Carl Brahe
I ordered a fan to sit on our wood stove to distribute heat throughout the room. I expected a slow moving fan powered by rising heat waves that ran some kind of simple hot air turbine something like the merry-go-rounds that are driven by heat from candles. What I received is an application of new technology that is truly mind blowing in its implications for future building materials and home power generation.
The fan is run by a electric motor powered by a small thermoelectric generator that produces enough current to turn the fan while still cool enough to comfortably put your hand on it. The hotter it gets the faster it spins. The TEG (thermoelectric generator) looks like a phone battery sandwiched between a metal stand that channels heat to the bottom of the device. On top of the TEG is a heat dissipation device made of metal that allows air flow through cooling chambers. Electricity is generated by heat flowing through the TEG caused by the difference in temperature at the top and bottom. The more efficiently heat is accumulated and released the more power is produced.
As TEGs get cheaper and more efficient more products will be produced to generate power from waste heat. Small TEGs are available on Ebay for around $20.The heat that accumulates in an attic or under roof coverings might be used to make electricity for household needs. Driveways might melt themselves and produce electricity to charge the car batteries in the process. Small thermoelectric generation systems are available now that provide small amounts of power from bio-fuel sources. One unit uses the heat from tea candles to power a small LED lamp. Others are made to be incorporated in wood cooking ovens in poorly developed areas. This is a relatively new area of technological development that will produce many new and innovative products for use in construction and daily living. New discoveries will bring new uses.
An alloy created in 2011 at the University of Minnesota converts heat to electricity directly. They combined nickel, cobalt, manganese and tin, all common, inexpensive metals, to create a multiferroic alloy. Multiferroic alloys have the ability to change directly from one solid material into another using small amounts of heat. This particular alloy is magnetic in one state and not magnetic in the other. When placed next to a permanent magnet electricity is produced as the heat passes through the alloy.
In this age of super fast development and innovation TEG technology is a rising star. Devices and building materials using this technology will be common in our homes in the next few years.
