Published on May 6th, 2013 | by Tina Casey3
“Saran Wrap” Thermoelectric Breakthrough Converts Leftovers To Electricity
Researchers at the University of Michigan have just announced a new breakthrough for making a class of relatively cheap thermoelectric materials that are as lightweight and tough as your favorite kitchen wrap. When wrapped around a hot object or a piece of motorized equipment, thermoelectric materials convert waste heat to electricity, and they can also be used to provide a cooling effect without the need for chemical refrigerants. While the new materials would still not be as efficient as their conventional counterparts, their low cost and flexibility could help speed their introduction into the mainstream of energy efficiency products.
A New Class Of Thermoelectric Materials
The new thermoelectric materials would use organic semiconductors, which until now have played the role of wallflower in the thermoelectric world due to their low rate of efficiency. However, that is beginning to change.
Researchers have begun to take another look at organic semiconductors because the shortcomings of conventional materials are becoming problematic in today’s world. Though suitable for specialty applications (including space-going vehicles), thermoelectric devices need to break through the affordability and hardiness barriers to transition into mainstream use.
As described by U-M writer Nicole Casale Moore, conventional materials include bismuth, tellurium and selenium, which are rare, expensive and toxic, and not particularly durable, either.
A Thermoelectric Breakthrough
The gamer-changer would be a drastic increase in the efficiency of organic semiconductor thermoelectric materials, and that is what the U-M team achieved: an improvement of almost 70 percent, for a material that would perform effectively at up to 250 degrees Fahrenheit.
The nexus of the improvement was a compound of the polymer PEDOT and the polyelectrolyte PSS, which is also commonly found in organic LEDs and solar cells.
The team found that excess PSS in the compound was inhibiting the material’s performance, and developed a solvent-based method for removing some of the extra PSS molecules.
The Thermoelectric World Of The Future
Consider that thermoelectric materials could be used on car exhaust, factory emissions and machinery, and you can see the enormous potential for energy harvesting in the U.S. and other industrialized nations with a low cost, effective thermoelectric material at hand.
That explains why U-M is not alone in its efforts. A research team at Virginia Tech is also looking into a new class of low cost materials based on skutterudites (cobalt arsenide minerals) and silicides (silicon-based compounds), and a thermoelectric brain trust of researchers from Brookhaven, Argonne, and Los Alamos national laboratories and from Columbia University, Northwestern University and the Swiss Federal Institute of Technology has been working on a foundational research project aimed at revealing the molecular secrets behind the “flipping” behavior that enables certain materials to block heat transfer.