The exploitation of warm tunnel water through the example of the Lötschberg Base Tunnel in Switzerland / Nutzung warmer Tunnelwässer am Beispiel des Lötschberg-Basistunnels in der Schweiz

The drainage of the north side of the Lötschberg Base Tunnel in the Bernese Oberland in Switzerland continuously produces about 100 litres of water per second at about 20 °C. This water is discharged into the local river Kander. In order to protect wetland areas and water rights, the responsible authorities imposed limitations on the quantity of drainage from the tunnel. At the same time, the warming of the Kander by the discharged groundwater has to be limited to 0.5 °C to protect the lake trout from the Thunersee lake, which swim up the Kander to spawn. Particularly in the cold winter months when the water flow in the Kander is low, this requires the withdrawal of about 4 MW of thermal energy, or the cooling of the groundwater by about 10 °C. Instead of artificial cooling, the Tropenhaus Frutigen in combination with a local heating network exploits the warm groundwater for sturgeon farming together with tropical green houses. A high added value is achieved through sustainable use with polycultures, closed circulations and the use of alternative energies. The project has aroused great interest nationally and internationally.