Nanostructured thermoelectric energy scavenging

Article By:

Chen, Gang Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts.

Last reviewed:2014

DOI:https://doi.org/10.1036/1097-8542.YB140340

Approximately 50–60% of the energy input that our society uses is eventually wasted as heat. Automobiles use only approximately 20–25% of the heat output of combustion, with about one-third of the remaining energy being rejected as heat through the exhaust pipe and another third being lost through the radiator. Even electricity is eventually dissipated as heat, a fact that is made evident by the whirring of fans cooling computers and other consumer electronics. Recovering a fraction of this wasted heat and converting it into usable electricity will reduce our overall energy needs and benefit our environment. Capturing this waste heat and converting it into useful energy, however, is difficult because of the distributed nature of the sources of the waste heat and other constraints such as space, weight, and cost. Nevertheless, many people are working on different approaches to utilize the waste heat, one of which is based on thermoelectric energy conversion. This article discusses the principles of thermoelectric energy generators, the need to increase the efficiency of thermoelectric devices if they are to be widely used, the search for thermoelectric materials with higher efficiencies, and finally, the use of nanostructures to improve thermoelectric efficiency. In conclusion, challenges to thermoelectric conversion of waste heat and the present status of the field are discussed.

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