France's €35 Million Géomy3 Geothermal Heating Station Officially Commissioned

en.Wedoany.com Reported - The Géomy3 geothermal heating station in Le Chesnay-Rocquencourt, Yvelines, France, has held its official commissioning ceremony. With a total investment of €35 million, the project utilizes geothermal water at a depth of approximately 1,500 meters to provide heating and domestic hot water for a heat load equivalent to 9,000 homes. The facility began supplying geothermal heat in June 2026; following official commissioning, geothermal energy accounts for 75% of the energy supply of the Parly 2 district heating network, and is expected to provide approximately 71 GWh of renewable heat per year.

Géomy3 was jointly developed by French energy company ENGIE, the Yvelines departmental government, the Le Chesnay-Rocquencourt municipal government, and the Parly 2 residential property owners. Of the total project investment, €8.9 million came from the French Agency for Ecological Transition (ADEME) heating fund. The project company's shareholding structure is 75% held by ENGIE, 14% by the Yvelines departmental government, 6% by the municipal government, and 5% by Parly 2 residential property owners, with ENGIE responsible for operating the heating facilities.

The geothermal heating station utilizes geothermal water from the Dogger aquifer in the Paris Basin, employing a geothermal doublet system consisting of a production well and a reinjection well. The geothermal water releases heat through surface heat exchange facilities before being reinjected into the aquifer; the recovered thermal energy is transported via newly built connecting pipelines to the existing Parly 2 district heating facilities. The project constructed approximately 3 km of connecting pipelines and completed adaptive retrofitting of the existing gas heating facilities and customer heat exchange stations.

The Parly 2 residential area comprises 278 buildings and approximately 7,500 homes, with a resident population of about 15,000. The new geothermal facility has been connected to Parly 2, the Nouvelle France residential area, and several public buildings, with heating targets including the André Mignot Hospital of the Versailles Hospital Center, Guynemer School, Charles Péguy Middle School, the municipal swimming pool, and the town hall. The project distributes heat through the existing approximately 20 km district heating network, serving a total scale equivalent to the heat demand of 9,000 homes.

Following project commissioning, the Parly 2 district heating system—which previously relied primarily on natural gas—has been adjusted to an energy mix with geothermal as the primary heat source. According to the project's published annual operating targets, the geothermal system is expected to provide approximately 71 GWh of heat per year and reduce carbon dioxide emissions by approximately 18,500 tonnes. The above heat supply and emission reduction figures are annual projected targets of the project, not cumulative operating data already achieved as of the commissioning date.

The local government has also proposed advancing a subsequent district heating expansion project, VerdY, which plans to supply renewable heat to five municipalities—Le Chesnay-Rocquencourt, La Celle-Saint-Cloud, Noisy-le-Roi, Bailly, and Bougival—starting in 2028. This project is a separate subsequent expansion plan and is not included in the 9,000-home equivalent heating scale of the Géomy3 official commissioning.