More than 10,000 homes heated by geothermal energy in Grigny and Viry-Châtillon, France

Geothermal heating plant of Sipperec in Rosny-sous-Bois, France (source: SIPPEREC)
Alexander Richter 20 Jun 2018

Following the inauguration of a new geothermal district heating sytem in Grigny and Viry-Châtillon in the greater capital region of Paris, France, there is a great social and environmental impact. Not only are up to 15,000 tons of CO2 abated, but the local population benefits from significant savings in heating costs.

Inaugurated earlier this month, the new heating network Grigny and Viry Chatillon already produces 124 GWh heat on an annual basis, the equivalent of heating for 12,000 homes

The new geothermal plant was planned and built to fight against “fuel poverty” of sensitive neighborhoods, as reported by Les Echos in France.

Les Sablons, Tuileries, Grande-Borne, Plateau Viry-Châtillon: all these so-called “sensitive” neighborhoods, mainly made up of collective habitats, are now exclusively heated and supplied with hot water by the inter-municipal geothermal network. In all, 10,000 dwellings, but also schools, gymnasiums, colleges of the two cities, are connected.

Put into service last winter, the network can already provide 124 GWh of heat per year, equivalent to 12,000 homes. Hot water is drawn from the basement of the two towns at a depth of 1,800 meters! At this level, its temperature reaches 71 ° C.

Specialized companies

The pumping operations are outsourced to companies specialized in the drilling of fossil fuels. After transit through the heating network, the water is reinjected into the aquifer. It warms up again slowly in contact with the rock. Thus, in principle, the underground water reservoir never dries up. This is the fourth geothermal heating network set up by the intercommunal syndicat in the greater Paris region for energy and communication networks (Sipperec), after Arcueil-Gentilly, Bagneux-Châtillon and Rosny-sous-Bois-Noisy -the- Sec -Montreuil.

Sipperec owns 51% of the renewable energy company, Seer, which manages the project; the city of Grigny 34% and Viry, 15%. “This project is entirely carried by the public, the development was long and complex, we had moments of concern, but today, everything is perfectly successful,” says Therese Leroux, president of the Seer, and mayor of Villiers-sur-Orge.

Great savings expected

The project’s advantages are environmental because geothermal energy does not produce carbon dioxide. The geothermal heating plant reduces the annual emission of 15,000 tons of CO2 in the atmosphere, the equivalent of the emissions of 700 cars, according to Sipperec.

But the goal of the operation is also social. Geothermal heating must be much cheaper than gas or electricity. Still according to Sipperec, the new heat network would save EUR 800,000 per year in heating costs and hot water on the cities. This should help the co-ownership Grigny 2, the second largest in France, to reduce its debt by several million EUR. “The inhabitants of this district have abnormally high heating costs that can reach up to 60% of the expenses,” says Laurent Georges, general manager of Sipperec.

Depreciation expense

These economies include the fact that geothermal energy, like all renewable energies (wood, gas, biomass, etc.), benefits from a reduced VAT rate of 5.5 %. In Grigny, this reduction is estimated between 15 and 20% for the 36 communal buildings. In the long run, the savings should increase further, estimates Laurent Georges. According to him, the price of geothermal heating should not increase, unlike gas. Because most of the costs come from depreciation and maintenance expenses and not from the fluctuation of energy prices.

It took an investment of around EUR 29.1 million to build the Grigny-Viry geothermal network. The State, through the Local Investment Support Fund, granted aid worth EUR 2.6 million, while the region and Ademe paid EUR 8.9 million.

Source: LesEchos, Sipperec