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Science

Boeing to Develop a Fuel Cell Powered Airplane 205

Posted by chrisd from the lightest-element dept.
gilgsn writes: "From Yahoo News: Boeing is working with a light airplane manufacturer in Spain on a fuel cell powered plane. The efficiency of electric motors, with their reliability, acceleration, lack of vibrations and noise has a lot to offer to general aviation. The project aims at exploring environmentally friendly modes of propulsion. I can easily imagine a hybrid aircraft using fuel cell technology for take-off and altitude gain, coupled with solar cells to sustain flight. I hope a kitplane manufacturer in the United States will read this. I can't wait to fly a fuel cell powered ultralight!" CD: The question is can a fuel cell deliver enough energy for a flight long enough to be practical.
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Boeing to Develop a Fuel Cell Powered Airplane More

Boeing to Develop a Fuel Cell Powered Airplane

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  • Risks involved (Score:3, Informative)

    by metlin ( 258108 ) on Wednesday November 28, 2001 @04:14AM (#2623791) Journal

    He recently witnessed a demonstration of a hydrogen-fueled automotive fuel cell that was so environmentally friendly its only byproduct was water safe enough to drink.


    So they are talking about a H-O fuel cell. Agreed, but what about the risks of explosion? Seriously, I'd done some fuel cell research a couple of years back and one of the biggest problems the people doing it faced was regulating the flow of hydrogen & oxygen. More often than not, the flow would go awry. Ofcourse I'm not talking about small scale ones, I'm talking of large ones, developed for seeing how well fuel cells could be used in industrial areas. I'm sure these would be the kind of ones which would be used in such things as planes, too.

    And given something like a plane, we cannot afford to have such uncertainities and risks.
    • And oil-based fuels are harmless?
      • He said the Cells were dangerous. Not the fuel itself. That's like asking if an IC engine design is 'safe' and we know it is, since we can regulate the flow well. When was the last time a car engine (not gas tank) just blew up?
    • Ford are roadtesting fuel-cell cars at the moment.
      The Focus version looks pretty snazzy :)

      Well the point of this is that if a large scale manufacturer like ford feels that it is safe enought to drive the roads, then I can't see why it could not be made viable for planes.
    • "Agreed, but what about the risks of explosion?"


      Jet fuel can explode too. A 767 jet carries 200,000 gallons of jet fuel. Enough to fill a very large swimming pool. That can blow a plane apart no problem. I was just 3 blocks from the world trade center when the planes hit and believe me I say that during the explosion, the sound was so loud that it could be heard as far as 20 miles away and the fireball was over 30 stories high and blew over the top of the towers. I talked to people as far as staten island which is about 15 miles away and they heard it. Even if the sound was from the high acceleration of the aircraft hiting the building and not the fuel exploding, the size of the fireball itself showed how much power an exploding tank can do. Either way, if an oil filled tank or a fuel cell explodes the passengers are dead.

    • Re:Risks involved (Score:4, Interesting)

      by Gordonjcp ( 186804 ) on Wednesday November 28, 2001 @05:41AM (#2623936) Homepage
      Well, one (imperial) gallon - 4.5 litres - of petrol, in vapour form, has roughly the explosive power of 1kg of dynamite. So, consider the explosive power of the average fully-fueled car. My Citroen XM has a 17-gallon (roughly 80l) fuel tank. Big boom.

      The explosion risk is actually slightly higher for unleaded petrol (technically they're all unleaded in the UK now, but in this case I mean 95RON lead-free) than for 98RON Lead-free Four Star. This is because instead of nice, safe, but *slightly* poisonous Tetraethyl Lead, lead-free uses Benzine, which is much more volatile, extremely poisonous and highly carcinogenic.

      Diesel fuel doesn't really explode well at all. Jet fuel (basically very clean paraffin, like heating oil) is somewhere in between.
      • Well, one (imperial) gallon - 4.5 litres - of petrol, in vapour form, has roughly the explosive power of 1kg of dynamite.

        Actually, gasoline has an energy density ten times that of dynamite. Your gallon of gas fumes (almost 3kg) is closer to 30kg of dynamite.

        And yes, it's a very big boom [google.com].

    • The heisenburg exploded because it was painted with reactive metal paint.
      Static discharge in the atmosphere caused the explosion with flames you can see.

      Hydrogen burns in UV frequencies, you can't see it.
  • This stuff seems to be coming along faster and faster these days. Heck, I wouldn't be surprised if in the next 3-5 years they have small fuel cell generators for backup power in homes (I know it requires a converter, but who knows?). But I'd rather have one of these in my electric cars rather than 12 or so huge car batteries, and having it last twice as long is a good bonus!

    One more way to reduce pollution in urban areas.
    • GE is currently testing home fuel cell power generators. I have no idea how much longer they want to collect data though.

      http://www.gepower.com/dhtml/distributed_power/e n_ us/microgen/faqs.jsp/
  • resgarding to the idea of a plane that takes off using fuel cells and sustains flight with solar power (valid given the relative immaturity of fuel cells and their small power capabilities for something like a cross-country flight), it doesn't seem like something that'd find commecial success. with more restrictions on what you can bring on the plane with you these days, planes that need to fly through at least patches of direct sunlight are just going to annoy their passengers. there are enough reasons to for flights to be late now*. why introduce another one?

