The Ecofan have a thermoelectric module which acts as a small generator to power the fan's motor. When this generator experiences a heat differential between its top and bottom surfaces, it pumps out electricity. The bottom surface of the module is heated by the base of the fan while the top of the module is kept cooler by the fan's top cooling fins. Ecofans are made from anodised aluminium that will not rust. Bi-metal strips in the base of the Ecofans help prevent the fan from overheating. Ecofans are economical to run and will help to move hot air from your stove into other parts of the room / house.