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One of the most elegent ways of generating electricity from thermal energy is the use the thermoelectric effect. The theoretical analysis of this phenomena has been know for many years. Seebeck, in 1822, did pioneering work on generating voltages and Peltier followed this work in 1844 by showing that a cooling effect occured if a direct current was passed through a circuit of dissimilar metals.
With the arrival of semiconductors in the 1940 there was a re-invigoration of the subject as thermoelectric effects in these materials is much larger then those shown in metals. A simple thermoelectric generator (TEG) is shown below:
The diagram on the left shows that free carriers will migrate away from the hot end of a semiconductor sample so that a voltage is developed. Now, by having a combination of p-type and n-type material the voltages are additive and therefore a generator is formed by connecting the two in series as given on the right hand diagram. Any situation where there is "low grade" heat we can have a thermoelectric generator to produce electricity. Silicon is not the best material to use and more exotic semiconductors, such as Bismuth Telluride, give higher outputs.
The above example shows that unused heat from an oil lamp generates electricity to power a somewhat antiquated radio. Lap-tops, iPods and the like could equally be powered from a TEG.
On a larger scale we know that power stations or, for that matter, the countless vehicles on the roads, waste all their low grade heat into the atmosphere ---- surely we could recoup some of this energy by using TEG's.
More information in www.wikipedia.com or the Diino site https://sth-se.diino.com/f.thompson/migrated_data/EandH . Daniel Pollard's classic book of Thermoelectricity is available on Google Books
For more commerical information visit www.melcor.com or www.tellurex.com .
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