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Thread: Airships

  1. #1 Airships 
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    Would an airship powered by helium be a good alternative to an aiplane (since it does not produce any CO2) or are there major safety issues - besides the obvious risks which apply to airplanes and anything that is high altitude! This is more a question of the safety and also efficiency/viability of helium as a fuel + any other issues with airship mechanics.

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    Would an airship powered by helium be a good alternative to an aiplane (since it does not produce any CO2)
    Modern airships still produces Co2 from the engines' combustion that propells them. I'd guess they are probably a lot more efficient by some measure like pound_Co2/(person*mile) etc.


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  4. #3 Re: Airships 
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    Quote Originally Posted by emetzner
    Would an airship powered by helium be a good alternative to an aiplane (since it does not produce any CO2) or are there major safety issues - besides the obvious risks which apply to airplanes and anything that is high altitude! This is more a question of the safety and also efficiency/viability of helium as a fuel + any other issues with airship mechanics.

    Thank you
    Helium is inert. You can't use it as a fuel.
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  5. #4 Re: Airships 
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    Quote Originally Posted by emetzner
    What is used to power a modern one?
    Usually 2 airplane piston or turbo props.



    --
    Ouch.

    Sorry emetzner I hit the edit instead of quote and accidentally mauled the rest of your post. You did nothing wrong, it was my mistake.

    Please continue with this interesting subject. I'll be more careful.

    Lynx
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  6. #5 Re: Airships 
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    Quote Originally Posted by Bunbury
    Helium is inert. You can't use it as a fuel.
    Hydrogen then. Historic spectacles aside, hydrogen airship is no more accident-prone than a modern jumbo jet. Either could fail catastrophically, and don't fail because we're very careful.
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  7. #6 Re: Airships 
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    Quote Originally Posted by Pong
    Quote Originally Posted by Bunbury
    Helium is inert. You can't use it as a fuel.
    Hydrogen then. Historic spectacles aside, hydrogen airship is no more accident-prone than a modern jumbo jet. Either could fail catastrophically, and don't fail because we're very careful.
    Not so sure of that, according NASA commercial planes are hit about once a year from lightning. I was unfortunately to be on a P3-Orion weather research plane hit by lightning once. The avionics were unaffected but it took down our tail Doppler radar, the cloud physics station I was monitoring and other systems. I don't see how hydrogen, which is much more volatile and less well protected than jet fuel, could be made nearly as safe.
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  9. #8 Re: Airships 
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    Quote Originally Posted by Lynx_Fox
    hydrogen, which is much more volatile
    ...when oxygen is present. Have we technologically advanced enough to build a tighter airship yet?

    A quick check on Hindenburg tells us - incredibly - 2/3 of passengers survived the accident, with deaths attributed more to falls and burns from the exploding engine fuel tanks. Hydrogen flames and explodes decidedly upward. Hindenburg took about 30 seconds to burn out and settle on the ground. We also learn the Hindenburg, like all airships, had been struck by lightning many times, and this was obviously not a problem.

    So, I dunno Lynx_Fox shall we conclude jets are most dangerous because lightning frazzles their critical electronics, and then they plummet at unsurvivable velocity?
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    Suriving a couple hits is hardly gives confident that they're immune to lightning. The Hindenburg was lucky to be only a couple hundred feet up, which is why most of them survived--over the Northern Atlantic, or from cruising altitudes it probably would have been much worse. We know planes are occasionally downed by lightning but it's an exceedingly small number because of extraordinary measured of electrical grounding protection of the fuel lines and tanks and relative safe composition of the fuel well as can be and still run the engines. I don't think hydrogen could be protected to anywhere near that level.

    And why use hydrogen, which we know is potentially dangerous when safer gases which are almost completely safe allow nearly the same capability? If you offered completely safe jet fuel you can be sure it would quickly adopted by the FAA and aviation industry.
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  11. #10  
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    What about methane or alcohol?
    Dick, be Frank.

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  12. #11  
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    Quote Originally Posted by Lynx_Fox
    Suriving a couple hits is hardly gives confident that they're immune to lightning.
    Now it was a fluke the airship lines ran for years around the globe getting struck by lightning without harm? You're brushing off because unwilling to think deeper into hydrogen airships. Come on, it is time to unblock.

