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Low pressure hydrogen storage

  1. Aug 24, 2016 #1
    What is the most practical and cost efficient way to make a 10m3 gas bag for the storage of hydrogen?

    I am thinking of storing H2 from water electrolysis in an outdoor area, a bit like the way biodigestor gas is stored in low cost, small scale installations.

    My concern is the high effusing nature of the gas through membrane material. My first thought was to use reinforced PVC like that used for truck tarpaulins but I can't find any info on effusing rates verses other materials. Ideally the gas would be able to remain in the bag for a minimum 2-3 weeks until needed.

    Any thoughts and advice would be gratefully received! This is an experiment on the practical applications of locally produced hydrogen for home use, so I hope to be able to follow up any advice by constructing the gas bag and reporting back with the project progress.
     
  2. jcsd
  3. Aug 24, 2016 #2
    Use lawn bags sprayed with Pam cooking spray. That will get you the coolest looking explosions.
     
  4. Aug 25, 2016 #3
    Thanks for the reply. I'm looking for storage ideas rather than explosions though!
    Nick
     
  5. Aug 26, 2016 #4
    Well they do go together.
     
  6. Aug 26, 2016 #5
    It's hard to keep Hydrogen in a low pressure container since being the smallest atom it can easily leak out of containers like say rubber or plastic.
    Less is lost if it's cooled a lot, pressurized, and held in a more substantial container like a thick Iron bottle.
    Another way to go (industrially, not back-yard) is to store the hydrogen as a bigger molecule which nevertheless has high energy density which can be exploited, eg ammonia, hydrazine.
     
  7. Aug 26, 2016 #6
    Pressurized reduces leaking? Or is that a side effect of the other stuff?
     
  8. Aug 26, 2016 #7
    Pressurizing doesn't help with leakage, it helps to keep more of the stuff in a confined space.
    So that's why you need cooling and fairly thick rigid containment
     
  9. Aug 26, 2016 #8

    SteamKing

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    The Germans used gas bags like this for storing their low pressure hydrogen:


    Hindenburg_at_lakehurst.jpg

    Alas, someone didn't mind the leakage of the hydrogen, and this is what happened:


    Hindenburg_disaster,_1937.jpg

    The gas bags of older airships were made from several layers of goldbeater's skin folded together to give an impermeable membrane. Goldbeater's skin is made from the outer layer of a calf's intestine, so one airship requires making a lot of veal, which comes in handy when your national cuisine prizes wiener schnitzel. :smile:

    But, times and technology change, and by the 1920s, goldbeater's skin had been displaced in airship construction by a synthetic material developed in the USA by the Goodyear company. As a result, good veal has been hard to find in the USA ever since, unless you have a suit with a monsignor's stripe on it, as claimed by father Guido Sarducci. :wink:

    The material Goodyear developed was called gelatinized latex, and the outer skin of the airship was made reflective so that infrared and UV radiation would not damage the gas bag materials inside.

    https://en.wikipedia.org/wiki/LZ_129_Hindenburg

    Still, with all this non-veal producing technology at work, major accidents can still occur. :oops:
     
  10. Aug 26, 2016 #9
    Hmm yes, and I think the outer skin was made reflective by coating it with a thin layer of Alu.
    That might have contributed to the inferno once it got going.
     
  11. Aug 26, 2016 #10

    SteamKing

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    This article provides a few details about the composition of the outer skin:

    https://en.wikipedia.org/wiki/Hindenburg-class_airship
     
  12. Aug 26, 2016 #11
  13. Aug 26, 2016 #12

    SteamKing

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    I thought everybody knew that. In the Thirties, everybody smoked. :wink:

    Still, the smoking lounge was pressurized to prevent any hydrogen from leaking in, and because this lounge was pressurized, access to and from could only be gained by passing thru airlock doors. Passengers using the lounge were carefully (and I'm sure thoroughly) scrutinized by the crew to make sure they did not try to smuggle smoking materials back to their cabins. o_O
     
  14. Aug 27, 2016 #13
    Wow, great answers and really helpful links, many thanks everyone! Next time I order a schnitzel I'll be thinking of the Hindenburg!

    Am I right in thinking that helium is more "leakable" or effusive than hydrogen, given helium is monatomic rather than diatomic, so if I can find a good membrane material for helium, as in looking at tried and tested balloon technology, then it should perform even better for hydrogen? Flammability of the material would also be an issue.

    Of course safety is the prime concern and even though this is a one off test, needless to say, I will be following a rigid safety protocol and will keep the storage volume low and in a remote outdoor area.
     
  15. Aug 27, 2016 #14

    SteamKing

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    Unfortunately, helium gas is not more effusive than hydrogen. Although hydrogen is diatomic, a single helium atomic nucleus is twice as heavy as a hydrogen molecule.

    The daily loss rate of hydrogen sometimes ran as high as 13.5%, at least in balloons. During the age of the airship, helium was much more expensive than hydrogen, so designers took great pains to minimize the loss of such a precious resource. In fact, the first helium dirigible constructed for the US Navy, the USS Shenandoah (ZR-1), contained most of the world's supply of helium when it was first inflated in 1923.

    http://www.globalsecurity.org/military/world/airship-helium.htm
    Apparently, modern blimps are constructed using polyurethane vinyl.

    http://www.blimpguys.com/helium.htm
     
  16. Sep 9, 2016 #15
    I want to thank Steamking and everyone for the informed and helpful responses. Its given me a lot of food for thought to take things forward.

    So Hydrogen has a higher loss rate than helium. What I find puzzling is that some of the latest balloon technology such as the Red Bull Stratos uses very thin material such as polyethylene. Presumably with high altitude balloons there is also the issue of weight which is also an important consideration and more so in the case of temporary, short term use.

    Presumably the thicker the material I use, the lower the loss rate? Excuse my ignorance if I'm stating the obvious here. I'm thinking of a thick vinyl material that if necessary I could also laminate in layers. Could I expect that by doubling the thickness of a given material I would half the loss rate?
     
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