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Limitless Green Energy?

  1. Jan 23, 2010 #1
    The Earth rotates in inertial space. The amount of rotational kinetic energy is enormous ... millions of mankind's annual consumption. Is there any kind of apparatus, perhaps one based on gyros, that could tap into this energy?
  2. jcsd
  3. Jan 25, 2010 #2
  4. Jan 25, 2010 #3
  5. Jan 25, 2010 #4
    I don't this can work at all. To use the kinetic energy of the earth we must slow it down, and that can only be done by transferring the angular momentum of the earth to something else (the moon for tidal energy).
  6. Jan 27, 2010 #5
    Gyros? Well, the energy required to sustain their action exceeds the energy able to be extracted from this or any other arrangement.
  7. Jan 27, 2010 #6


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    From an engineering perspective, I think it would be rather difficult to get the other portion of the contraption to stand still (i.e. you have to have something that's not rotating with the Earth to take advantage of the Earth's rotation). Good luck with that!


    I hadn't considered Foucault. Neat idea.
  8. Jan 27, 2010 #7


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    Anyway, if you change the period of rotation of the Earth, many species wouldn't adapt and die.
  9. Jan 27, 2010 #8


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    Well, I wouldn't deny that's true for a significant change in the period. But at what point do we consider it significant?
  10. Jan 27, 2010 #9
    What about conservation of angular momentum?

    Try tidal power.
  11. Jan 27, 2010 #10


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    Another good one! This one is already being used too! There's several different engineering approaches to it.
  12. Jan 28, 2010 #11
    Don't imagine that there would be any significant change in the period of rotation if you consider the mass of the Earth.
    It might actualy be speeding up at present due to the amount of hydro electric scheems in the northern hemisphere.
    I imagine any slowing would be counteracted by rainfall, by angular momentum when it falls or dams.
  13. Jan 28, 2010 #12


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    ...anyone going to attempt to quantify the issue...?
  14. Jan 28, 2010 #13
    If you do not use the moon in some way, the energy you can gain is exactly zero, since there's no way to reduce the angular momentum of the earth.
  15. Jan 28, 2010 #14
    How's that? doesn't driving a car give angular acceleration the the earth?
  16. Jan 29, 2010 #15
    And it takes it away again as soon as you stand still again. The angular momentum of the earth with the car remains the same.
  17. Jan 29, 2010 #16


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    As the Earth rotates, the tidal bulge follows a bit behind the Earth-Sun line (neglecting the moon) and so there is a tidal torque on the Earth reducing its rotational angular momentum and converting some of that to orbital angular momentum. You can alter the angular momentum of the Earth but not of the Earth-Sun or Earth-Sun-Moon system except by exterior effects (e.g. Jupiter).

    As mentioned tapping tidal energy is tapping the rotational kinetic energy of the Earth. Tapping tidal energy would imperceptibly but quantifiably increase the lag of the tidal bulge, increasing the rate of tidal slowing of the Earth's rotation.
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