Max Krause was thinking of buying some bitcoin, as one does. But Krause is an engineer\u2014mostly he works on modeling greenhouse gas emissions from landfills\u2014so his first step was to run the numbers. He looked at price, of course, but also how fast the world\u2019s bitcoin miners create new bitcoins and the ledger that accounts for them. And he looked at how much electricity that would seem to require. \u201cI thought, man, this is a lot of energy,\u201d Krause says.