New material raises hope of turning waste heat into power

Scientists in Bangalore have synthesised a novel thermoelectric material that they say displays unprecedented performance in turning waste heat into electricity and comes close to the ideal and long-sought hybrid of glass and metal.

By G.S. mudur
  • Published 4.03.18
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New Delhi: Scientists in Bangalore have synthesised a novel thermoelectric material that they say displays unprecedented performance in turning waste heat into electricity and comes close to the ideal and long-sought hybrid of glass and metal.

The new material made from silver, copper, and tellurium shows high levels of thermoelectric performance that the scientists are hoping could some day be harnessed to extract electricity from waste heat of chemical, thermal, or steel power plants.

Thermoelectric generators have been used for decades - US spacecraft have relied on electricity obtained from the heat of plutonium radioisotopes, a German car-maker has tried to turn waste heat from exhaust pipes into electricity for the car's systems. Last year, scientists at the US National Renewable Energy Laboratory described thermoelectric thin films that could be integrated into fabrics.

"Despite such advances, we're looking for the ideal thermoelectric material," said Kanishka Biswas, assistant professor at the Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, who led the research.

"An ideal thermoelectric material would have the lowest possible heat conductivity of glass and the highest possible electrical conductivity of metal," said Biswas. "The silver-copper-telluride material we've fabricated is close to such a hybrid."

Standard commercial thermoelectric materials are at present typically made from bismuth and tellurium, but show their highest performance at room temperatures, and melt and decompose at high temperatures.

The material synthesised by Biswas and PhD scholars displays a thermoelectric performance unit of 1.6 while functioning at temperatures of up to 400°C. While a different thermoelectric material containing lead and tellurium currently shows an even higher performance of 2.2 units, Biswas says industry is unlikely to find that attractive because of the presence of toxic lead.