https://motherboard.vice.com/en_us/article/7xmvbq/bitcoin-energy-science-world-electricity-demand https://www.cell.com/joule/fulltext/S2542-4351(18)30177-6 https://digiconomist.net/ http://blog.zorinaq.com/bitcoin-electricity-consumption/
https://hardware.slashdot.org/story/18/05/16/1713243/nobody-knows-how-much-energy-bitcoin-is-using