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Can Water be used as fuel?

  1. Mar 23, 2004 #1
    I am curious about whether water could be used as fuel. Water is H2O right. So if water is two molecules of hydrogen and one molecule of oxygen can thus hydrogen be used as a propulsion fuel and oxygen a burning agent?
  2. jcsd
  3. Mar 23, 2004 #2


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    No. Water is, in essence, hydrogen ash; it is what you get when you burn hydrogen.

    To re-burn the hydrogen, you would have to separate it from the oxygen, and this would take more energy than you would get from burning the hydrogen. So you would end up losing energy in the process.
  4. Mar 24, 2004 #3
    This isn't the same thing as using water for fuel, but I read a guy claim that the hottest possible fire could be obtained by letting oil and water drip onto a preheated metal plate.

    His setup was to start a normal wood fire, place the metal plate over it, and let the oil and water drip onto the plate from containers to the side of the fire in a ratio of three drops of water to one drop of oil. The oil was used motor oil.

    I think the reason this fire was so hot was because the water dissociated (both because of the heat on the metal plate and the heat of the oil burning) the O2 released probably went right to the combustion of the oil, and the H2 probably joined up with atmospheric O2.
  5. Mar 24, 2004 #4
    Water can't be used as fuel, but keep it away from cesium!
  6. Mar 24, 2004 #5
    In egypt it can be used as a fuel, if you mix it with a highly thermo-conducting substance, like a black one, and a heat changer. pretty simple really.

    The heat changer is an aluminium cone (or parabole) filled with carbon concentrating the light into a beem (partly making it more frequent) and sending it away, thereby cooling the water.

    the aluminium parabole can be turned around to heat the water carbon mixture.

    Ofcourse there are other ways of solving this problem. Just change the shape of the parabole.
    Last edited: Mar 25, 2004
  7. Mar 24, 2004 #6
    Sariaht, more details, please.
  8. Mar 24, 2004 #7
    I finished my post. The method is superior due of it's closed cylinder system. It don't have to be open since you can regulate it's heat. One could even drink the water when the vehicle is finished.
  9. Mar 24, 2004 #8
    Sariaht, what do you think "fuel" means? Is this device supposed to face the sun at all times?

    *update* I looked up the word "fuel" in a dictionary. It means anything that can be used to produce energy. So, Sariaht is right. The device that he describes, what I think is called a solar collector, does use water to produce energy.

    I was thinking in terms of chemistry. A chemical fuel, is a chemical, which when combined with oxygen or some other oxidizer, produces energy.

    If you combine water with sodium, cesium, lithium, potassium, or rubidium, you do produce energy. However, these latter elements are not oxidizers. Take your pick. Water is or is not fuel.
    Last edited: Mar 24, 2004
  10. Mar 24, 2004 #9


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    No, as the name implies, a "collector" doesn't produce energy, it collects energy.
  11. Mar 24, 2004 #10
    No, the water acts as energy transfer or storage. All the energy in this device come from the sun, and none from the water.
  12. Mar 24, 2004 #11
    Semantics strikes again.

    Energy is energy, agreed. However, it exists in various forms. Often we want energy in one form PRODUCED from energy in another form. E.g. solar energy ==> heat (hot water e.g). Chemical energy ==> motive energy (moving car). Atomic energy ==> electricity.

    Ultimately energy production is simply conversion of one form of energy to another. Granted, we often collect energy and often store it, but even so we may need to convert from one form to another. Chemical energy in gasoline ==> roto-motive energy ==> electricity ==> chemical energy in battery.
  13. Mar 24, 2004 #12
    The reason water isn't a fuel in this case is because, when everything is over, the water is whole, complete, and the same. It has lost nothing. The fuel, here, are the sun's elements, which have lost mass, and are changed.
  14. Mar 24, 2004 #13
    I now think the dictionary definiton is a poor one. One reason is that what we really want from all the energy conversion is power, ultimately, energy doing something. Another reason is that it is too broad; it fails to exclude the solar collector and the battery, as it should. What, then, shall we use as the definition of fuel? Let us not be fuelish [sorry].
  15. Mar 24, 2004 #14
    My dictionary defines fuel as: a material that can be used to produce heat or power by burning;;a material from which atomic energy can be liberated esp. in a reactor

    I think it is safe to say that what is going on in the sun could be comprised by the second definition.

    You just need a more comprehensive dictionary. This is a really good online dictionary that will instantly get you the definitions from several different dictionaries so you can compare and contrast:

    OneLook Dictionary Search

  16. Mar 27, 2004 #15
    What of the potential for water (well, the deuterium and tritium in the water) to be used as a fuel source for fusion? What % is D and what % is T and how easy is it to get D and T out of H2O?
  17. Mar 27, 2004 #16
    Dorje, turning water into fuel is not the same as using it as fuel. Your questions are off topic. I will now leave your questions to someone else, if anyone can and want to answer them.
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