Capturing excess heat to convert it into electricity can help the world become more energy-efficient, but currently technologies are expensive and not efficient enough. Panasonic is hoping to change that in the coming years with a tubular thermoelectric technology it has developed to tap wasted heat from sources such as hot springs and factories and convert it to electricity. The company says it overcomes certain shortcomings with previous generators, which are complex, flat and difficult to scale up.
Panasonic’s thermoelectric tube allows heat transfer without any additional heat exchangers, increasing the rate of conversion from heat to power. The company says the 10 cm-long tube can generate 1.3 W of electricity by running hot water at a temperature of 90°C inside, and cold water at 10 °C outside the tube. In terms of power density, it could be as high as 10 kW with 1 m3 of volume. How much power could be generated with this thermoelectric generator would depend on its size and the amount of heat available.
The tube is made of two materials: the thermoelectric material (bismuth telluride) and metal (nickel). The researchers stacked conical rings of both materials, whose manufacturing keeps electrical and thermal losses to a minimum. One of the key features of Panasonic’s thermoelectric tube is that it benefits from transverse thermoelectric effect, a phenomena that occurs in tilted multilayer made of thermally-resistive thermoelectric materials and thermally-conductive metals. This effect makes it possible to control heat flow and electric current independently in materials and no complicated electric junctions and planar substrates are necessary.
There is no commercial product in sight before 2018, as a Panasonic researcher says in this video produced by Dvice. For now the company is developing a system design, improving manufacturing processes and assessing how the generator could be packaged in a compact, efficient and economical way in order to tap geothermal energy and waste heat in factories world over.
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