    *my favorite was when i was flying on a smaller outfit, and our plane couldn't get into the terminal and unload because the union workers were on their mandatory breaks and when they got back serviced the big airlines (which arrived after us).

  • Which Fuel? (Score:5, Interesting)

    by squaretorus ( 459130 ) on Wednesday November 28, 2001 @04:25AM (#2623813) Homepage Journal
    With Fuel Cells you boil down to a trade off between the efficiency and cost of the fuel.

    Plain old hydrocarbons are cheapish, easy to handle, and not overly dangerous in a 'leak' situation.
    But they require hyper advanced self cleaning fuel cells that wear out quickly.

    Pure methanol is expensive (purification always costs), easy to handle, and not overly dangerous in a leak situation.
    It works in cheaper, more reliable, longer lasting and lighter fuel cells.

    Hydrogen is expensive, difficult to handle, and pretty damn dangerous stuff in ANY situation.
    It works best with fuel cells, pretty much optimal.

    A fuel cell that can handle ANY carbon rich material, and takes O2 from the atmosphere would be the holy grail. You could use argicultural by products to produce methonal, dig up oil, LPG, any burnable liquid essentially.

    A rethink on the air network strategy to produce lighter, smaller, more efficient aircraft which possibly fly a bit slower and take shorter 'hops' would bring Fuel Cell flight closer.
    This would be a worthwhile trade off for a more environmentally sound and sustainable flight infrastructure.

    Boeing and Airbus both seem committed to increasing the size of aircraft overall. Maybe its time for a serious rethink?

    • Re:Which Fuel? (Score:2, Informative)

      by redcliffe ( 466773 )
      The good thing about hydrogen/oxygen is that it is easily rechargeable. You can hook it up in a closed loop, with the fuel cell taking 2H2 and O2, and converting it to 2 H2O. You can then take the resultant water to a storage tank, then during charging electrolsys splits the water back into Hydrogen and Oxygen. I'm not sure of any other fuel cell system that can do this.

      David
      • Yes but you loose energy everytime you do it. The amount of power you get out of burning the H2 is *LESS* then you need to split the H20 into H2 and 02. So while it is a reversable change it costs energy each time.

        Its the 2nd Law of thermodynamics.

    • Re:Which Fuel? (Score:1, Flamebait)

      by JimPooley ( 150814 )
      So you want to finish the job of destroying global tourism that scaredy-cat yanks are already starting, eh?
      Personally I'd rather we made bigger concordes!

    • Re:Which Fuel? (Score:3, Insightful)

      by tbo ( 35008 )
      A rethink on the air network strategy to produce lighter, smaller, more efficient aircraft which possibly fly a bit slower and take shorter 'hops' would bring Fuel Cell flight closer.
      This would be a worthwhile trade off for a more environmentally sound and sustainable flight infrastructure.

      Even more environmentally friendly would be if everyone just walked. I got news for you--transportation technology is based on getting people where they want to go fast and cheap. Many small planes on short flights means a lot more overhead, and a hell of a lot more fuel spent taking off and landing (the most inefficient parts of flight), not to mention longer travel times.

      • Re:Which Fuel? (Score:3, Interesting)

        by znu ( 31198 )
        You're ignoring the "where they want to go" part of your own statement. Smaller planes flying to smaller airports will put people closer to their final destinations. Direct flights everywhere will save people the frustration involved in layovers. Less reliance on major hubs will relieve congestion and delays. All things considered, in most cases you'd probably have much shorter total travel times (including time to get to/from airport and to get through the airport onto the plane and into the air), and a major reduction in the sort of circumstances that bring on "air rage".
      • Many small planes on short flights means a lot more overhead

        WRONG. Long haul flights are no nore efficient overall than regional flights of under 1000 miles which would, probably, be within the range I refered to.

        In the UK it is cheaper to fly the length of the country than to take a coach / train because the overheads of flight are so low. These are normally relatively small aircraft.
    • A rethink on the air network strategy to produce lighter, smaller, more efficient aircraft which possibly fly a bit slower and take shorter 'hops' would bring Fuel Cell flight closer.
      This would be a worthwhile trade off for a more environmentally sound and sustainable flight infrastructure.

      And for better hops, just power it with beer.

    • Re:Which Fuel? (Score:2, Insightful)

      by blane.bramble ( 133160 )

      A rethink on the air network strategy to produce lighter, smaller, more efficient aircraft which possibly fly a bit slower and take shorter 'hops' would bring Fuel Cell flight closer.

      That doesn't solve the problem of trans-atlantic flights. Or any long-distance flight (how many people would want to take off and land 8 times to go from the UK to Australia for example?). Also as take-off and landing are the most dangerous parts of air-travel, increasing the frequency of them would make air-travel more dangerous as well.

      • Agreed. This isn't a one shop solution. I walk to the toilet, I cycle to work, I drive to visit my parents, I fly to the Med for a holiday.

        That an environmentally preferable solution is available for short haul should be a good thing. That we have to stick with 747s for long haul may just be a law of physics.
        • It is a long way to getting a Fuel Cell Airliner. It sounds like they want it for an APU (to supply power on the ground etc) As it works out a 747 is rather Enviormentally friendly. The 777 more so. Yes they burn a lot of Jet-A but if you take the amount of Fuel per passenger mile or Kilogram mile its probably less than a lot of other forms of transport.
          • As it works out a 747 is rather Enviormentally friendly

            I'm sorry, but this is untrue urban legend nonsense that rears its head whenever people think the green movement is trying to take away their right to fly.

