RE:NEWS - Jan 26, 2018 ... now that's turning Gas into $$$ 5 billion GH/s current mining rate. (6/6/17) Bitcoin currency statistics
Antminer S4—0.703 watt/GH Bitcoin mining hardware
World wide power = 5 billion x 0.703 = 3.515 billion watts = 3.515 million kw
It takes 3.515.million kw hrs to earn 12 bitcoins 6 times in an hour or 72 btc/hr.
That works out to: 48,800 kw hrs/bitcoin.
That is optimistic. Most mining gear is less efficient than the Antminer. Further, the calculation is at a moment in time. A single node with perhaps 2000 GH/sec will not earn fast enough to keep up with the growth of mining power.
Added 6.22.2017 As a cross check: Using 0.32 W/GH as the assumptions from https://digiconomist.net/bitcoin-... and their value for world wide mining power, it is easy to calculate the energy cost as 20.37 thousand kw hrs/bitcoin.
Want a third opinion? Their estimated electricity used over the previous day is 38,068,441 (KWh) Divide this by 24 x 6 x12.5 (number of bitcoins mined in a day.) This leads to 21.149 thousand kw hrs/bitcoin