Potsdam the provincial capital of the German state Brandenburg started with an ambitious program to reduce its climate impact about 10 years ago. The program includes the substitution of fossil energy sources for district heating by renewable energy. The investigation of the geothermal potential of the urban area forms an important component of this strategy.
Several deep saline aquifers in the closer surrounding of Potsdam show a potential for a geothermal utilization. They are used for different purposes like natural gas storage (Buntsandstein), underground heat storage (Jurassic), balneology (Rhaetian) or injection of process water (Muschelkalk, Jurassic). The exploration campaign started with 2D seismic measurements which were focused on the investigation of the Mesozoic succession up to a depth of about 2,500 m bgl. Based on the seismic results a drill site was determined where a vertical borehole was drilled into a depth of 2,157 m bgl. The exploration well encountered the succession down to the Muschelkalk formation with partly surprising results. The investigation of the encountered aquifers favoured the further exploitation of the Middle Jurassic Aalenian sandstone as a geothermal reservoir. Accordingly, the second well was deviated to reach this horizon in a deeper situated part of the structure.
Hydraulic tests of the aquifer show promising results with respect to a future use in a local heating system of the surrounding residential buildings. The overrun could be feed into the nearby district heating network. Besides, the results will be used for the development of further locations for a geothermal utilization.