            A single transatlantic flight is equivalent to 5 years of the average British commute by car (35 minutes a day in each direction). And that is the 'per person' figure.

            Then you factor in the ozone depletion, the various other high atmosphere problems high altitude jets cause, and the fact that those car journey we are comparing to are many times more polluting than bus/train commuting.

            747s are NOT environmentally friendly.

            If you want references try these:
            http://www.epa.gov/globalwarming/tools/ghg_calc. ht ml
            http://www.ans.neep.wisc.edu/~eic/personal.impac t. html
            http://www.rides.org/main/environmentalcalculato r. htm
            http://www.flightsciences.com/environ.htm
            http://www.climatechangesolutions.com/english/in di viduals/resources/default.htm
            http://ottawa2000.commuterchallenge.net/pollutio n. phtml

    • Re:Which Fuel? (Score:5, Informative)

      by Rogerborg ( 306625 ) on Wednesday November 28, 2001 @05:26AM (#2623911) Homepage
      • Hydrogen is expensive, difficult to handle, and pretty damn dangerous stuff in ANY situation

      What's so dangerous about hydrogen in "ANY" situation? AFAIK, the big danger is leakage during storage, which is harder to detect than a leak of hydrocarbon vapour. A leak in use - in a moving vehicle - isn't significantly more likely than a hydrocarbon leak, nor more dangerous, as you have to be very unlucky to achieve the right fuel/air mixture at the right ignition point for sustained combustion.

      Is this some Hindenburgh knee jerk response? The Hindenburgh was painted in a substance not dissimilar to rocket fuel, and even so, 61 of the 97 people on board survived. That's a pretty good survival rate for an aircraft that exploded on landing.

      References that demonstrate the danger of hydrogen in "ANY" situation would be greatly appreciated.

  • I'm about to begin constructing an electric car, and instead of using batteries which are heavy and expensive, I've been thinking about building a hydrogen fuel cell. Anyone know of some good web pages about that? Thanks,

    David

  • Electric? (Score:3, Funny)

    by Komarosu ( 538875 ) <nik_doof@nikdo[ ]net ['of.' in gap]> on Wednesday November 28, 2001 @04:30AM (#2623821) Homepage
    Eletric plane? what about a power drop? it needs a UPS i tell you :)

  • Hydrogen dangerous? (Score:4, Insightful)

    by CheezWizFire ( 534072 ) on Wednesday November 28, 2001 @04:34AM (#2623826) Homepage
    Is hydrogen that dangerous? In a leak situation it quickly disperses and floats away right? As opposed to other fuels that will burn in an accident. I mean everyone dies in plan crashes anyways, I donlt think the survival record can get much worse. And if we all had secure hydrogen fuel tanks in a safe location in our cars and then I proposed that we instead carry around many gallons of flamable and explosive gasoline in thin tanks that rupture in accidents followed by the fuel spilling and flowing until it found a spark you would all call me crazy.

    -Steven

    • Is hydrogen that dangerous? In a leak situation it quickly disperses and floats away right?

      Tell that to the passengers of the Hindenburg.

      • It wasn't the hydrogen that burnt, it was the fabric of the skin. See here [ttcorp.com] for details
      • Why? It was the flammable fabric [ttcorp.com] that burned.

      • Re:Hydrogen dangerous? (Score:2, Interesting)

        by DarenN ( 411219 )
        I would like to point out that that fuek used is _liquid_ hydrogen, not gaseous like the hindenburg.

        It is extremely difficult to hangle due to the fact that it is stored at waaaaaaay below 0C. IIRC it isn't particularly flammable as it vapourises. Plus, the tanks it's stored in are pretty robust.
      • Keep up to date. 60 years back, in the investigation of the accident, they knew it wasn't the hydrogen that burned in the Hindenburg. Yet every time someone mentions hydrogen as a power source, some wazzock always brings up the Hindenburg as a reason not to do it. Just mark it down to "great urban legends of our time", I guess.

        Grab.

  • The airline industry wanted this for years (Score:5, Interesting)

    by Billly Gates ( 198444 ) on Wednesday November 28, 2001 @04:46AM (#2623842) Journal
    This is definitely good news. Not for the technology or environment per say but for political stability in the middle east and terrorism. Ibet none of you have any idea of how much power the oil indistry has to suppress such research for years on in.

    The oil industry has such an effect in this country that its totally unbelievable (USA, for Europeans who hate American centered comments :-))! Basically they lobbied the FAA to make sure that fuel cell technologies for planes would never be approved. Boeing who is afraid of developing an engine that the energy-industry sponsored FAA would not allow them to sell, decided to only research fuel cell technology but not build any prototypes for obvious reasons.

    However the September 11 attacks changed this. I was within 2 or 3 blocks from the World Trade Center and it was not the plane attacks that brought the buildings down but over an hour of intense 2000F heat that melted the support beams. As much as 2 Olympic sized swimming pools of jet fuel went inside the 2 buildings. 200,000 gallons in total. I am amazed that the towers even stood for that long. I assume most of the 4,000 people who perished would of survived if it wasn't for the deadly fire and jet fuel. Many didn't make it out in time or the heat was so intense that the stairways actually melted where the fire was.

