What are the prospects and potential of deep geothermal energy in Switzerland?

Deep geothermal energy for electricity production is an unproven technology in the Swiss geological context and its prospects therefore remain uncertain. If its development goes according to plan, deep geothermal energy could eventually contribute around 4.4 TWh, or between 6 and 9% of our electricity supply, in 2050. In contrast, medium-deep geothermal energy for heat production is established in Switzerland, particularly for remote heating and thermal baths.

The deeper you go down, the higher the temperature rises. Deep geothermal energy consists of extracting heat at high temperatures (100-300°C) from the bowels of the earth to produce electricity or cogeneration of heat and electricity. One of the advantages of deep geothermal energy is the ability to supply power continuously because this energy is available continuously, regardless of weather conditions, unlike the intermittent production of wind and solar energy.

Worldwide, geothermal power plants for electricity production have mainly been built in regions of high tectonic or volcanic activity, which benefit from high temperatures close to the surface (less than 500 m). At the end of 2018, 14 GW of installed electrical capacity was available, mainly in California, the Philippines, Indonesia, Mexico and Italy. At the same rate of development, installed capacity could reach 15-18 GW in 2020. This is a significant contribution; by way of comparison, the power of our nuclear park is 3.4 GW.

In Switzerland, due to the thermal gradient of 30°C per km, it is necessary to descend to depths of 3 to 5 kilometres to obtain sufficient temperatures for the production of electricity. However, drilling at such depths represents a major technical challenge and economic risk. This context is not conducive to attracting private investment. Added to this are the seismic risks potentially induced by drilling and the problem of popular acceptance [→ Q48]. The difficulty of financing and the lack of successful projects in Switzerland are currently the main obstacles to the development of geothermal energy in Switzerland, despite the fact that southern Germany already has seven power plants in operation and many more in the pipeline.

By 2018, only mid-depth geothermal energy (600-1500 m) will be exploited in Switzerland. A number of thermal baths benefit from this, as does the remote heating network in Riehen in the canton of Basel, which has been in operation for more than 20 years. On the other hand, deep geothermal energy for electricity production still lacks the maturity to make a significant contribution by the time our nuclear power plants are decommissioned, unless significant developments are made in the coming years. Five projects are currently under consideration in Switzerland, but the premature termination of the Basel and St. Gallen projects due to seismic events has seriously hampered the development of this technology [→ Q62]. In addition, a detailed assessment of deep geothermal resources and their exploitation potential is currently lacking. A project is being developed in Lavey (VD) with the aim of generating 4.2 GWh of electricity and 15.5 GWh of heat.

In view of the large potential of the resource, deep geothermal energy nevertheless remains one of the renewable technologies that could play an important role overall in the long term, including in Switzerland.