Sep 06, 2013 |
Researcher in nanostructured thermoelectrics finds new opportunites for waste heat
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(Nanowerk News) Physicists at the University of Houston’s physics department and the Texas Center for Superconductivity are working on an innovation that could boost vehicle mileage by 5 percent and power plant and industrial processing performance as much as 10 percent.
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Their research uses non-toxic materials – tin telluride, with the addition of the chemical element indium – for waste heat recovery.
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Telluride has been studied for years, said Zhifeng Ren, M.D. Anderson Chair professor of physics at UH and lead author of a paper describing the work, published in the Proceedings of the National Academy of Sciences ("High thermoelectric performance by resonant dopant indium in nanostructured SnTe").
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Zhifeng Ren, left, and Qian Zhang
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But earlier work faltered because lead-containing telluride, despite its strong thermoelectric properties, can’t be used commercially because of the health risks associated with lead, Ren said.
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That has sparked the rush for a similar, but safer compound.
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“Without lead, there is a much better chance for it to be commercialized,” he said.
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The research shows the potential for building a device that can capture waste heat – from vehicle tailpipes, industrial smokestacks, power plants and other sources – and convert it to electricity to boost productivity.
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Ren and his research team arrived at UH in January from Boston College. This work continues his long-standing research into nanostructured thermoelectrics and thermoelectric energy conversion.
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The research was conducted with colleagues from the Massachusetts Institute of Technology and Boston College.
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Qian Zhang, a research associate in Ren’s group who designed the experiment, said she ultimately decided to add another element, known as a dopant, to alter the electrical properties of the tin telluride. In this case, she added indium to boost its conducting properties.
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In one example, the device could capture heat from a car’s tailpipe and convert it to power the car’s electronics, improving the car’s mileage by about 5 percent, Ren said.
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“Even 1 percent, every day, would be huge,” he said, considering how much crude oil is consumed worldwide.
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The United States and China, the world’s most energy-intensive nations, consumed 18.6 million barrels and 10.3 million barrels of crude oil daily respectively in 2012, according to the U.S. Energy Information Administration.
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And energy consumption in other countries is growing. ExxonMobil, in its annual energy forecast for the next 30 years, predicted global energy demand will increase 35 percent by 2040.
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The increase in demand makes even a small gain in efficiency valuable, Ren said, although he also said the process could be made more efficient in the future.
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But capturing car exhaust and converting it to electricity is only one example of how the process can be used. It could also be used in power plants – Ren suggested it could boost the conversion rate of coal-fired power plants from 40 percent to as much as 48 percent -- and other industrial plants.
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In some cases, Ren said, the efficiency gain could reach 10 percent.
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