Another geothermal heating project to kick off within larger area of Paris, France

Another geothermal heating project to kick off within larger area of Paris, France Rueil-Malmaison, Place de l'Église, France (source: Pymouss44, commons, wikimedia)
Alexander Richter 18 Feb 2021

Local developer set up by Engie Solutions and the local municipality, the commune of Rueil-Malmaison in the greater Paris area is pushing ahead with a planned geothermal heating project. Drilling is to start around mid-2021.

The geothermal potential of the Paris Basin is no longer a secret with numerous separate geothermal heating systems. Like other cities in the Paris region, the city of Rueil-Malmaison, a western suburb in the Hautes-de-Seine department of the Ile-de-France region, is planning the drilling of a geothermal well  in 2021.

With regards to concerns related to energy prices, noise pollution and seismic risk, the City is anticipating and responding to concerns of residents, while the preparation work has just started. The future heating system is expected to come into service in May 2022.

Two 1.5 km deep boreholes

Created for this purpose,  GéoRueil , owned 88.5% by  ENGIE Solutions and 11.5% by the City of Rueil-Malmaison, will dig the well and build the geothermal installation. This company, with the public service delegate which has not yet been validated, will invest in this project estimated at 65 million euros excluding taxes, including 23 million that the town hall hopes to see subsidized by ADEME (Environment Agency and energy management) and the Ile-de-France region .

GéoRueil will carry out two boreholes (one for pumping water, the other for its reinjection) over 1,500 meters deep on the site of the former Robespierre nursery school , rue Gustave Flaubert. The sports field requisitioned for the works will be returned in the summer of 2022. Of the 5,000 m 2 of the plot, around 1,000 m 2 will  belong to SAS GéoRueil.

Non-potable water from the Dogger aquifer , heated to 62 degrees Celsius due to its closer proximity to the earth’s core, will produce heat via a heat exchanger. Once cooled, it will be returned to the underground aquifer about one kilometer from the sampling point “so that the water table remains at a constant temperature”, as mayor Patrick Ollier explains.

60% of homes affected

The energy produced will circulate in a network that will reach 25 kilometres within five years. It will first provide collective buildings, “that is to say social landlords and condominiums”, before an extension to individual residences. According to the deputy mayor in charge of town planning, the eco-district and land law, Monique Bouteille , geothermal energy will eventually supply 60% of the homes in the region and, in 2025, the network could be extended to the offices of Rueil-sur-Seine (behind the RER station).

Between 15% and 20% savings over 10 years

In 2021, the price of gas climbs by 3.5% and that of electricity by 1.6%. Mayor Patrick Ollier explains: “The price of these energies is increasing and will continue to increase. With geothermal energy, it will be complete price stability. The exit price is around EUR 72 per MWh. Today, one MWh of electricity is EUR 157 and one MWh of gas for consumers is EUR75. ”

According to municipal estimates, this difference amounts to 15 to 20% savings over 10 years for users. The renewable nature of energy should also reduce carbon dioxide emissions linked to consumption in the region.

“The use of geothermal energy will prevent the emission of 21,000 tonnes of CO2 into the atmosphere each year, ie the equivalent of 11,600 vehicles in circulation.”, so City of Rueil-Malmaison

Earthquake risks?

In Alsace,  a geothermal borehole above a geological fault caused tremors  on several occasions. In the Paris Basin, the context is different. “It is not at all the same technique, nor the same depth,” explains Monique Bouteille.

Earthquakes are therefore unlikely. To ensure this, the dug hole will be continuously monitored by sensors and the tools used will be fitted with safety systems.

Noise in schools?

Another concern crosses the residents and the two neighboring schools: noise pollution. The drilling will be carried out 24 hours a day from May to August. Here again, the ENGIE Solutions expert is reassuring. Acoustic protections are planned “to reduce the sound footprint as much as possible”. The noise barriers will isolate the rig. The tools will be powered by the electrical network and not by noisier generators. Deputy Mayor Monique Bouteille announces that noise modeling is underway to reduce it as much as possible.

Overview of Planned Work

  • schedule February to May 2021: installation of the drilling platform
  • May to August 2021: drilling
  • September 2021 to May 2022: construction of the power plant and its equipment
  • November 2021: Launch of network works
  • Testing and commissioning in May 2022