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Buoyancy and Energy Conservation

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tszaboo:

--- Quote from: NiHaoMike on May 20, 2020, 07:13:38 pm ---I think that if the practicality problems were somehow overcome, the limiting factor is the finite (even if very large) amount of hydrogen available to run the process with. Hence it would not be perpetual motion any more than tidal power is perpetual motion.

--- Quote from: Zero999 on May 20, 2020, 12:19:20 pm ---Underwater is a good example. Imagine the balloon is deflated and underwater. The deeper it is, the more pressure and thus work will be required to displace the same volume of water, so lift the same mass.

--- End quote ---
Underwater, a volume of gas can lift far more weight than it can in air, thus increasing the energy that can be extracted from lift. So electrolyze water deep in the ocean to lift bags that power a generator. Or actually, forget the bags and just have a pipe to the surface, using the pressure of the water to pressurize the gas. Something doesn't seem right since you could burn the hydrogen after using the pressure, getting back water to allow the process to not use up anything.

--- End quote ---
What makes you think, that it requires the same amount of energy to do electrolysis at high pressure than at 1 bar?

Zero999:

--- Quote from: NANDBlog on May 21, 2020, 09:02:02 am ---
--- Quote from: NiHaoMike on May 20, 2020, 07:13:38 pm ---I think that if the practicality problems were somehow overcome, the limiting factor is the finite (even if very large) amount of hydrogen available to run the process with. Hence it would not be perpetual motion any more than tidal power is perpetual motion.

--- Quote from: Zero999 on May 20, 2020, 12:19:20 pm ---Underwater is a good example. Imagine the balloon is deflated and underwater. The deeper it is, the more pressure and thus work will be required to displace the same volume of water, so lift the same mass.

--- End quote ---
Underwater, a volume of gas can lift far more weight than it can in air, thus increasing the energy that can be extracted from lift. So electrolyze water deep in the ocean to lift bags that power a generator. Or actually, forget the bags and just have a pipe to the surface, using the pressure of the water to pressurize the gas. Something doesn't seem right since you could burn the hydrogen after using the pressure, getting back water to allow the process to not use up anything.

--- End quote ---
What makes you think, that it requires the same amount of energy to do electrolysis at high pressure than at 1 bar?

--- End quote ---
It depends on what you mean by the same amount?

The higher the water pressure, the more work will be required to displace the same volume of water. If the pressure is higher, then more moles of hydrogen and oxygen will need to be produced, to displace the same volume of water. Another issue is, more of the oxygen and hydrogen produced will simply disolve in the water, rather than emerging as gasses.

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