Almost exactly a year ago, Google held a gathering for "leaders of the IT industry" — the Efficient Data Center Summit — where they explored the steps the company takes to reduce resource use and energy consumption in particular. And although most of what went on is so technical as to be land law to a layman, I thought you might like to learn some of the more intelligible highlights of Google efficiency. After all, in practice or at play, we call on Google daily; and the absence of great clanking noises and bursts of steam when we do, can lead us to imagine that free searches are free of environmental consequences, which ain't the case.
(As well, though I remind myself constantly that these giant corporate forces in our society exist for "the love of money," I'm at times impressed by, and even awed at, their accomplishments. Google, moreso than others, tempts me into this admiration, and I'll gush a little here. But only a very little.)
What got me looking into this was a short piece in the New Scientist, "Search engines' dirty secret," that made the astonishing claim that "one search [on Google] has the same energy cost as turning on a 100-watt light bulb for an hour." It turns out, thanks to the discussion in the comments, that this conclusion is seriously flawed. One commenter reckoned the figure may be something closer to the energy expended by a 2.5-watt light bulb. Google's own estimates put it at 1kJ (0.0003 kWh) per search.
Whatever the number, it results from some pretty serious efforts by Google to keep costs down, costs for them and for the environment. Energy is, of course, the resource at issue here: energy to run Google's servers, energy to cool them. Reliable estimates are hard to come by, but the figure that gets bandied about is that Google has a million servers. But these are not just off-the-shelf servers such as you might find down the hall in the hot IT room: Google rolls its own, and has done pretty much from the start. And one key, energy-saving feature of these home-made uglies has to do with the power supply. In your computer, as I understand it, one of the great inefficiencies occurs in converting AC current to DC (in varying voltages) for use by the chips, and in ferrying that power around inside the machine over wires. Google servers run with efficient wiring on 12 volts throughout; and they're supplied with backup power not via the usual centralized and wasteful "uninterruptible power supplies" but through individual batteries within each server.
Google's servers are housed, 1160 at a time, in standard shipping containers, which in turn are gathered in hangars. There's a six minute video that takes you on a tour through one of these buildings and inside some of the server farm containers. I particularly like the the vignette of the kid using the (low-tech, high efficiency) scooter to do his rounds. Another video talks about the problem of cooling and the associated matter of water use.
Grounded in these realities of water, coal-generated power, silicon chips, and steel buildings, Google achieves numbers that are not just figuratively astronomical: 87.8 billion searches are performed on Google each month; this and others of Google's services causes them to process 20 petabytes of data every single day, which, as WolframAlpha tells us, is 2 times 10 with 16 zeros after it. Which, were it dollars, would be well more than I make in a week.