On 21/10/2020 13:23, Chris Hogg wrote:

Been talked about for several decades. The Rosemanowes 'hot rocks'
project in Cornwall in the 1970's was one such.
https://en.wikipedia.org/wiki/Rosemanowes_Quarry
Never came to anything, even though it was said the be the site in the
UK with the highest heat flow in England at 120 milliwatts per square
metre (which sounds rather small to me; if correct, perhaps it's not
surprising nothing came of it).

snipped

Small scale use here...

https://jubileepool.co.uk/pool-info/geothermal/

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Cheers
Clive