Paint has graduated from being more than just a coloring material. We already know of photovoltaic paint — the kind of paint that can absorb solar energy and convert it into usable electric power. Another kind of innovative paint has just been invented. Developed through the combined efforts of researchers from the Korea Electrotechology Research Institute, the Korea Institute of Science and Technology (KIST) and the Ulsan National Institute of Science and Technology (UNIST), it’s called thermoelectric paint and it can transform waste heat into electricity.
Currently, majority of the thermoelectric devices being used are flat and rigid. When they’re attached to objects that emit heat like refrigerators or engines, they are prone to losing a considerable amount of energy because of the space created between the flat thermoelectric generators and the curved surfaces where they’re on. With the new thermoelectric paint, this kind of loss is avoided.
Thermoelectric paint contains bismuth telluride (Bi2Te3), a type of particle that most types of conventional thermoelectric devices use. By adding molecular sintering aids to the paint mix, the problem on incomplete contact surface is solved as the thermoelectric particles react by adhering to each other when heated, covering the entire surface completely regardless of its shape, thereby increasing their density and their ability to convert energy.
Based on the demonstration done, after the thermoelectric paint was applied and heated for 10 minutes to 840 degrees Fahrenheit (450 degrees Celsius), it formed a uniform film that was about 50 micrometers thick. This enabled the painted surface to convert more heat into electricity. That’s an output power density of 4 mW cm2 — more than double the highest reported values for in-plane type devices; and 26.3 mW/cm2, almost the same as existing through-plane type devices. These results show that compared with any other existing ink-based or paste-based thermoelectric material, thermoelectric paint appears to have the highest energy conversion rate.
According to the research team, thermoelectric paint would especially be useful during the summer months when temperatures can go as high as 122 degrees Fahrenheit (50 degrees Celsius). Jae Sung Son, one of the authors of the research believes that “If we apply thermoelectric paint on the walls, we can convert huge amounts of waste heat into electrical energy.”
Aside from applying thermoelectric paint on large surfaces like buildings, ships, and cars, the research team is expecting that the technology can also be used in a variety of applications including wearable devices, 3D printing, and electronic painted art.
In the face of the potentially catastrophic global warming problem we are facing, any kind of energy saving technique will surely be a welcome move. And thermoelectric paint is a step in the right direction. Hopefully, it can be perfected and made commercially available soon because it will not only benefit our wallets (lower electric bill), it has the potential to help save our environment too.