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| Author | Topic: Fuel Cells |
| Miniature fuel cells may oust batteries |
posted 6/8/04 5:18 AM
Miniature fuel cells may oust batteries 09:30 08 March 04 A trick that boosts the power of miniature hydrogen fuel cells by up to 50 per cent has been revealed by US researchers. Such fuel cells could help keep portable gadgets up and running - cellphone giant Nokia warned last week that battery technology is not keeping pace with advanced phone functions. Mechanical engineers Suk Won Cha and Fritz Prinz at Stanford University in California found they can dramatically increase efficiency by shrinking the channels that deliver fuel to the cell's heart. The apparent downside is that the effect only works with hydrogen fuel cells, whereas liquid methanol is currently the fuel of choice for consumer electronics firms like Motorola and NEC that are developing fuel-cell-powered cellphones and laptops. They favour methanol because it releases more energy than hydrogen, volume for volume, so methanol-powered gadgets would be able to have smaller "fuel tanks". However, methanol is toxic, and the fuel cells that use it produce the greenhouse gas carbon dioxide as a waste product. Hydrogen produces only water, and this, along with Cha's efficiency-boosting trick, could make it a strong contender for fuelling mobile devices. Exchange membrane Fuel cells work by combining the fuel with oxygen from the air and using the energy liberated to drive an electrical current. Cha's fuel cell contains a polymer-based "proton exchange membrane" sandwiched between an anode and cathode layer, each containing a platinum catalyst. Hydrogen travels to the anode through a polymer block bored with channels 500 micrometres wide. At the anode, the platinum helps break the hydrogen down into protons and electrons. The protons cross the membrane and react with oxygen and electrons from the cathode, and this drives the electrons left at the anode around an electrical circuit to the cathode. The Stanford team decided to see what would happen if they made the channels smaller and more numerous. They used a microchip etching process to bore channels just 20 micrometres wide. The effect was to increase the speed at which the hydrogen is delivered and prevent the anode being flooded with fuel. This boosted the rate of proton exchange and increased the fuel cell's power by half as much again. Clogging fear Standard laptop batteries can usually run for two to four hours without a recharge. Some hydrogen fuel cell companies hope to produce cells that run up to 20 hours, says Cha, and he claims that his technique should increase the running time by as much as 50 per cent on top of that. Or you could achieve the same running time for just 70 per cent of the fuel. David Hart, head of fuel cell research at Imperial College London, says it should be possible to scale up the Stanford team's technique to build much larger fuel cells out of many smaller cells. But Manfred Stefener, head of Smart Fuel Cells in Germany, is worried about waste water clogging the microchannels. "The smaller you make your channels, the higher the risk of water getting stuck in that channel," he says. "This can be disastrous." Cha acknowledges the design will have to take account of this. Duncan Graham-Rowe http://www.newscientist.com/news/news.jsp?id=ns99994734 |
| Fuel cell-propelled aircraft preparing to fly |
posted 6/8/04 5:21 AM
Fuel cell-propelled aircraft preparing to fly 17:44 12 May 03 NewScientist.com news service The world's first crewed aircraft powered by fuel cells could be ready for test flights by December 2003. The experimental one-person craft, being built by US aerospace company Boeing, will rely entirely on a 25-kilowatt fuel cell for propulsion once airborne. The fuel cells will provide electrical power for propeller motors. However, the aircraft will need to use batteries to accelerate to the required speed during take off. "If there was ever a way to demonstrate that fuel cells are safe and usable, this is it," says Judith Agar of Intelligent Energy, the UK company chosen by Boeing to build the fuel cells. "But it's essentially a modified glider, so it could glide back to the ground if the propulsion fails." Fuel cells use a chemical reaction to generate electricity from hydrogen and oxygen and the only by-products of the process are heat and water. The cells are considered a long-term alternative to the internal combustion engine, which produces greenhouse gases in its exhaust fumes. Storage problem A US company, Lynntech, has already built fuel cells for uncrewed, long duration surveillance aircraft. But Lynntech's Craig Andrews says it is not feasible to propel anything larger than a light aircraft using current fuel cell technology. "The fuel cells are not the problem, it's the hydrogen storage," he told New Scientist. Providing enough power for a heavier airplane would require more hydrogen than could feasibly be carried, he says. "Where primary propulsion is concerned, it's a matter of weight and power efficiency." However, Boeing does plan to introduce fuel cells on larger aircraft as a source of auxiliary power for lighting, heating and in-flight entertainment. Larger airplanes currently use batteries that are recharged by running the main engines. Agar says the use of fuel cells could therefore cut the pollution this produces. A spokesman for Boeing says: "Fuel cells are inherently cleaner and quieter than auxiliary power units, have fewer moving parts, and can generate more than twice as much electricity." Will Knight http://www.newscientist.com/news/news.jsp?id=ns99993717 |
