Optimized thermoelectrics for energy harvesting applications

Abstract

This chapter highlights the design characteristics of thermoelectric generators (TEGs), electronic devices capable of harvesting power from small temperature differences. Power produced from these generators is low, typically in the microwatt to low milliwatt range. Due to the TEG's unique nature, not only does the TEG's electrical resistance have to be matched to the connected electrical load, the TEG also needs to be thermally matched to the attached heat sink, which is used to dissipate heat to the surrounding ambient. Proper TEG-to-heat sink thermal matching is required to produce sufficient power and voltage to continuously power small wireless sensors, switches, and other wireless devices from temperature differences as small as 5-10,°. Traditional bulk thermoelectric devices and thin film thermoelectric devices are not well suited for these low Δ T, low heat flux applications. When used with small, natural convection heat sinks, TEGs containing hundreds of thermocouples with extreme length-to-area ratios are necessary. New TEG device structures which incorporate thin, adhesive-filled gaps to separate the TEG elements are the best TEG device configuration for small Δ T energy harvesting applications. © 2009 Springer US.