New material provides 25 percent greater thermoelectric conversion efficiency

Feb 15, 2011
Thermoelectric materials and technology have powered spacecraft for decades. But, thanks to advances in efficiency discovered at the Ames Laboratory, thermoelectric materials may have new, broader “green” energy applications. Credit: U.S. Dept. of Energy's Ames Laboratory

Automobiles, military vehicles, even large-scale power generating facilities may someday operate far more efficiently thanks to a new alloy developed at the U.S. Department of Energy's Ames Laboratory. A team of researchers at the Lab that is jointly funded by the DOE Office of Basic Energy Sciences, Division of Materials Sciences and Engineering and the Defense Advanced Research Projects Agency, achieved a 25 percent improvement in the ability of a key material to convert heat into electrical energy.

"What happened here has not happened anywhere else," said Evgenii Levin, associate scientist at Ames Laboratory and co-principal investigator on the effort, speaking of the significant boost in efficiency documented by the research. Along with Levin, the Ames Lab-based team included: Bruce Cook, scientist and co-principal investigator; Joel Harringa, assistant scientist II; Sergey Bud'ko, scientist; and Klaus Schmidt-Rohr, faculty scientist. Also taking part in the research was Rama Venkatasubramanian, who is director of the Center for Solid State Energetics at RTI International, located in North Carolina.

So-called that convert heat into electricity have been known since the early 1800s. One well-established group of thermoelectric materials is composed of tellurium, antimony, germanium and silver, and thus is known by the acronym "TAGS." Thermoelectricity is based on the movement of charge carriers from their heated side to their cooler side, just as electrons travel along a wire.

The process, known as the Seebeck effect, was discovered in 1821 by Thomas Johann Seebeck, a physicist who lived in what is now Estonia. A related phenomenon observed in all thermoelectric materials is known as the Peltier effect, named after French physicist Jean-Charles Peltier, who discovered it in 1834. The Peltier effect can be utilized for solid-state heating or cooling with no moving parts.

In the nearly two centuries since the discovery of the Seebeck and Peltier effects, practical applications have been limited due to the low efficiency with which the materials performed either conversion. Significant work to improve that efficiency took place during the 1950s, when thermoelectric conversion was viewed as an ideal power source for deep-space probes, explained team member Cook. "Thermoelectric conversion was successfully used to power the Voyager, Pioneer, Galileo, Cassini, and Viking spacecrafts," he said.

Despite its use by NASA, the low efficiency of thermoelectric conversion still kept it from being harnessed for more down-to-earth applications – even as research around the world continued in earnest. "Occasionally, you would hear about a large increase in efficiency," Levin explained. But the claims did not hold up to closer scrutiny.

All that changed in 2010, when the Ames Laboratory researchers found that adding just one percent of the rare-earth elements cerium or ytterbium to a TAGS material was sufficient to boost its performance.

The results of the group's work appeared in the article, "Analysis of Ce- and Yb-Doped TAGS-85 Materials with Enhanced Thermoelectric Figure of Merit," published online in November 2010 in the journal .

The team has yet to understand exactly why such a small compositional change in the material is able to profoundly affect its properties. However, they theorize that doping the TAGS material with either of the two rare-earth elements could affect several possible mechanisms that influence thermoelectric properties.

Team member Schmidt-Rohr studied the materials using Ames Laboratory's solid-state nuclear magnetic resonance spectroscopy instruments. This enabled the researchers to verify that the one percent doping of cerium or ytterbium affected the structure of the thermoelectric material. In order to understand effect of magnetism of rare earths, team member Bud'ko studied magnetic properties of the materials. "Rare-earth elements modified the lattice," said Levin, referring to the crystal structure of the thermoelectric materials.

The group plans to test the material in order to better understand why the pronounced change took place and, hopefully, to boost its performance further.

The durable and relatively easy-to-produce material has innumerable applications, including recycling waste heat from industrial refineries or using auto exhaust heat to help recharge the battery in an electric car. "It's a very amazing area," Levin said, particularly since many years of prior research into TAGS materials enables researchers to understand their nature. Better understanding of the thermoelectric and their improvement can immediately result in applications at larger scale than now.

Additionally, the Ames Laboratory results – dependent as they were on doping TAGS with small amounts of cerium or ytterbium – provide yet more evidence of rare-earth elements' strategic importance. Cerium or ytterbium are members of a group of 15 lanthanides, deemed essential to just about every new technology from consumer electronics and cell phones to hybrid car batteries and generator motors in wind turbines. The Ames Laboratory has been a leader in rare-earth research going back to the closing days of World War II. Fears of shortages of rare-earth elements have caused these little-known materials to be a much-talked-about subject in the news lately.

