To save energy: take dirt, add heat

MICHIGAN STATE (US) — Researchers have developed a new thermoelectric material by using common minerals found pretty much anywhere there’s dirt.

That’s important, because the vast majority of heat generated from, for example, a car engine, is lost through the tail pipe. It’s the thermoelectric material’s job to take that heat and turn it into something useful, like electricity.

The researchers, led by Donald Morelli, a professor of chemical engineering and materials science at Michigan State University, developed the material based on natural minerals known as tetrahedrites.


“What we’ve managed to do is synthesize some compounds that have the same composition as natural minerals,” says Morelli, who also directs Michigan State’s Center for Revolutionary Materials for Solid State Energy Conversion. “The mineral family that they mimic is one of the most abundant minerals of this type on Earth—tetrahedrites.

“By modifying its composition in a very small way, we produced highly efficient thermoelectric materials.”

The search to develop new thermoelectric materials has been ongoing. While some new, more efficient materials have been discovered as of late, many of those are not suitable for large-scale applications because they are derived from rare or sometimes toxic elements, or the synthesis procedures are complex and costly.

“Typically you’d mine minerals, purify them into individual elements, and then recombine those elements into new compounds that you anticipate will have good thermoelectric properties,” he says. “But that process costs a lot of money and takes a lot of time. Our method bypasses much of that.”

As reported in the online journal Advanced Energy Materials, the new method involves the use of very common materials, grinding them to a powder, then using pressure and heat to compress into useable sizes. “It saves tremendously in terms of processing costs,” Morelli says.

The researchers expect this discovery could pave the way to many new, low-cost thermoelectric generation opportunities with applications that include waste heat recovery from industrial power plants, conversion of vehicle exhaust gas heat into electricity, and generation of electricity in home-heating furnaces.

The work, a partnership with the University of Michigan and UCLA, is supported by a grant from the US Department of Energy/Office of Science. Other institutions involved with the Michigan State-based center are Northwestern University, Ohio State University, Wayne State University, and Oak Ridge National Laboratory.

Source: Michigan State University