shallow geothermal application in Bochum consists of two units, a low-temperature stage with ammonia as refrigerant and a high-temperature stage using butane. The system extracts heat from a flooded shallow coal mine, operating between 12°C and 60°C and can inject pressurized water into the district heating grid at temperatures up to 120°C. A second heat pump test rig is connected to the same geothermal capacity, but designed for deep geothermal applications. In the respective project, a 500 kWth HTHP prototype using water as refrigerant is aiming to produce heat up to 200°C, in a closed-loop or mechanical vapor recompression application. Finally, the envisaged integration and operation concept of the reversible ORC/HTHP 200 kWel demonstrator is presented for a real geothermal combined heat and power project. |