Explore further: Chemists achieve new technique with profound implications for drug development

More information: E.M. Levin, B.A. Cook, J.L. Harringa, S. L. Bud'ko, R. Venkatasubramanian, K. Schmidt-Rohr, "Analysis of Ce- and Yb-Doped TAGS-85 Materials with Enhanced Thermoelectric Figure of Merit," Advanced Functional Materials, 2010, in press. DOI:10.1002/adfm.201001307

Related Stories

Explained: Thermoelectricity

Apr 27, 2010

(PhysOrg.com) -- Thermoelectricity is a two-way process. It can refer either to the way a temperature difference between one side of a material and the other can produce electricity, or to the reverse: the ...

Promising new material that could improve gas mileage

Oct 09, 2008

With gasoline at high prices, it's disheartening to know that up to three-quarters of the potential energy you are paying for is wasted. A good deal of it goes right out the tailpipe instead of powering your car.

Recommended for you

World's fastest manufacture of battery electrodes

23 hours ago

New world record: Scientists at the Karlsruhe Institute of Technology (KIT) increased the manufacturing speed of electrode foils coated batch-wise by a factor of three – to 100 meters per minute. This was ...

Waste, an alternative source of energy to petroleum

23 hours ago

The group led by Martín Olazar, researcher in the UPV/EHU-University of the Basque Country's Department of Chemical Engineering, is studying the development of sustainable refineries where it is possible ...

User comments : 27

Adjust slider to filter visible comments by rank

Display comments: newest first

Walter_Mrak
3.4 / 5 (5) Feb 15, 2011
"including recycling waste heat from industrial refineries or using auto exhaust heat to help recharge the battery in an electric car" ???

What sort of exhaust is emitted by an electric car?
kaasinees
0.5 / 5 (26) Feb 15, 2011
What sort of exhaust is emitted by an electric car?

They are probably talking about hybrid cars, which are the worst cars ever and not electric cars.
Batteries do get hot though, maybe we can reuse that heat to charge the battery, but it would add extra weight for just a little bit, not really viable.
The key to a good car is reducing the weight, which is done in electric cars, especially when we get better batteries.
NotAsleep
4.8 / 5 (6) Feb 15, 2011
Maybe the heat from the electric motors...?
h0dges
3 / 5 (2) Feb 15, 2011
"including recycling waste heat from industrial refineries or using auto exhaust heat to help recharge the battery in an electric car" ???

What sort of exhaust is emitted by an electric car?

A hydrogen fuel cell car produces water as a by-product. Heat could possibly be extracted from that.
kaasinees
0.3 / 5 (22) Feb 15, 2011
Maybe the heat from the electric motors...?

Depends on the electric motor.
NotAsleep
5 / 5 (3) Feb 15, 2011
Netherlands technology continues to surprise me, kaasinees! What kind of electric motors did you develop for your cars there that don't produce heat?
kaasinees
0.1 / 5 (22) Feb 15, 2011
Ball bearing motors REQUIRE heat.

electricstuff.co.uk/bbmotor.html

If you would take that heat, the efficiency of the motor drops!
kaasinees
0.1 / 5 (22) Feb 15, 2011
Oh and btw. Who has won all the solar car races? Geuss who? :D

And who made the hydrogen racecar in the shell competition that drives 1 liter to 3000 km?
kaasinees
0.3 / 5 (23) Feb 15, 2011
And geuss where electricity was invented?
Geuss who has the best boats in the world?
And geuss what company made chip-production possible in the first place?

All in The Netherlands, baby.
Doug_Huffman
3 / 5 (2) Feb 15, 2011
Maybe the heat from the electric motors...?

Depends on the electric motor.
Yep. The really high-tech ones avoid RI^2 losses by not using I, and using unobtanium rare earth magnets. They produce no waste heat. Unfortunately they are also the source of Depleted Unobtanium when recycled. That DU is deadly stuff.
Skultch
3.5 / 5 (6) Feb 15, 2011
And geuss where electricity was invented?


Everywhere, some time after the big bang. :P
kaasinees
0.5 / 5 (24) Feb 15, 2011
And geuss where electricity was invented?


Everywhere, some time after the big bang. :P


Ah good one... but in that way nothing was really invented...
lexington
4.4 / 5 (7) Feb 15, 2011
And geuss where electricity was invented?


Everywhere, some time after the big bang. :P


Ah good one... but in that way nothing was really invented...


No, lots of things were invented. Electricity happens to be one of the things that was discovered.
kaasinees
0.4 / 5 (25) Feb 15, 2011
I dont really acknowledge a diffrence between inventing and discovering. But that would semantics...

We discover flight, and invented the plane right?
We dicovered electricty and invented electronics. Right?

My mistake.
ereneon
5 / 5 (2) Feb 15, 2011
I've worked with thermoelectrics before, and their bad efficiency has always annoyed me. This sounds like some really cool work!
FrankHerbert
2.6 / 5 (7) Feb 15, 2011
"including recycling waste heat from industrial refineries or using auto exhaust heat to help recharge the battery in an electric car" ???

What sort of exhaust is emitted by an electric car?


