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Wärmeverbund Riehen AG is planning a second geothermal plant in Switzerland

21/05/2020

In order to meet the increased demand for climate-neutral energy, Wärmeverbund Riehen AG is planning a second geothermal plant with the “geo2riehen” project. How the financial challenges of the next few years can be mastered in partnership is to be regulated in a new contract between the two shareholders, community of Riehen and the Industrielle Werke Basel (IWB).

Expansion of district heating network, Riehen/ Switzerland (source: Erdwaerme Riehen/ geothermie-schweiz.ch)

The Riehen heating network has been supplying Riehen households reliably with geothermal energy for 26 years. The heart of the heat network is the geothermal plant, which has been in operation since 1994 and pumps 67 ° warm water from a depth of over 1500 meters. This is used in the 38-kilometer district heating network and today covers the heating requirements of around 8,500 people. And the demand continues to rise.

Geothermal energy in Riehen today and in the future: Riehen remains an energy city

Geothermal energy is a renewable, CO2-free technology. Riehen is one of the most suitable locations in Switzerland. The heat removal from the interior of the earth is low and the subsoil remains unchanged.

The amount of energy obtained from geothermal energy has more than doubled in the past ten years from 10 GWh to 23.3 GWh in 2018. This corresponds to approximately 2,200 tons, or approximately 2.6 million liters of crude oil per year. Many new customers have been connected in the past few years and the heat procurement has been increased.

In order to meet increasing demand and increase the share of CO2-free energy, a second “geo2riehen” plant is to be built and long-term financing to be reorganized. According to current planning, the new system is to supply around 4,000 additional people within a few years within the supply perimeter.

Riehen was the first municipality in Europe to receive the European Energy Award Gold in 2004 and continues to pursue the goal of remaining in this area thanks to forward-looking projects.

Positive result of the feasibility study

A feasibility study in 2018 showed that the chances of operating a second geothermal plant are good thanks to favorable geological conditions. The next step is to confirm this with trial drilling. Before this, the course of the underground rock strata is modeled in a so-called measurement campaign in order to be able to define a drilling target. With existing bores on the Bachtelenweg and in the Stettenfeld, a favorable water supply was proven. Based on this experience, the probability of success is relatively high.

Before the project can continue and test drillings can be carried out, the cooperation between the shareholders must be reorganized.

Federal support

A grant was requested from the Federal Office of Energy (SFOE) in December 2018 and the project was examined by a BFE expert group. After the examination was completed, a subsidy contract of CHF 1.2 million was signed for the measurement campaign in January 2020. A further subsidy is requested for the drilling and until then the project will continue to be accompanied by the BFE expert group.

Project risks are very low

The project managers consider the risk of a noticeable earthquake to be very low in the planned drilling. No incidents have occurred in previous drilling and geological conditions are very similar.

In Riehen, as with the 1988 drilling, the naturally broken, permeable and water-bearing subsoil is used. No new fractures are generated, so that no noticeable tremors can be expected.

All project risks are continuously monitored and, depending on the project development, measures are taken to further minimize risk and communicated about it.

The canton's new energy directives require a partnership at eye level

In order to achieve the ambitious goals of the “geo2riehen” project, Wärmeverbund Riehen AG faces very major technical and financial challenges. The interest of homeowners in connecting to the heating network will remain high. The federal and cantonal energy policy requirements are all aimed at increasing the promotion of environmentally friendly geothermal energy.

In addition to the investment for "geo2riehen", further investments in the existing production facilities and in the networks will be necessary in the next few years. This against the background that the new BS energy plan requires a CO2 reduction (“decarbonization”) of the heating system. As a result, both WVR AG and the IWB face major challenges that need to be solved in partnership. Replacement and new investments for production facilities and the expansion of the district heating network are pending in Riehen. Because the district heating in Riehen and Basel district heating are already technically connected, it is very important that the interests are brought into line.

Depending on the demand scenario, the investment requirement in the coming years is estimated at 42 to 49 million francs, with "geo2riehen" accounting for around 14 million francs after deducting the possible subsidy contributions. In order to be able to meet these challenges, the two shareholders (the municipality of Riehen and the IWB) reviewed their partnership.

In the future, the shares will be 50% instead of 72.9% today (Riehen municipality) and 27.1% (IWB). With regard to energy supply, the IWB are not only the most important actor in the canton of Basel-Stadt, but also an indispensable partner of the community in the Riehen heating network and have extensive technical and operational know-how.

With the shift in the equity component, the IWB also assume more financial responsibility and risk.

The next steps

The Riehen residents' council is expected to approve the bill in June 2020. The population is expected to be informed in detail about the project in autumn 2020.

KeyFacts Energy: Geothermal news

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