A potential breakthrough has been made with regard to waste heat recovery — potentially boosting vehicle mileage by around 5% and boosting power plant and industrial processing performance by up to 10% — thanks to new research from the University of Houston’s physics department and the Texas Center for Superconductivity.
The researchers there have found a non-toxic substitute for the lead that’s used in thermoelectric devices based on lead-containing telluride. Such devices — while possessing great thermoelectric properties — can’t be used on the commercial scale because of the significant health issues that accompany the use of lead. The non-toxic substitute — tin telluride, doped with the chemical element indium — is nearly as effective as the lead-containing telluride.
Telluride has been studied for years, 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. This has sparked the rush for a similar, but safer compound.
“Without lead, there is a much better chance for it to be commercialized,” stated Zhifeng Ren, MD Anderson Chair professor of physics at UH, and primary author of the new research paper.
The press release from the University of Houston explains the significance of the new research:
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. This work continues his long-standing research into nanostructured thermoelectrics and thermoelectric energy conversion.
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. 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%.
“Even 1%, every day, would be huge,” Ren noted — especially when you consider just how much crude oil is actually being consumed around the world currently.
“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 US Energy Information Administration,” Ren added. “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% by 2040.”
With that in mind, the value in even modest improvements to efficiency are clear — reduced operational costs, and reduced greenhouse gas emissions.
“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% to as much as 48% – and other industrial plants. In some cases, Ren stated, the efficiency gain could reach 10%.”
The new research was just published in the Proceedings of the National Academy of Sciences.