Devices that generate electricity through the thermoelectric effect – that is, the conversion of differences in temperature to an electric voltage – are showing up in everything from clothing to paint, and they could go a long way towards reclaiming some of the heat lost during energy production. Now researchers at the University of Utah have developed a thermoelectric material that doesn't use the toxic chemicals common in others, but is still efficient and affordable enough for use in everyday products.

Thermoelectric devices work by taking advantage of a temperature difference between two sides of the material. Charge carriers in the material will diffuse from the hot side to the cold side, creating an electric current in the process. The problem is, these devices often rely on elements that are toxic to humans, like cadmium, telluride and mercury, or are relatively expensive and inefficient, like some small wearable generators.

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Instead, the University of Utah team's new material is made using a combination of calcium, cobalt and terbium, making for a safe and inexpensive alternative.

"There are no toxic chemicals involved," says Ashutosh Tiwari, lead researcher on the project. "It's very efficient and can be used for a lot of day-to-day applications."

This diagram demonstrates how the thermoelectric material works, by harnessing the difference in temperature between a hot side – a stovetop fire – and a cold side, of water, which can generate enough electricity to charge a phone (Credit: Ashutosh Tiwari)

The team has plenty of suggestions for what the new material could be used for. Implanted medical monitors could be powered by jewelry that generate electricity by the difference in temperature between body heat and cool air. Cars and planes could power themselves by harnessing the difference between the warm interior and the cold exterior. Pots and pans (or devices like the JikoPower Spark) made from the stuff could generate enough power while cooking to charge a phone, which could be especially useful in developing countries. Or, like other materials, it could be built into power plants to reclaim some of the energy that's typically lost as heat.

"In power plants, about 60 percent of energy is wasted," says Shrikant Saini, first author of the study. "With this, you could reuse some of that 60 percent."

According to the team, the first applications for the new thermoelectric material will be in cars and biosensors, and to get it started, they have applied for a patent.

The research was published in the journal Scientific Reports.

Source: University of Utah

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