Renewable energy: geothermal energy and biomass combined for an innovative heating network

How could a former iron mine in Lorraine be converted for use in the establishment of a "green" urban heating network? Imhoff Industrie, a VINCI Energies business unit, is taking on this project for an innovative energy plant combining geothermal energy and biomass.

biomass-geothermy-fontoyHow to rehabilitate a former iron mine that was operated for more than 100 years and abandoned at the beginning of the 1950’s? The municipality of Fontoy (Moselle) has launched an innovative project: 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 supply 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. 

An urban heating network based on local renewable energy

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 for extra heating, using wood from local producers while a gas boiler will be used for spells of very cold weather.

 Combining geothermal energy and biomass in the same network: one of the first experiences in France

This network should make it possible to reduce the annual gas consumption of this municipality by 348 MWh (or the annual gas consumption of a school) and avoid the emission of 87 tons of CO2, (the equivalent of a car with an average engine driving 348,000 km/year) . This network will operate at 90% thanks to renewable energy, 35% of 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.

For this project, Imhoff Industrie is in charge of the installation of the heat pump, of the boiler plant using wood chips and the creation of 7 heat distribution sub-stations and the making of the distribution networks, the establishment of 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 ml 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.