Pressure may be key to fighting climate change with thermoelectric generators

Pressure may be key to fighting climate change with thermoelectric generators
Artist's conception of how applying pressure in the diamond anvil cell changes the electronic structure of lead selenide. Credit: Xiao-Jia Chen

Pressure improves the ability of materials to turn heat into electricity and could potentially be used to create clean generators, according to new work from a team that includes Carnegie's Alexander Goncharov and Viktor Struzhkin published in Nature Materials.

Alternative energy sources are key to combating climate change caused by carbon emissions. Compounds with thermoelectric capabilities can convert 's innate, physical need to spread from a hot place into a cold place into energy—harvesting electricity from the temperature differential. In theory, generators built from these materials could be used to recover electricity from "wasted" heat given off by other processes, making major contributions to the nation's energy budget.

However, engineers have been unable to improve the performance of any thermoelectric materials in 60 years, meaning that devices built to take advantage of this capability are only practical for some very specific applications, including remote gas pipelines and spacecraft.

"Our measurement of the efficiency of room-temperature thermoelectricity has not budged in more than half a century," said Goncharov. "Thermoelectric compounds have demonstrated improved performance at high temperatures, but we really need them to work well at room temperature to make the most of their potential for green energy."

This is precisely the kind of problem that is suited to address.

The research team—led by Liu-Cheng Chen of the Center for High Pressure Science and Technology Advanced Research—found that they could improve the thermoelectric capability of lead selenide by applying pressure and mixing in charged particles of chromium.

By squeezing the material in the diamond anvil cell —which acted as a sort of "chemical pressure"— and adding the chromium, the lead selenide was encouraged to undertake a structural rearrangement at the , enabling the most-efficient demonstration of room-temperature thermoelectric generation ever recorded.

Under 30,000 times normal atmospheric pressure, the chromium-doped lead selenide was able to produce electricity with the same efficiency that the top-performing thermoelectric materials do at 27 degrees Celsius (80 degrees Fahrenheit).

"Our work presents a new way to use compression techniques to improve the thermoelectric performance, bringing us closer to practical applications that could help fight climate change," concluded Xiao-Jia Chen of the Center for High Pressure Science and Technology Advanced Research (formerly of Carnegie).


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More information: Enhancement of thermoelectric performance across the topological phase transition in dense lead selenide, Nature Materials (2019). DOI: 10.1038/s41563-019-0499-9, https://nature.com/articles/s41563-019-0499-9
Journal information: Nature Materials

Citation: Pressure may be key to fighting climate change with thermoelectric generators (2019, October 7) retrieved 15 October 2019 from https://phys.org/news/2019-10-pressure-key-climate-thermoelectric.html
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Oct 07, 2019
By squeezing the material in the diamond anvil cell —which acted as a sort of "chemical pressure"— and adding the chromium, the lead selenide was encouraged to undertake a structural rearrangement at the atomic level, enabling the most-efficient demonstration of room-temperature thermoelectric generation ever recorded.
Does this material retain this "structural rearrangement" after the release of the pressure or does it revert to its original state? If it does that's great, if not then I frankly do not see the point, unless this research can be used as a guide for other thermoelectric materials that *do* retain this form after the release of the pressure.

Oct 08, 2019
Even if it retains its properties: Thermoelectric generators don't produce a lot of power - but it takes a lot of power to create those kinds of pressure. I'd be surprised if one could achieve a lifetime break-even energy balance from such an element.

Oct 08, 2019
Doesn't seem very practical. They've only managed to make something work at enormous expense and effort that already works fine at room temperature and pressure.

Oct 08, 2019
Imagine all the electricity being produced by thermoelectric compounds under the immense heat and pressure at the Earth's core.

Oct 08, 2019
Imagine all the electricity being produced by thermoelectric compounds under the immense heat and pressure at the Earth's core.

They don't produce electricity out of heat but out of heat difference. If you just slam these deep in the Earths core, there is no heat difference and there is no electricity.

Oct 08, 2019
@cortezz
I meant it as a joke, but now you have me asking there has to be a heat gradient from the core to the surface. Still, you are most likely correct and so I'll stick by my joke.

Oct 08, 2019
Ofc if they could be built in a such way that the cold side of the device is in ocean floor or otherwise near the surface, your idea would be awesome.

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