I was just thinking, it might be cool to use some of the heat from a coal stove to make a bit of electricity.
This wouldn't actually "use" the heat, as long as it's generated using a temperature differential, and the power is used in the house. This is because, even if the generation method has very low efficiency, the heat is still used, and pretty much all electricity ends back up as heat.
There are 3 methods I can think of for making electricity:
1. Stirling engine generator. Yes, there is no "e" in Stirling. It is an engine that runs on a temperature differential. There is a commercially-available unit for woodstoves which directly drives a small fan to blow the air in the room around. There is another company which makes a larger cogeneration unit, which burns gas to generate both heat and electricity. The stirling engine in this is capable of producing 750 watts, which is not insignificant. This would be rather expensive, but would pay for itself about as quickly as a stove.
2. Thermocouples. The seebeck effect allows you to directly generate electricity from a temperature differential. Again, there is a small fan available for woodstoves that blows air around the room. There is also a commercial unit available that will run a circulation pump.
3. Steam generation. This is probly the worst option, since it is quite complicated and would need more maintenance. This might be the easiest option for the do-it-yourselfer. It would just require a pressurized boiler and a small steam engine/generator. The steam could then be used in radiators.
Ideally, the method selected would produce enough power to run a stoker. This seems quite easy if you only have to run the pusher motor, since it goes so slowly, a very low-power system could be used.
To run blowers would require much more power, and if even more is available, it could be used for other purposes, such as lighting.
Has anyone though about or tried to produce power from the heat of your stove?