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View Diary: Recent DOE Break-Through with Hydrogen Fuel Cells, should make them Affordable (275 comments)

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  •  If a fuel tank ruptures , (4+ / 0-)
    Recommended by:
    Sneelock, jamess, WisVoter, Matt Z

    the fuel leaks out and maybe burns .
    With gasoline the fuel pools under the leak and if it catches fire it burns slowly from below .
    With hydrogen , propane , natural gas , it leaks out quickly and up wards , the fuel can move up and away . If it catches fire it can burn quickly from above .

    They burn in different ways , some say that a fuel tank rupture with a hydrogen , propane , natural gas tank is "safer" than a gasoline one . The H,P,NG does not stay at the site of the rupture the way gasoline does .   H,P,NG does not cling onto , soak into clothing , hair etc .

    "Drop the name-calling." Meteor Blades 2/4/11

    by indycam on Sun Apr 24, 2011 at 09:29:33 AM PDT

    [ Parent ]

    •  That makes sense (2+ / 0-)
      Recommended by:
      jamess, Matt Z

      So, the fuel doesn't sit around waiting for a spark, like gasoline does.  The source of fuel for a fire is shorter lived and more localized.

      But if a fire does start.  What happens then?  Does the fuel just burn off as it escapes?  Or does the tank eventually bust open, and there is a huge explosion?  How big?

      •  It depends on the rupture (3+ / 0-)
        Recommended by:
        Sneelock, Matt Z, jamess

        if its a rupture where all the contents are lost at once , a "cloud" goes up with or without burning . If that sort of leak ignites it goes off like one big explosion . If on the other hand a fitting is knocked loose and the fuel is leaking out via a small leak and it catches fire , it can be a long flame .


        "Drop the name-calling." Meteor Blades 2/4/11

        by indycam on Sun Apr 24, 2011 at 11:29:49 AM PDT

        [ Parent ]

    •  Not So Much The Leak, The Accumulation (0+ / 0-)

      (Don't misunderstand my comments as a belittlement of the danger of hydrogen.)

      Allowing it to leak and accumulate causes a lethally explosive situation, see the Rei post below.  Proper ventilation is an absolute necessity as is avoiding a full pressure loss upon a tank rupture.  If, hypothetically, a leak could be burned off rather than allowed to accumulate and explode, the explosion potential would be reduced.  Hydrogen may be an order of magnitude or more explosive than gasoline (flame propagation rate and flammability limits) but the thermal content is much less, meaning a pound of gasoline is capable of producing much more raw heat than a pound of hydrogen, therefore making hydrogen a poor substitute for gasoline as a combustion fuel.

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