New Alloy Converts Waste Heat Directly into Electricity

Just discovered: an alloy that converts heat directly into electricity, and which might have a wide-ranging impact on generating eco-friendly electricity from waste heat. "This research is very promising because it presents an entirely new method for energy conversion," engineering professor Richard James, who led the University of Minnesota research team, says in an unusually concise press release. During a small-scale demonstration in the lab, the new material created by the researchers began as a non-magnetic material. It suddenly became strongly magnetic when the temperature was raised a small amount. James said, "It's the ultimate 'green' electricity because it uses waste heat to create electricity with no carbon dioxide." Watch the video above to see the moment of conversion.

Professor Richard James' research team conducts demonstration

During the conversion, the material absorbs heat and spontaneously produces electricity in a surrounding coil, which could potentially be used to capture waste heat from a car's exhaust produce electricity for charging the battery in a hybrid car. Other possible future uses include capturing rejected heat from industrial and power plants or from temperature differences in the ocean to create electricity. The research team is looking into possible commercialization of the technology. Here is a research paper schematic:

And a short description of the alloy's composition:

To create the material, the research team combined elements at the atomic level to create a new multiferroic alloy, Ni₄₅Co₅Mn₄₀Sn₁₀. Multiferroic materials combine unusual elastic, magnetic and electric properties. The alloy Ni₄₅Co₅Mn₄₀Sn₁₀ achieves multiferroism by undergoing a highly reversible phase transformation where one solid turns into another solid. During this phase transformation the alloy undergoes changes in its magnetic properties that are exploited in the energy conversion device.

While some heat is lost in a process called hysteresis, the team discovered a critical way to minimize it during phase transformations. For more detail on the research, read the entire paper published in Advanced Energy Materials at http://z.umn.edu/energyalloy. The team is also working with University of Minnesota chemical engineering and materials science professor Christopher Leighton to create a thin film of the material that could be used to convert waste heat from computers into electricity. "This research crosses all boundaries of science and engineering," James said. "It includes engineering, physics, materials, chemistry, mathematics and more. It has required all of us within the university's College of Science and Engineering to work together to think in new ways."

What other innovative methods are currently used to reuse waste heat?

Photo: Professor James and researchers, University of Minnesota Graphic: Schematic, Wiley Online Library Photo: alloy, YouTube video screengrab