One of the largest geothermal district heating projects is now working on a third plant at Villejuif in the greater Paris Region, France.
Ahead of the Climate meetings in Paris this December, there are news about new geothermal heating development.
In 1985, a geothermal heating network was developed, which provides sufficient heat for about 29,000 inhabitants of Val-de-Marnais in the greater Paris region in France.
The Paris basin has five major geothermal aquifers, the best known is that of Chevilly-Larue, l’Haÿ-les-Roses and Villejuif, at about 2,000 meters deep. It extends on over 15,000 km 2 with water ranging from 56 to 85 degrees Celsius.
The geothermal heating system that supplies the towns of Chevilly-Larue, the Hay-les-Roses and Villejuif is one of the largest of its kind in Europe, it is managed by the firm Semhach. The network is currently supplied by two geothermal plants.
Each unit is comprised of two wells, a “doublet”, a drilling and production drilling of reinjection. Concretely, a well for pumping hot water and one for re-injecting in the same layer, at least one kilometer away so as not to cool the hot water source. A mandatory re-injection to preserve the resource and also because water is very salty, it can not be re-injected surface for environmental reasons.
The wells consist of a steel casing subjected to severe corrosion in particular due to its salinity. So, chemicals are used for maintenance, but in case of leakage, there are risks of pollution and especially groundwater. But there is a new solution being applied here for the rehabilitation of two geothermal power stations of the network of Semhach is ongoing. Rather than re-introducing new steel tubes in the wells, they are fiberglass tubes which replace them.
The company is now building a third plant for the heating network of Villejuif. An additional 10,000 people should benefit from a very advantageous energy, price according to Semhach, which is “30% cheaper than gas.”
The new plant is expected to start operation in the winter of 2016 and supply heat to nearly 40,000 households in total by 2020, saving the planet more than 36,000 t of CO2 per year by not no burning fuel.