The term "geothermal energy" refers to the energy that is stored in the form of heat below the earth's surface and is produced from the decay of naturally occurring radioactive elements. The temperature of the ground is constant throughout the year at a depth of around 15 metres below the surface. In Switzerland, the temperature at a depth of 5,000 metres is approximately 200° C. Geothermal energy can be utilised with the aid of a variety of methods:
Vertical geothermal probes, groundwater wells, geothermal structures (foundation piles, diaphragm walls) and hot tunnel water are normally used in combination with a heat pump for heating - and in some cases, cooling - purposes. By means of deep drilling, hot groundwater sources (aquifers) can be tapped into, and energy can be extracted from dry bedrock using enhanced geothermal systems technology. At temperatures above 100° C it is possible to produce electricity, while the residual heat can be used for heating purposes.
Currently, no electricity is being produced from geothermal sources in Switzerland. One of the main obstacles to the development of this technology is the fact that very little is known as yet about the local conditions deep underground. For this reason, geothermal energy projects are able to benefit from a guarantee financed from the network surcharge fund. In this way, the risks associated with exploration can be reduced.
The potential for geothermal electricity production in Switzerland is very high, but there is still a great deal of uncertainty regarding the associated costs and feasibility. Nonetheless, this inexhaustible, clean and constant energy source offers a variety of highly attractive advantages: it is CO2-free, yields base-load energy and requires very little space. Experts anticipate that, by 2030, around a dozen geothermal plants will be in operation which will produce a combined total of 800 GWh of electricity. In the longer term it is conceivable that a significant proportion of the electricity consumed in Switzerland could be produced at geothermal power plants.