Commissioning of the Terra Confort Geothermal Network: A Major Milestone for the Territory’s Energy Transition
Deep Geothermal Energy: Tapping Local Heat from the Earth
The Terra Confort network is built around a geothermal plant that exploits the heat of the Dogger aquifer, located between 1,600 and 1,700 metres below the Paris region. At this depth, the water naturally reaches a temperature of around 68 °C, making it possible to produce a stable and abundant source of heat for district heating and domestic hot water.
The geothermal doublet – the pair of wells needed for production and reinjection – was drilled between summer 2025 and January 2026, demonstrating the technical expertise of Groupe Coriance in deep geothermal energy. Thanks to this commissioning, the network now reaches 88% renewable and local energy, an exceptional performance for a district heating system of this size.
A €96 Million Structuring Project for the Territory
An Investment Matching Ambitious Climate Goals
With a total investment of €96 million, the Terra Confort network is a structuring project for Châtenay‑Malabry, Le Plessis‑Robinson and, more broadly, the Greater Paris metropolitan area. This financial effort covers the construction of the distribution network, the geothermal plant and the upgrading of subscriber substations.
The project includes in particular:
- A heat distribution network that will eventually reach 37.5 km in length.
- The installation or renovation of 213 substations supplying buildings.
- The construction of the geothermal plant and associated production facilities.
Beyond the figures, this investment expresses a strong political will to speed up the local energy transition by using resources available in the territory rather than imported fossil fuels.
Strong Support from the State and Public Partners
Recognised as a project of strategic interest, Terra Confort receives substantial financial support from the French State via the Heat Fund managed by ADEME (the French Agency for Ecological Transition), amounting to €29.25 million. The Greater Paris Metropolis also contributes €1.9 million, confirming the importance of Terra Confort among the major energy projects in the Paris basin.
This funding setup illustrates a virtuous model of cooperation between:
- Local authorities that drive the vision for the energy transition.
- National public bodies that provide funding and technical expertise.
- Specialised private operators, such as Groupe Coriance, which ensure design, operation and long‑term technical performance of the network.
A High‑Performance, Low‑Carbon and Cost‑Effective Heating Network
Significant Environmental Benefits
At full capacity, the Terra Confort network will supply 133 GWh of heat per year, mainly from geothermal energy and other local renewable sources. This production will avoid emitting around 31,500 tonnes of CO₂ annually, equivalent to the emissions of approximately 26,250 vehicles, a very tangible environmental impact for the territory.
The drastic reduction in greenhouse gas emissions goes hand in hand with decreasing dependence on imported fossil fuels, whose prices are often volatile. By prioritising a local, renewable resource, the network helps the municipalities move towards carbon neutrality while making their energy system more resilient.
Competitive, Stable Heat Prices Independent of Fossil Fuels
One of geothermal energy’s main advantages is the stability of its cost over the long term, because it relies on a natural, free resource once the infrastructure is built. Terra Confort can therefore offer heat at competitive and stable prices, shielded from sudden jumps in gas or oil markets.
For residents and businesses in the area, this translates into:
- More predictable energy bills over the long term.
- A reduced risk of energy poverty linked to spikes in fossil fuel prices.
- Enhanced value for buildings connected to a renewable district heating network.
This economic dimension is central to the vision promoted by the municipalities. As Carl Segaud, Mayor of Châtenay‑Malabry and President of Vallée Sud – Grand Paris, emphasises, providing residents with urban heating that is ecological, modern and affordable is a key priority.
A Project Carried Out Closely with Residents
Education and Transparency During Construction
The success of a geothermal urban project also depends on public support, as residents are directly affected by works, changes in their surroundings and future heating arrangements. For Terra Confort, a particularly robust communication and outreach plan was set up, especially during the drilling phase.
A dedicated educational bungalow was installed on site and welcomed 950 visitors, including 285 schoolchildren and 451 local residents. This space made it possible to:
- Explain how deep geothermal energy works and its role in the energy transition.
- Present the different stages of the project, the temporary constraints and the long‑term benefits.
- Answer questions about safety, environmental impact and the siting of installations.
This participatory approach shows that the energy transition is not only a matter of policy documents; it is built in dialogue with citizens.
Rooting the Energy Transition in Everyday Life
By involving residents, schools and neighbours at key moments of the project, the municipalities turn a technical construction site into a shared collective experience. Children who visit the educational bungalow become ambassadors within their families, and residents gain a better understanding of the project, which strengthens trust.
This close relationship helps anchor the idea of energy transition in daily life: district heating networks, geothermal plants and substations become familiar features of the urban landscape, associated with a more sustainable future.
Terra Confort: An Exemplary Network for Carbon Neutrality
Controlling Costs and Emissions Over the Long Term
With the commissioning of the geothermal system, the Terra Confort network is designed to:
- Keep energy costs under control over time thanks to a local, stable resource.
- Significantly cut greenhouse gas emissions by replacing fossil fuels with renewable energy.
- Strengthen local energy sovereignty by harnessing the potential of the Paris region’s subsurface.
- Support municipalities in achieving their long‑term sustainable development goals.
Taken together, these elements make Terra Confort a model low‑carbon district heating network, aligned with France’s national carbon‑neutrality targets and the commitments of the Greater Paris Metropolis.
A Symbol of Local Energy Sovereignty
In a context of tension on global energy markets, controlling local resources is increasingly strategic. By exploiting the Dogger aquifer, Terra Confort gives the municipalities a powerful tool for energy sovereignty, capable of meeting a significant share of their heating needs without relying on imported fuels.
This approach reduces vulnerability to crises and allows territories to retain control over their energy choices while fully assuming their role in fighting climate change.
Coriance: A Leading Player in Geothermal Energy in Île‑de‑France
Proven Expertise in Deep Geothermal Systems
Deployment of Terra Confort is part of Groupe Coriance’s wider strategy, as it is recognised as a leader in geothermal energy in Île‑de‑France. The group currently operates 39 geothermal wells in the region, making it a key player in managing low‑carbon district heating networks.
Overall, Coriance runs 47 heating and cooling networks, with 73.6% of the heat supplied coming from renewable or recovered energy. The group’s stated objective is to operate more than 50 geothermal wells by 2030, further increasing the share of geothermal energy in the regional energy mix.
A Committed Partner for Local Authorities
Coriance’s environmental performance reflects a strong commitment to helping local authorities reduce their emissions and promote sustainable energy solutions. Drawing on proven technologies and a long‑term vision, the group contributes to turning cities into territories that are more energy‑efficient, more resilient and more autonomous.
The Terra Confort network is therefore both a showcase of Coriance’s expertise and, above all, a concrete example of what tomorrow’s district heating networks can look like: renewable, efficient, financially sustainable and co‑designed with residents.
Terra Confort as a Milestone for the Energy Transition
The commissioning of the Terra Confort geothermal network is more than just a technical achievement; it embodies a new way of thinking about cities and energy. By bringing together environmental, economic, social and educational dimensions, the project offers an inspiring roadmap for other territories that want to accelerate their energy transition.
With 88% renewable and local energy, 133 GWh of green heat delivered each year and 31,500 tonnes of CO₂ avoided annually, Terra Confort proves that it is possible to combine high‑quality service for residents with ambitious climate action. Driven by the municipalities, supported by the State and operated by a committed specialist, this geothermal network stands out as one of the most concrete expressions of the energy transition in Île‑de‑France.
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Source : Group Coriance
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