luckily, difficulty has slowed right down and the next step will probably be the smallest difficulty jump in a very long time - which could allow bitcoin miners to hang in there awhile longer. and who knows, difficulty might even go backwards now that the price of bitcoin is so low and the cost of mining is relatively speaking, so high.
Fancy and complicated answer for a simple question. How low can TerraMiners go with efficiency was my question. From your answer I understand that they can go as low as 0.23W/GH which I don't believe it. Maybe you were referring to the chip efficiency, not the whole system, but even so I still find it hard to believe it. I want to see it!
They also sold much of that power at a massive profit to their cloudhashing customers, so instant profit there.
I guestimate that it is not running much better than 1W/GH but their operational cost should be quite low in terms of $ /kWh due to economies of scale.
(Then again, only their newly built 20MW facility in Canada, which isn´t finished yet, should have the very lowest cost per kWh).
This recent option to pre-order their newest miner is only a way for them to recover/finance the MASSIVE NRE (which already is around $7-15M for 20nm development) faster.
Actual internal cost of these units could be around half of the current 28nm cost, which is slightly below 0.4$/GH on good 28nm designs.
(Assuming cheap labour costs and very high production volume, a little higher for water-cooled setups).
That's a total of 7MW on top (or not?) of their 20MW facility in Canada. I am sorry, but I am not impressed. Bitfury can do 20MW every 2 months. That's impressive! Remember that they still need a couple of millions on top of NRE costs in order to build their new miners. Also we must not forget that HF defaulted with how many tens of millions in pre-orders? 30M$? 50M$?