Self Powered Woodstove Fan  

Here's another niche energy saving device from TreeHugger, for those who have wood stoves - a fan powered by the Peltier effect.

Would you need more than heat during cold winter nights when your ultra efficient woodstove is running at full capacity ? Well ecofan won't require more wood but will add efficiency to the heating process as a whole by distributing hot air faster, without asking for plug, batteries or any kind of outsider's energy : Ecofan runs silently by itself when left at the top of the stove, wings powered by a side effect of the heat known as the Peltier effect. The hotter your stove, the faster it spins.

Even though simple in its function, the technology inside this little marvel is more complex than it seems. Here is a sample explanation of the Peltier effect that powers ecofan as temperature on the top of your woodstove climbs to hundreds : at the same temperature, two dissimilar semiconductors (p-type and n-type) connected together 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.