    Why use hydrogen. Well, it's the lightest gas. It's non-polluting and in the not so distant future we'll be cleanly producing it in volumes great enough to fuel our cars. Oh yeah, and your airship may conveniently carry tanks of hydrogen for fuel as well.
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  13. #12  
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    Quote Originally Posted by marcusclayman
    What about methane or alcohol?
    As a fuel methane would have to be kept under high pressure. Alcohols have a lower energy density than diesel or gasoline so you'd have to carry more weight. Otherwise they make fine fuels. (Not much good for lifting though.)
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  14. #13  
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    Quote Originally Posted by Lynx_Fox
    Suriving a couple hits is hardly gives confident that they're immune to lightning. The Hindenburg was lucky to be only a couple hundred feet up, which is why most of them survived--over the Northern Atlantic, or from cruising altitudes it probably would have been much worse. We know planes are occasionally downed by lightning but it's an exceedingly small number because of extraordinary measured of electrical grounding protection of the fuel lines and tanks and relative safe composition of the fuel well as can be and still run the engines. I don't think hydrogen could be protected to anywhere near that level.
    You don't think similar measures could be put in place for a hydrogen blimp? If modern safety engineering had been in place at the time of the Hindenburg, do you think the accident would have been as catastrophic?

    Personally, I'd be more interested in using them for shipping of materials instead of people (I can't imagine that a person would want to travel that slow), so for a cargo blimp, you may only need to accommodate the safety of 2 or 3 operators.



    And why use hydrogen, which we know is potentially dangerous when safer gases which are almost completely safe allow nearly the same capability? If you offered completely safe jet fuel you can be sure it would quickly adopted by the FAA and aviation industry.
    Hydrogen is cheaper, and the craft would be more aerodynamic because hydrogen imparts more lift per unit volume.

    With Helium, you have to find it and harvest it from somewhere. With Hydrogen, you just make it by electrolyzing water. There's a virtually unlimited supply of hydrogen.
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  15. #14  
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    Quote Originally Posted by kojax
    Personally, I'd be more interested in using them for shipping of materials instead of people (I can't imagine that a person would want to travel that slow), so for a cargo blimp, you may only need to accommodate the safety of 2 or 3 operators.
    In that case r/c. Compared to remote controlling fighter jets and toy helicopters a heavy lifter blimp would be relatively simple. This would be more cost effective than outfitting a cabin.


    Yet enough people do want to travel slowly that we have cruise ships. An airship offers better views. How'd you like to take a cruise over Africa? Day stop at the summit of Mount Kilimanjaro, disembark on a Giza pyramid?
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  16. #15  
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    There must be a way to make hydrogen relatively inert.

    If the hydrogen was contained in smaller capsules made of reinforced carbon/silicon-aerogel, it could be much safer.

    A matrix of capsules inside the balloon, each with a smaller capsule of some kind of fire suppressant and hydrogen. If the hydrogen ignites it releases the fire suppressant long before penetrating the aerogel wall. The suppressant puts out the fire while releasing excess pressure upwards(an intentional weak point in the aerogel maybe), preventing the fire from spreading.


    This will weight more that just hydrogen, but a certain ratio of hydrogen-aerogel-suppressant, will weight less than helium. It's just a matter of whether the gains in safety are worth the losses in aerodynamics. A good medium could be designed.
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  17. #16  
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    Quote Originally Posted by kojax
    With Helium, you have to find it and harvest it from somewhere. With Hydrogen, you just make it by electrolyzing water. There's a virtually unlimited supply of hydrogen.
    Helium comes out of the ground with natural gas. You only have to separate it from the NG and this is routinely done in gas production facilities.

    Electrolysis requires large amounts of energy. Before you can claim there's a virtually unlimited supply you must first work out how you are going to generate the power, without releasing gobs of CO2. Most hydrogen today is produced from oil and coal. Wind and other renewable resources might do it but you are jumping the gun to claim unlimited availability.
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  18. #17  
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    Quote Originally Posted by Pong
    Quote Originally Posted by Lynx_Fox
    Suriving a couple hits is hardly gives confident that they're immune to lightning.
    Now it was a fluke the airship lines ran for years around the globe getting struck by lightning without harm? You're brushing off because unwilling to think deeper into hydrogen airships. Come on, it is time to unblock.
    Actually there were at least 5 burning accidents on these types of ships during a period the industry was tiny compared to current aviation. Besides lightning there those accident highlight other risk, power lines for example.

    During WWI incendiary rounds were able to set observation balloons afire which were filled with hydrogen--these indicates a possible terrorist threat--what would be easier than shooting down a slow, huge passenger airship with a few incendiary light caliber rounds?

