Thermoelectric generator

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Thermoelectric generators (also called Seebeck generators) are devices that convert heat (temperature differences) directly into electrical energy, using a phenomenon called the Seebeck effect (a form of thermoelectric effect).

History[edit]

In 1821, Thomas Johann Seebeck discovered that a thermal gradient formed between two dissimilar conductors produces a voltage.[1] At the heart of the thermoelectric effect is the fact that a temperature gradient in a conducting material results in heat flow; this results in the diffusion of charge carriers. The flow of charge carriers between the hot and cold regions in turn creates a voltage difference. In 1834, Jean Charles Athanase Peltier discovered the reverse effect, that running an electric current through the junction of two dissimilar conductors could, depending on the direction of the current, cause it to act as a heater or cooler.[2]

Efficiency[edit]

Their typical efficiencies are around 5–8%. Older devices used bimetallic junctions and were bulky. More recent devices use highly doped semiconductors made from bismuth telluride (Bi2Te3), lead telluride (PbTe),[3] calcium manganese oxide, or combinations thereof,[4] depending on temperature. These are solid-state devices and unlike dynamos have no moving parts, with the occasional exception of a fan or pump.

Radioisotope thermoelectric generators can provide electric power for spacecraft. Automotive thermoelectric generators are proposed to recover usable energy from automobile waste heat.

Uses[edit]

Thermoelectric generators can be applied in a variety of applications. Usually, thermoelectric generators are used for small applications where heat engines (which are bulkier but more efficient) such as Stirling engines would not be possible. Another deciding factor is that while inefficient, thermoelectric generators are more reliable and have a smaller chance of breaking over time and use. Spacecraft are a typical example of an application where maintenance is next to impossible after launch.

Efficiency[edit]

Thermoelectric generators typically have lower efficiency than mechanical generators such as Stirling engines, i.e. they generate less electric power for the same heat flow. For a discussion of the factors determining and limiting efficiency, and ongoing efforts to improve the efficiency, see the article Thermoelectric materials - Device efficiency.

Limitations[edit]

Besides low efficiency and high cost, two general problems exist in such devices: high output resistance and adverse thermal characteristics.

See also[edit]

References[edit]

  1. ^ See:
  2. ^ Peltier (1834) "Nouvelles expériences sur la caloricité des courants électrique" (New experiments on the heat effects of electric currents), Annales de Chimie et de Physique, 56 : 371-386.
  3. ^ http://www.nature.com/nature/journal/v489/n7416/full/nature11439.html
  4. ^ http://www.thermoelectric-generator.com/ultra_high_temperature_teg_power_modules.htm
  5. ^ http://www.engadget.com/2011/06/14/usb-power-pot-uses-excess-heat-to-charge-your-gadgets/
  6. ^ http://www.stovelite.com
  7. ^ http://www.stealthpowersystems.com
  8. ^ https://www.tegmart.com
  9. ^ http://www.espressomilkcooler.com/complete_thermoelectric_generators_assemblies.htm/
  10. ^ http://www.devilwatt.com//
  11. ^ http://www.tegulator.com//
  12. ^ http://engr.case.edu/leinweber_lawrence/eecs651/04.7_2_0715.pdf DOI: 10.1109/DATE.2008.4484669

External links[edit]