I've just heard a fantastic talk by Andy Hopper at the Royal Society Ubiquitous Computing discussion meeting. Much of it was over my head, but one thing really struck me, partly because it sounded exactly like something you'd read about on BLDGBLOG. (You could try the abstract but the pdf doesn't seem to work on a mac. Which seems to be the opposite of ubiquitous computing; it doesn't even work on some computers.)
Anyway. He was talking about "Computing For The Future Of The Planet", suggesting, among other things that "computing will play a key part in optimising use of physical resources and ultimately their substitution by the digital world". Which makes sense.
But he was very aware that computing has its own energy needs, and that they're growing, so you can't throw computation at problems without thinking about energy appropriate ways to do it. Part of that involves reducing the energy requirements of the huge server farms. But he also pointed out a much more interesting possibility - moving the servers to areas where there's loads of free energy going to 'waste'. Because it's cheaper to transmit data and computing tasks than it is to transmit energy. So you could imagine server farms in the North Atlantic, powered by windmills, crunching the USA's data. (Really, just a natural extension of this.)
Or, as he suggested, maybe the Isle Of Lewis could become the UK's data centre. There's a lot of wind there, but it's hard to get the energy where it's needed. It might be more efficient to keep the energy there and move all the computation to it.
