@Gusti: I don't disagree that the "flat" economy is energy intensive. However, I don't think we can easily compare them yet. Bitcoin is hardly a smudge compared to the US economy. Will it scale proportionally? And if so, is it still greener?
@goatpig: Not that its really that relevant (it has nothing to do with energy for me), but I own neither a video game console or a high end graphics card. I can steer clear of the mining, but I would still be supporting an energy intensive system. Sure mining for gold is energy intensive too, but I still have to wonder the same thing I asked Gusti above.
@sgornick Looks like you posted while I was typing this. I see the argument, but as an engineer, I like to see numbers and evidence. It very well could be that this system is much more efficient. If it is, awesome! I just want to see numbers and some scaling bounds.
However, something that was not addressed is the fact that we can throw as much energy at the block solving problem as we want and still get the same output. Yet, as people get interested in mining, the energy used will invariably increase. What will prevent this from skyrocketing and people wasting lots of energy? My only thought on the bound would be that the difficulty would increase to the point that bitcoins are equal to the cost of energy required to produce them.
Well, as you say, Bitcoins can't logically out cost the energy the network needs to validate the transaction. As such, you have an upper limit of sort, which doesn't exist on fiat money. The other thing you need to consider is that while Bitcoin adopters do expect the currency to valuate alot, you have to keep in mind that this valuation means there is less wealth circulating in the fiat system as a consequence. So even if Bitcoin is a concurrent system to fiat currencies, it isn't concurrent on the energy level.
As for scaling, I can only provide an opinion, I have no figures to contribute, but I expect it to be widely less energy intensive than the systems it is aiming to replace. Also, considering the amount of electronics drawing power for no other purpose that leisure, I think the return from the energy spent is worthwhile on its own.
I will agree with you that Bitcoin mining is highly compatible with home electric production solutions.