Deep geothermal energy is climate-neutral and has enormous potential for supplying heat to Bavaria. About the possibilities of the energy source and the question of why so little has been invested in the technology so far.
Shortly after leaving the Salzburg autobahn near Holzkirchen, anyone driving from Munich to Lake Tegernsee will pass a sprawling complex of buildings with conspicuously large fans on the roof and light-colored wooden facades. This is the Holzkirchen market geothermal power plant. Deep groundwater with a temperature of 157 degrees is pumped up from a depth of a good 5,000 meters at a rate of around 60 liters per second. They are routed through heat exchangers in the system and drive a power generator and a heating circuit. This creates green electricity for 5000 households and climate-neutral heat for up to 7500 households. A fossil plant would have to burn three million liters of heating oil a year and blow 10,000 tons of CO₂ into the atmosphere. After the deep groundwater has done its job, it is channeled back to a depth of 5,000 meters via a second borehole, the so-called injection borehole.