>By far the most power-hungry crypto in our study, we found that a single Bitcoin transaction uses an average of 1,173 Kilowatt Hours (kWh). If we consider that the average monthly electricity usage for a UK household is 350 kWh, that’s enough to power the typical UK home for more than three months at a cost of roughly £125 ($173), based on a fixed cost of £0.11 ($0.148) per kWh

>In the U.S, it would equate to roughly 6 weeks of electricity based on an average household electricity usage of 877 kWh per month (U.S Energy Information Administration).

Not quite an entire year, but definitely a number of months.

Also according to digiconomist's latest figures, it's currently at around 1500kWh per transaction. So even worse.