    Another problem we have is politics in the middle east. Americans have historically been strict isolationists. I would like it to stay that way. This all changed during both world wars and also during the rise of the oil industry. The 1991 gulf war was not about the suffering of those poor Kuwaiti's but for Exxon's, enrons, as well as Mobile's stock prices and profits. Bush senior received large amounts of money from the oil industry and we went to war to defend there interests and their cash. This is what started this whole Afghanistan mess we are in now. This is why China and the Arab world views Americans as empirialists. We represent more of the British empire in early America more then our original government. Our taxes now are actually much higher then before the American revolution! Believe or not. No wonder they view us as self serving empirialists. We actually are. Saudi Arabia is oppressive and the latest posts here on slashdot which state there intent to block internet access confirms this. We have no reason to support them other then for our energy interests. The sooner we lossen the oil industries grip the better. Also the Israeli's are being persecuted by terrorists groups funded by Arab's. I am aware the same can be said of the Palestinian persecution but when one group attacks another they both point fingers at each other and become more militant and oppresive. Before the 1950's the Arabs were all poor and lived in third world conditions. They ignored Israel before they had the money to fund Hummus. Thank oil for changing this. Anyway greed is bad and I am glad the government now is realizing that our dependence on foreign oil is bad. I believe fuel cell technology is the wave of the future for not only planes but cars as well.

      • The 1991 gulf war was not about the suffering of those poor Kuwaiti's

      Uh, the major cause of suffering for Kuwaitis has been the DUP's and unexploded ordinance dropped inside Kuwait by the good old US of A.

      I'm actually agreeing with your point, I'm just saying that there never was an ethical or moral motivation in the Gulf War. It was purely pragmatic: restore the regional balance of power, prop up a friendly dictatorship (sorry, "monarchy"), try out some new war toys, score a huge PR coup. And oil, oil, oil.

    • 200,000 gallons of fuel? Thats nearly one million litres! Or to put it another way approximately 1000 tonnes of fuel.

      I don't think so!

      • 200,000 gallons /2 = 100,000 gallons. I got the numbers from a New York Times article. I use to clean swimming pools when I was a teenager. You could fit 80,000 gallons (average sized household pool) by a 50 foot by 15 feet with one half 2 feet deep and 8 at the other end. Thats around 3750 feet cubed.

        A 767 jet is a big plane. I guess several hundred feet long and I assume 15 feet wide with probably a 3 foot deep tank. Assuming the tank length is 200 feet that would equal 9000 feet cubed. Thats over twice the volume.

        I may know shit about airplanes but I believe its possible.A 767 is a big plane and I got my source from the the New York Times and CNN

        .
    • 1. Fuel cell technology won't do much to change our dependance on oil. Oil is the major source of combustable carbon and hydrogen, which are used in Fuel cells.

      2. Fuel cells have been off the market because of expense, expense, and expense. Only recently has the price gone down.

      3. Greed is good.

      4. Isolationism helped cause World War II and the great depression (see the trade barriers put up the week before the market crashed), and kept the United States from interfering in a war which threatened all our allies and ourselves as well.

      -Ben
  • What about the risk of explosion in a fuel cell? Hydrogen is very volatile - you need a really good system that prevents tampering, leakage, electrical activity outside the plane, and can withstand crashes. I'm thinking about the Hindenburg airship disaster here when making comparison at the moment. I'm not an expert on these things so I would really like to know how the gas used in the auxiliary unit would "burn" in comparison to hydrogen in the event of a disaster. If it's just a safe (and maybe quieter) I wouldn't mind having it at as a power source - i mean it doesn't actually power the engines themselves so we should be quite safe.

    It's good to see that they are changing over to some environmentally friendly stuff. Most people have this stereotypical view that US companies are not very "green" - this might set them straight (although it's interesting that they've based the work in Europe...) Testing the fuel cell on cars would be a good idea as well - someone's probably already done this, but if hydrogen can be cheaply produced (cheaper than oil that is - nobody's going to change over to a new fuel source unless it is cheap) it should be an excellent fuel (practically no pollution).
    • The amount of hydrogen in a fuel cell is a lot smaller than was in the huge bladders of the Hindenburg.

      It's also packed very tightly between "wafers" in the core of the cell. Leakage would take quite a bit of strucural damage; definately more than is required to puncture a conventional gas tank.

      I doubt it would survive a crash, but then I doubt any kind of large power source would survive a crash. I'd expect the fuel cell would flare up or jet fire, but not the roiling, plane-consuming fireball you usually get from conventional fuels.

    • Brief Lesson On Hydrogen Safety (Score:5, Informative)

      by Self Bias Resistor ( 136938 ) on Wednesday November 28, 2001 @05:44AM (#2623940)

      What about the risk of explosion in a fuel cell? Hydrogen is very volatile - you need a really good system that prevents tampering, leakage, electrical activity outside the plane, and can withstand crashes. I'm thinking about the Hindenburg airship disaster here when making comparison at the moment. I'm not an expert on these things so I would really like to know how the gas used in the auxiliary unit would "burn" in comparison to hydrogen in the event of a disaster.

