Re: The cost in kW
If one person paid for a TfL bus fare by Bitcoin, the transaction would use enough electricity to take that bus to Leeds
Surely - the amount of power used to derive a bitcoin is a function of when the coin solution was found? Early coins were quick and easy to make, current ones not so much. And (by design) it's only ever going to get harder to derive a coin so the energy cost is only ever going to go up.
Which is why the early bitcoin miners have such a huge stack - the early coins were not hard to compute and (even with the fairly primitive methods used) lots of coins were minted quickly.