Printed thermoelectric generators could capture energy from waste heat
By Ben Coxworth
April 3, 2013
Thermoelectric materials, putting it simply, are able to generate electricity via differences in temperature. If thermoelectric felt were used to make a jacket, for instance, it could generate a current using the temperature gradient between the warm interior and cold exterior of the garment. Like many such promising technologies, however, the cost of thermoelectrics is something of an issue ... although thanks to a new process developed at Germany’s Fraunhofer Institute for Material and Beam Technology, that might not be the case for much longer.
Using technology not unlike ink jet printing, the Fraunhofer scientists have been able to create thin flexible sheets of tiny thermoelectric generators (TEG). Instead of ink, the printing cartridges deposit successive ultra-thin layers of an inexpensive thermoelectrically active polymer paste. The researchers believe that conventional 3D printing technology could also be used to produce the material.
It is now hoped that films of the generators could be applied to the inside walls of concrete cooling towers at power stations, to take advantage of the temperature difference between their cool outside surfaces and their steam-heated interiors. This would allow some value to be obtained from the station’s waste heat, that currently just passes through the towers and into the atmosphere.
Although the efficiency of thermoelectrics in general isn’t huge – the most efficient are able to convert 15 to 20 percent of waste heat to electricity, although figures of around 8 percent are more typical – the sheer area of the towers that could be cheaply covered with the material would reportedly make the effort worthwhile.
Additionally, the polymer is said to be completely innocuous, unlike other TEG materials that are made from toxic components such as lead.
The technology is soon to be publicly demonstrated on a model cooling tower, at the Hannover Messe trade fair.