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Heat from London Underground tunnels will be used to keep homes in Islington warm under a new scheme, Transport for London (TfL) has said.

From the beeb:

https://www.bbc.co.uk/news/uk-england-london-49482840?fbclid=IwAR2FQeotE8wrhq5oa9W5isEVm1Snt5pwkmjhdqnMgsXCPCPj9Nabk4SweVc

This did come up before, in the first "how things work" thread, and I found the same scheme announced by the mayor of London (https://www.london.gov.uk/press-releases-5910) in 2013 (yes, him ...). Quite why it's news now, when it's not finished and starting operation yet, I've no idea.

But to fill a few gaps in, this was the old City Road station that was closed in 1922 and has been used as a ventilation shaft. Such inter-station access or ventilation shafts are about the only place you can fit one of these heat extraction systems (as described in this CIBSE article (https://www.cibsejournal.com/technical/londons-tunnel-vision/)), but older deep tubes didn't have them. What was left of the surface building, at the north end of Central Street, has been taken down to build the head house.

The earlier CHP scheme, to which this adds on, used a diesel generator to provide heat and electricity (the energy centre is halfway down Central Street). In 2012 that was a green option ... doesn't that seem a long time ago now.