This chart compares the useful transport energy requirements for a vehicle powered from a hydrogen process (left) vs. electricity (right). Image Credit: Ulf Bossel. “Ultimately, hydrogen has to be made from renewable electricity by electrolysis of water in the beginning,” Bossel explains, “and then its energy content is converted back to electricity with fuel cells when it’s recombined with oxygen to water. Separating hydrogen from water by electrolysis requires massive amounts of electrical energy and substantial amounts of water.” Also, hydrogen is not a source of energy, but only a carrier of energy. As a carrier, it plays a role similar to that of water in a hydraulic heating system or electrons in a copper wire. When delivering hydrogen, whether by truck or pipeline, the energy costs are several times that for established energy carriers like natural gas or gasoline. Even the most efficient fuel cells cannot recover these losses, Bossel found. For comparison, the “wind-to-wheel” efficiency is at least three times greater for electric cars than for hydrogen fuel cell vehicles. Another headache is storage. When storing liquid hydrogen, some gas must be allowed to evaporate for safety reasons—meaning that after two weeks, a car would lose half of its fuel, even when not being driven. Also, Bossel found that the output-input efficiency cannot be much above 30%, while advanced batteries have a cycle efficiency of above 80%. In every situation, Bossel found, the energy input outweighs the energy delivered by a factor of three to four. “About four renewable power plants have to be erected to deliver the output of one plant to stationary or mobile consumers via hydrogen and fuel cells,” he writes. “Three of these plants generate energy to cover the parasitic losses of the hydrogen economy while only one of them is producing useful energy.”This fact, he shows, cannot be changed with improvements in technology. Rather, the one-quarter efficiency is based on necessary processes of a hydrogen economy and the properties of hydrogen itself, e.g. its low density and extremely low boiling point, which increase the energy cost of compression or liquefaction and the investment costs of storage. The alternative: An electron economyEconomically, the wasteful hydrogen process translates to electricity from hydrogen and fuel cells costing at least four times as much as electricity from the grid. In fact, electricity would be much more efficiently used if it were sent directly to the appliances instead. If the original electricity could be directly supplied by wires, as much as 90% could be used in applications.“The two key issues of a secure and sustainable energy future are harvesting energy from renewable sources and finding the highest energy efficiency from source to service,” he says. “Among these possibilities, biomethane [which is already being used to fuel cars in some areas] is an important, but only limited part of the energy equation. Electricity from renewable sources will play the dominant role.”To Bossel, this means focusing on the establishment of an efficient “electron economy.” In an electron economy, most energy would be distributed with highest efficiency by electricity and the shortest route in an existing infrastructure could be taken. The efficiency of an electron economy is not affected by any wasteful conversions from physical to chemical and from chemical to physical energy. In contrast, a hydrogen economy is based on two such conversions (electrolysis and fuel cells or hydrogen engines). “An electron economy can offer the shortest, most efficient and most economical way of transporting the sustainable ‘green’ energy to the consumer,” he says. “With the exception of biomass and some solar or geothermal heat, wind, water, solar, geothermal, heat from waste incineration, etc. become available as electricity. Electricity could provide power for cars, comfortable temperature in buildings, heat, light, communication, etc. “In a sustainable energy future, electricity will become the prime energy carrier. We now have to focus our research on electricity storage, electric cars and the modernization of the existing electricity infrastructure.”Citation: Bossel, Ulf. “Does a Hydrogen Economy Make Sense?” Proceedings of the IEEE. Vol. 94, No. 10, October 2006.By Lisa Zyga, Copyright 2006 Physorg.com This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
Citation: WPA Wi-Fi Encryption Cracked In Sixty Seconds (2009, August 28) retrieved 18 August 2019 from https://phys.org/news/2009-08-wpa-wi-fi-encryption-sixty-seconds.html (PhysOrg.com) — Two Japanese computer scientists have developed a way to crack the WPA encryption between wireless routes and devices in 60 seconds. Explore further The Final ‘Final’ Nail in WEP’s Coffin?
