Geothermal and biomass heating in France

Imhoff Industrie, a VINCI Energies business unit, has taken on this innovative power plant project combining geothermal energy and biomass energybiomasse 2.

The municipality of Fontoy (Moselle) has started an innovative project: rehabilitating a former iron mine, operated for more than 100 years and abandoned at the beginning of the 1950’s, and to use it to supply a geothermal heat pump which, accompanied by a biomass boiler, will provide heat and hot water to municipal buildings. More than the mine itself, it is the stock of water that it contains that will supply the pump. Over time, underground water seeped into the mine, which now has a large reserve of water.

The water filling the mine, pumped at a depth of 40m at a temperature of about 12°C, will be used by the heat pump to supply the low and very low temperature networks. A biomass boiler will be used as a backup, using wood from local producers, while a gas boiler will be used for major cold spells.

This network should reduce the annual gas consumption of the municipality by 348 MWh (or the annual consumption of a school) and avoid the emission of 87 tons of CO2, (the equivalent of a medium-engine car driving 348,000 km/year). This network will operate at 90% thanks to renewable energy, of which 35% which will come from the mine water. This is the first time in France that the same network uses both geothermal energy and biomass. In addition to its environmental value, this project is a good example of a successful reconversion of an old mine through the use of other underground resources.

At the work site, Imhoff Industrie is in charge of the installation of the heat pump, the boiler plant using wood chips, the building of 7 heat distribution sub-stations and the realization of the distribution network, the making of the high and low temperature heat networks to supply the Atre retirement home and its extension and the installation of the cooling loop via a 250 lm pumping network on shaft water from mine galleries. The work also includes the electricity, the Centralized Technical Management, the connection to the existing urban network, the civil engineering (opening of the building for the passage of the wood process) and the painting of the premises.