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The Bagneux geothermal heating network… The energy we need, underneath our feet!

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A local source of clean, renewable energy

The town of Bagneux on the outskirts of Paris committed to a long-term, green project to build a geothermal heating network to support the energy transition, reduce energy poverty and supply energy at competitive prices. Dalkia drew on its geothermal expertise to build and operate the network through its subsidiary Bagéops(*).
(*) Bagéops: "Ba" for Bagneux, "Gé" meaning earth in Greek and "Ops" meaning wealth in Latin.

Aerial view of Bagneux © Mairie de Bagneux

An eco-friendly investment

Geothermal energy involves harnessing the heat found below ground to supply heating and electricity. It is the number-three source of renewable energy in France, and the number-one renewable in the Ile-de-France region, where the geology is extremely conducive to such solutions. Geothermal systems provide a clean source of energy on tap, ensuring stable operating costs and reducing CO2 emissions tenfold compared with natural gas.
The Bagneux geothermal heating network (Bagéops) came on stream in autumn 2016 and reflects renewed interest in this fast-growing energy source. Nearly half of the population of Bagneux and part of the population of nearby Châtillon now benefit from the new system.

How does it work ?

Geothermal energy harnesses the natural heat within the earth. One or more "production" wells are used to extract hot water from the ground using a submersible pump. This water warms the water in the district heating network via a heat exchanger to provide heating and hot water to homes and buildings connected to the network. This is known as a geothermal loop. The water drawn from the ground then returns to the aquifer from which it was extracted through one or more recharge wells, without any use of chemicals. The hot water drawn from the ground flows through a closed loop, never coming into contact with the water piped to end users.


MW, the total output of the two heat pumps used.

9 500

households (municipal facilities, multi-dwelling units and companies).


km, the long network of heating network


Geothermal energy can overcome economic and environmental challenges while improving quality of life for local people. The town of Bagneux achieved this very goal with the Bagéops heating network. Environmental benefits : 15,000 tons of CO2 avoided every year; the equivalent of taking 5,000 cars off the road, 60% renewable energy rate. Economic benefits : users pay reduced VAT of 5.5%, the network supplies more than 75% of social housing as part of an outreach initiative to tackle the energy poverty affecting more and more households.

Illustration of the internal structure of the earth © Vadim Sadovski/Shutterstock

For Bagneux, geothermal energy meets two goals: environmental and social. The energy gives us a means to tackle the problem of climate change through a solution that emits no greenhouse gases. We have also found a new way to offset fuel poverty by offering families inexpensive energy at stable rates. All of this reflects our goal of continuing to build a modern, sustainable town that promotes solidarity.




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