Waste not: Turning industrial heat into electricity

Reposted from EarthTechling with permission

By Beth Buczynski 

Ready for a shock? Fifty-eight percent of all the energy generated in the United States is wasted as heat. With the high financial and environmental cost of creating electricity, especially with fossil fuels, this waste is unacceptable. According to Yue Wu, a Purdue University assistant professor of chemical engineering, finding a way to recover even 10 percent of this wasted heat could take a huge bite out of our collective energy consumption and power plant emissions.

Researchers at Purdue have been working to develop just such an energy-saving solution, and they’ve developed a new “thermoelectric” material that could make it a reality. Through the use of nanotechnology, the team says they will be able to harvest heat from hot pipes or engine components to potentially recover energy wasted in factories, power plants and cars.

Nanocrystal-coated fibers might reduce wasted energyimage via Purdue University/Scott W. Finefrock

To recover energy that would have otherwise been wasted as heat, researchers dipped glass tubes in a solution containing nanocrystals of lead telluride, and then exposed the tubes to heat in a process called annealing that fuses the crystals together. When the thermoelectric materials are heated on one side electrons flow to the cooler side, generating an electrical current.

Such fibers could be wrapped around industrial pipes in factories and power plants, as well as on car engines and automotive exhaust systems, to recapture much of the wasted energy. The “energy harvesting” technology might dramatically reduce how much heat is lost, Wu said.

In addition to generating electricity when exposed to heat, the materials also can be operated in a reverse manner: Applying an electrical current causes it to absorb heat, representing a possible solid-state air-conditioning method. Future work could focus on higher temperature annealing to improve efficiency, and the researchers also are exploring a different method to eliminate annealing altogether, which might make it possible to coat polymer fibers instead of glass. Such fibers might one day be woven into cooling garments or used in other cooling technologies.

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