For perspective - a SINGLE dam on the Columbia River (of the appx. 10 owned between Chelan, Douglass, and Grant counties) generates well over 2000 Megawatts of electricity.
257 Megawatts compared to human power consumption as a whole is trivially small - and SOME of that usage replaces "space heating" power/fuel usage for at least part of the year for most of us home miners and to some small degree for commmercial miners.
I suspect most major farms are running "green" through power from various hydroelectric projects around the world - specifically including at least some and possibly ALL of the major Chinese farms.
MOST major industrial powers burn a fair bit of coal for power generation, as hydro and wind are NOT PRACTICAL for many areas.
There seems to be an assumption that Bitcoin mining should be more electrically efficient.
It's been moving that way for a long time now. Every new ASIC generation has been quite a bit more efficient than the generation before it.
The down side is more folks have gotten involved, moving the target higher every time they add hashrate to the network....