Geothermal heating plant inaugurated at Fort de L’est in Saint-Denis, France
Inauguration ceremony of the Fort de L'est geothermal heating plant in Saint-Denis, France (source: Sabine Le Néchet / City of Saint-Denis)
Carlo Cariaga
24 Nov 2025
A new geothermal heating plant has been inaugurate at the Fort de L'est site, marking the third such facility in Saint-Denis, France.
A new geothermal heating plant has been inaugurated at the Fort de L’est site in the commune of Saint-Denis in France. Operated by Plaine Commune Energie, a local subsidiary of ENGIE Solutions, the new heating plant has a total capacity of 18 MWth (geothermal and heat pumps) and supplies the heating demand of an equivalent of 7,500 homes.
Under the management of the Joint Syndicate for Heat Energy Networks (SMIREC), around 50 companies were mobilized from 2023 to 2025 to build 9 kilometers of heating network and drill a geothermal doublet to 1800 meters depth, targeting the Dogger Formation. The project required an investment of EUR 29.5 million. The Fort de L’est heating plant now runs on an exemplary combination of biomass and deep geothermal energy with gas as an emergency fuel supply.
The Fort de L’est facility is now the third geothermal heating plant in Saint-Denis, after the launch of geothermal heating in Pleyel in late 2023 and another geothermal heating plant in Villetaneuse, which started operations only earlier this year. According to a recent report by the municipality, about 66% of the heating network in Saint-Denis is being supplied by renewable energies as of 2024.
“The commissioning of this power plant is fully in line with the trajectory we have set with the Territorial Climate Air Energy Plan: a territory that reduces its emissions, strengthens its energy sovereignty and protects the quality of life of its inhabitants,” said Mathieu Hanotin, Mayor of Saint-Denis.
“This new power plant, in the Plaine Commune area, demonstrates that the alliance between public governance and industrial ambition can produce concrete solutions for the climate. It reminds us that the energy transition is not just a goal: it is built here and now, ” added Laurent Monnet, President of SMIREC.
Earlier this year, the French Government through the Ministry of Energy and Industry published a document with seven concrete measures to support sustained geothermal growth for heating, both in mainland France and in other territories.
Source: Saint-Denis and SMIREC
