AsianScientist (Jul. 4, 2018) – In a study published in Nature Communications, a team of scientists in Japan and Taiwan has improved the conversion of wasted heat into usable electricity by using a ‘sandwich’ consisting of conducting and insulating layers.
More than 60 percent of energy produced by fossil fuels is lost as waste heat. One way to address this problem is to convert the wasted heat into electricity, known as thermoelectric energy conversion.
Thermoelectric materials convert heat into electricity when there is a temperature difference, a phenomenon known as the Seebeck effect. In the present study, researchers led by Professor Hiromichi Ohta at Hokkaido University, Japan, more than doubled the ability of a material to convert heat into electricity. The group built upon technology they had developed previously, whereby an artificial superlattice composed of conducting ultrathin layers was sandwiched by thick insulating layers.
An earlier version of the superlattice yielded higher voltage but did not improve conversion rates. The researchers predicted that the performance of their superlattice could be significantly improved if electrons with longer de Broglie wavelength, which means they are more spread, are confined into a narrow conducting layer.
They designed a superlattice in which electrons are spread by 30 percent wider as compared to previous experiments, achieving this by keeping the thickness of the conducting layer below the de Broglie wavelength. This meant that the de Broglie wavelength of the electrons is longer relative to the two-dimensional material, resulting in a much higher voltage and a doubling of the thermoelectric conversion rate compared to previous methods.
“This is a significant step forward towards reducing the amount of heat wasted by power plants, factories, automobiles, computers and even human bodies,” said Professor Hiromichi Ohta of Hokkaido University who co-authored the study.
The article can be found at: Zhang et al. (2018) Double Thermoelectric Power Factor of a 2D Electron System.
Source: Hokkaido University.
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