On Tuesday, 7th June 2016, Ségolène Royal, the French Minister of the Environment, Energy and Marine Affairs, has inaugurated the brand new Rittershoffen geothermal plant located in Northern Alsace, France. The deep geothermal plant provides overheated steam to a starch factory located in Beinheim, 15 km away from the geothermal site. The geothermal brine (100g/L) is pumped from a fractured reservoir located at the interface between the sedimentary cover and the top crystalline basement. Two geothermal wells (production, injection) with depths of 2 600 m have been drilled from 2012 to 2014. Between the geothermal doublet and the starch factory, located along the Rhine river, a 15 km surface loop for transporting the heat to the industrial site, has been built in 2015.

The production well discharges a very saline geothermal fluid on the surface with a temperature of 165 °C. After drilling operations, due to a low initial productivity index, the first geothermal well was successfully stimulated thermally, chemically and hydraulically. The post-stimulated injectivity index allows reaching an operational flowrate of 70 kg/s. Due to the high salinity of the geothermal fluid, the geothermal energy is transferred via a series of tubular heat exchangers to fresh water circulating within the horizontal loop. Thus, 24 MWth of geothermal energy are provided to the starch factory. It allows reducing annual CO₂ emissions by 39 000 tons.

Rittershoffen is now operational and has shown the maturity of the environmentally friendly Enhanced Geothermal System (EGS) technology developed by Électricité de Strasbourg (ÉS), with the help of its scientific and technical partners. The plant was built by ÉS, Roquette Frères and the Caisse des Dépôts with the financial backing of the French Agency for Energy and Environment (ADEME), and the Regional Council of Alsace. The three partners have formed a joint venture with a 40 % share each held by ÉS and Roquette and 20 % by the Caisse des Dépôts.