MIT is doing heavy research into replacing batteries with tiny turbine engines.

http://web.mit.edu/newsoffice/2006/microengines.html

This is an interesting idea. I do wonder how much waste heat they would produce, though. My personal laptop has a 150W power supply, which is pretty damn big for a laptop. The thing makes so much heat that it is regularly occupied by the bodies of one or more of our feline roommates. Would these little guys be able to cook a meal on their waste heat, or would it be better than it is now?

If one of these little generators cranks out 10W of power, would I need a box with 15 of them to run my laptop, or would it be better to create units with larger capacity and use fewer of them? When the laptop is not sucking power at full load, would they turn off some of them or just run all of them at a lower setting?

Another big question is fuel capacity. How much fuel would you need to run one of these 10W beauties for four hours? I’d hope that it would run on ethanol – if you leave out liquor taxes, the stuff is super-cheap and burns clean. Because ethanol is created from materials produced by plants, it would also be pretty close to a net zero change in the carbon dioxide level of the atmosphere.