2013 was a year where the network hash rate grew over 40,000%. As I write this the network hash rate is 16,371 TH/s. If you assume 600W per 1 THs which is probably conservative, it works out to about 10 MWh (Mega watts hours) being spent on bitcoin mining. This is still a tiny fraction of the world’s total electrical power production which is currently around 22,500 TWh. (Terra watts hours) Source:

http://yearbook.enerdata.net/#world-electricity-production-map-graph-and-data.htmlSo far no concerns but look what happens if the growth continues at the same torrid rate:

World's Electrical Power Production in 2012 ~ 22500 TWH

Current power consumption of bitcoin hashing ~ 600J/TH/s * 16371 TH/s = 9,822,600W

(Going with BurtW correction here)

To get units of ENERGY so you can compare it to an annual ENERGY production of 22,500 TWh you need the number of hours in a year:

24 hours/day * 365.25 days/year = 8765.76 hours per year.

Annual ENERGY consumption of the Bitcoin hashing would be:

9,762,600 Watts * 8765.76 hours per year = 85,576,608,576 Wh = 85.6 GWh

Assuming same torrid growth rate of network growth and constant power production

NOW : 85.6 GWh - 0.00038 % of World's electical power production

Year +1 : 34.2 TWh - 0.00152 %

Year +2 : 13696 TWh - .6 %

Year +3 : 5478400 TWh - 243.48 % of the World's electircal power production

So it seems likely that soon the network growth is going to start hitting serious limits. Keep in mind I’m only looking at electrical power here. There are many more potential limits like just running out places to house the mining and producing smaller faster ASICs will become very hard.

Thoughts?

Edit note - Many corrections made ... thanks!