| New Process Could Help Make Hydrogen Fuel Affordable |
posted 8/28/04 10:23 AM
New Process Could Help Make Hydrogen Fuel Affordable Stephanie Peatling in Sydney for National Geographic News August 27, 2004 Scientists in Australia say they have have made a breakthrough in the efficiency of using sunlight to generate hydrogen from water. It may be a step toward an affordable source of clean energy. A renewable source of energy to replace the world's declining fossil fuel reserves is perhaps the scientific community's holy grail. Hydrogen is all around us. It is seen by many as the cleanest and most efficient fuel for powering everything from vehicles to furnaces and air-conditioning—if only we can find an affordable way to harness it. Now two researchers in Australia say they have made substantial progress. Hydrogen propels the space shuttle and other rockets into orbit. The shuttle's electricial systems are powered by hydrogen fuel cells, producing a pure byproduct— drinking water for the crew. Hydrogen could power cars, trucks, aircraft—and generate the bulk of Earth's electricity. Scientists are working on ways to harness sunlight to produce hydrogen from water. Pulse of the Planet Scientists have known for a long time how to split water into its two elements, oxygen and hydrogen. But the problem is that the process requires electricity—typically derived from fossil fuels—which makes the process counterproductive and expensive. Janusz Nowotny and Charles Sorrell are researchers from the Centre for Materials Research in Energy Conversion at the University of New South Wales in Sydney, Australia. They have been looking for an economical way to use titanium dioxide to act as a catalyst to split water into oxygen and hydrogen—using solar energy. The Stuff of Toothpaste Titanium dioxide (TiO2) is widely used as a white pigment in paint, paper, cosmetics, sunscreens, and toothpastes. It is found in its purest form in rutile, a beach sand but is also extracted from certain ores. Rio Tinto, a mining company that produces titanium oxide, helps fund Nowotny's and Sorrell's research. Nowotny and Sorrell announced their breakthrough today at the International Conference on Materials for Hydrogen Energy, hosted by the University of New South Wales in Sydney. They believe they have found a way to considerably improve the productivity of the solar hydrogen process (using sunlight to extract hydrogen from water) using a device made out of titanium dioxide. "This is potentially huge, with a market the size of all the existing markets for coal, oil, and gas combined,'' Nowotny said in a news statement released ahead of the conference. "Based on our research results, we know we are on the right track." Although Australia's sunny climate makes it an ideal place to generate solar energy, Sorrell said the technology could be used anywhere in the world. "It's been the dream of many people for a long time to develop it, and it's exciting to know it's within such close reach," Sorrell said. Honda-Fujishima Effect The Australians' research has not been tested yet by other scientists, although the findings were applauded by the pioneers of the solar hydrogen process, Akira Fujishima and Kenichi Honda. In 1967 the Japanese scientists discovered that titanium dioxide could be used to extract hydrogen from water in a process that has become known as the Honda-Fujishima effect. The finding was reported in the journal Nature and led to numerous awards, including the 2004 Japan Prize in the category Chemical Technology for the Environment. Hydrogen is "very simple but very efficient,'' said Fujishima, who is also in Sydney for today's conference. "We must keep working hard on it.'' Since the 1967 discovery much research has focused on the materials that might be used to split water with sunlight. Fujishima, chairman of the Kanagawa Academy of Science and Technology, says using titanium dioxide as a catalyst means energy production will result in "cleaner air, cleaner water, and a cleaner atmosphere." Many Years to Hydrogen Power The world is still a long way off from large-scale conversion from fossil fuels to hydrogen for its energy needs. For one thing, the Honda-Fujishima effect, even if