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Information about the Laws of Energy

  1. Sep 18, 2005 #1
    I have been trying to work out some information about the Laws of Energy and have come to a stand still. For example if you take a molecule of water, it contains a finite amount of energy, e.g. you can't produce energy out of nothing (according to the laws of energy), so if it takes so much energy required to split the water, you get the same amount of energy back by combining the hydrogen and oxygen to make water. So how does pressure effect the rate at which water can be split? If you had a litre of water in a 1.5 litre air tight pressured container with electrodes and started splitting the water at what point would the pressure in the container be too much for the water to be split? Or does pressure not have an effect on the rate and energy required to split water?

    Secondly if you allowed the hydrogen and oxygen to float freely up to a fuel cell above, when the fuel cell combines the hydrogen and oxygen back into water it also creates electricity and heat (The same amount of energy that is required to split the oxygen and hydrogen in the first place) but with that water now sitting above the electrolyzers below, you could in turn send the water back down a tube to where the electrolyzers are and have it spin a turbine on the way down, in thoery meaning you get energy from gravity's effect on molecules. So when people say that there is limited energy in everything, how does it take into consideration gravity's effect on matter and things like kinetic or potential? Because the water falling down is gravity causing the water to generate kinetic energy. So in theory it is possible to create a device that uses the same matter to generate excess energy as a result of gravity?

    So if there is a limited amount of pressure you can create in a container before it effects the electrolysis process (Amount of energy required to produce the hydrogen and oxygen) is that pressure going to be enough to spin a turbine (Similar to using a compressed air canister to spin a turbine).

    I want to test this theory out, but fuel cells are expensive, so was hoping someone with a physics back ground could provide me with some feedback.
  2. jcsd
  3. Sep 18, 2005 #2


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    Staff: Mentor

    1. Pressure is essentially a form of energy, so yes, it has an effect.

    2. Conservation works for gravity too. If pressure pushes the hydrogen and oxygen up, that's doing work against gravity - then gravity pulls the water down, that's getting the energy back. No net gain.

    No need to test your idea - its a perpetual motion machine and it doesn't work because of the 1st law of thermodynamics. You just need to broaden your understanding of the 1st law: find where the energy you think you are gaining is really coming from.

    edit: also, neither fuel cells nor electrolysys are 100% efficient, so you also lose energy due to the 2nd law of thermodynamics, in the form of waste heat.
  4. Sep 18, 2005 #3


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    energy of conservation is practically holy in the wolrd of science. Don't ever try to sell a perpetual motion machine to a physicist. It's about where you get your input energy from, and how you transfer it to useful output energy.

    if you get your input energy from natural forces, then you don't have to come up with the input energy, you just have to capture it. The laws of thermodynamics, however, aren't broken, because one system (like the wind or the sun) is giving up energy to power your system. No energy is created or destroyed, you're just drawing a tiny bit of power off of a huge (but hard to capture) power source.

    Gravity only pulls down, so you have to move things back up so that they can be worked on by gravity (pulled down) to generate energy again. Moving something back up costs energy. If you want to generate energy by throwing rocks off of a mountain, you're slowly spending the energy that tectonic plates created by pushing the ground farther away from the earth (forming the mountain). The only reason they gained energy in this aspect is because they moved farther away from the earth.

    However, it will cost you more energy to make a conversion from solar or wind power to electrical or mechanical power. This comes from the the law of entropy (a themordynamic law) which is proven to show approximately how much energy is lost every time you convert or redirect energy.
  5. Sep 18, 2005 #4
    I think what he is asking is if electrolysis of water at 10 ft costs the same amount of energy as 10k ft below water, and if so then the spinning of tumblers on the bubbles way up must create more energy given there is a greater distance for that bubble to travel much like the falling of a rock it has greater potential energy and greater heights, and if so then it's comming from gravity, and if so how so? I don't believe in energy for nothing either but I do guess that this device is capable of generating more energy than is seemingly(for reasons I don't understand) put into it-yet not economical practical. If there is no manipulation of gravity on some unknown scale here then electrolysis of water at greater depths should cost more energy instead of the same, I don't know wether it does or doesn't.
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