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New Thermoelectric Works Efficiently At Room Temperature
August 1, 2019 | Leave a Comment
University of Houston (UH) researchers have reported the discovery of a new material thermoelectric that works efficiently at room temperature. The new material requires almost no costly tellurium, a major component of the current state-of-the-art material.
The widespread adoption of thermoelectric devices that can directly convert electricity into thermal energy for cooling and heating has been hindered, in part, by the lack of materials that are both inexpensive and highly efficient at room temperature.
The material could be used to cool electronic devices or charge the batteries in overheated vehicles.
You may have noticed your steering wheel can be too hot to touch during the summer.
The new thermoelectric material has been reported with a paper published in the journal Science.
Zhifeng Ren, corresponding author on the work and director of the Texas Center for Superconductivity at UH, where he is also M.D. Anderson Professor of Physics said, “We have produced a new material, which is inexpensive but still performs almost as well as the traditional, more expensive material.” The researchers say future work could close the slight performance gap between their new material and the traditional material, a bismuth-tellurium based alloy.
Thermoelectric materials work by exploiting the flow of heat current from a warmer area to a cooler area, and thermoelectric cooling modules operate according to the Peltier effect, which describes the transfer of heat between two electrical junctions.
Thermoelectric materials can also be used to turn waste heat – from power plants, automobile tailpipes and other sources – into electricity, and a number of new materials have been reported for that application, which requires materials to perform at far higher temperatures.
Thermoelectric cooling modules have posed a great challenge because they have to work at cooler temperatures, where the thermoelectric figure-of-merit, or ZT, is low because it is dependent on temperature. The figure-of-merit is a metric used to determine how efficiently a thermoelectric material works.
Despite the challenge, thermoelectric cooling modules also, at least for now, offer more commercial potential, in part because they can operate for a longer lifespan at cooler temperatures and thermoelectric power generation is complicated by issues related to the high temperatures at which it operates, including oxidation and thermal instability.
The market for thermoelectric cooling is growing. “The global thermoelectric module market was worth ~0.6 billion US dollars in 2018 and it is anticipated to reach ~1.7 billion US dollars by 2027,” the researchers wrote.
Bismuth-tellurium alloys have been considered the best-performing material for thermal cooling for decades, but the researchers said the high cost of tellurium has limited widespread use.
Jun Mao, a post-doctoral researcher at UH and first author on the paper, said the cost has recently dropped but remains about $50/kilogram. That compares to about $6/kilogram for magnesium, a primary component of the new material.
With Ren and Mao, additional authors on the paper include Hangtian Zhu, Zihang Liu and Geethal Amila Gamage, all of the UH Department of Physics and TcSUH, and Zhiwei Ding and Gang Chen of the Department of Mechanical Engineering at the Massachusetts Institute of Technology.
The team has reported that the new material, comprised of magnesium and bismuth and created in a form carrying a negative charge, known as n-type, was almost as efficient as the traditional bismuth-tellurium material. That, combined with the lower cost, should expand the use of thermoelectric modules for cooling, they said.
To produce a thermoelectric module using the new material, researchers combined it with a positive-charge carrying, or p-type, version of the traditional bismuth-tellurium alloy. Mao said that allowed them to use just half as much tellurium as most current modules.
Because the cost of materials accounts for about one-third of the cost of the device, that savings adds up, he said.
The researchers also reported the new material also more successfully maintains electrical contact than most nanostructured materials.
The past few weeks has seen a flurry of thermoelectric papers getting published of which the most interesting have be posted here. This one seems to have the most going for it in consumer terms. Running at a usual familiar to living temperature that can address the cooling effect and generate some power has immense appeal from cooling computers and batteries – on to the car sitting in the sun or just about anywhere heat gathers.
One hopes engineers and marketing folks find the price motivation in this new technology to help make too warm into cool with more useful power.
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