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Thread: Why is it so difficult to store hydrogen ?

  1. #1 Why is it so difficult to store hydrogen ? 
    Forum Professor leohopkins's Avatar
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    Why is it so difficult to store hydrogen ? (for cars)


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    This is just a guess, but it probably has to do with the equipment needed to keep it at a high enough pressure to carry a decent amount around with you. I'd imagine the reaction between hydrogen and oxygen is also pretty exothermic, and potentially explosive if there was a leak or something.


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    I suspect your question is not only about the physical storage problem but also why hydrogen is not an efficient method of energy storage.

    First you have to generate the electriciy to make the hydrogen by electrolysis. Then you have to compress the gas. Then you burn it in an internal combustion engine. There are inefficiencies in each of these processes.

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    to get a reasonable energy per unit volume the gas needs to be stored at very high densitys and so you need a highly pressurised tank.
    However this means that the tank is really not safe and you are basically driving around a bomb.
    everything is mathematical.
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  6. #5 Re: Why is it so difficult to store hydrogen ? 
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    Quote Originally Posted by leohopkins
    Why is it so difficult to store hydrogen ? (for cars)
    The problem is that hydrogen has a very low energy density. It is possible to store enough to run a car, you would just need an enormous gas tank that would be bigger then the rest of the car.
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    Steels can be subject to hydrogen embrittlement when under stress as they would be in a high pressure cylinder, and a brittle hydrogen tank is not something you'd want in the back of your car. Materials for hydrogen containment in cars are I believe being developed based on layered carbon fiber/resin construction.

    What Harold says about inefficiencies is right on the money. Hydrogen as a major fuel is pie in the sky. However it can and is easily produced by other means than electrolysis, such as gasification of coal or refinery coke. A by-product is CO2 though.
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    Is it possible to use the alternator of your car to electrolize the water at a rate that you could actually produce enough Hydrogen on the fly without having to store large amounts of it? This is also with the idea of using a system similar to burning LPG and Natural Gas in your car instead of using the typical carburator/fi for gasoline. What i mean is most of the ideas on the net today are trying to run the hydrogen line directly to your air intake instead of using the gas conversion kits.
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    In one word : NO. the reasons why are numerous.
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    Quote Originally Posted by Nogold4u
    Is it possible to use the alternator of your car to electrolize the water at a rate that you could actually produce enough Hydrogen on the fly without having to store large amounts of it?
    You can't magically get energy from nothing. If you use electrolysis to get hydrogen from water, the energy that you can get out of the hydrogen by burning it is equal to the energy that you spent doing the electrolysis. If you power a car by using a
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  11. #10 Re: Why is it so difficult to store hydrogen ? 
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    Quote Originally Posted by Raggedjoe
    The problem is that hydrogen has a very low energy density. It is possible to store enough to run a car, you would just need an enormous gas tank that would be bigger then the rest of the car.
    BMW has already demonstrated a car with a 140 liter hydrogen tank (about twice the size of a car's normal gasoline tank) that has a range of 350 km. It's a four-door sedan that's the size of a "regular" car. You wouldn't know that there's anything unusual about it if you saw it driving on the street (except for the fact that it has "Powered by hydrogen!" plastered all over it). So yeah, the tank needs to be larger, but the size isn't a problem and it definitely doesn't need to be bigger than the rest of the car. In numerous crash tests the hydrogen tank was found to be no more dangerous than a conventional gasoline tank (which is also pretty explosive, as you might recall).
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    HYDROGEN FIRES are actually safer than a gasoline spill and fire, if you can call any accedental fire safe. Hydrogen rises rapidly and the fire is above the vehicle up in the air. Gasoline puddles and runs all over the place making it a big barbaque under and around the vehicle. hyhrogen is not explosive unless already mixed with air.
    That still doe not adress the issue that it is not efficienly generated to begin with.
    Its another tree hugger pipe dream.
    The altenator idea is also bogus because you can't generate it as fast as you burn it without a massive generator unit. Look at the CFM consumed its massive.
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    Quote Originally Posted by fizzlooney
    That still doe not adress the issue that it is not efficienly generated to begin with.
    Its another tree hugger pipe dream.
    Hydrogen can be generated very efficiently via electrolysis using the right catalysts, and can then be converted into kinetic energy in a car via a fuel cell and motor at efficiencies approaching 45% or greater. That's competitive with an internal combustion engine, which are usually 30% or less efficient. If the energy for the electrolysis comes from nuclear or solar power, it's all basically pollution-free.
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