I've conducted the most detailed and precise energy estimate of Bitcoin miners and bounded it to 5.61-10.93 TWh/year as of 28 Jul 2017: http://blog.zorinaq.com/bitcoin-electricity-consumption/ Today it's probably closer to ~15 TWh/year which represents ~0.01% of the world's energy consumption.
However this article claims 29.05 TWh/year, basing it on Digiconomist which is the work of an amateur and known to overestimate by ~2×: http://blog.zorinaq.com/serious-faults-in-beci/