The European Research Project

Soultz-sous-Forêts, France

The European Geothermal Hot-Dry-Rock Project for extracting energy from hot underground started out in Soultz-sous-Forêts in 1987. The project's objective was to develop concepts for producing thermal energy from fractured crystalline rock and to design the technologies needed for massive stimulation. The final goal was a pilot plant for heat and power production.


soultz-sous-forets EEIG "Heat Mining"



 2 x 1.5 MW electrical power (1.5 MW capacity currently installed)






Vertical Depth


5.000 m




> 180°C


Flow Rate


2 x 35 l/s






Power Plant






1987 to 2005




2005 to 2008


Status feed-in of up to 1.5 MWe



Géothermie Soultz online





The success of the Soultz project is the result of twenty years of international cooperation, which started out with the geological and geophysical exploration of the underground and is now focusing on optimizing the layout of both the thermal water circulation and the power plant, testing production pumps and different materials.


Currently, the project is coordinated and operated by the EEIG "Heat Mining" (GEIE Exploitation Minière de la Chaleur, an industrial consortium consisting of the following companies: Electricité de Strasbourg, Electricité de France, EnBW and BESTEC). The project is presently being financed by the industrial partners.


The project is still of the critical importance for the development of geothermal energy in Germany. Being the only existing petrothermal project in the region, the Soultz project facilitates the technical development and testing of the huge energy potential stored in the local crystalline rock. The project also serves as a platform for basic research and testing, particularly regarding the transfereability of data to other projects in the Upper Rhine Graben. Soultz is also the perfect location for evaluating different power plant and pumping technologies.