Thermo Electric Generators
Being able to generate electricity by simple means anywhere where heat is available is a fascinating thought. The enormous potential of this technology is underlined simply by the fact that by harvesting additional electricity from waste heat it can significantly increase the efficiency of known technologies.
How it works
TEGs consist of two materials placed in contact with each other via bridges. Electricity can then be generated if there is a temperature difference between the two materials and the heat begins to move from one side to the other.
TEGs have no moving parts and thus can be considered as mostly maintainance free.
Uses of TEGs
TEGs in improved stoves
TEGs are an interesting way to improve ICS performance. For example Aprovecho and Biolite have attached a TEG driven Fan to a rocket stove. The Side Feed Fan Stove has shown significant results by reducing Fuel use by 42%, PM emission by 94%, and CO emissions by 91% compared to three-stone fire.
Small TEGs could also be used to improve the working conditions at the cooking place for example by additional lighting with LEDs. (see page 19 of the presentation linked above, to see how much light you could get out of a single candle)
TEGs in big engines and appliances
A lot of research has been done to make this technology efficient. Together with the Fraunhofer Institut SAM-Thermoelectric technologies have developed a way to generate electricity at 30% efficiancy (see product description PDF). A license has been purchased by the O-Flexx GmbH. They are now developing very promising ways to improve different technologies by converting waste heat into electricity. The SAM TEGs are beeing used to increase the efficiancy of solar systems, automotive engines, transport and more.. (see their products and solutions). These big appliances with the SAM Technology will be commercially launched by end of 2010.
TEGs as cooling devices
As Jean-Charles Peltier showed in 1834 the effect of thermoelectrics is versatile. Connecting a TE module to a low voltage will actively move heat from one side to the other. (Peltier effect)
