According to the researchers, they have illustrated a step further in transforming waste heat from smokestacks and industrial, power generating plants of even automobile tailpipes – into electricity.
The work, utilizing a thermoelectric compound made of titanium, niobium, antimony and iron, succeeded in raising the power output density of materials dramatically by utiling an extremely hot pressing temperature of around 1373 Kelvin or about 2,000 degrees Fahrenheit to prepare the substance.
“The major proportion of industrial energy input is lost as waste heat,” confirm the researchers. “Transforming some of the waste heat into vital electrical power will result in diminishing of fossil fuel consumption and carbon dioxide emission.
Thermoelectric substances release electricity by exploiting the movement of heat current from a warmer area to a cooler substance and their efficacy is estimated as the measure of how efficiently the substance transforms heat – often waste heat produced by power plants or other industrial procedures into power. For instance, a substance that takes in 100 watts of heat and generates 10 watts of electricity has an effectiveness rate of 10 percent.
That is the conventional method of considering thermoelectric substances, says ZhifengRen, MD Anderson Lecturer of Physics at the University of Houston and head author of the research. But having a relatively big conversion efficacy does not guarantee big power output that estimates the volume the amount of power released by the substance rather than the rate of conversion.
Since waste heat is an abundant, and free, source of fuel, the conversion rate is less vital than the overall volume of power that can be released, says Ren, who is also a chief investigator at the Texas Centre for Superconductivity at UH. “In the past, it has not been emphasized.” In addition to Ren, the scientists involved in the project were Jun Mao, Ran He, HeekSeok Kin, Yuan Liu, Qing Jie and Paul C.W. Chu, belonging to the LingpingZeng, Gang Chen and Daniel Kraemer Massachusetts Institute of Technology, YuchengLan of Morgan State University, David Broido of Boston College and Chunhua Li.
The scientists also tweaked a compound created of iron, antimony and niobium, substituting between 5 to 4 percent of the titanium and niobium. Processing the novel compound at a range of high temperatures suggested that an extremely high temperature, 1373 Kelvin, leading to a substance with an unusually high power factor.
“For most of the thermoelectric substances, a power factor of 40 is good,” says Ren. “Most of them have a power factor of 30 or 20.” The novel substance has a power factor of 106 at a room temperature and scientists were able to illustrate an output power density of 22 watts per square centimetre, far bigger than the 5 to 6 watts typically generated, he says. “Such aspect of thermoelectric requires to be emphasized,” he says. “You cannot just consider the efficiency, rather you also need to consider the power output and power factor.”
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