A Radical Departure

Konusu 'News Physics' forumundadır ve physicist tarafından Oca 17, 2013 başlatılmıştır.

  1. physicist

    physicist Moderator Staff Member

    Ara 20, 2012
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    Although they are not expected to reach the mass market before 2010, fuel cell vehicles (FCVs) may someday revolutionize on-road transportation.
    This emerging technology has the potential to significantly reduce energy use and harmful emissions, as well as our dependence on foreign oil. FCVs will have other benefits as well.
    A Radical Departure
    FCVs represent a radical departure from vehicles with conventional internal combustion engines. Like battery-electric vehicles, FCVs are propelled by electric motors. But while battery electric vehicles use electricity from an external source (and store it in a battery), FCVs create their own electricity. Fuel cells onboard the vehicle create electricity through a chemical process using hydrogen fuel and oxygen from the air. Chevy Sequel Fuel Cell Vehicle
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    FCVs can be fueled with pure hydrogen gas stored onboard in high-pressure tanks. They also can be fueled with hydrogen-rich fuels; such as methanol, natural gas, or even gasoline; but these fuels must first be converted into hydrogen gas by an onboard device called a "reformer."
    FCVs fueled with pure hydrogen emit no pollutants; only water and heat; while those using hydrogen-rich fuels and a reformer pr
    oduce only small amounts of air pollutants. In addition, FCVs can be twice as efficient as similarly sized conventional vehicles and may also incorporate other advanced technologies to increase efficiency. VIDEOS
    Meeting Challenges Together

    Before FCVs make it to your local auto dealer, significant research and development is required to reduce cost and improve performance. We must also find effective and efficient ways to produce and store hydrogen and other fuels.
    Automakers, fuel cell developers, component suppliers, government agencies, and others are working hard to accelerate the introduction of FCVs. Partnerships such as the DOE-led FreedomCAR initiative and the California Fuel Cell Partnership have been formed to encourage private companies and government agencies to work together to move these vehicles toward commercialization.