Brakes generate heat.
PPihkala
3.3 / 5 (4) Feb 15, 2011
What sort of exhaust is emitted by an electric car?


Brakes generate heat.

In electric car one is obviously using regenerative braking, so there is not so much heat coming from brakes.
Sanescience
1 / 5 (5) Feb 16, 2011
A hydrogen fuel cell car produces water as a by-product. Heat could possibly be extracted from that.


FAIL! That is a... triple fail? molecular hydrogen as an energy carrier (=dumb), primary exhaust as "by-product", and heat extraction just because there is water. Yup, triple fail.

Wait, the term "fuel cell" was used, fuel cells are looking *really* dumb of late. QUADRUPLE FAIL!

Don't even get me started why hydrogen is a retarded application of time and money. Oi.
Bob_Kob
1 / 5 (1) Feb 16, 2011
Maybe the heat from the electric motors...?

Depends on the electric motor.
Yep. The really high-tech ones avoid RI^2 losses by not using I, and using unobtanium rare earth magnets. They produce no waste heat. Unfortunately they are also the source of Depleted Unobtanium when recycled. That DU is deadly stuff.


For a second there I was about to google this outstanding development that i'd somehow missed -.-
Bog_Mire
1 / 5 (2) Feb 16, 2011
...and guess how you spell guess?
apex01
2 / 5 (4) Feb 16, 2011
Hydrogen is a joke. Hydrogen needs substantial tech breakthroughs and infrastructure of which there is none.
NotAsleep
4 / 5 (1) Feb 16, 2011
And geuss where electricity was invented?
Geuss who has the best boats in the world?
And geuss what company made chip-production possible in the first place?

All in The Netherlands, baby.

Electricity: The Greeks, who discovered that rubbing fur on amber causes an attractive force

The best boats? How do you quantify that?

Chip production: Not sure what you're getting at here but the first analytical machine was designed by a brit by the name of Charles Babbage in 1837. The first functional computer was built in 1939 by John V. Atanasoff and Clifford Berry in the USA. Lastly, Henry Ford developed the assembly line.

Get your facts straight, kaasinees
Sanescience
not rated yet Feb 16, 2011
Yes, yes, people don't like it when you point out how hydrogen is bad for the environment. But then again they tend to be lazy or cowardly and not look into the issues or challenge their eco-social group of friends who accept hydrogen in an almost religious like fashion.
kaasinees
0.1 / 5 (22) Feb 16, 2011
Electricity: The Greeks, who discovered that rubbing fur on amber causes an attractive force

That doesnt mean they understand the concept electricity. There is also a theory that egyptians used chemical batteries, and that means nothing in todays sociecity since the knowledge was lost. Electricity was named after a UK scientist. It was discovered in a Netherlands science convention, scientist from over europe were present.

The best boats? How do you quantify that?

Any oil/transport/towing company will call for a boat from The Netherlands. And because of the netherlands we were able to make better boats in the first place.

Lastly, Henry Ford developed the assembly line

Henry Ford developed a AUTOMOBILE assembly line. Are you confused?
NotAsleep
not rated yet Feb 16, 2011
You're getting tiring, but I'll play along because work is slow today.

Electricity: From the New Latin electricus, "amber-like", coined in the year 1600 from a Greek word meaning amber.

The English scientist William Gilbert distinguished the lodestone effect from static electricity produced by rubbing amber in the 1600s

The Danish Hans Christian Orsted connected electricity with magnetism

Largest ship: Seawise Giant- Japan
Fastest ship: Bluebird K7 - British
Largest naval fleet: USA
Who I call to transport my oil: Mobil

As for "geuss (ouch) who made chip production possible in the first place", that statement really doesn't point to anything really Dutch-related... what are you talking about?

The Netherlands produces fine paintings, beautiful women and fantastic people but bashing NASA with your economics just doesn't work. Please back up your blathering with facts and statistics instead of your opinions. This is a science website, not your
NotAsleep
not rated yet Feb 16, 2011
You're getting tiring, but I'll play along because work is slow today.

Electricity: From the New Latin electricus, "amber-like", coined in the year 1600 from a Greek word meaning amber.

The English scientist William Gilbert distinguished the lodestone effect from static electricity produced by rubbing amber in the 1600s

The Danish Hans Christian Orsted connected electricity with magnetism

Largest ship: Seawise Giant- Japan
Fastest ship: Bluebird K7 - British
Largest naval fleet: USA
Who I call to transport my oil: Mobil

As for "geuss (ouch) who made chip production possible in the first place", that statement really doesn't point to anything really Dutch-related... what are you talking about?

The Netherlands produces fine paintings, beautiful women and fantastic people but bashing everyone else with your economics just doesn't work. Please back up your blathering with facts and statistics instead of your opinions. This is a science website, not your blog
kaasinees
0 / 5 (21) Feb 19, 2011
I suggest you read an actual history textbook and come back.