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New Approach to Developing Thermoelectric Materials Doubles Efficiency | Green News | Eco News
ad telluride (Tl-PbTe), has a zT of 1.5. The new material is most effective between 450° and 950°F—a typical temperature range for power systems such as automobile engines. The application of TE material to automotive waste heat recovery systems is of interest to the research team, and to one of the project funders, BSST Corporation. ( Earlier post .) The dimensionless zT for thermoelectric materials is calculated by the formula zT= T*(S2σ)/κ), where S is the thermoelectric power or Seebeck coefficient of the TE material, σ and κ are the electrical and thermal conductivities, respectively, and T is the absolute temperature. Recent progress in increasing the efficiency of thermoelectric materials has primarily involved decreasing κ by using nanomaterials to lower the thermal conductivity by scattering phonons. Quantum-dot superlattices have reported values of zT >2, and silicon nanowires have such a reduced κ that zT approaches that of commercial materials. Although this certainly provides the evidence that high-zT material can be prepared, the results were obtained on thin films or nanowires that are challenging for high-volume applications that normally rely on bulk materials. Structural complexity on various length scales has successfully reduced κ in bulk TE materials, also yielding zT >1. Unfortunately, in bulk material at least, there is a lower limit to the lattice thermal conductivity imposed by wave mechanics: The phonon mean free path cannot become shorter than the interatomic distance. The minimum thermal conductivity of PbTe is about 0.35 W/mK at 300 K, a value measured on quantum-dot superlattices. Although lower values have been seen for interfacial heat transfer, progress beyond this point in bulk materials must come from the numerator [of the equation] and in particular the Seebeck coefficient; we describe here a successful approach in this direction for bulk materials. —Heremans 2008 For the new material, the researchers left out the nanostructures, and instead focused on how to convert the maximum amount of heat that was trapped in the material naturally. A 2006 paper (S. Ahmad et al.) published in the journal Physical Review Letters suggested that elements such as thallium and tellurium could interact on a quantum-mechanical level to create a resonance between the thallium electrons and those in the host lead telluride thermoelectric material, depending on the bonds between the atoms. It comes down to a peculiar behavior of an electron in a thallium atom when it has tellurium neighbors. We’d been working for 10 years to engineer this kind of behavior using different kinds of nanostructured materials, but with limited success. Then I saw this paper, and I knew we could do the same thing we’d been trying to do with nanostructures, but with this bulk semiconductor instead. —Joseph Heremans Heremans designed the new material with Vladimir Jovovic, who did this work for his doctoral thesis in the Department of Mechanical Engineering at Ohio State. Researchers at Osaka University—Ken Kurosaki, Anek Charoenphakdee, and Shinsuke Yamanaka—created samples of the material for testing. Then researchers at the California Institute of Technology—G. Jeffrey Snyder, Eric S. Toberer, and Ali Saramat—tested the material at high temperatures. Heremans and Jovovic tested it at low temperatures and provided experimental proof that the physical mechanism they postulated was indeed at work. The team found that near 450° F, the material converted heat to electricity with a zT of about 0.75&madsh;close to that of sodium doped telluride—but as the temperature rose, so did the efficiency of the new material. It peaked at 950° F with a zT of 1.5. Heremans’ team is continuing to work on this patent-pending technology, and is targeting boosting zT by another factor of two. We anticipate that deliberately engineered impurity-induced band-structure distortions will be a generally applicable route to enhanced S and zT in all TE materials. We are optimistic about the commercial use of such PbTe-based materials because there is an extensive knowledge base among the manufacturers of thermoelectric generators about the assembly of PbTe-based devices, in particular the ability to make stable metallic contacts with low thermal and electrical resistance. —Heremans 2008 The research was funded by the BSST Corporation; the State of Ohio Department of Development’s Center for Photovoltaic Innovation and Commercialization at Ohio State University; the Beckman Institute; the Swedish Bengt Lundqvist Minne Foundation; and NASA’s Jet Propulsion Laboratory. Go to Source If you liked this article, Digg it! or click here to subscribe to my RSS feed and receive periodic alternative energy news. Posted in Green News on Jul 25, 2008 Comments RSS Leave a Reply Name (required) Mail (will not be published) (required) Website Notify me of followup comments via e-mail ← Vauxhall’s Ellesmere Port plant could get Volt production in Europe Peugeot Citroën Japan To Release Lower-Priced Entry-Level Car →
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FT.com / Companies / Energy Utilities Mining - BHP on course for sixth year of growth
BHP Billiton is on course to report its sixth consecutive year of profits growth after the Anglo-Australian mining group on Wednesday published annual production figures that showed bumper results from its petroleum, iron ore, manganese and copper operations.
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World’s first plastic motor powered light - future seems to be brighter! | Green News | Eco News
this first-of-a-kind motor converts light directly into mechanical energy,
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Mkushi copper project granted mining licence … « Zambian Chronicle
LUSAKA, July 18 (Reuters) - Zambian authorities have granted a licence for the new Mkushi copper project where production of copper concentrate is scheduled to start in mid-2010 and peak at 59,000 tonnes
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Freeport-McMoRan's second-quarter profit drops | Industries | Industrials, Materials & Utilities | Reuters
NEW YORK, July 22 (Reuters) - Freeport-McMoRan Copper & Gold Inc (FCX.N: Quote, Profile, Research, Stock Buzz) said on Tuesday second-quarter profit fell 14 percent as output of the two metals dropped at its massive Grasberg mine in Indonesia.
