Bitcoin mining does use a lot of electricity, on par with some countries. Supporters argue that the energy is what secures the network, and much of it comes from cheap or wasted power.
Go deeperMiners hunt for the cheapest power they can find, which often means stranded natural gas, curtailed wind and solar, or hydro in off-peak seasons. Some grids use miners as flexible demand they can switch off during peaks. How green the mix is depends on who you ask, and estimates vary.