FWIW, from BBC:
Bitcoin's energy consumption 'equals that of Switzerland'
https://www.bbc.com/news/technology-48853230
Bitcoin uses as much energy as the whole of Switzerland, a new online tool from the University of Cambridge shows.
However, one expert argued that it was the crypto-currency's carbon footprint that really mattered.
Currently, the tool estimates that Bitcoin is using around seven gigawatts of electricity, equal to 0.21% of the world's supply. That is as much power as would be generated by seven Dungeness nuclear power plants at once.
Mr de Vries said that Bitcoin still appears to use far more energy per transaction than all the world's banks put together, when considering the amount of energy used by data centres.