In Riehen, Switzerland, the way is clear for the expansion of another geothermal system. The residents' council approved a corresponding application from the municipality on September 24, 2020. With the end of the referendum period on October 29, 2020, this decision is now legally binding. The Wärmeverbund Riehen AG can thus advance the expansion of the climate-friendly heating supply in Riehen. As a next step, a measurement campaign should show a clearer picture of the subsurface.
The Riehen geothermal system has been reliably delivering climate-friendly thermal energy to the 8500 residents of Riehen for over 26 years. For the future, Wärmeverbund Riehen AG (WVR) expects continued high demand. A second borehole should therefore tap more naturally available thermal water for heat utilization. The potential is there: a feasibility study confirms that the project has good prospects of success. The drilling to pump the thermal water and the construction of the facility will cost around 20 million francs. In 2026, an additional 4,000 people can be supplied with climate-friendly energy from Riehens underground.
The costs are shared by the two shareholders, the municipality of Riehen and the Basel energy supplier IWB. The Swiss Federal Office of Energy has pledged funding of 1.2 million francs and has announced a further 5.1 million francs. The greater participation of IWB (now 50% instead of 27%) makes it easier to finance the project. On the other hand, the WVR can better coordinate the operation of the systems and the growing supply network with IWB. This is particularly advantageous with regard to the legally prescribed decarbonization of the heat supply in the canton of Basel-Stadt: The gradual and partial shutdown of the gas supply is thus optimally coordinated with the growth of the Riehen heating network.
The next steps are seismic surveys to explore the subsurface for "geo2riehen" in summer 2021. These are important to be able to determine the suitability of a later drilling target. If the feasibility of the project is confirmed, the first of two wells could begin in 2023. The WVR works together with experts who have valuable experience in deep geological explorations. Those responsible for the project consider the occurrence of a noticeable earthquake to be extremely unlikely. No incidents occurred during the previous wells in Riehen. In order to live up to its responsibility, WVR AG carefully examines all project risks, takes appropriate measures and proceeds step by step throughout the project in order to keep adding new knowledge.
Comprehensive information and the involvement of the Riehen population is very important to the WVR, the municipality of Riehen and the IWB. WVR AG is available for questions and will continue to provide in-depth information about each project stage. In addition, it will offer events for the population under the moderation of the independent Risk Dialogue Foundation.