High Temperature Quantum Well Thermoelectric Materials

A very large amount of waste heat (10 quads/year) is continually being generated by large industrial plants. This renewable source of energy could be tapped to replace more than 7% of the nation¿s imported oil, by using thermoelectric materials to convert this heat into electricity. However, current thermoelectric materials are not efficient enough to make this conversion process economical. In Phase I of this project, alternating Si/SiGe Quantum Films were upgraded in performance to yield efficiencies >20% at relatively low temperatures such as a TH of 300EC and TC of 100EC. Higher efficiencies (greater than 30%) were indicated at the elevated temperatures. A single crystal Si with very low thermal conductivity was developed, which should greatly limit bypass heat losses. Thermal stability annealing tests for Si/SiGe at a TH of 300EC exhibited no signs of degradation. Phase II will fabricate additional films, and thermal conductivity and efficiency will be determined as a function of temperature. Different bonding techniques will be pursued for the low temperatures (up to 300EC) versus the higher temperatures (up to 1000EC). Commercial Applications and Other Benefits as described by the awardee: The technology should be of use to industrial users, such as steel mill furnaces and aluminum plants, that have a considerable amount of waste heat at various operating temperatures. Another potential application would be cars and trucks, where two-thirds of the fuel going into the vehicle ends up as waste heat.