Xelasnave.1947
Valued Senior Member
Could have been..my spell checker likes playing tricks.
Alex
Pressure Harvesting - from ocean depths
- Thread starter Quantum Quack
- Start date
Alex
Write4U
Valued Senior Member
Keeping it simple.
800 meters of ocean water pressure ----> valve----> generator ----> empty tank.
Which way do you think the water will flow? Look at the illustration. Big downward pointing arrow = pressure
Neddy Bate
Valued Senior Member
When I was young, I tried to swim to the bottom of a deep pool while carrying one end of a garden hose. The other end stayed above the surface of the water, open to the atmosphere. I was wondering if I could inhale air through the hose while under water, and thereby stay under water for as long as I wanted to.
The first thing I noticed was that, in order to prevent the hose from filling with water, I had to hold my thumb over the end while I swam down. This made it harder than usual to swim to the bottom, because all of the hose that was under the surface was full of air, and therefore buoyant. So, the farther down I went, the harder it was to pull the hose with me as I swam down.
Once I got to the bottom, I put the hose to my mouth, and the next thing I noticed was that I could not inhale any air from it, because my lungs were not strong enough to apply the suction (negative pressure) pressure needed to bring any more air down to where I was. It was like there was a vacuum over my mouth, trying to suck the air out of my lungs. I quickly realised that my lungs would have to provide as much negative pressure as the water was exerting on my body at that depth, just to get any air moving.
I could have exhaled what little air I had in my lungs into the hose, and that one breath could have pressurized a small balloon over the other end of the hose. But after all of the effort to swim down there carrying the hose, it would have been much more efficient for me to just stay out of the pool and do that.
This is exactly the same problem that occurs with QQ and W4U's vague idea of harvesting pressure from the bottom of the ocean. If all of the laws of physics are not enough to convince them, I suggest that they try my idea themselves.
The first thing I noticed was that, in order to prevent the hose from filling with water, I had to hold my thumb over the end while I swam down. This made it harder than usual to swim to the bottom, because all of the hose that was under the surface was full of air, and therefore buoyant. So, the farther down I went, the harder it was to pull the hose with me as I swam down.
Once I got to the bottom, I put the hose to my mouth, and the next thing I noticed was that I could not inhale any air from it, because my lungs were not strong enough to apply the suction (negative pressure) pressure needed to bring any more air down to where I was. It was like there was a vacuum over my mouth, trying to suck the air out of my lungs. I quickly realised that my lungs would have to provide as much negative pressure as the water was exerting on my body at that depth, just to get any air moving.
I could have exhaled what little air I had in my lungs into the hose, and that one breath could have pressurized a small balloon over the other end of the hose. But after all of the effort to swim down there carrying the hose, it would have been much more efficient for me to just stay out of the pool and do that.
This is exactly the same problem that occurs with QQ and W4U's vague idea of harvesting pressure from the bottom of the ocean. If all of the laws of physics are not enough to convince them, I suggest that they try my idea themselves.
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Yep. There's no free lunch, no matter how hard you try to bend the rules.
Xelasnave.1947
Valued Senior Member
How about you try to understand the idea before you criticize it?
Say you take a big breath and you swim down to the bottom of the pool (say 10 feet). You then push all that pressurized air in your lungs into a storage tank that stays at the bottom of the pool.
You then swim back up and repeat the exercise as many times as you like.
You then port the compressed air in the tank to the surface.
Compare pressures:
your lungs at atmospheric pressure and the pressure from the tank...( 10 feet deep pressure )
once you understand the basic concept of allowing the pool water to pressurize the air then review the more detailed version.
I must admit I did try this as a teen myself using an extended snorkle ...Not a good thing to do. can do major damage to your lungs.. as all the air in your lungs is rapidly expelled under pressure.
Just shows you though how much pressure (potential energy) exists in a large volume of water.
you obviously do not understand how the weight of the vessel and the weight of the ocean can compress air inside the vessel.
In fact the laws of physics demand it...
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Xelasnave.1947
Valued Senior Member
I am not sure but I think others have pointed out that energy is required to get your potential energy to the surface.
Alexander
Compressed air via a rigid tube to the surface is pushed by the compressed air....
btw the two posters that actually know what they are talking about do not dispute this factor...perhaps you should have a read of them...
If you wish to believe ignornant posters go for it... but perhaps it would be best to work it out for your self.
Drop a loaded fire extinguisher into a deep pool and vent it to the atmosphere using a hose. What do you think would happen?
Atm pressure is about 14psi
Chem Fire extinguisher average 175psi
So,
average 175psi vs 14psi ...who wins?
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just to help
say you drop a rigid vessel that has only atmospheric pressure in it down to 1000 meters.
Attached to this vessel is a turbine generator that operates when you open the vessel to the flow of ambient pressurized water.
The turbine generator will spin for as long as the water is flowing in to the vessel to equalize pressures.
