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Politics : The Environmentalist Thread -- Ignore unavailable to you. Want to Upgrade?

To: maceng2 who wrote (22463)	7/24/2008 3:21:52 PM
From: one_less	Respond to of 36917

Material that turns heat to power gets efficiency hike 19:00 24 July 2008 NewScientist.com news service Your car wastes around 60% of the energy you put into it as heat. But that could soon change, thanks to a new way to boost the efficiency of thermoelectric materials that are able to convert heat into electricity. Just as steam engines use heat to move water vapour to drive the machinery, thermoelectric devices use heat to move electrons that can be harnessed usefully. Since so many mechanical and electrical devices produce waste heat, the materials could potentially allow huge efficiency savings. Adding small chunks of thermoelectric material to any heated surface, like a car exhaust or a computer processor, could produce essentially free energy. But existing thermoelectric materials have poor efficiencies, as described by their zT figure. Despite decades of study, the best commercial thermoelectrics have a zT of around 0.7. To compete with mechanical engines that convert heat into electricity a zT of 3 to 4 is considered essential, but is far from being achieved. Efficiency boost One limit on zT is the amount of heat a given piece of material can convert to power at any one moment. Only now has it proved possible to increase that property. Joseph Heremans and Vladimir Jovovic at Ohio State University in Columbus have developed a new way to alter the common thermoelectric material lead telluride to have that effect. Inside lead telluride, a limited number of electrons can posses the right amount of energy, known as Fermi energy, to convert heat into electricity. Heremans and Jovovic realised that adding small quantities of thallium to lead telluride would make it possible for more electrons to attain that energy level. It works because of a convenient resonance between electrons in the added thallium and those within the host material. Tests show that the thallium-doped compound is most effective between 230 and 510 °C – the temperature range of motor engines. At 510°C, the zT reached 1.5. Combined effect "The peculiar resonance between electrons on the thallium impurity and those on the neighbouring tellurium atoms was calculated to exist by Professor Mahanti [at Michigan State University, East Lansing] in 2006," says Heremans. Earlier this year, Zhifeng Ren at Boston College, Massachusetts, and his team produced a thermoelectric material with a zT of 1.4 using a different technique. They physically altered the crystalline structure of bismuth antimony telluride to reduce the rate at which heat passed through the material. That increases the proportion of heat that can be converted into electricity, increasing efficiency. "It is very good timing to see [Heremans and Jovovic's] new development after our significant enhancement on zT through reducing thermal conductivity," Ren says. "The beautiful thing is that our approach can be used together with the approach used by Zhifeng Ren," says Jovovic. "The upper limit of zT is hard to estimate, but it is clearly much higher than 1.5." Journal reference: Science (DOI: 10.1126/science.1159725)

To: maceng2 who wrote (22463)	7/24/2008 3:36:34 PM
From: Thomas A Watson	Read Replies (1) \| Respond to of 36917

Pearly, what is did I read the paper again. I quoted directly from the paper. I have pdf and pdf as text that I use to cut and paste directly. I have verified the facts, the details and all the logically false statements and bogus citations of Smith. I quoted the a clear and accurate response to Gerhard Gerlich and Ralf D Tscheuschner's paper. I verified the the footnote 1. did you not read claims1. The results presented here are not new. However the form of presentation is designed to clearly and accurately respond to recent claims1 that a physics-based analysis can ?falsify? the atmospheric greenhouse effect. In addition citations 2 3 and 4 are books never mentioned by Gerhard Gerlich and Ralf D Tscheuschner's paper. There are only 5 citations and the last is Smith's opinion of a a good discussion of the development of more and more detailed climate models. That predict a fingerprint that does not exist. To make it clear, this is the I. INTRODUCTION The results presented here are not new. However the form of presentation is designed to clearly and accurately respond to recent claims1 that a physics-based analysis can ?falsify? the atmospheric greenhouse effect. In fact, the standard presentation in climatology textbooks2 is accurate in all material respects. The following explores in more detail certain points that seem to have been cause for confusion. claims1 is ?Falsification Of The Atmospheric CO2 Greenhouse Effects Within The Frame Of Physics? by Gerhard Gerlich and Ralf D. Tscheuschner, arXiv:0707.1161(2007). I am not confused, well only in that I do not know of you are really confused or just handwaving bull in a dishonest attempt at misdirection.