Highly Efficient Thermoelectric Unicouples

Advanced unicouples that contain carefully tailored combinations of thermoelectric materials are being investigated in an effort to develop thermoelectric power generators that would operate with relatively high energy-conversion efficiencies between heat-source temperatures of about 1,000 K and heat-sink temperatures of about 300 K. [A thermoelectric unicouple is a part of a thermoelectric generator; a unicouple comprises one electron-conduction (n-type) leg and one hole-conduction (p-type) leg thermally connected in parallel and electrically connected in series.] Thermoelectric generators have no moving parts, are reliable, can operate unattended in hostile environments, and are environmentally benign; because of these characteristics, they are particularly attractive for extracting electric power from waste heat from such diverse sources as geothermal power plants, industrial heat-generating processes, and automobile exhausts.