Grünwald is a (rich) city south of Munich, Germany. Population: about 11000 people. As is often the case in Germany, the city is heated by a central system, meaning there are hot water pipes running under the streets delivering heat to the individual homes. This centralised system has the advantage that the central heat source can be optimised to save energy. Some power plants burn waste, generate electricity and distribute the heat generated. In Grünwald, they chose to pump heat generated by our planet. There is an aquifer running down the alps under the whole of south Bavaria, manifesting itself by hot springs in Erding north of Munich, for example. Deep under Grünwald, the water runs at 130°C. This is a general view of the station:
What you see here are the exits of the inlet and outlet pipes. The pipes go down 4km to the aquifer. They pump hot water out (130°C) and, after the heat has been used, reinject it down at about 50-60°C. The pump is 600m below the surface. The station pumps about 140l/s. The whole complex produces 40MW of heat.