A group of researchers have developed a new material that can be used to turn waste heat into electricity. This technology could allow power plants to recycle their waste heat and save money, while reducing our fossil fuel consumption and helping the environment. Their results are published in a paper in the Proceedings of the National Academy of Sciences.
In many power generators, such as coal plants and automobile engines, most of the energy produced ends up as heat. Some of this heat is then used to produce electricity but much of it typically gets lost when it escapes into the atmosphere. If it could be reclaimed and used to generate more electricity, it could dramatically improve the efficiency of those generators.
That's the idea behind thermoelectric compounds—materials that convert heat into electricity. Thermoelectric materials convert a temperature difference into a voltage, essentially turning heat into electricity.
All materials show this effect to a small degree, but the challenge is to find a material with a strong enough effect to be useful. A useful material will either have a high efficiency or a high power factor. Efficiency is a measure of how well the material converts heat into electricity, while the power factor is a measure of how much electricity the material can generate at once.
Most research is dedicated to improving efficiency, but this group decided to try and improve the power factor instead. For large-scale applications like coal plants with lots of waste heat, efficiency is less important than total power.
The researchers developed a custom material made of niobium, iron, antimony, and titanium. They discovered that pressing the material at extremely high temperatures, around 2000 degrees Fahrenheit, resulted in an extremely high power factor.
As a result, the new material can generate around 22 watts per square centimeter, which is much higher than the 5 or 6 watts typically produced.
This could be a high enough power factor to justify using on a large scale, which would allow power plants to recycle waste heat into extra energy. This in turn would reduce the amount of fossil fuels we'd have to burn, which could save money and help prevent climate change.
Recommended reading source: Popular Mechanics
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