      Flammable fuels are only explosive when it has mixed with air in a sufficient quantity to form a fuel-air mixture. This is different from volatility, which is a measure of how easily a compound turns into gaseous form (petrol/gasoline, for example, is quite volatile, as is ethanol). The fact is that Hydrogen is the lightest element on the periodic table and hence diffuses through leaks and openings much more quickly than, say volatile fumes from regular petrol or JP9 jet fuel (where the fumes consist of multiple gaseous hydrocarbons, which have greater molecular weights and are hence much heavier). This is why there is no gaseous Hydrogen in the Earth's atmosphere. The Hydrogen simply floats away into space.

      If you were to be involved in an accident involving an aircraft equipped with a Hydrogen fuel cell, you'd find that the chief cause will not have been the Hydrogen. The combustion of the fuel used in the aircraft's engines (remembering that the Hydrogen fuel cell will be used as a backup device to generate air and power for the aircraft and not as a means of propulsion) would have caused the lion's share of the damage. The only noticeable effect the Hydrogen would have on the acccident is to perhaps allow the fire to burn a little longer (assuming that enough of the Hydrogen is still contained in the air and has not diffused into the atmosphere). When being used in fuel cells, Hydrogen chiefly stored as a compressed, possibly liquefied gas. Hydrogen can also be stored in certain metallic compounds (known as metallic hydrides, which hold the Hydrogen atoms in a similar way to amalgum containing Mercury) to increase energy densities. In the first case, the rapid diffusion of the Hydrogen gas would not cause a fire for the reasons outlined above. In the second case, the Hydrogen would not be released because it is still bound to the metallic hydrides. In either case, it is unlikely that the cause of the accident will be the Hydrogen fuel. Hydrogen has, in fact, been proven to be a safer fuel to handle than gasoline. The byproduct of the fuel cell is water vapour, so it's also much better for the environment.

      Your comparison to the Hindenburg disaster is not really applicable in this case, as it was conclusively demonstrated that it was the Aluminium compounds in the paint on the Hindenburg that caused it to burst into flames and not the Hydrogen gas. The Hydrogen ignited later, burning much more slowly and for a lot longer and hence actually acted as a fuel that sustained the fire, as opposed to the agent that caused the ship to burst into flames in the first place (remembering that the ship still burned even though the outer material had been completely destroyed).

    • It would be nice if Slashdot had a memory, maybe we wouldn't have to have this damn "Hindenburg" conversation every time there's a story about fuel cells.


      So once again:


      1) A fuel cell does not necessarily mean a molecular-hydrogen based fuel cell. The Hydrogen - Oxygen to Water reaction is the most common but there are a huge range of potential molecular fuels.


      2) Even a molecular hydrogen based fuel cell need not rely on compressed gaseous hydrogen. There is tons of fruitful research going on to store hydrogen in solid substrates.


      3) Compressed hydrogen in tanks is not particularly dangerous compared to, say, liquid fuels. Mixture with oxygen tends to be a limiting factor in accidental combustion, and hydrogen disperses very quickly.


      4) Hydrogen was almost certainly not the cause of the Hindenburg explosion. Anyalysis of evidence makes a compelling case that the disaster was caused by the "doping" material used to treat the dirigible hull fabric, a combination of iron oxide, cellulose acetate and aluminum powder. A good brief article on the subject can be found at http://engineer.ea.ucla.edu/releases/blimp.htm


      5) Hydrogen as a fuel is not completely safe. Airplanes are not completely safe. Is it safe? No. Is it insurmountably and unacceptably more unsafe than conventional fuel vehicles? No. If it were, thousands of corporations would not be spending billions of dollars developing it. We call it common sense, people.

  • Tandential benefits. (Score:5, Interesting)

    by karlm ( 158591 ) on Wednesday November 28, 2001 @04:56AM (#2623856) Homepage
    The biggest problem with fuel cells in airplanes should be the weight and bulk of the entire system. This is especially true for small aircraft. However, fuel cells provide many befets, especially compared to the piston engines used in sport aircraft.


    The article mentions that fuel cells are twice as efficient as heat engines. I thought the efficiency gap was larger. In any case, the laws of thermodynamics place an upper limit on the efficiency of a heat engine (such as a turbine or piston engine). This upper limit is known asw the Carnot efficiency. It is determined by the ambient temperature and the temperature of combustion. 30% is a decent estimate of the Carnot efficiency for a gasoline engine with the ambient temperature about room temperature. I thought fuel cells were about 80% efficient, but then again I'm on a coding break at 5 a.m.


    The MGM brushless DC motor developed at NTU in Australia has an efficiency around 99%.


    The main advantages of fuel cells for sport aviation are the extremely high efficiencies and the good reliability of the components. Electrical components and non-moving mechanical components have much higher reliability/cost ratio than their moving counterparts. I've held aircraft pistons with valves imbedded in them. Some people much prefer the Wankel rotary engine in aircraft for its simplicity. Turbines are much better in terms of reliability, but their cost is much higher. One should also consider maintenance costs. An aircraft piston engine typically needs to completely overhauled every 20,000 hours of operation to ensure reliability. Fuel cell inspection and overhaul involves many fewer parts and is probably much cheaper and probably needs to be done less frequently. The same should be true for electric motors.