    FreedomCAR is a new cooperative research effort between the DOE and the U.S. Council for Automotive Research (Ford, General Motors, and DaimlerChrysler) formed to promote research into advanced automotive technologies, such as FCVs, that may dramatically reduce oil consumption and environmental impacts. FreedomCAR's goal is the development of cars and trucks that are:
    Cheaper to operate Pollution-free Competitively priced Free from imported oil
    California Fuel Cell Partnership (CaFCP)
    The California Fuel Cell Partnership is a collaboration of auto companies, fuel providers, fuel cell technology companies, and government agencies demonstrating fuel cell electric vehicles in California under day-to-day driving conditions. The goals of the partnership are to test and demonstrate the viability of FCVs and related technology under real-world conditions, move them toward commercialization, and increase public awareness. The Partnership expects to place about 60 FCVs and fuel cell buses on the road by 2003.
    In the western corner of West Sacramento, in a promontory of light industrial buildings that runs along the south frontage of Interstate 80, is the home of the California Fuel Cell Partnership. They are a depot for most of the hydrogen fuel cell powered cars in North America. In a new building on Industrial Boulevard, are spaces for auto makers and other partners from all over the world. When we visited last week, in front of the building the flags of eight nations snapped in the Pacific breeze, and across the street the vast floodplains of the Sacramento Delta stretched away to the south.
    Although the facility opened up on November 1st, most of the suites are still vacant. Only Daimler-Chrysler and Honda actually have cars and crews on site. According to Linda Ortiz, the office manager, the California Fuel Cell Partnership has eighteen partners, they are auto manufacturers, energy and fuel providers fuel cell companies and governmental agencies.
    There are eight suites for auto manufacturers, two of them occupied already by Daimler-Chrysler and Honda, as well as vacant ones for Volkswagon, Ford, Nissan, Hyundai, Toyota, and General Motors. Cars delivered here will be demonstrated from this site and will be open to the public. The cars won't stay there all the time, they'll be moved around on a regular basis to go to shows and events around the US and around the world.
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    So where are these cars? We headed into the back of the property, where the bays for the auto makers faced onto a back lot that looked out onto the freeway. On our way, we ran into the Chief Engineer for Honda, Shiro Matsuo, standing in the parking lot behind the building, watching for incoming cars while his team tested a fuel cell car. The car was doing laps across the length of the back lot.
    We asked him what the car was doing, going in circles around the lot, and his answer indicates the cars are still very much in a development stage, "This fuel cell is not very good at lower temperatures, so we do not want to start the fuel cell system on a public road." The car in question, Honda's V-3, is one of the most advanced hydrogen fuel cell cars in the world, but it can not run on the open road before being warmed up for at least 5 minutes. So much for a quick start.
    Honda's other models of fuel cell cars are the V-1, which uses a metal hydride fuel tank, and the V-2, which runs on methanol using a reforming device to convert the methanol to hydrogen. The systems on these cars are so big, particularly the reformer on the methanol car, that both versions are only able to have two seats. Matsuo mentioned that California is building another depot, probably in the Bay Area, that will house new cars that use reformer technologies, such as Honda's V-2.
    Shiro Matsuo
    Chief Engineer, Honda
    From a technological standpoint, methanol cars are further from being ready for the road than hydrogen cars because of the weight added by the reforming system. But there are technical obstacles to be overcome before hydrogen cars will be seen on the roads. In addition to the problem of slow warm-up, hydrogen fuel cell cars have a short range. Honda's V-3 only has a range of 110 miles, a defect which can only be partially offset by designing a larger hydrogen tank into the car, since a bigger tank adds weight and takes up more space. A higher efficiency vehicle is still in development and won't be ready for another year. Moreover, progress is incremental, so next year's model will not be a breakthrough, just an improvement.
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    When asked about diesel cars, Matsuo had definite opinions, since it turned out he had a background in diesel engineering. His comments were interesting: "The efficiency of the diesel engine is very good, but the bad point is that it can't get rid of some of the pollutant material, especially the particulate matter. The newest carburators produce precise high pressure injection into the cylinder which greatly increases combustion."
    Like others we talked with that day, Matsuo's comments reflected a perception that the U.S. market, and California in particular, is more committed to zero-emissions than the rest of the world. When asked how close the new diesel cars have come to complying with ultra-low emissions standards, Matsuo wasn't sure. He said "there are new catalysers being developed to absorb more particulate matter, it's getting better year by year."
    Hydrogen Fuel Station
    West Sacramento
    California USA
    Toxins from methanol leak into the soil from bad tanks and accidental spills, particles from diesels foul the air, even methanol reformers emit some pollution, about 20% of what a typical gasoline automobile produces. Nothing is perfect, except hydrogen, which can be made from electricity and water and can be produced in limitless quantities using nothing more than solar energy and water. If hydrogen burns, it leaves no trace in the air, except for a bit of water vapor.
