I have a solar charger/battery. Surprising how often you can't get enough sun to matter, as you need many hours of continuous direct bright light to collect anywhere close to enough.
I'm imagining a sort of pencil-sized Sterling; stick one end in the fire and the other in a cup of cold water. Not reliant on ambient/weather conditions for power.
I've got a miniature Stirling on my shelf. It's a two cylinder setup that runs off of two small alcohol lamps (about the equivalent of two candles), and is air cooled. It weighs about a pound (but could probably be lighter). I don't know exactly how much power it puts out, but it's not much - you can stop the flywheel with light finger pressure.
More heat would produce more power, but I think pencil sized may be a bit optimistic. I like the idea though.
aah, that's very interesting.. though I'm skeptical a pencil sized one will be able to output that much of power :).
The problem with Stirling engines is that power output is kind of low when compared with a similar sized IC engine.
http://www.kickstarter.com/projects/ryochijiiwa/bootstrapsol...
http://www.kickstarter.com/projects/davefoster/lilypad-using...