    Another important factor in using electric motors is that the propellers can be designed more optimally if they don't have to deal with the large accelerations and decelerations that a 6-cylinder piston engine produces 3 times per revolution. Piston engines (even with flywheels) are very rough running, and propellers are beefed up so that they don't tear or shake appart under these loads. Any time you have to beef something up, you end up increasing the cost, weight, and/or innefiencies.


    Let's not forget that most sport aircraft require 110 octane "low lead" fuel that is expensive and releases polluting lead compounds into the environment.

    • Hehe... forgot to proof read the subject line. It's 5 a.m. give me a break.
    • ``Our ultimate goal is to replace the auxiliary power unit,'' said Dave Daggett, associate technical fellow in the environmental performance strategy group. ``But first, we're going to learn more about fuel cells by powering a small airplane

      I think it is a strange route they take. To have it for the power unit (i suppose the electrical generator) they first power a plane with it.

    • Re:Tandential benefits. (Score:5, Informative)

      by FreeUser ( 11483 ) on Wednesday November 28, 2001 @09:29AM (#2624346)
      An aircraft piston engine typically needs to completely overhauled every 20,000 hours of operation to ensure reliability.

      Very interesting post, but your decimal point is one off. My Lycombing O-360 (180 hp) engine has a TBO of 2000 hours, though I wish it were 20,000. :-) Airframes typically outlast multiple engines if they're well cared for, particularly if they're hangared (which mine is).

      When it comes time to overhaul or replace my engine I'd love to replace it with a hydrogen fuel cell system (which is far less explosive than 60 gallons of 100LL), assuming I could get comparable performance from it. Not likely, of course, but one can dream.
  • I remember reading somewhere some six months ago (maybe SciAm, maybe /., can't readily remember) an article that stated that a gasoline-powered fuel cell would be far more efficient than those that derived their power from water/distilled hydrogen.

    Now, I can see how a gasoline fuel cell could prove more effective than one that runs off of water/hydrogen/methanol. Pound-for-pound, gasoline produces far more energy than hydrogen, and is more cost effective than methanol.

    But... I'm not exactly certain on the intricate workings of the fuel cell, so I'm not certain if the gasoline fuel cell is feasable, or if it's just a scam perpetrated by the oil companies to perpetuate their stranglehold on the transportation industry?

    Now I can totally not wait for little tiny nuclear reactors under the hood... mmmm, efficient electric cars... Too bad it'll never happen though...

    • Is there any fuel that can be used in a closed loop that has a better efficiency than hydrogen and oxygen? I want to be able to plug my car into a power point to charge it up, not fill it with gas. Thanks,

      David
    • Now, I can see how a gasoline fuel cell could prove more effective than one that runs off of water/hydrogen/ methanol. Pound-for-pound, gasoline produces far more energy than hydrogen, and is more cost effective than methanol.

      "Pound-for-pound" ??
      Are you sure you don't mean "Litre-for-litre-at-room-temperature-pressurized-t o-atmospheric-at-sea-level"? Hydrogen compresses significantly with ease. This gives it a "Pound-for-pound" greater than most fuels.
      • "Pound-for-pound" ??
        Are you sure you don't mean "Litre-for-litre-at-room-temperature-pressurized-t o-atmospheric-at-sea-level"? Hydrogen compresses significantly with ease. This gives it a "Pound-for-pound" greater than most fuels.

        He meant pound for pound. The mass doesn't change with temperature, pressure, altitude, or zodiac sign. How well it compresses has nothing to do with it's energy density by unit mass.

        And no, H2 doesn't compress easily, at least not to anything really useful. The parent was right, pound for pound hydrogen has 3 times the energy density of gasoline. But it can't be compressed to anything like the mass density of gasoline. Even as a liquid it's only 1/10th as dense. And liquifying it is no answer, it takes several times the energy you get from combusting it to cool it to that point.

    • Re:Gasoline Fuel Cells (Score:2, Informative)

      by Anonymous Coward

      Now, I can see how a gasoline fuel cell could prove more effective than one that runs off of water/hydrogen/methanol. Pound-for-pound, gasoline produces far more energy than hydrogen, and is more cost effective than methanol.


      No no. Liquid hydrocarbon fuel (gasoline) holds 45 Megajoules of energy per kilogram. Hydrogen packs 129 Megajoules with the same weight. It is also much more efficient to burn. The problem is hydrogen is gaseous so it takes a lot of space. You need to build a strong storage unit and enormous amount of energy to compress em.

      Gasoline molecule does not work on proton-exchange membrane (PEM) so gasoline powered fuel cell is a misnomer. What they might be saying is extract the hydrogen from the gasoline using a reformer. The hydrogen is then used in the fuel cell unit. So you actual need to separate units, the fuel cell and the reformer.

      Ford is currently building a fuel cell vehicle. Right now we could not find a supplier who build an efficient reformer so we opt for direct hydrogen. Once somebody comes out with a good reformer and a good fuel cell, we'll all be using fuel cell technology.

      Later,

      A guy working at Ford.

  • Electric powered aircraft (Score:5, Informative)

    by mactom ( 515670 ) on Wednesday November 28, 2001 @05:24AM (#2623904)
    Hi,

    There are already several electrically powered aircraft flying. Ok, most of them are gliders that use the engine for take off and then retract it and continue flying, gliding and gaining altitude in thermals. But there is already a powered glider, the icare, which uses solarcells to power an electric motor for take off and sustained cruise.