it is greatly enhanced by the research breakthrough announced today, still has to be adapted into devices that can be used on a commercially viable scale. Engineers will have to design fuel cells that collect sunlight from rooftops and elsewhere. The world's energy infrastructure is primarily based on fossil fuels and nuclear energy. Transitioning from gasoline-powered vehicles and gas stations to hydrogen-fuel replacements would require a huge investment and many years. Storage and safety issues still need to be resolved. But the vision of a world powered by hydrogen is gaining momentum and science and technology is catching up. T. Nejat Veziroglu is the director of the Clean Energy Research Institute at the University of Miami and the president of the International Association for Hydrogen Energy. He was called a "hydrogen romantic'" when he first started talking about a world powered by hydrogen in the 1960s. Veziroglu recently appeared before a U.S. Congressional hearing. Afterward, he said, he was stopped by a committee member who told him hydrogen would never be as cheap as existing forms of energy. "I said, make the companies responsible for environmental damage and no one will use anything but hydrogen. That way the whole world will benefit.'' http://news.nationalgeographic.com/news/2004/08/0827_040827_hydrogen_energy.html#main |
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Making society independent of fossil fuels - Danish researchers reveal new technology (Moderator) |
posted 10/30/05 12:09 AM
Making society independent of fossil fuels - Danish researchers reveal new technology <BR> <BR>Scientists at the Technical University of Denmark have invented a technology which may be an important step towards the hydrogen economy: a hydrogen tablet that effectively stores hydrogen in an inexpensive and safe material.<BR>With the new hydrogen tablet, it becomes much simpler to use the environmentally-friendly energy of hydrogen. Hydrogen is a non-polluting fuel, but since it is a light gas it occupies too much volume, and it is flammable. Consequently, effective and safe storage of hydrogen has challenged researchers world-wide for almost three decades. At the Technical University of Denmark, DTU, an interdisciplinary team has developed a hydrogen tablet which enables storage and transport of hydrogen in solid form. <BR>“Should you drive a car 600 km using gaseous hydrogen at normal pressure, it would require a fuel tank with a size of nine cars. With our technology, the same amount of hydrogen can be stored in a normal gasoline tank”, says Professor Claus Hviid Christensen, Department of Chemistry at DTU. <BR>The hydrogen tablet is safe and inexpensive. In this respect it is different from most other hydrogen storage technologies. You can literally carry the material in your pocket without any kind of safety precaution. The reason is that the tablet consists solely of ammonia absorbed efficiently in sea-salt. Ammonia is produced by a combination of hydrogen with nitrogen from the surrounding air, and the DTU-tablet therefore contains large amounts of hydrogen. Within the tablet, hydrogen is stored as long as desired, and when hydrogen is needed, ammonia is released through a catalyst that decomposes it back to free hydrogen. When the tablet is empty, you merely give it a “shot” of ammonia and it is ready for use again. <BR>“The technology is a step towards making the society independent of fossil fuels” says Professor Jens Nørskov, director of the Nanotechnology Center at DTU. He, Claus Hviid Christensen, Tue Johannessen, Ulrich Quaade and Rasmus Zink Sørensen are the five researchers behind the invention. The advantages of using hydrogen are numerous. It is CO2-free, and it can be produced by renewable energy sources, e.g. wind power. <BR>“We have a new solution to one of the major obstacles to the use of hydrogen as a fuel. And we need new energy technologies – oil and gas will not last, and without energy, there is no modern society”, says Jens Nørskov. <BR>Together with DTU and SeeD Capital Denmark, the researchers have founded the company Amminex A/S, which will focus on the further development and commercialization of the technology. <BR>Contact persons: <BR>Prof. Claus Hviid Christensen, Center for Sustainable and Green Chemistry, Department of Chemistry, Building 206, Technical University of Denmark, phone: +45 45252402, chc@kemi.dtu.dk <BR>Prof. Jens K. Nørskov, Center for Atomic-scale Materials Physics, Department of Physics, Technical University of Denmark <BR>Building 307, DK-2800 Lyngby, Denmark, phone: +45 4525 3175, norskov@fysik.dtu.dk <BR>Dr. Tue Johannessen, CTO of Amminex A/S, Kemitorvet, Building 206, DK-2800 Lyngby, phone: +45 22546242, tj@amminex.com <BR>This newsitem was written 07.09.05 by Michael Strangholt, mst@adm.dtu.dk<BR> http://www.blogexplosion.com/show_page.php?SiteID=37995 |
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