No, I don't know anything about thermoelectrics or solar. I once saw a video on youtube about recharging a Cell Phone by connecting wires to a potato (or maybe it was a citrus fruit), but I never got to experiment on alternate power generation at all.
From what I understand, EARTH BATTERIES are easy to make (videos on youtube).
The only plans I can find for a Mendocino motor are here...(price raised to $19.50, but email him for any price increase)...
There are different kinds of L.E.D.s, there's even one from Edmund Scientific that can be held in the hand and will light up when you walk across a rug (static electricity).
If you have a junk yard near you and can get the generating coil from a mini bike and attach that to a stirling engine that has good speed, that would supply a decent voltage similar to a car cigarette lighter socket.