    Take a look at the following websites:

    Lange Flugzeugbau [lange-flugzeugbau.de]
    Icare [uni-stuttgart.de]
    Silent AE1 [alisport.com]

    Conventional self launching gliders are already very sophisticated, but the engines they use, require a lot of maintenance and are sometimes not as reliable as you might wish. Well anyway, if the engine fails I land on a field, no problem there, ... that is if a field is in range. Electric engines should increase reliability quite a lot. Hopefully they are available soon.

    Regards, Thomas.

  • Environment Friendly Flying (Score:3, Interesting)

    by dhart ( 1261 ) on Wednesday November 28, 2001 @06:14AM (#2623973)
    This is Fantastic!

    I fly regularly between Australia and the US. I would gladly extend the duration of the already long trip (14 hours) for the trade offs:

    o Environmentally Friendly (by a large degree)
    o Quieter

    With longer fight times and lower fuel carrying requirements, hopefully these new planes would become more passenger friendly as well (no more deep vein thrombosis). If there's a bar and a free Internet connection, I have no problem spending 24 hours on a plane!


  • Good Lord people, stop talking about how impossible it is an welcome it as a good thinng. If nothing else then it will, at the very least, foster some additional research into a promising area of clean, renewable energy sources. At the best they come up with a light, clean, cheap, powerfull fuel cell that could have applications in many other areas. Its a win win situation for everyon except boing (if it fails it could lose money). Any way even if it is impossible that just makes it more attractive. Since when did progress rely only on what was possible?

  • Did ANYONE bother to read the article? (Score:5, Informative)

    by John Harrison ( 223649 ) <johnharrison@@@gmail...com> on Wednesday November 28, 2001 @07:50AM (#2624111) Homepage Journal
    From the article:

    Fuel cells and electric motors will not replace jet engines on commercial transports, but they could one day replace gas turbine auxiliary power units. Auxiliary power units, which typically are located in the rear fuselage with exhaust ports through the tail, are coupled to generators and compressors to produce electricity and air for airplane systems while on the ground and for backup use in flight.

    Let me repeat, they are NOT trying to use fuel cells to replace the jet engines. They are going to use them to replace auxilary power units, which simply produce electricity.

    So basically, this entire discussion here on /. is about the wrong thing! Not only is it about the wrong thing, but the thing that has been announced isn't that big of a deal. These are not electric aircraft that they are producing!

    So move along now, the really is nothing to see here.

    • Fuel Cells to replace APUs would be a Good Thing for civil and military aviation.

      Some of the APUs for aerospace use nasty chemicals like Hydrazine. Replacing those APUs with a fuel cell (The Shuttle uses a combination of APUs and Fuel Cells) would make the planes alot safer for mainatance people.
    • Of course I RTFA! And I almost wrote a comment like yours, but

      Boeing Commercial Airplanes will develop and test an electrically powered demonstrator airplane,

      so they are building a plane. It looks to me like they are setting the bar low. No, I don't expect them to come out with a fuel-cell powered business jet, that wouldn't be possible would it, but they are exploring environmentally friendly fuel cell technology for future Boeing products. Note the plural.

      The exciting thing about this announcement is that a sector which uses huge amounts of fossil fuel is looking into environmentally sound alternatives!
      • You selected the most misleading sentence of the whole article:

        Boeing Commercial Airplanes will develop and test an electrically powered demonstrator airplane, They are making a demonstration plane that has a propeller that is powered by fuel cells. However, this NOT the goal of their project. And as you stated this is not going to lead to fuel-cell powered jumbo-jets. Once again from the article:

        ``Our ultimate goal is to replace the auxiliary power unit,''

        and

        ``Fuel cells show the promise of one day providing efficient, essentially pollution-free electrical power for commercial airplane primary electrical power needs,''

        Now I agree that this is great, but everyone seems to be running around thinking it is something that it isn't.

  • congrats Boeing, you're SECOND (Score:5, Interesting)

    by mr.ska ( 208224 ) on Wednesday November 28, 2001 @07:59AM (#2624123) Homepage Journal
    A fuel cell-powered airplane is being worked on. Admittedly, it's not an airliner, but it's still the same problems, just on a smaller scale.

    EVWorld.com [evworld.com] has the two-part story and interview with the plane's builder here (1) [evworld.com] and here (2) [evworld.com].

  • Solar Cells (Score:5, Insightful)

    by Spudley ( 171066 ) on Wednesday November 28, 2001 @08:32AM (#2624193) Homepage Journal
    I've always thought that aircraft wings are one of the most obvious places to put solar cells. On a day-time flight, you're practically garuanteed maximum sunshine for the whole duration.

    Even if you don't use it directly to power the engines, there's still plenty of electronics on your average aircraft that could use it.
    • On a small civil air craft like the story is talking about, you're not always going to get sunshine for the whole flight.

      It's much more efficent to power your avionics with a wind driven turbine that hangs outside the plane (like the jammer EA-6 use) or from an alternator off the engine.
    • Except that on commerical airliners, the wings also contain 100K+ gallons of fuel. Do you really want to put an electrical generating system in such a close proximity to all that jet-a?

      Also, if you deduct the area of the wing that is comprised of moveable surfaces (ailerons, flaps, air brakes, slats) the top surface of the wing is relatively small. The top of the fuselage would be a better place to put solar panels.

