Now this is a big point.  the entire network is 236ph give or take a few ph


https://bitcoinwisdom.com/bitcoin/difficulty


Bitcoin Difficulty:   29,829,733,124
Estimated Next Difficulty:   33,192,651,006 (+11.27%)
Adjust time:   After 1574 Blocks, About 10.1 days

Hashrate(?):   236,199,455 GH/s

now what does that number mean?

simple      at 1 watt per gh     the entire network is burning 236,200 kwatts or 236 mega watts.





  that is not that much power


look at this puppy

http://www.power-technology.com/projects/gurihydroelectric/

10,200 mega watts or more power then 43 current btc networks.  what do they charge for power?


the official rate is 3.1 cents

http://en.wikipedia.org/wiki/Electricity_pricing

so they could run the entire btc network at 3 cents a kwatt. There are more then 14 countries on the wiki list with power under 5 cents.
so at    3.1 cents per kwatt an    s-1 under volted and down clocked
 is  cheaper to run then a 10 cent per kwatt  sp30 .    Since the sp30 does around .6 watts a gh and the downclocked under volted s-1 does 1.3 watts a gh.  I could argue a large builder of chips/machines could have 2 plants 1 north hemi   1 south hemi    as long as he can get 3 cent power.  he can keep one turned off when it is hot.