Geothermal district heating has helped to reduce carbon emissions from Paris’s three airports by around 63 per cent since 2009, new data from the airport operator show.

Groupe ADP, which runs the city’s Charles de Gaulle, Orly and Le Bourget airports, reported that the reduction in CO2 emissions took place between 2009 and 2016.

A 135 MWth/12 MWe geothermal district heating system, which came online in 2011, provides 70 per cent of the heat and sanitary water used in Orly’s terminals and new office facilities and has saved 50,000 metric tonnes of CO2 over the system’s lifetime, Groupe ADP said.

In addition, the system has reduced Orly’s gas use by 4000 tonnes of oil equivalent, allowing the airport to reduce its CO2 output by around 9000 tonnes annually.

The district heating system features two 1800-metre-deep wells which produce water at 74 degrees C. The water is then distributed through a 35 km pipe network.