TeliaSonera launches first commercial 4G/LTE network Who needs faster wireless networks? Nearly half of US consumers say they don’t. A new survey finds that nearly half of U.S. consumers feel they just do not need 4G LTE. “Colossal power!” “Scorching speed!” “Take your office across the map!” Promotional slogans about 4G LTE devices from carriers and phone vendors about fourth-generation (4G) Long Term Evolution (LTE) networks apparently are not working. The survey from investment firm Piper Jaffray polled 3,000 individuals, results of which were released in a research note this week by analyst Christopher Larsen. A total of 47% of US consumers in the survey felt they have no need for 4G LTE- and only 15 percent of those polled thought 4G LTE is the best network technology.The Piper Jaffray survey also found that consumers are ambivalent about which U.S. carrier has the best 4G LTE network. Among those polled, 51 percent indicated they don’t know who has the best 4G network, or that all 4G networks are the same.Apple released its first 4G LTE device earlier this year with the third-generation iPad. Apple’s next iPhone 5 is expected to also feature 4G LTE connectivity. “This model will almost certainly include 4G LTE wireless capabilities because it would be innovation suicide to not offer it,” said VentureBeat recently. “Top-notch Android phones have been offering 4G data connections since before the iPhone 4S launched.”Interestingly, more enthusiasm according to poll results was shown toward the word iPhone than discussions of connectivity. The poll asked consumers about Apple’s next iPhone, and found that 55 percent of those surveyed said they are considering purchasing it. Of the 55 percent contemplating the iPhone purchase, 44 percent said they would choose Verizon as their carrier; 29 percent said AT&T; 14 percent were for Sprint; and 13 percent for T-Mobile which is not expected to offer the new smartphone.Larsen said that this mixed bag of carrier choice results is good news for them all. Verizon gains from brand recognition, but the fact that so many consumers don’t have an opinion about the different 4G networks means that there’s still time for other carriers to win more consumer attention. The poll’s results generally show competition opportunities for all carriers regarding 4G LTE.The poll also indicates an odd disconnect between a lack of marketing success in sparking 4G LTE awareness in consumers and actual technology advancements. Carriers are busy expanding their networks and providing more 4G LTE coverage; vendors are busy creating buzz about their devices’ 4g LTE features at tradeshows and technology forums.4G LTE delivers mobile network speeds faster than 3G networks. As of Q4 2011, thirty-eight mobile network operators worldwide had launched 4G LTE networks commercially. According to a Reportlinker.com study released this month, governments worldwide have held 4G spectrum auctions or are planning to in coming years, and many Tier 1 mobile operators are building and deploying commercial LTE services. Key drivers are higher data speeds, simplified all-IP networks and the commercial availability of over 200 4G LTE -enabled devices. For consumers, the 4G LTE technology will enable streaming, downloading, and uploading data and playing online games faster than before. With all this activity, nonetheless, the poll results have come as a rude reminder that American consumers are not, at least as of yet, really focused on 4G LTE. Motorola Atrix 4G © 2012 Phys.Org Citation: Almost half of Americans yawn over 4G LTE (2012, August 24) retrieved 18 August 2019 from https://phys.org/news/2012-08-americans-4g-lte.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Explore further
“Autonomous motors of a metal–organic framework powered by reorganization of self-assembled peptides at interfaces” has been published in the journal Nature Materials. The journal presents new research in materials science and engineering. The study authors noted that a variety of microsystems have been developed that harness energy and convert it to mechanical motion, but they have developed “new autonomous biochemical motors by integrating a metal–organic framework (MOF) and self-assembling peptides.”.The team designed a type of molecular motor that is capable of propelling itself across a liquid surface. They used a highly porous MOF device constructed to leak organic peptide molecules out of the slit, which propels the boat. “The MOF is applied as an energy-storing cell that assembles peptides inside nanoscale pores of the coordination framework,” they wrote. The researchers, led by Hiroshi Matsui of Hunter College, filled the pores in an MOF with the peptide diphenylalanine and floated the particles on water. Adding ethylenediaminetetraacetate (EDTA) partially degraded the MOF which allowed the peptide to escape from the pores. “The neat MOF particle is descended immediately to the bottom of the EDTA solution with no transitional and rotational motions and it does not decompose visibly under the microscope in the time frame of this experimental setting,” they wrote.Explaining their work further, Chemistry World, the Royal Society of Chemistry publication, said. “Upon reaching the water, the peptide spontaneously reassembles into a hydrophobic aggregate, reducing the surface tension at that point. The creation of a surface-tension gradient