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

Geothermal energy, a clean energy, is an efficient way to keep warm while reducing our energy dependency. Vibrating cars are trying to find new resources in Île-de-France.

A carbon-free source of energy, available seven days a week, 24 hours a day and located under our feet? Geothermal energy is presented as an efficient way to heat up in the winter while reducing our dependence on gas or electricity. However, this resource is still underutilized. To support the development of new projects, very special trucks, called vibration trucks, have been driving the roads of Île-de-France in the middle of the night for a month. Their mission: to map the subsoil and identify warm water reserves.

Every night until April 4, three vibratory cars and about twenty operators are mobilized for the “Geoscan” operation. That night in Meudon in the Hauts-de-Seine, when the vibrating truck went into action, it caused a small earthquake. “We feel the vibrations describes Alexandre Stopin, a geophysicist from the Geological and Mining Research Bureau (BGRM). The trolley is mounted on a vibration plate and vibrates. He left for eight hours of work.’ Vibrations are produced every ten meters for 40 seconds until the end of the night.

In a month, the operators collect data on more than 280 km, in roughly a hundred municipalities. “The vibrations that this car puts out will travel into the bedrock, and every time there’s a change in the rock, there’s some of those vibrations that will come up to the surface as an echo.”explains the geophysicist.

The vibrations create an echo, which then allows images of the subsurface to be created.  (BORIS HALLIER / FRANCEINFO / RADIO FRANCE)

This echo is recorded by sensors placed on the surface, and the data then allows images of the subsurface to be obtained. “What we see in the middle is where the vibration happeneddetails Alexandre Stoppin, and all other tracks are records that were taken by sensors. It’s a bit like an ultrasound.”

Warm water reserves up to a depth of 3,000 m

With this operation, geologists hope to identify new geothermal resources in the west and south of Île-de-France. These areas have so far been little explored. “There are different depths. So here the resources we are interested in are located at a depth of 500 meters and can reach up to 3 000 meters deep, points out Camille Maurel, a hydrogeologist at the Office of Geological and Mining Research. So we’re really imaging the entire subsurface and characterizing different features of interest.”

In an age of decarbonisation and energy sovereignty, the stakes are high. We need to focus on geothermal energy, insists Norbert Bommensatt of Ademe, the Agency for Ecological Transformation: “We have a sheet of water under our feet on the 1st 500 meters deep, which is between 50 and 65 degrees. If we manage to evaluate it, it’s really interesting, we have energy that is not sensitive to the volatility of fossil fuels.”

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

Norbert Beumanzatt, engineer at Ademe

at franceinfo

In France, 59 urban heating networks are powered by deep geothermal energy. However, Île-de-France remains the main region where deep geothermal energy is used, with 54 installations and almost a million residents of Ile-de-France benefiting from it. This avoids 400,000 tons of CO2 emissions per year compared to a gas boiler. The goal now is to double or even triple the number of projects.

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