deep ocean pressure question

[lostowl]

i was pondering tapping the pressure under the ocean and doing research like 2 months ago i came across this guys website and sent him a email asking why it wouldn't work but he never replied maybe never checks website anymore but here is his article

http://www.lhup.edu/~dsimanek/museum/osmosis.htm

and i asked him to please explain to me why if extending the pipe lower and lower to finally get it to work that if they took one of them seashell looking things that channel the water in turbines to multiply the force and flipped it upside down so the pressure crushed up into the seashell and was multiplied up the pipe

if anyone can please explain to me why this wouldn't work i would greatly appreciate it

also without the water filter so it is all salt water pushing a turbine on top or just under the ocean

thank you for you're time

[Shadesz]

water pressure is caused by the weight of the top water molecule pushing down on the molecule below it which pushes down on the next molecule with a weight of its own... and on and on and on...

Think 1 is the top molecule 10 is the bottom, and c is the weight of a water molecule...

Weight from top molecule = c
Weight from top and second molecule = c + c
Weight at third molecule = c + c + c
4th = c + c + c + c
5th = c + c + c + c + c
...
10 = c + c + c + c + c + c + c + c + c + c

So regardless of whether you are in an open ocean or in a pipe within that ocean if you go down so deep, the molecules above you will be pushing down with the same combined force of weight.

So, no there is no way to do this the way you describe. His method is interesting. I'll share some numbers in a second that may explain why it is not feasible.

[Shadesz]

Now to discuss the idea he mentions in that article...

For this calculation we need to compare the density of the water in each pipe (fresh water pipe, and salt water pipe). We will assume that the temperature of water in each pipe is equal so we do not have to worry about it affecting density.

His idea is that salt water is more dense than fresh water... meaning it weighs more per gallon for example. So, if you take a long pipe with salt water and measure the pressure at the bottom it will be greater than the same length of pipe filled with fresh water. If this pressure difference is great enough to push water through a semi-permeable membrane (a reverse osmosis filter) then the salt water side will push itself to the fresh water side... but without the salt getting through. Hence the fresh water side has more water which then overfills into the saltwater side and dissolves the salt. And the process continues.

If we assume this is possible, how long of a pipe will we need? Well we need a long enough pipe so that the pressure difference between fresh and salt water is great enough to push through a semi-permeable membrane.

It requires roughly 800 pounds per square inch of pressure (22,140 grams per square centimeter) to push ocean water through a reverse osmosis filter. Hence we need a weight difference of that amount to get the system to start working without considering friction.
QUESTIONS AND ANSWERS ABOUT REVERSE OSMOSIS, WATER PURIFICATION AND FILTRATION

So how long (deep) does our pipe need to be for this to work? Well... a ml of fresh water weighs about 1.0 grams and a ml of ocean water weighs about 1.025 grams. Seawater - Wikipedia, the free encyclopedia

That means that there is a difference of 0.025 grams per milliliter (aka cubic centimeter). So now if we take the total required pressure difference of 22,140 grams and divide it by the weight difference per cubic centimeter we find that we need...

22,140 / .025 = 885,600 cubic centimeters stacked on top of each other.

This means that our pipe needs to be 885,600 centimeters long.. or 8856 meters... or 29,055 feet or...
5.5 miles deep!

The average depth of the ocean is about 2.7 miles. So most of the ocean isn't even deep enough.

If you think about it, we have a hard enough time building submarines that can go 1/7th of the required depth. So there is not way that we could build a system at that depth.

Then think about friction as the water moves inside the pipe--- you also have to up the required PSI (at least double I'm guessing) as soon as you try to generate any sort of power from it and the idea is even less feasible. You would probably have to go down at least 13 miles (the deepest part of the ocean isn't even that deep.

Then realize that this whole system assumes that the salt in the one side immediately diffuses... which on a pipe that long at those low temperatures... it wouldn't diffuse hardly at all.

So even if you could build it, and build it deep enough, it wouldn't work because the salt wouldn't "dissolve" quickly enough into the fresh water that spilled over and the system would be so slow you probably wouldn't get more than a trickle.

It's a fun idea that theoretically could work... once you think about it economically and practically, it becomes a cool idea but a bad plan.

I hope this helps.

Edit: I just realized that you don't need a down pipe all you need is an input at that depth and then dump the fresh water back into the ocean. Still though, even if we can get more than a trickle... it is still unrealistic.

[lostowl]

thank you for your time i understand more but i still dont understand why we can't multiply the pressure

say if i put a solid pipe in the water to a certain depth so there is no water molecule stack above them. would the water under the solid pipe still have the same pressure as the water the same depth not under the solid pipe?

and if it does have the same pressure then i dont understand how if i made a pipe small enough for 1 molecule stack to fit through it with a funnel at the bottom that opened to a 50 molecule circumference why wouldn't it push the 1 molecule stack up the pipe

thank you for you're time

[aljhoa]

How do you create pressure differential and for how long?

Bobbling gases inside a pipe can change density of the ocean water.
High-pressure electrolysis - Wikipedia, the free encyclopedia

Al

[lostowl]

thank you was an interesting read but it takes electricity

im trying to tap deep ocean pressure to push a turbine i'm not even worried about making fresh water.i just trying to understand why an upside down funnel with 50x the pipe end wont push the 1x up the pipe. in my mind it has to work and im not stupid i have a 132 mechanical iq so i am reaching out for someone to explain to me why the mechanical advantage wont work here so i can stop obsessing over it.

thank you for you're time

**edit** i picture this as a very long pipe with a short funnel that widens quickly or a shell funnel from dams

[Joit]

Hi Lowstowl.