To maximize the output you would vent any compressed air to the surface as the vessel filled.
net outcome
Electrical energy and high pressure air - at the surface.
But you can only do this once unless you spend energy removing all that water that is now inside the tank.
Just because it will cost energy to empty the tank to repeat the cycle doesn't invalidate the principle involved.
Economics is really another aspect when working out viability.
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Xelasnave.1947
Valued Senior Member
I have thought about it, at length, as the proposition is interesting.
I certainly have had similar ideas, and by that I mean ideas that seem viable but finally I run into the fact that these things usually meet physics that kills the idea.
And perhaps remember no matter what one presents those around will look first as why to why it can not work and it is sensible to address their concerns.
But I assure you I look at how it can be made to work but unfortunately so far I can not imagine any mechanism that allows one to harvest the pressure such that the energy output is greater than the input.
But don't worry the quest for fusion energy did not let that halt research. But I think fusion energy will be with us before you make your idea work. Maybe that's it..use the pressure to contribute conditions for fusion?
As I pointed out there is pressure at sea level, which although not as great, should be sufficient to establish viability.
There is pressure in a swimming pool sufficient to establish that your device will work or not.
I suggest your first step would be to make a proto type and test it in say a swimming pool.
I wish you well but to take it further you really need a proto type that can show a result.
A working model is the only way to show those who say it won't work that you have beaten their concerns.
Alex
how so?
there is a pressure differential between the compressed air and atmospheric pressure...
How do you think the water pressure stops the pressurized air from going to the surface by a pipe or tube?
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For me now it is not a matter of whether the oceans depths potential energy can be exploited or not, it is now only a question of energy economics. Is it worth it? And is it better than other green systems?
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Still no free lunch. You can do all sorts of tricks to get compressed air. None of them will give you compressed air without a steady input of even more energy.
nonsense!
Perhaps you don't know what a variable volume pressure vessel is?
I know it very well. Again, no free lunch. You gotta pay your dues if you wanna . . . get compressed air from the seafloor.
Xelasnave.1947
Valued Senior Member
Get a balloon fill it with air.
Measure its diameter at the surface and again at say 6feet under. You will notice the two measurements will differ...the measurement at the surface being greater than the measurement at 6 ft under..the difference is due to pressure...the pressure is from the 6 ft of water
Even in the open air we are subject to pressure, we don't feel it but it is considerable...think a mercury barometer...the air pressure holds up 30 inches of mercury in a tube or 28 feet of water...think about the pressure around you that you can use to prove your concept..or not.
What you should look into is how in earlier times one could create a vacuum from "dripping" mercury...interesting if nothing else...but there is a point where the dripping mercury resists the air pressure slightly such that it can create a vacuum..but still there is change..you have to do work to lift the mercury...
If you want to harvest energy look into harvesting energy from lightning ... I spent a lot of time on that one...but at least you deal with "change" and you need that to have any hope of harvesting energy..look at gravity...water down a hill ...simple all you need is water at the top of a hill...perhaps the first example of humans harvesting energy.
But think of this..if the water runs out you have to carry (work energy) water back up the hill.
Coal and gas you are harvesting the energy of the Sun finally. And if we get fusion we can say nuclear is solar.
But harvesting energy is like making (or lossing money) on the stock exchange...there has to be change. You can't canwin Youor lose unless prices go up or down..change.... harvest energy from the tidal change, or from the waves (change in height and thus gravity potential) or from wind ( horizontal air pressure change) but it all involves "free" change. To harvest pressure you need a "change" I feel.
Here is an idea.
Get a bucket with a tube to the surface..take it down six feet in a pool and see how hard that is..hard work means energy..see what air flow you get..you can convert air flow to electricity via a simple computer fan wired appropriately to become a generator of electricity...put a metre on the circuit see what you produce.
My father cursed me when I was 11 telling me there could be no perpetual motion. My life quest was to prove him wrong..I invented the electric motor at 11.. but at 11 I could conclude wear and year would prevent it being perpetual well before I conceeded that the motor needed energy..one needs electro magnets you see..my first version was to use only permanent magnets which exposed me to the problem you face but I feel can not comprehend.
As I said a proto type that works in a pool can establish the concept so start there.
Alex
Xelasnave.1947
Valued Senior Member
By rejection you cut off valid input. A wise man would ask well how can we get around the problems you perceive.
Alex
unless the rejection is explained it is simply rejection with out explanation therefore nonsense...
You at least are attempting to explain your rejection.
You use a balloon for example but fail to see why it is not relevant.
I explain why it is irrelevant and you go on using your balloon as a reason for rejection.
So nonsense it is...
The balloon is expanded by atmospheric air pressure and little more pressure, care of the human.
You tie it to a brick and sink it in 10 feet of water.
The volume of the balloon shrinks in size and the air pressure inside the balloon increases and matches the ambient water pressure.
The weight of the brick and pool water is pressurizing the balloon.
are you with me so far?
any questions?
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