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Boeing to Develop a Fuel Cell Powered Airplane
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.
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.
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
ecosoul sells a fuel cell kit, and there are instructions (pdf) from homepower mag about how to construct one.
"Where shall the word be found, where will the word resound? Not here, there is not enough silence." -T.S. Eliot
Hi,
... that is if a field is in range. Electric engines should increase reliability quite a lot. Hopefully they are available soon.
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
Icare
Silent AE1
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,
Regards, Thomas.
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.
If you were blocking sigs, you wouldn't have to read this.
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).
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When the pin is pulled, Mr. Grenade is no longer our friend.
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.
. Mankind evolved from apes, JonKatz is still a baboon.
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.
Lasers Controlled Games!
An aircraft piston engine typically needs to completely overhauled every 20,000 hours of operation to ensure reliability.
:-) Airframes typically outlast multiple engines if they're well cared for, particularly if they're hangared (which mine is).
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.
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.
The Future of Human Evolution: Autonomy
Well, you are a way off. Right off the Boeing web site there is a max fuel capacity of a little less than 24,000 gallons in all 767 models.
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.
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.
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).
-- Alastair