Development of high efficiency thermoelectric generators using advanced thermoelectric materials

Abstract

Despite their relatively low efficiency, thermoelectric generators are used in a limited number of industrial applications where they are preferred to other energy conversion devices because of their high reliability, low maintenance and long life, in particular when considering harsh environments. New more efficient thermoelectric materials and devices are needed to expand the range of application of thermoelectric generators. Several new terrestrial applications requiring higher efficiency generators have been recently described in the literature. Heat sources for these applications range from low grade waste heat at 325–350 K up to 850 to 1100 K for heat recovery from processing plants of combustible solid waste. Commercial thermoelectric generators are usually built using Bi2Te3- or PbTe-based alloys depending on the maximum hot side temperature. A new approach consisting of using new high performance thermoelectric materials developed at the Jet Propulsion Laboratory (JPL) and operating the generator over a larger temperature difference is presented. By using novel segmented legs based on a combination of state-of-the-art thermoelectric materials and p-type Zn4−xCdxSb3 alloys, p-type CeFe4Sb12-based alloys and n-type CoSb3-based alloys, an increase in the thermoelectric materials conversion efficiency of about 60% is expected compared to Bi2Te3- and PbTe-based generators. The maximum thermoelectric materials efficiency will be about 20% for the optimum generator configuration. Various issues related to the fabrication of new segmented legs, including bonding and temperature stability tests, will be briefly discussed.