Re: Bitcoin is now consuming 1% of the world's electricity. Is that sustainable?
bitcoin is sustainable entergetically? my answer is: yes. Based on a research, almost 80% of the energy used to mine bitcoins comes from renewable sources
sources: https://coinshares.co.uk/wp-content/uploads/2018/11/Mining-Whitepaper-Final.pdf (page 9)
You forgot to remove your blinkers sources: https://coinshares.co.uk/wp-content/uploads/2018/11/Mining-Whitepaper-Final.pdf (page 9)
instead of bitcoin mining, this green energy you talk here, could replace some coal power plants for real world electricity needs instead 
its useless, don't try to greenwash bitcoin, it is not sustainable. point.I agree that the source of power for Bitcoin mining is irrelevant, which is why Bitcoin mining itself doesn't have a carbon footprint.
However, your point appears to be that Bitcoin is not worth the amount of energy spent on it. What about the amount of energy spent on entertainment: video games, youtube, netflix, music, automobile racing, driving to a football game? Are those activities sustainable? Surely, all the energy spent on those activities is wasted, too.