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Hydrogen fuels

  1. Nov 22, 2015 #1
    I have got a question. If we do electrolysis with waterand get : H2 + 02 , and then we make hydrogen explode and make a piston move , for example. Then it would be H2O again? So we could do this forever and get as much energy as we want? That would be super awesome but i am not sure.
  2. jcsd
  3. Nov 22, 2015 #2
    No, this a perpetual motion idea, and it is not possible due to entropy.
    Yes you will get H2O again, but there will be energy lost as heat.
    The mechanical energy produced by the piston will be less than the electrical energy needed to do the electrolysis.
    It will quickly run down unless you supply more energy from an external source.
  4. Nov 22, 2015 #3
    I meant that we do electrolysis with hydroelectric energy , solar panels , something sustainable and then use hydrogen for combustion and there we go! it gets into h20 and we have electrolysis again and that process goes again and again and we would never , ever , ever be out of hydrogen and water right?
  5. Nov 22, 2015 #4
    Sure, as long as you provide electrical power to the system from an external source.
  6. Nov 22, 2015 #5
    Awesome! It is 101% sustainable or even more . There should be more hydrogen cars. Is there a better fuel than hydrogen that runs in a cycle like this?
  7. Nov 22, 2015 #6
    As far as I know hydrogen is about as good as it gets in terms of energy released per volume of fuel.
    ... but ... supplying the extra electrical energy has a cost, especially if it generated from carbon fuels.
  8. Nov 22, 2015 #7
    You mean , the energy for electrolysis? , there are other methods to do it like by solar energy getting concentrated into a spot by mirrors that heat the water and then we separe the gases by their properties.
  9. Nov 22, 2015 #8
    No, using solar energy to vapourise water will just result in water vapour, not Hydrogen.
    You need electricity to separate the Hydrogen from the Oxygen.
  10. Nov 22, 2015 #9
    Water can only be separated by electricity?
  11. Nov 22, 2015 #10
    Well there are chemical methods of splitting water into hydrogen and oxygen as well as electrolysis.
    However these also require the supply of energy in some form, and they are less efficient than simply using electricity.
  12. Nov 22, 2015 #11
    Thanks for helping me with my questions.
  13. Dec 6, 2015 #12


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    You can either use the electricity to make hydrogen and use that to power cars or put the electricity in a battery and use that to power a car. Important to consider which is more efficient?
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