in the Paris region, vibrating trucks search for geothermal sources underground

Geothermal energy, a clean energy, is an efficient way to heat ourselves while reducing our energy dependence. Vibrator trucks are trying to find new sources in Île-de-France.

A carbon-free energy source, available seven days a week, 24 hours a day and located under our feet? Geothermal energy is presented as an effective way to heat ourselves in winter while reducing our dependence on gas or electricity. But this resource still remains little exploited. To encourage the development of new projects, very special trucks, called vibrator trucks, have been traveling the roads of Île-de-France for a month, in the middle of the night. Their mission: to map the subsoil to identify hot water reserves.

Every night until April 4, three vibrator trucks are mobilized as well as around twenty operators for the “Geoscan” operation. That night, in Meudon in Hauts-de-Seine, when the vibrator truck came into action, it had the effect of a small earthquake. “We feel the vibrations, describes Alexandre Stopin, geophysicist at the Geological and Mining Research Bureau (BGRM). The truck is being mounted on its vibrating plate and it is vibrating. He left for eight hours of work.” Vibrations are produced every ten meters for 40 seconds, until the end of the night.

In one month, the operators will collect data over more than 280 km, in around a hundred municipalities. “The vibrations that are emitted by this truck will propagate into the subsoil and each time we have a change in rock, there is a part of this vibration that will rise to the surface like an echo”explains the geophysicist.

This echo is recorded by sensors placed on the surface and the data then makes it possible to obtain images of the subsurface. “What we see in the middle is the place where the vibration occurreddetails Alexandre Stoppin, and all the other traces are the recordings that were made by the sensors. It’s a bit like an ultrasound.”

Hot water reserves up to 3,000 m deep

With this operation, geologists hope to identify new geothermal sources in the west and south of Île-de-France. These areas have until now been little explored. “There are different depths. So here, the resources we are interested in are located between 500 meters deep and they can go up to 3 000 meters deep, underlines Camille Maurel, hydrogeologist at the Bureau of Geological and Mining Research. So we’re really going to image the entire subsurface and characterize the different formations of interest.”

The stakes are high at a time of decarbonization and energy sovereignty. We must focus on geothermal energy, insists Norbert Bommensatt, from Ademe, the Ecological Transition Agency: “There under our feet, we have a sheet of water at 1 500 meters deep, which is between 50 and 65 degrees. If we manage to valorize it, it’s really interesting, we have energy that is not sensitive to the volatility of fossil fuels.”

“It’s a truly promising energy for decarbonizing cities.”

Norbert Beumanzatt, engineer at Ademe

at franceinfo

In France, 59 urban heating networks are powered by deep geothermal energy. But Île-de-France remains the main region where deep geothermal energy is used with 54 installations and nearly a million Ile-de-France residents who benefit from it. This avoids the emission of 400,000 tonnes of CO2 per year compared to a gas boiler room. The objective is now to double or even triple the number of projects.