Paint converts waste heat to power

ENGINEERS have developed a paint that efficiently converts waste heat into electricity.

The team from Ulsan National Institute of Science and Technology (UNIST) in Korea says its paint overcomes the inefficiencies of existing flat or angular thermoelectric (TE) devices that cannot be snugly fit to the sorts of irregular surfaces and structures that give off heat in the likes of engines, power plants and refrigerators.

The thermoelectric paint contains thermoelectric bismuth telluride particles that are commonly used in conventional thermoelectric devices. The team also added a sintering aid that increases the density of the thermoelectric particles, boosting the paint’s energy conversion efficiency.

The team says it’s achieved “excellent thermoelectric properties” at temperatures ranging from 25–125^oC, noting that the values are higher than those obtained with typical bismuth telluride ingots and 3–4 times greater than values from studies into thermoelectric inks or pastes.

“In summary, this study demonstrates that the painted TE devices exhibiting high output power of 4.0 mW/cm² can be easily prepared on any-shaped surfaces by the molecule-level sintering effect,” the team reports.

Study leader Jae Sung Son said: “By developing integral thermoelectric modules through a painting process, we have overcome limitations of flat thermoelectric modules and are able to collect heat energy more efficiently.”

In an interview with PhysOrg, he added: 'I expect that the thermoelectric painting technique can be applied to waste heat recovery from large-scale heat source surfaces, such as buildings, cars, and ship vessels.'

The team also reports that it strongly believes the technology can be easily transferred to 3D-printing techniques.

Nature Communications doi.org/btpc