PCs now account for, ooh, a lot* of the world's energy consumption. The US Department of Energy has blamed some of its recent 'brownouts' (temporary power outages in some areas) on the increase in the use of home computers. And that, in turn, means greater pressure on the power utility companies to come up with new sources of energy. And that means digging up more oil and coal, building more nuclear power stations, and generally heating up the planet.

Consider the latest processors from AMD and Intel. They consume a fair amount of power, and immediately put out a lot of that power in the form of heat. It then takes even more power, from cooling fans, to dissipate that heat. It used to be a joke that you could heat your house with a PC, but it's becoming less funny. In these hot summer days, I switch off my 1.1GHz AMD Athlon system and make do with a 166MHz Pentium machine instead. It's slower, but not dramatically so, yet it's also quieter and doesn't make the office unbearably hot. Actually, I rarely use the Athlon machine at all now, except for the latest games. Sometimes its nice to use a PC that thinks more slowly than you.

There are alternative forms of computing power, such as the RISC (reduced instruction set computing) technology espoused by ARM and others. And a company by the name of Transmeta has a low-power processor that can conserve battery life, and we'll have a review of a notebook powered by this chip on IT Reviews in the near future. But there's always a compromise, and in this case it's performance. Low power consumption often equals slow processing, it seems. Slow in benchmark numbers, anyway. In real world tests you're unlikely to notice much difference, except in some specific cases, which is one reason why we're not fans of benchmarks here at IT Reviews.

But I digress. Again.

What can you do about all this? Replace your central heating boiler with a Pentium 4? Perhaps not. Setting the power saving options in your PC's BIOS would help, as would switching off the PC when you're not using it. But, perhaps more importantly, you could just... wait. Within the next five years, there should be fuel cells capable of powering computers. These make use of electrolytic reactions, usually with hydrogen, to generate electricity without no waste product other than water. And they could last a long time, too. At that point, the only problem will be how to generate all that hydrogen in the first place.

In the meantime, perhaps some enterprising company will come up with a high-efficiency, black silicon solar panel battery for laptop computers. Then you'd have a real excuse for whipping out your notebook while on the train.