    Why use hydrogen. Well, it's the lightest gas.
    Fire risk. Even the Zeppelin company preferred to use the 90% lift capable but much more safe helium on their designs. This was largely responsible for an excellent safety record before the Hindenburg disaster. The prototypes of the Hindenburg were designed for helium but modified (including the skin coatings) for hydrogen due to an American embargo on helium.

    It's non-polluting and in the not so distant future we'll be cleanly producing it in volumes great enough to fuel our cars. Oh yeah, and your airship may conveniently carry tanks of hydrogen for fuel as well.
    Tanks, liquid solutes, and other materials that store hydrogen can be made much more safe than the nearly pure hydrogen protected by extremely thin layers of materials necessary for airships. There might be some less volatile hydrogen+other gas mixtures that are safer.
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  19. #18  
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    Quote Originally Posted by Bunbury
    Quote Originally Posted by kojax
    With Helium, you have to find it and harvest it from somewhere. With Hydrogen, you just make it by electrolyzing water. There's a virtually unlimited supply of hydrogen.
    Helium comes out of the ground with natural gas. You only have to separate it from the NG and this is routinely done in gas production facilities.

    Electrolysis requires large amounts of energy. Before you can claim there's a virtually unlimited supply you must first work out how you are going to generate the power, without releasing gobs of CO2. Most hydrogen today is produced from oil and coal. Wind and other renewable resources might do it but you are jumping the gun to claim unlimited availability.
    What makes me like zeppelins is that they might provide a very convenient way to ship hydrogen around without having to compress it first. If we ever move toward a hydrogen economy, wind and solar would probably be used to generate it, since those are too unreliable to contribute very much to the power grid directly.

    We don't have to worry about where we're getting the hydrogen if it's actually intended to be part of the cargo.


    Quote Originally Posted by marcusclayman
    There must be a way to make hydrogen relatively inert.

    If the hydrogen was contained in smaller capsules made of reinforced carbon/silicon-aerogel, it could be much safer.

    A matrix of capsules inside the balloon, each with a smaller capsule of some kind of fire suppressant and hydrogen. If the hydrogen ignites it releases the fire suppressant long before penetrating the aerogel wall. The suppressant puts out the fire while releasing excess pressure upwards(an intentional weak point in the aerogel maybe), preventing the fire from spreading.


    This will weight more that just hydrogen, but a certain ratio of hydrogen-aerogel-suppressant, will weight less than helium. It's just a matter of whether the gains in safety are worth the losses in aerodynamics. A good medium could be designed.
    I'm thinking more along the lines of just making a 2 layered balloon. You put a totally inert gas between the outer layer and the inner layer, and then only fill the inner layer with Hydrogen. The air ship would have some compressed reserves of the inert gas in case something happened to cause some of it to seep out. (And they'd probably land the blimp as a safety proceedure at that point anyway.)

    I wonder if you chose the gas strategically enough, if it might also help prevent Hydrogen from seeping out through the walls of the balloon during the trip?
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  20. #19  
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    If we ever move toward a hydrogen economy, wind and solar would probably be used to generate it, since those are too unreliable to contribute very much to the power grid directly.
    Wind, solar and conventional fossil generators will be integrated into the Smart Grid, making electric vehicles more attractive than hydrogen powered vehicles. Unreliabilty of renewable sources is a short-term issue that will become a non-issue as the power distribution and storage technology catches up with generation technology. Of course fossil fuel interests would like you to think otherwise.

    Here's a good read:

    http://www.oe.energy.gov/Documentsan...rid-report.pdf
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  21. #20  
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    Quote Originally Posted by Bunbury
    electric vehicles more attractive than hydrogen powered vehicles
    Perhaps more atractive due to wasteful quirks of the market or consumer, but not in ultimate cost or utility when considered frankly. Some localities (or, corners of the grid) can compress hydrogen very cheaply, because electric generation is locally cheap (and incidentally "green" too). Once compressed, this fuel may be moved by ship at negligible cost and zero transmission loss, and still is profitable to distribute by truck or pipeline much as gas is. Now look at the consumers. They want cheaply manufactured yet powerful vehicles. A combustion vehicle will always answer that better than an electric one.
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  22. #21  
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    Others, notably Dr. Chu, our energy secretary, would disagree. A hydrogen infrastructure looks like a long range and very expensive project.
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  23. #22  
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    Quote Originally Posted by Bunbury
    Others, notably Dr. Chu, our energy secretary, would disagree. A hydrogen infrastructure looks like a long range and very expensive project.
    Everyone is worried about how hard it will be to adapt gas systems, pipelines, and etc over. Compression is also an issue. Basically Hydrogen has a great energy efficiency by mass, but horrible efficiency by volume unless you compress it (It's a lighter than air gas, after all.) But some new technologies are emerging:

