Medium-deep geothermal resources in the Molasse Basin: A geological, techno-economic, and ecological study of large-scale heat pump integration

Medium-deep geothermal systems, with low exploration and investment costs, offer a solution to decarbonize the heating sector. The South German Molasse Basin (SGMB) is a reservoir with significant hydrothermal potential, where exploration has largely focused on depths greater than 2500 m. Here, medium-deep geothermal systems could provide water temperatures of 30 °C–80 °C. Large-scale heat pumps can raise supply temperatures for integration into district heating networks. While previous studies have concentrated on specific cases, this study adopts a more comprehensive approach, by examining the region of the underexplored northern SGMB. Geological parameters, such as depth, temperature, and water flow rates, were analysed to evaluate the techno-economic and ecological feasibility. At 1000 m depth, a base scenario with thermal water temperatures of 45.6 °C and a mass flow rate of 100 kg/s was evaluated. Following, sensitivity analyses varied geological parameters like depth and flow rate, based on the geological analyses, to represent the entire region, revealing LCOH between 77 and 151 €·MWh−1 and GWP between 53 and 136 kg CO2 eq./MWh. These holistic analyses demonstrate the significant benefits of medium-deep geothermal systems combined with heat pumps for sustainable heating. And provide guidance to local authorities and operators.