Physicists find a compound to more efficiently convert waste heat to electrical power

September 6, 2013, University of Houston

Physicists at the University of Houston's physics department and the Texas Center for Superconductivity are working on an innovation that could boost vehicle mileage by 5 percent and power plant and industrial processing performance as much as 10 percent.

Their research uses non-toxic materials – tin telluride, with the addition of the chemical element indium – for .

Telluride has been studied for years, said Zhifeng Ren, M.D. Anderson Chair professor of physics at UH and lead author of a paper describing the work, published in the Proceedings of the National Academy of Sciences.

But earlier work faltered because lead-containing telluride, despite its strong , can't be used commercially because of the health risks associated with lead, Ren said.

That has sparked the rush for a similar, but safer compound.

"Without lead, there is a much better chance for it to be commercialized," he said.

The research shows the potential for building a device that can capture waste heat – from vehicle tailpipes, industrial smokestacks, power plants and other sources – and convert it to electricity to boost productivity.

Ren and his research team arrived at UH in January from Boston College. This work continues his long-standing research into nanostructured thermoelectrics and thermoelectric .

The research was conducted with colleagues from the Massachusetts Institute of Technology and Boston College. Qian Zhang, a research associate in Ren's group who designed the experiment, said she ultimately decided to add another element, known as a , to alter the of the tin telluride. In this case, she added indium to boost its conducting properties.

In one example, the device could capture heat from a car's tailpipe and convert it to power the car's electronics, improving the car's mileage by about 5 percent, Ren said.

"Even 1 percent, every day, would be huge," he said, considering how much crude oil is consumed worldwide.

The United States and China, the world's most energy-intensive nations, consumed 18.6 million barrels and 10.3 million barrels of crude oil daily respectively in 2012, according to the U.S. Energy Information Administration.

And energy consumption in other countries is growing. ExxonMobil, in its annual energy forecast for the next 30 years, predicted global energy demand will increase 35 percent by 2040.

The increase in demand makes even a small gain in efficiency valuable, Ren said, although he also said the process could be made more efficient in the future.

But capturing car exhaust and converting it to electricity is only one example of how the process can be used. It could also be used in power plants – Ren suggested it could boost the conversion rate of coal-fired from 40 percent to as much as 48 percent – and other industrial plants.

In some cases, Ren said, the efficiency gain could reach 10 percent.

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1 / 5 (14) Sep 06, 2013
"The research shows the potential for building a device that can capture waste heat – from vehicle tailpipes"

Why in the hell would you try to capture heat at the tailpipe? You would incorporate this thing into the existing heat management system. The radiator. In fact if it was really good at scavenging heat, you could eliminate the cars alternator. If it was really really good, you could eliminate the alternator and run a air compressor to send boost to the engine increasing hp and gas mileage even further. Up to 65% of gas energy is wasted as heat in a car.
1.6 / 5 (13) Sep 06, 2013
Thermoelectronics are very important, revolutionary devices. We need to get them going so we can replace the centuries-old steam turbine! Why recapture lost heat when we could simply power anything from electricity generated from heat, without the good-ole steam turbine that we still use in nuclear power plants, and really any power plant the world over. If we can get them to generate electricity at low temperatures, they could solve our energy crisis and combat global warming directly, by sucking up excess heat and converting it to electricity. Thermoelectrics ROCK! This is very important tech and if it can be made efficient, it could revolutionize the way we produce and gather electricity!
4 / 5 (6) Sep 06, 2013
Thermoelectrics are not magic or "revolutionary." They have been around for nearly 200 years. They do not cheat on the laws of thermodynamics and they have the same kind of energy losses all other heat engines have. The reason they are important is that they can use some of the lower quality energy (waste energy) that steam or combustion turbines cannot. The result is that they can add efficiency onto other systems. However, if you think you can pick up the lost energy in a combustion or steam engine, you do not understand the laws of thermodynamics. TE devices follow those laws and are just one more tool for use. Don't get me wrong, they are great for a "bottoming" cycle, but they cannot do better than Carnot defined.
3 / 5 (2) Sep 06, 2013
I don't think that many process come *that* close to the Carnot cycle, so recuperating another fraction may help. Though I'd think that making the initial process more efficient would do more than a secondary system to recoup the waste heat.

That said, if you have several systems working in tandem dumping to a single heat management system you may be able to reclaim a significant portion that may make it worthwhile. Similar to Apple's "Thermal Core" idea (I know they weren't the first to think of such a system, but they are at least a well known example to be familiar to a plebe like myself.) but that is more focused on heat extraction.
1.4 / 5 (11) Sep 07, 2013
If you could mount such a device right after the catalytic converter it would have a great source of high temperature gas as a heat source.
5 / 5 (2) Sep 07, 2013
I am following Cyclone Power Technologies' waste heat engine,which is nearing production.It could be fed with exhaust gases and would allow designers to eliminate the parasitic devices running off engine power: http://www.cyclon...whe.html
1.1 / 5 (11) Sep 07, 2013
Thermodynamics. You wrote a whole paragraph of text but didn't say anything at all. Who cares about the Carnot cycle? It literally has nothing to do with what that man said. Let me explain it to you more simply, so you can understand. So lets just imagine that the planet has a fucking ton of wasted heat laying around. Yes maybe at first these devices will be used as heat scavengers to increase the efficiency of engines that waste heat. (basically anything using combustion.) But if we were to develop thermoelectrics that were as efficient as possible and also dirt cheap to produce, then maybe we could scavenge some of the 384.6 yottawatts (3.846×1026 W) of power the sun is producing every second. Which as krundoloss said would indeed revolutionize the way we gather and produce energy. These things at their maximum theoretical efficiency could indeed power the planet. I am sorry you lack an imagination, don't bully others who have one.
1 / 5 (1) Sep 07, 2013
jalmy said: " But if we were to develop thermoelectrics that were as efficient as possible and also dirt cheap to produce, then maybe we could scavenge some of the 384.6 yottawatts (3.846×1026 W) of power the sun is producing every second."

And he said it rudely: " I am sorry you lack an imagination, don't bully others who have one."

The point I was making is that all heat engines are restricted to an upper bounds by the Carnot cycle, Consequently, thermoelectric cycles are limited by the source and sink temperatures. In general, they are less efficient than the Rankine or Brayton cycles that are produced by turbines (and all are much less efficient than the Carnot cycles). As I said above, thermoelectrics have a place as "bottoming cycles" when combined with Rankine or Brayton cycles, or even with high temperature solar or geothermal (again as the bottoming cycle). I suggest you take a first course in thermodynamics to better understand energy.
3 / 5 (2) Sep 09, 2013
The price of indium is already high because it is used in LCDs and touch screens. So this material combo will have only fringe uses.

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