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Indefinite hydrolysis?

  1. Oct 11, 2011 #1
    Is it possible to have a tank of water, run electricity through it, collect the hydrogen and oxygen, use it as fuel to heat the same tank of water into steam, use the steam to spin a turbine generating electricity to run through the water once more to create more hydrogen and oxygen to use as fuel once again and run this process indefinitely? (Granted I provide a constant source of water)

    Or would this combustion of hydrogen and oxygen not be sufficient enough to create enough steam to create enough electricity to create enough hydrogen and oxygen?
  2. jcsd
  3. Oct 11, 2011 #2


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    Staff: Mentor

    Welcome to the PF.

    Each of those steps is not 100% efficient, so energy is lost (as waste heat for one thing) at each step. So it cannot run indefinetly.

    This area of discussion is known as Perpetual Motion Machines (PMMs) or Free Energy. Here are some links to previous discussions here at the PF to help you understand why they cannot work. The links are from the Forbidden Topics section of the PF Rules link at the top of the page.

  4. Oct 11, 2011 #3


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    Staff: Mentor

    Let me try it with the other law of thermodynamics:

    Even if every process were 100% efficient, all you could do is sustain the device. You'd never be able to extract any energy from it.
  5. Oct 11, 2011 #4
    for sure.
  6. Oct 11, 2011 #5
    You could do it by combining some of the hydrogen and/or oxygen with an additional reactant, if that reaction produced more energy than needed for hydrolysis (plus the inefficiencies in the system). That would not be perpetual motion, it would just be burning fuel. You would have to keep supplying the reactant along with the water, and the product of the second reaction would be waste.
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