The Caframo Ecofan is a heat powered fan designed to circulate the warm air created by a wood or gas stove. These fans do not use any batteries or mains power.
These fans have a thermoelectric module which acts as a small generator to power the fan’s motor. When this generator module experiences a heat differential between its top and bottom surfaces, it pumps out electricity. The base of the fan heats the bottom surface of the module, while the top of the module is kept cooler by the fan’s top cooling fins.
The Seebeck Effect
The generator module is a unique semiconductor device that relies upon the Seebeck effect to generate electricity. When two dissimilar semiconductors (p-type and ntype) at the same temperature are connected together they establish a static electric potential difference. With the introduction of a temperature difference heat flows across the joined semiconductors which in turn permits electrons to flow. With the electron flow or current comes the ability to power electrical devices such as the fan’s motor.