    http://blogs.edmunds.com/greencaradv...ined-idea.html

    http://www.greenoptimistic.com/2009/...rogen-storage/


    I'm not impressed by the idea of hydrogen powered cars. Platinum is a necessary component for the portable Hydrogen-electric process, which makes it kind of impractical to try and build enough converters for everyone. Power plants, on the other hand, could use hydrogen to even out their output when trying to incorporate Wind and Solar.
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  24. #23  
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    Quote Originally Posted by Bunbury
    Others, notably Dr. Chu, our energy secretary, would disagree. A hydrogen infrastructure looks like a long range and very expensive project.
    At least you can look hydrogen over in detail. The alternative "a non-issue as the power distribution and storage technology catches up" is optimistic fortune telling, so yeah, hard to criticise. I rather not bet our future on a raft of future technologies.

    Don't complain if you find yourself driving a golf cart feebly powered by backyard whirligigs, all made in China.

    Anyway I don't see airships taking up much of a hydrogen economy. And they can't beat surface ships for bulk transport. More likely just some heavy lifting where cranes are impractical, and over-land cruises of course.


    EDIT: @Kojax. Platinum? You're making this too complicated. Drive into a hydrogen gas station, get your H-car's tank filled with compressed fuel, then burn that fuel with air in a combustion engine. It's not much different than what we do today, 'cept you can steam a tasty dish of spinach with the car exhaust.
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  25. #24  
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    Quote Originally Posted by Pong
    I rather not bet our future on a raft of future technologies.
    That is exactly what we are doing with hydrogen: future fuel cells (far from being perfected); no infrastructure ($200billion investment); wind, solar in areas where water isn't; oil companies ramp up hydrogen production from natural gas. Hydrogen is impractical for an ICE because liquid H2 has one fifth the volumetric energy density of gasoline (i.e fuel tank five times bigger for same distance traveled), assuming you can store it as a liquid. The only long term practical hydrogen car is a fuel cell vehicle because fuel cells can make up in efficiency what is lost in volumetric energy content of the stored fuel.

    Don't complain if you find yourself driving a golf cart feebly powered by backyard whirligigs, all made in China.
    Hate those Chinese golf carts...

    http://www.teslamotors.com/performan...and_torque.php
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  26. #25  
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    Quote Originally Posted by Bunbury
    Hydrogen is impractical for an ICE because liquid H2 has one fifth the volumetric energy density of gasoline (i.e fuel tank five times bigger for same distance traveled), assuming you can store it as a liquid. The only long term practical hydrogen car is a fuel cell vehicle because fuel cells can make up in efficiency what is lost in volumetric energy content of the stored fuel.
    Ah. Now I know better, I retract my argument!
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  27. #26  
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    Well I was a bit off too. I just found this on Wikipedia and the 5 times factor actually seems to apply to gaseous hydrogen at 700 bar. With liquid hydrogen it's only about 3.5 times.

    http://en.wikipedia.org/wiki/File:Energy_density.svg
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  28. #27  
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    Quote Originally Posted by Bunbury
    A hydrogen infrastructure looks like a long range and very expensive project.
    Not sure where to put this but here seems somewhat reasonable. Maybe this will help defray some of the overall cost to a hydrogen infrastructure. From http://www.ecogeek.org/biofuels/2845:

    Hydorgen seems like a logical choice for fuel - it's energy dense and emits only water upon combustion - but upon closer examination we see that it's extremely expensive to make from water, so all the hydrogen in production today is made from fossil fuels. But Gerardine Botte at Ohio University has figured out an easy and efficient way to break the bonds in urea to produce hydrogen. The process consumes roughly one quarter of the energy needed to electrolyze water. And, yes, the world has a fairly plentiful (and renewable) supply of urea. Maybe not enough to power all our cars, but it's a start.
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  29. #28  
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    So, integrate a hydrogen infrastructure with the sewage treatment infrastructure. That idea stinks.
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  30. #29  
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    Quote Originally Posted by Bunbury
    So, integrate a hydrogen infrastructure with the sewage treatment infrastructure. That idea stinks.
    Definitely want to use un-manned blimps.
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