During a small-scale demonstration in the lab, Univ. of Minnesota researchers showed how their new material can spontaneously produce electricity when the temperature is raised a small amount. Pictured (from left) are aerospace engineering and mechanics professor Richard James, PhD student Yintao Song, and post-doctoral researchers Kanwal Bhatti and Vijay Srivastava.

Univ. of Minnesota engineering researchers in the College of Science and Engineering have recently
discovered a new alloy material that converts heat directly into electricity.
This energy conversion method is in the early stages of development,
but it could have wide-sweeping impact on creating environmentally friendly
electricity from waste heat sources.

Researchers say the
material could potentially be used to capture waste heat from a car’s exhaust
that would heat the material and produce electricity for charging the battery
in a hybrid car. Other possible future uses include capturing rejected heat
from industrial and power plants or temperature differences in the ocean to
create electricity. The research team is looking into possible
commercialization of the technology.

“This research is very
promising because it presents an entirely new method for energy conversion
that’s never been done before,” said Univ.
of Minnesota aerospace
engineering and mechanics professor Richard James, who led the research
team.”It’s also the ultimate ‘green’ way to create electricity because it uses
waste heat to create electricity with no carbon dioxide.”

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.

During a small-scale
demonstration in a Univ. of Minnesota lab, the new material created by the
researchers begins as a non-magnetic material, then suddenly becomes strongly
magnetic when the temperature is raised a small amount. When this happens, the
material absorbs heat and spontaneously produces electricity in a surrounding
coil. Some of this heat energy is lost in a process called hysteresis. A
critical discovery of the team is a systematic way to minimize hysteresis in
phase transformations. The team’s research was recently published in Advanced Energy Materials.

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