Drilling of geothermal doublet starts in Aulnay-sous-Bois, France
Artist's rendering of future geothermal heating plant in Aulnay-sous-Bois, France (source: Groupe Coriance)
Carlo Cariaga
27 Mar 2026
Drilling of a geothermal doublet and construction of the heating plant have started for a geothermal heating project in Aulnay-sous-Bois, France.
The Coriance Group has announced the start of drilling of a geothermal doublet in the commune of Aulnay-sous-Bois in the Île-de-France region of France. Construction of the heating plant is also expected to start by March 2026 targeting completion by early 2027.
The drilling work will extender over four months, from the end of March to early July 2026. The geothermal system is then scheduled to be operational in January 2027.
The geothermal doublet will be drilled to a depth of 1700 meters, targeting the Dogger formation. At this depth, thermal waters at around 70 °C are expected. Using this geothermal resource, 93% of the supply of the heating network will be from renewable energy. Gas will be used as a backup and supplementary source. Geothermal heating will ultimately reduce annual emissions by 28,000 tonnes of CO2.
The existing district heating network will also undergo a significant expansion, allowing more residents to benefit from stable heat prices. The existing 15-kilometer network, which already serves an equivalent of 5,500 homes, will be expanded by an additional 22 kilometers.
As part of their community engagement work, the Coriance Group will be hold a series of workshops for both children and adults to give simple explanations of how geothermal energy can be used to heat buildings while reducing environmental impact. The workshops will be held for three months across different municipal spaces.
Commissioning is expected to start soon for the geothermal heating plant that will serve the towns of Dugny and Le Bourget in Seine-Saint-Denis, which is being developed and operated by a subsidiary of the Coriance Group.
Source: Groupe Coriance
