Thermoelectric generation (TEG) utilizes heat flow through a device, composed of semiconductor materials, to generate an electric current. It has no moving parts, and relies on heat differential on one surface of the device compared to the other. Most commercially available devices have a heat limit on the "hot" side of the device of 300°C, or 572°F, and a maximum "cold" side heat of 180°C, or 356°F. The greater the difference between a hot site and cold side, the greater the electric energy produced.
Most devices are one or a few inches square, and a fraction of an inch thick. They have very long functional lives and are maintenance free. Although peak power output is not especially high, utilizing a few of them at once may produce meaningful output. Certainly, enough to recharge a cell phone or other battery recharging device, or even operate a 12 V light bulb.
For example, a single 2.2 in.² device that is 572°F on the "hot" side and 86°F on the "cold" side produces nearly 15 W of power. These temperatures suggest that this technology may be ideal for coal stoves. The difficulty may involve adequate cooling of the "cold" side. Most manufacturers recommend applying a heat sink to the cold side, and I'm guessing that a heat sink repurposed from a PC may be a reasonable choice. In my hand fired stove, a great deal of cold air rushes back of the stove to enter the ash pan vents, and I'm trying to figure out a way to direct some of this flow over the heatsink fins.
The 2.2 in.² device costs about $80 purchased singly, or $60 each when purchasing 10 devices. Manufacturers claim that their devices are much cheaper than solar technologies considering power output.
I came across some interesting links today and thought I would post them here:http://www.customthermoelectric.com/powergen.htmlhttp://www.tegpower.com/ http://www.tegpower.com/pro3.htmhttp://www.customthermoelectric.com/pow ... ec_sht.pdfhttp://www.customthermoelectric.com/app ... aphite.pdf