      I would guess that a air powered turbine would produce more electricity than solor panels; it it would induce some drag, but as long as the plane is flying, it works - unlike solar panels which won't work at night, on overcast days or when flying IFR.
  • I've been playing around with the idea of a Moller Skycar-like personal aircraft with super-simple computer-aided controls (accel, decel, left, right, up, and down, plus GPS assistance), and it occured to me that a fuel-cell powered propultion system would be VERY sweet, but maybe not practical for a few years (a few very short years, based on their swift progress! =])
  • "The question is can a fuel cell deliver enough energy for a flight long enough to be practical."
    The question is will you be able to recharge with California's energy problems?

  • Different types of Fuel Cells (Score:3, Interesting)

    by ArhcAngel ( 247594 ) on Wednesday November 28, 2001 @10:50AM (#2624706)
    Many of the posts alude to the potential of a hindenburg type explosion on a plane that used such a fuel cell system because of the Hydrogen involved. According to the article Boeing is looking at using fuel cells but it doesn't specifically mention hydrogen fuel cells except to say one was seen used in an automotive demonstration. There are many different types of fuel cells http://www.fuelcells.org/fctypes.htm each having it's pros and cons. I do see a move to "alternative" types of fuel but, as always, economics will drive the shift as much as anything else. Right now energy companies are scrambling to figure out how to profit long term on systems that are so efficient. Anyone old enough to remember when an automobile wouldn't go over 75,000-100,000 miles without a MAJOR overhaul? It wasn't because they couldn't be more reliable but becaue the big 3 made $$$ off of the repair parts as well as new car sales. If the Japanese companies hadn't offered more efficient/reliable products in the 70's we might still be seeing the trend.
    OK, I think I sufficiently wandered off topic

  • Energy density problems? (Score:3, Informative)

    by michael_cain ( 66650 ) on Wednesday November 28, 2001 @11:25AM (#2624893) Journal
    Early in October the subject of hydrogen-powered airliners was discussed [slashdot.org]. The primary problem pointed out was not explosion, but the low energy density of even liquified hydrogen. I believe someone worked it out and that a New York to LA flight required filling the entire interior of the plane -- cargo space, passenger cabin, etc -- with liquid hydrogen to have enough fuel for the flight. Assuming fuel cells to produce electricity to drive efficient motors to drive big props are twice as efficient as just burning the hydrogen in a jet, low energy density is still a serious problem.

    As others have suggested, if I could just invent a fuel cell that dealt handily with carbon- and nitrogen-rich fuels, I could help the environment and get rich.

  • Makes a lot of sense (Score:3, Informative)

    by AJWM ( 19027 ) on Wednesday November 28, 2001 @12:38PM (#2625269) Homepage
    The question is can a fuel cell deliver enough energy for a flight long enough to be practical.

    The answer is, "yes".

    Fuel cells are very efficient at converting chemical to electrical energy -- the cells NASA has been using on manned spacecraft since the 1960s run at about 75% efficient -- compare that to the roughly 30% efficiency of a combustion engine. (Although for a proper comparison we'd also need to factor in the efficiency of the electric motor. At 85%-90% (numbers I've seen quoted) that gives a net chemical-to-mechanical efficency of about 64%-67%.)

    As far as safety goes -- well, NASA has been running H2-O2 fuel cells on manned spacecraft since Gemini, and the only problem they've ever had with that system was due to a combination of spec changes and improper procedures causing an O2 tank to explode (Apollo XIII).

  • Modern fuel cells use alcohol to produce hydrogen (Score:3, Interesting)

    by SysKoll ( 48967 ) on Wednesday November 28, 2001 @12:53PM (#2625368)

    Everyone here is assuming that the fuel cell based auxiliary generator discussed in the article will be using hydrogen.

    Actually, a lot of work is being done on fuel cells burning alcohol (ethanol). Either you use a cracking step to produce hydrogen on-the-fly by decomposing the alcohol molecule with a catalytic grid, or you use a pretty fancy membrane to rip the hydrogen directly from the alcohol molecule.

    Either way, you don't need to carry a hydrogen tank. So save the Hindenburg references for a more appropriate topic.

    Since alcohol is actually less energetic per kilogram than kerosen, I don't see why it would be dangerous. The only problem is that it's one more fluid to carry in airports, and that would probably require even more work and red tape than getting an alcohol-burning fuel cell approved by the FAA.

    The residue of such a fuel cell is alcohol remains mixed with water and various catalytic by-products. In other terms, watered-down alcohol with metalic salt traces and a few moderately toxic molecules. Not very dangerous either. Heck, with a bit of luck, airlines will decide to tap this residue and sell it to passengers in lieue of the horrible Californian el cheapo wine they serve with meals. :-)

    --SysKoll
  • I don't know why people are going on and on about fuel cells. They're great for space vehicles, where weight is the #1 concern. But for aircraft, why not use nuclear power. Nice and clean. No emissions. And it's a technology that's been used for 50 years.

    Here's a great picture of a prototype [brook.edu]. Note the concept plane at the bottom. The flight deck "could be detached in cases of emergency." What more safety could anyone ask for?

  • Another advantage, which no one seems to have mentioned, is that fuel cells make aircraft far less *explosive*. Without gasoline, they are no longer flying bombs. Aircraft security issues are returned to pre-9/11 status.

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