How to harvest waste energy with printed thermoelectrics

Posted by Beth Buczynski, EarthTechling

Power plants, whether nuclear or coal-fired, produced a lot of electrical energy. Although keeping millions of homes lit and warm is no small task, these facilities are actually wasting more energy than they create.

Research shows that large power stations only rarely manage to convert more than 40 percent of the produced energy into electrical power. The rest is released unused, mainly via the cooling towers, into the atmosphere. A new development by researchers at Germany’s Fraunhofer Institute researchers could be key to capturing wasted heat and turning into electricity before it escapes into the atmosphere.

Thermoelectrics is the process of generating electrical energy from temperature differences. Power plant cooling towers are the perfect place to implement this technology because of differences in temperature between the escaping hot steam and cooler concrete surface.

Although we’ve understood thermoelectrics for a while, the technology has been expensive and not very efficient (around 8 percent). However, a new process developed at Fraunhofer’s Institute for Material and Beam Technology could create thin flexible sheets of tiny thermoelectric generators (TEG) that are both cheap and efficient. How? Well, they’re going to print them of course.

“Instead of ink, the printing cartridges deposit successive ultra-thin layers of an inexpensive thermoelectrically active polymer paste,” explains Gizmag. “The researchers believe that conventional 3D printing technology could also be used to produce the material.” Once applied to the inside walls of power plant cooling towers, the hot steam activates the electrons in the generator, the negatively charged particles migrate to the cooler side and an electrical voltage is produced.

“…If we succeed in producing TEG cost-effectively, on a large scale and from flexible materials we can install them extensively on the insides of the concave cooling tower wall,” said Dr. Aljoscha Roch. “In this way, through the enormous amount of energy produced in the huge plants – around 1500 liters of water evaporate per minute – we could generate large quantities of electricity.”

Besides capturing a vast amount of energy that previously went to waste, the printable TEGs could also help reduce the overall environmental-impact of the technology: ”TEG are today largely produced by hand from toxic components which contain lead for example. We are now using modern 3D printing technology and harmless polymers (plastics) that are electrically conductive,” explains Roch.

We wouldn’t call plastics “harmless” but it’s definitely a step in the right direction.

* Beth Buczynski, EarthTechling