Ha! Two blog posts in one day! You just can’t shut me up. 🙂
So, as you may have gathered, there’s active and passive cooling. Active meaning that your fans are spinning, passive meaning that they aren’t.
Now on the one hand, passive cooling does allow your laptop (or netbook in my case) to save power. But generally this is done by allowing it to slowly radiate heat, while your computer runs slower so that it stops producing too much heat for the passive cooling to deal with.
The thing is, not only does the heat make your computer run slower indirectly, it also makes the components directly use more power to run even though things are slower. At least until it cools down.
The net result is that yes, your battery lasts a little bit longer, but the actual time in which your computer is useful while you’re using it is (arguably) less, with programs skidding to a halt or slowing down considerably when the processor is trying to cool off.
Running the fan may cut your battery time in half, admittedly, if my experience with active cooling on battery today is anything to go by, but it’s something that I can live with if I’m not waiting for the computer to catch up with all those keystrokes I just made. 😉
Likewise, keeping the computer cool using active cooling also reduces power usage by the components which tend to get hot. It’s a trade-off, but I would argue that it is worth it because heat can also make the lifetime of those same components dwindle.