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The energy emitted by subways or data centers to heat our homes.

The technology has been tested for several years in major cities around the world.

© Marie Fontaine -

Heat from subway used to heat buildings.

In the subway, the thermal energy known as "waste heat", released by engines, brakes and human promiscuity can be reused to heat buildings thanks to heat pumps.

The residential area of Islington, in the northeast part of London, completed the installation of a system at the end of 2019 to provide heating and hot water to more than a thousand homes (1350 in total), as well as a school and two leisure centers. The heat pump system is installed at the former Chengcheng Road station on the Northern Line, an underground line that breaks all heat records and can reach 40 degrees in summer.

Clapham Common, Northern line
Clapham Common, Northern line

A year ago, the social landlord 'Paris Habitat', in partnership with RATP (the Parisian transport company), conducted a similar experiment on line 11 of its metro. The objective was to supply 35% of the needs of a 20-unit building located opposite the Georges Pompidou Center in the heart of the French capital.

Centre Georges Pompidou, Paris
Centre Georges Pompidou, Paris

This system will also allow for better ventilation of the metro during summer to ensure less suffocating and less polluted air for users.

A similar method to recover energy from data centers.

The so-called "digital" heating, consists of recovering this "fatal" heat emitted by computer equipment when they are running.

Data center
Data center

The solution appeared in France in 2017, where the Butte-aux-Cailles swimming pool was able to maintain a constant water temperature of 27°C thanks to heat of computer servers.

More and more companies specialized in this field are now installing mini data centers in the boiler rooms of buildings. This allows 10 to 50 households to benefit from renewable heating at the same price as natural gas.

Today, installations of this type exist in many main French cities, such as Lyon, Nantes, Lille and Bordeaux.

Similar initiatives have been deployed elsewhere in the world, notably in the city of Odense in Denmark, which is heated by Facebook's data centers.

These intelligent initiatives clearly show that by applying the principles of the circular economy to the energy sector - "nothing is created, nothing is lost, everything is transformed" - we can accelerate the energy transition for the greater good of the planet.


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