London will reuse excess heat from the underground to warm homes

The project will provide a cheaper, greener alternative for 450 houses this winter

Spotted: A joint project between Islington Council, TFL Underground and engineering firm Ramboll plans to use excess heat from the Northern Line to heat homes in the London Islington district. The project aims to provide a cheaper, greener alternative to current heating services. 

“We believe that the use of large-scale heat in this way connected to urban district heating systems will play a major part in decarbonising the UK’s heating energy demand,” said the director of district heating at Ramboll Lucy Padfield.

The main source of the heat comes from “Bunhill 2”, a ventilation shaft that expels excess heat from the Northern line. Engineering firm Ramboll has designed a heat pump to capture any excess heat from the shaft. This will then be further warmed to approximately 70 degrees Celsius and channelled to the Islington’s heat network, supplying heat and hot water to the local area. 

During the summer months, the process will be reversed. Instead of extracting heat, the ventilator shaft will be used to pump cool air into the tube tunnels.

The project forms the second part of Islington Council’s Bunhill Heat and Power scheme. The current network heats 700 homes, including local council housing, schools and a leisure centre. This second phase, which will be completed during the next few months, aims to heat 450 additional homes across the borough this winter.