[quantumf]

ASIC's consume very little power compared to a PC. One watt per gigahash is a rough value, although most promise quite a bit less. You'd need about 100 PC's, at 300W each, to produce a gigahash, using the assumptions in this article.

[betterunix]

Ah but that's the unfortunate twist. If you can get a gigahash for 30000W with PCs, you would have no incentive to go down to consuming only 1W with an ASIC. You would consume 30000W with ASICs and get 30000 gigahashes.

[EDIT: Corrected the numbers to match what you wrote. It is irrelevant, though -- if you get a gigahash for X watts with PCs, you'll use X watts to get X gigahashes with a 1W/gigahash ASIC.]

[cheald]

...assuming that you have the resources to purchase 30KW worth of ASICs. A 1W ASIC does not cost 1/300th of a 300W PC.

[betterunix]

All you are saying is that the transition to 30kW of ASICs will not happen overnight. If you stopped at 1W, you would quickly find that you are making less money than you were before -- your competitors will also switch to ASICs, and will consume more than 1W because they want to make more money.

To put it another way, not going to 30kW of ASICs is equivalent to taking 30kW of PC mining hardware and turning some of it off (in a pre-ASIC world where PCs are the most efficient mining hardware available).

[datphp]

If it's true it isn't that bad (yet). 30mn W is like what, 150'000 TVs? 400 cars? A few buildings worth of AC/heating?

I don't think we'll get to a point where BTC has a significant footprint anytime soon.