Between the computers, the networking gear, and the cooling systems which keep them all running smoothly, it's estimated that server farms like Google's (now partially solar-powered) consume 1.5% of all energy in the U.S. Only 1.5%, you say... why, that's hardly anything, right? Well, let's put that in perspective... that's still 1.5 quadrillion BTUs every year, or the equivalent of 268 million barrels of oil. At today's prices, that's a dollar amount only Dr. Evil can pronounce.

In the world's most power-hungry server farms, each square meter of electronics can consume as much electricity as six medium-sized homes, and keeping it all at optimum temperature can add up to more than 60% of the bill. Bean Counters take note: One of the best ways to save money in the IT department is to invest in greener technology, which runs cooler and consumes less power. Blade servers using virtualization are going to help HP consolidate its massive data centers into new energy-efficient configurations, and IBM is investing over ONE... BILLION... DOLLARS a year in green tech (mua-ha-ha!), which will save them a projected 40% on their electricity bill.

Sound interesting? The good people over at WorldChanging are putting together a comprehensive guide to Green Computing in Data Centers, which highlights some of the latest innovations in the field. New power supplies, blade servers and updated software represent incremental efficiency gains of 20-50% each. Then there's my personal favorite: liquid cooling.

Water cooling is both more efficient than air cooling and can handle higher heat loads, simply because water is far more conductive of heat and has much higher thermal mass than air. It's been slow to catch on because administrators are paranoid about leaks (water and electronics certainly don't mix well), but systems are available now that have been proven reliable. IBM and HP have water-cooled server racks, and Knurr's even won a design award. The Pacific Northwest National Lab even proposed cooling via liquid metal, so that the fluid can be pumped hydromagnetically, with no moving parts.

Well...after all the naysaying, it took about a week for Wal-Mart's $200 green Linux PC to sell out of their online warehouses. Of course, it probably isn't selling quite that fast in stores.

The Everex machine, which runs on a power-sipping Via 1.5 Ghz processor, is the first Ubuntu machine to be sold by any major retailer. It's strange that Wal-Mart was the pioneer here, but their constant search for lower prices meshes well with the freeness of Linux. After all, you can buy the hardware for less than the cost of Microsoft Office and get everything you need (except a monitor).

Wal-Mart's sales page is now littered with positive reviews from people who've never used Linux before (and even a couple people who've never used a PC before). The overwhelming theme is that the machine isn't impressive in any way...but it is just as useful as the majority of Windows machines that roll off the shelves for two or three times the cost (without a built-in office suite).

In the end, it's a lower-end machine that runs blazingly fast because the OS doesn't hog all the resources. That's real efficiency, and if I wasn't so married to my graphics applications, I'd consider the switch myself.