I've read some analysis on Bitcoin profitability and energy consumption that seemed unreliable, so I thought I would put my two cents in on the subject.
For example, many sites are using the Digiconomist's work on Bitcoin energy consumption. However, I believe this analysis has overstated Bitcoin's energy consumption by a large degree. According to the Digiconomist, Bitcoin's annual electric use is approximately 24 TerraWatts per year (TWh/yr):
Read more at http://www.zerohedge.com/news/2017-11-04/bitcoin-vs-gold-which-ones-bubble-how-much-energy-do-they-really-consume.