forces the particles to move towards the area with higher surface tension, a phenomenon known as the Marangoni effect.”Scientific efforts to imitate nature’s motile life forms have been part of the quest for autonomous microscopic machines. The study authors said that “This demonstration opens the route towards new applications of MOFs and reconfigurable molecular self-assembly, possibly evolving into a smart autonomous motor capable of mimicking swimming bacteria and, with integrated recognition units, harvesting target chemicals.” The authors are Yasuhiro Ikezoe, Gosuke Washino, Takashi Uemura, Susumu Kitagawa and Hiroshi Matsui. Credit: Kyoto University ‘Seeding’ the next generation of smart materials © 2012 Phys.org (Phys.org)—Research towards self-propelling microscopic machines has a boost in the form of a newly published study by researchers at City University of New York-Hunter College and Kyoto University in Japan. They worked out a ‘molecular motor’ that can move, speedboat-style, across a liquid surface. Journal information: Nature Materials Citation: MOF speedboat study adds spark to smart autonomous motors (2012, October 30) retrieved 18 August 2019 from https://phys.org/news/2012-10-mof-speedboat-smart-autonomous-motors.html Explore further More information: www.nature.com/nmat/journal/va … t/full/nmat3461.htmlNature Materials, 2012, DOI: 10.1038/nmat3461 This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
First single-molecule measurement of Van Der Waals interactions at metal-organic interface Journal information: Physical Review Letters Mapping out the van der Waals interaction between two atoms. (a) In the experiment of Béguin et al. two atoms are trapped in the foci of two laser beams separated by a distance R. (b) Depending on R, the excitation laser field can couple the ground state |gg of the atomic pair to states containing one atom in the Rydberg state (|gr and |rg, respectively), or to a state with both atoms populating the Rydberg state |rr. The energy of the latter state is strongly shifted because of the van der Waals interaction UvdW between the atoms (see level diagram in the upper left), resulting in a distance-dependent coherent excitation dynamics of the atomic pair system. (c) By analyzing the time evolution of the atom-pair state, Béguin et al. deduce the van der Waals energy shift as a function of interatomic distance for different Rydberg states. Credit: Physics 6, 71 (2013) DOI: 10.1103/Physics.6.71 This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
Mystery at the core of the earth © 2017 Phys.org (Phys.org)—A team of researchers from several institutions in Japan has conducted experiments with results that indicate that silicon is likely the missing element in Earth’s core. The group gave a presentation outlining their findings at a recent meeting of the American Geophysical Union. Citation: Experiment suggests silicon missing element in Earth’s core (2017, January 11) retrieved 18 August 2019 from https://phys.org/news/2017-01-silicon-element-earth-core.html
Museum says mummy was Peruvian girl who lived centuries ago The archaeologists reported that along with the remains, there was a belt with beads and a buckle made of jet, a vase resembling those used by Huns of the period, and a box made of birch wood that held a small mirror. Other assorted ceramic utensils were also found. Initial examination of the mummified remains revealed patches of skin, soft tissue and cloth remnants that appeared to be made of silk.The researchers noted that the area where the grave was found is normally underwater, but this year, the reservoir created by the dam was abnormally low, exposing ground that had been submerged since the 1980s. As the researchers were exploring the exposed land last month, they came upon the tomb.The researchers suggest the clothing and materials in the grave indicate the girl was likely a nomadic Hun—likely one of high regard. She could have been part of the nobility. They also note that the vase contained what appeared to be a funeral meal and that a sack of pine nuts had been placed on her chest. The Huns, the researchers note, lived in parts of what is now modern China and Siberia almost 2000 years ago. They were migratory, and prior studies have shown they tended to mix with local people.The remains and other artifacts have been removed from the gravesite and have been transported to a location suitable for studying them. The researchers report that a lot of work is required to learn more about the girl’s origins and how she came to be mummified. They will also be working to understand how her remains and other artifacts were able to withstand being submerged under the reservoir for over 30 years. Credit: Marina Kilunovskaya A team of researchers from St Petersburg’s Institute of History of Material Culture has found the naturalized remains of a mummy in an ancient gravesite near the Sayano-Shushenskaya Dam in Russia. In speaking with the press, the researchers reported that the remains were those of a mummified young girl lying in a stone gravesite and that they believe she lived almost 2000 years ago. © 2018 Phys.org Explore further This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Citation: 2000-year-old mummy found near Russian reservoir (2018, June 29) retrieved 18 August 2019 from https://phys.org/news/2018-06-year-old-mummy-russian-reservoir.html