Paris is heating its apartments with water pulled from an aquifer two kilometres beneath the city. This is not a new idea — it has been running since the 1970s.

 

"Paris is heating its apartments with water pulled from an aquifer two kilometres beneath the city. This is not a new idea — it has been running since the 1970s.

The Paris geothermal district heating network is one of the world's largest and longest-running urban geothermal systems. The Dogger aquifer — a porous limestone formation saturated with hot saline water at around 57 to 85°C — lies beneath much of the Paris Basin at depths between 1,500 and 2,000 metres. This warm water is pumped to the surface, its heat extracted through heat exchangers, and the cooled water reinjected into the aquifer. No combustion. No emissions. Just geology, physics, and engineering.

The network currently supplies heating to over 500,000 people across the Paris metropolitan area — roughly 5% of the region's heating demand. Geothermal installations operate in dozens of Paris suburbs including Creil, Meaux, Melun, and Limeil-Brévannes, with the largest systems serving tens of thousands of homes from a single doublet well pair.

France is now accelerating expansion. The energy crisis triggered by Russia's invasion of Ukraine in 2022 made the appeal of non-gas heating technologies urgent and political. Grants, loan guarantees, and fast-track permitting for new geothermal installations followed. By 2030, France aims to triple its geothermal heating capacity.

Paris does not advertise its underground infrastructure. It rarely does. The city focuses on the surface — art, architecture, cuisine. But two kilometres down, it has been quietly heated by the Earth for half a century.

Source: BRGM (Bureau de Recherches Géologiques et Minières), France, 2023

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