New seismic event puts longer pause on geothermal project in Alsace, France
Drilling rig on site of Vendenheim project, Alsace/ France (source: Fonroche)
Alexander Richter
6 Dec 2020
With a small earthquake experienced in the Alsace region of France and contributed to work by a geothermal developer, there is hope for a continuation yet also calls for a stop of the project.
Reported locally, a new earthquake contributed to activities of a geothermal project near Strasbourg in the Alsace region of France, has again hit the wider region.
With previous incidents in 2019 and this year, there are now calls by several local elected officials, including the president of the Eurometropolis of Strasbourg, for a stop of the project by Fonroche in Vendenheim. The project is supposed to provide electricity and heat for dozens of people. thousands of households.
Seismologists quickly classified this tremor as an “induced event”, that is to say caused by human activity. Its epicenter was located just below a well used by the Fonroche company for its deep geothermal power plant, installed between Vendenheim and Reichstett in the north of the agglomeration.
It was even following one of these earthquakes, of magnitude 3.1 on November 12, 2019, that the activity of the geothermal power plant was suspended. On 1 st October, the prefecture of the Lower Rhine had authorized “tracer tests” to determine whether the shock was related to geothermal activity, as claimed by the seismologists of the School and Observatory of Earth Sciences (EOST) or of natural origin as argued by Fonroche. These tests caused about ten tremors in one month.
The earthquake on Friday morning, for which Fonroche takes full responsibility this time, caused the complete shutdown of the geothermal power plant. It will be effective in 3 weeks to a month, the time to accompany the pressure drop in the “safety flow” of the underground reservoir. This period could be accompanied by new tremors, of a magnitude “between two and three”, according to Jean-Philippe Soulé, director of Fonroche Géothermie. A first aftershock was also felt at 11:10 am, of magnitude 2.6.
For the director of seismology research at the CNRS, member of the School and Observatory of Earth Sciences (EOST), Jean Schmittbuhl, the water pressure injected into this well is the cause.
“At the Soultz power station, which is cruising, the water is sent to 20 bars. On the Vendenheim side, the site is supposed to be inactive, but the water is sent to 60 bars. We learned that on Friday morning. If the pressure does not drop, more similar earthquakes are to be expected and a larger shock cannot be ruled out.”
Director of Fonroche Géothermie, Jean-Philippe Soulé, recognized a hard blow but does not think that this new earthquake puts an end to deep geothermal energy in the Eurometropolis: “All over Europe, geothermal power plants operate with micro-seismic activity that is not felt by the inhabitants. This technology, which pumps hot water to one location to return it further, is reliable but requires some adjustments at start-up, which are sometimes difficult. Here we are in the case of a difficult start. ”
For the rest, he wants to “think about the possible options and share them with the territory”. He presents technical solutions: “Additional cleaning, different jobs, different positioning…” But “for the moment, this is technical and scientific work”. The time for debate, and political support, will come next. The total shutdown of the site will last at least several months.
Fonroche Géothermie, a subsidiary of the Fonroche group specializing in renewable energies, has invested 90 million euros in this equipment, the authorization of which was obtained against the advice of the mayors of the municipalities concerned. The local authority has been relying on this technology for several years to achieve its energy self-sufficiency objectives in 2050. Fonroche first proposed the creation of a deep geothermal power plant at Robertsau, north of Strasbourg, near Seveso classified installations. from Port-aux-Pétroles. The Eurometropolis ended up withdrawing its support for this project in front of the opposition of the inhabitants and Fonroche had withdrawn in 2015, after an unfavorable opinion of the public inquiry.
Three other projects are submitted near Strasbourg. The one in Illkirch-Graffenstaden is operated by ÉS Énergie and is not in operation. Fonroche also has two drilling authorizations, one between Eckbolsheim and Oberhausbergen, the other in Hurtigheim. But she hasn’t started digging yet.
Source: Rue89 Strasbourg