    This pristine appeal to environmentalists, combined with the fact that fuel cells really aren't technologically ready to power a car on any fuel but hydrogen, is why California built this facility before any others and why the major auto makers of the world are trying to make sure they keep their foot in the door. Opposite the back parking lot, just in front of the wire fence that separated us from the whizzing eastbound traffic on I-80, was a giant hydrogen fuel station. Hydrogen is stored under great pressure, 3600 and 5000 PSI in the big tanks, 7000 PSI in the smaller distribution tanks.
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    Hydrogen may be ecologically and technologically the logical fuel right now for fuel cell cars, but there is no consumer distribution system in place. While methanol, a liquid, can be piped, trucked and stored in the existing network for gasoline with minor conversion costs, hydrogen will require an entire new fuel distribution infrastructure. Partly for this reason, fuel cell vehicles even in California, where government subsidies and regulations are the most favorable to fuel cell development in the world, fuel cell vehicles are not expected to be on the road in significant numbers until 2004. Even by that time, most of them will be in commercial and government fleet use, where they will have a hydrogen station on site. Don't expect to see hydrogen stations on the freeway off ramps for the next several years, if ever.
    Hydrogen Storage TankBut hydrogen retains its appeal, and the prospect of gas stations that require no fuel deliveries, just solar electricity and water to convert to hydrogen to recharge their storage tanks, is a seductive vision. On vehicles that can be refueled often or have low range requirements, setting up a fleet that would run on fuel produced in limitless quantities at an on-site station will probably be a competitive economic investment within five years or sooner. Fleets of buses, which can tolerate a bulky power system, will probably be one of the first places hydrogen fuel cell vehicles will be strongly competitive. As Matsuo said, "in the long run, fuel cell vehicles will gain a percentage of the market but I don't know if they will ever dominate."
    What will be the next generation car? Diesels, hybrids, or ultra-efficient & ultra-clean gasoline or methanol powered cars using combustion engines? The answer is all of the above. Will one type dominate? The correct answer to that question will make a lot of people rich, but it's probably safe to bet it will not be fuel cell vehicles that dominate. What about hydrogen combustion engines, since they burn so clean?
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    Fuel Cell Systems
    We talked with Richard Tuso, an Electrical Technician at Daimler-Chrysler. He reiterated that the fuel cell vehicle is preferred because it "does a molecular conversion of hydrogen to electricity which causes zero emissions to the atmosphere." He noted that methanol vehicles use a reformer which catalyses the methanol to separate the hydrocarbon from the hydrogen, but the reformer puts out emissions that are still at about 20% of an internal combustion engine. Richard acknowledged that "Methanol is easier for the fuel infrastructure, but where we're heading for in the long run is zero emissions, not low emissions."
    When asked about the possible dangers of distributing and stockpiling huge amounts of hydrogen, which is highly pressurized and explosive, Tuso downplayed the dangers. Most of the supposed problems with hydrogen are based on a public perception that it is much more dangerous that it really is. "The perception is evident when you take into account the precautions we take here," said Tuso. "The fueling station we built here cost five times what a comparable station cost in Germany. We have hydrogen alarms and air ventilation systems that are constantly running."
    In reality, said Tuso, "The only real problem is the pressure that's involved, and that's not a problem with proper tanking systems." He showed us pictures of cars that had been dropped from 45', then from 90', and in all these test cases the hydrogen tank did not explode, in spite of being under pressure. Moreover, he said, "the tanks are designed to blow up, not out. If, for example, that tank back there exploded," said Tuso, referring to the hydrogen station in the lot behind the building, "90% of the debris would fall within the fence around it."
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    The Hydrogen EconomyThe danger from accidental hydrogen fires was even less of a problem, according to Tuso, because "Hydrogen is a very clean fuel, it would ignite easier than gasoline, but the likelihood of it igniting is still slim. If it did ignite, the flame doesn't put out much heat. Gasoline fires usually consume the whole car." He cited tests where hydrogen gas tanks were exploded and ignited, and invariably the flame went upwards and didn't burn very hot. The back windows, for example, would not typically be damaged in a hydrogen tank fire, whereas in a gasoline tank fire, the back windows usually melt.
    Notwithstanding the cost of building an entire fuel infrastructure for hydrogen, the biggest problem hydrogen fuel has may end up being a public perception that it is too dangerous to handle. "People here think of the Hindenberg and Hydrogen bombs," said Tuso, "Some people think we have a hydrogen bomb back here."
    We left that day not sure whether or not we'd found the car of the future. Hydrogen fuel cell powered cars will be part of the market, but they probably won't sit in everyone's garages, owning the car market the way gasoline powered cars do today. Hybrids have better range and overall performance, and they're already cheap to manufacture. Expect to see more of them in the near future. What will emerge in the long run is anybody's guess. Outside the U.S., cleaner burning cars using conventional fuels such as diesel and gasoline will probably stay on top of the market. How clean can they get? How clean is clean enough? Stay tuned.