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On Board Energy Storage - Reason Automobile Engineers Chose (Choose) Fossil Fuel : CleanTechnica
Batteries have to contain all of the chemicals on both sides of their energy releasing equation. The very best batteries available today can store about 0.4 MJ/kg (0.05 kw-hr/lb) including the cases and safety systems. In contrast, gasoline carries about 46 MJ/kg (5.7 kw-hrs/lb). Even with a 20% efficient IC engine, a gasoline tank stores 20 times as much energy as a battery of equal weight. As the vehicle is moving it gets rid of some of that weight. Battery powered vehicles must carry the full weight of their energy source. The energy density difference also plays a key role in the time that it takes to put more energy back on the vehicle once a fuel load is consumed. A two minute fill-up of a 12 gallon tank puts the equivalent of 87 kilowatt-hours into the vehicle, again, taking into account the 20% thermal efficiency. 87 kilowatt-hours in 2 minutes works out to 2.6 MegaWatts. Even with a 220 volt connection, that would require about 11,800 amperes of current. Just imagine the size of the electric cables for that current. There are certainly places and applications where electric vehicles have a role, but it is worth remembering that at least five or six generations of engineers have looked very hard at trying to meet transportation needs and they keep coming back to the same fact - when you want to move a vehicle, you need power, (energy per unit time).
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Morningstar - Dow Jones & Company, Inc.: Zambia Lumwana Mine Delay To Hit 08 Copper Output - Official
Zambia's copper output this year, which is already under threat from intermittent power outages, will be hit by the delay to the start of Lumwana mine's copper output this month, an industry official told Dow Jones Newswires Wednesday.
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CNW Group | WALLBRIDGE MINING COMPANY LIMITED | Wallbridge Mining Begins Exploration on Copper-Zinc and Nickel Targets in North-eastern Ontario
The copper-zinc and nickel properties are located within Wallbridge's Shipley and Hong Kong Township claim groups, approximately 10 kilometres southeast of Sultan, and about 100 kilometres north-west of Sudbury, Ontario
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Explorator Intercepts Significant Copper-Gold Mineralization in the La Viuda Zone
We are intersecting substantial oxide copper-gold mineralization in the La Viuda area, which will add to the overall estimated oxide resource of the El Espino-Venus Project.
more fromwww.marketwire.com
Indonesia's power crisis
Companies operating in Indonesia have criticised the government over power cuts and Jakarta's attempts to deal with them, including an edict forcing factories to move production to weekends from next week.
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8Mb rADSL is a far off pipe-dream - But it's what I'm charged for.
8Mb rADSL is a far off pipe-dream - only speed advantage over a modem is the connect time. But it's what I'm charged for.
more fromwww.zdnet.co.uk
CANOE -- CNEWS - Politics: Exploratory mining for copper begins in Clayoquot Sound
Exploratory mining for copper begins in Clayoquot Sound
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The Standard - Hong Kong's First FREE English Newspaper
Rio Tinto's second-quarter refined copper output tumbled 18 percent from the same period a year ago, facing lower yields at some operations, while production of iron ore, weighted toward sales in China, rose 13 percent, the company said.
more fromwww.thestandard.com.hk
Air Powered Motors: Small as Watermelons, More Efficient than Diesel | Air powered | The Green Optimistic
If you watch The Green Optimistic you already know that we covered air cars in previous posts, both MDI CAT’s and the Angelo DiPietro air motor. The first time we wrote about these inventions was about 6 months ago. Now, MDI and Angelo DiPietro have contracts all over the world with auto makers to sell them the compressed air technology
more fromwww.greenoptimistic.com
EU to tackle eco impact of consumerism
BRUSSELS (Reuters) - The European Commission will launch a raft of proposals on Wednesday to curb the environmental impact of consumerism in the 27-nation EU by supporting eco-friendly products and technology.\n\nThe plan comes as the European Union moves to cut energy consumption amid soaring fuel and power prices and as part of its ambitious mid-term goal of cutting carbon dioxide emissions by one fifth by 2020, compared to 1990 levels.\n\n"This will mainly be targeted at products that use a lot of energy, such as computers, televisions, water heaters and industrial fans," a source at the Commission, the bloc's executive arm, said on Monday.
more fromwww.reuters.com
IBM to prime pump for smart-grid start-ups | Green Tech - CNET News.com
The idea is to create a common set of communication protocols and data formats that utilities and smart-grid start-ups can adhere to.
more fromnews.cnet.com
Billboards Made of Money - Chevrolet Aveo Penny Billboard Disappears in Minutes (GALLERY)
Credit-crunched Londoners grabbed pocketfuls of pennies today at the launch of a 20-foot billboard advert made entirely from one-pence coins. The unique installation – made using over 20,000 pennies – only lasted 30 minutes as hundreds of opportunistic passers-by seized their moment to pick up a penny or two
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Aluminum Hinge Alternatives to Steel From H.A. Guden Co., Inc.
With the price of steel rising at unprecedented rates, aluminum can be an attractive alternative in many design applications.
more fromwww.prweb.com
Where are WEEE? The Environment Agency’s Adrian Harding talks recycling
Greenbang went down to Kyocera’s Green Card event earlier this year to hook up with Adrian Harding of the Environment Agency - he told us what’s happening with the Waste Electrical and Electronic Equipment Directive… Check him out on this film…
more fromwww.greenbang.com
Rio Tinto sees copper price surging to fresh peaks | Reuters
LONDON (Reuters) - Copper prices could hit fresh record highs this year as the Chinese economy continues to expand despite a slowdown in the United States, the chief economist of miner Rio Tinto (RIO.L: Quote, Profile, Research) said on Thursday.
more fromuk.reuters.com
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