The City of Stuttgart plans to implement a geothermal system into a new tunnel (Rosensteintunnel) in the vicinity of the city’s zoo “Wilhelma”. The geothermal heat and the waste heat of the traffic shall be used to heat one of the new buildings, i.e. the elephant house. At the same time the operation technology of the tunnel shall be cooled. The city will receive € 270,000 from the Federal Ministry for the Environment, Nature Protection, Building and Reactor Safety. The annual heat consumption of the elephant house is estimated to be 1,382 MWh/a and the electricity saved due to the alternative cooling method is 219 MWh/a. Thus the energy concept will save annually 201 tons of CO2.