Gravity. The Water is not able to lift other Water above its highest Level. Gravity is the cause for the Pressure in the Deep, but the Attraction is only in one Direction.
The amount from the Water defines the upper Level and the Borders around it, of course.
We had a similar Discussion about it already where you can compare it with a water level Gauge

http://www.energeticforum.com/renewable-energy/9958-short-video-perpetual-motion-machines.html

Else you may would need to place a stone slap into the big Funnel, and because of the higher weight, it presses the Water out from the Pipe.

Edit- or the upper Border at sea level, and when a Wave goes over it, and fills the Tube with Water, then the Water in the Tube is higher then the Sealevel and trys to spit it out through the smaller Pipe.

[aljhoa]

thank you was an interesting read but it takes electricity

im trying to tap deep ocean pressure to push a turbine i'm not even worried about making fresh water.i just trying to understand why an upside down funnel with 50x the pipe end wont push the 1x up the pipe. in my mind it has to work and im not stupid i have a 132 mechanical iq so i am reaching out for someone to explain to me why the mechanical advantage wont work here so i can stop obsessing over it.

thank you for you're time

**edit** i picture this as a very long pipe with a short funnel that widens quickly or a shell funnel from dams

Does a diver at constant depth feel water pressure?
Is a chimney producing updraft in stagnant air?
Electricity can come from number of free energy devices even from your turbine if you can create pressure differential e.g. bubbling gasses.

Al

[Shadesz]

say if i put a solid pipe in the water to a certain depth so there is no water molecule stack above them. would the water under the solid pipe still have the same pressure as the water the same depth not under the solid pipe?

and if it does have the same pressure then i dont understand how if i made a pipe small enough for 1 molecule stack to fit through it with a funnel at the bottom that opened to a 50 molecule circumference why wouldn't it push the 1 molecule stack up the pipe

thank you for you're time

if the pipe is full of air and you pushed it down deep in the water, yes the water would push up the pipe. One problem is that it would take and INSANE amount of energy to push a hollow pipe that deep. The other problem is even if the inside of the pipe is only 1 molecule wide as soon as the water pushes up to be equal with the water on the outside, the pressures will be equal and you will get no more movement, even if the open had a big catch funnel.

That's a good mechanical iq, now just work on your physics and chemistry knowledge.

[lostowl]

wouldn't need a stone slab

i picture the ocean in layers going down and each layer is more compressed then the other. so if we draw imaginary line 1.5 miles down or whatever and ignore everything above the line because its like one big stone slab crushing down on the layer.

why cant we pipe down to this level and the "funnel" would "umbrella" enough area from the pressure of upper layers "stoneslab" allowing the pressure of the layer to escape up the narrow pipe?

[aljhoa]

Does a diver at constant depth feel water pressure?
Is a chimney producing updraft in stagnant air?
Electricity can come from number of free energy devices even from your turbine if you can create pressure differential e.g. bubbling gasses.

What are the answers?
Al

[lostowl]

Does a diver at constant depth feel water pressure?
Is a chimney producing updraft in stagnant air?
Electricity can come from number of free energy devices even from your turbine if you can create pressure differential e.g. bubbling gasses.

Al

yea the driver feels pressure i would imagine thats why they have pressurized suits

and as for the chimney i would imagine it would mainly depend on the temperature inside and outside of the building amongst other factors.

[aljhoa]

yea the driver feels pressure i would imagine thats why they have pressurized suits

and as for the chimney i would imagine it would mainly depend on the temperature inside and outside of the building amongst other factors.

Divers do not feel the great pressure because the tissues of the human organism contain 65% of liquids that practically do not shrink. In inner cavities, the pressure of the inhaled air counteracts the external pressure. During descent, divers usually do not feel the increasing pressure.
The Physics of Diving: Pressure and Buoyancy

Liquid Breathing Interview with Thomas Shaffer - YouTube

Mouse breathing water - YouTube

Chimney is the analogy to your project, in stagnant and constant temperature air there is no pressure differential i.e. no updraft.

Al

[yaro1776]

Original Question

Hey Lostowl,

The original website from simaneksmosis explains all the details and answers all your questions very thoroughly from a technical standpoint. Other posters have taken your mission to heart and offered their well reasoned answers. Yes, it is very difficult to get one's head around all the concepts - however that is your challenge. This puzzle presents you with a unique learning opportunity to expand your intellectual horizons that will allow you to truly understand the concepts involved and then to go forward from there.

There is no free ride in training one's intellect - only hard work.

Basic hydraulic explanations are available from many sources - use them to your benefit. Check the Google gods... Bernoulli!

Use this site to further your knowledge in the puzzles that interest you - experiment! and keep up your questioning nature. Bon chance!

[lostowl]

hihihihi yaro

i posted this guys website earlier and his explanation seems to say if the ocean was deep enough you could make a pipe long enough for it to work but it wouldn't be cost effective.

i just dont understand if the pipe will work if it was like 10x longer why we cant just funnel the end out to 10x the size and get the same effect. but im thinking 50x to get same effect because the layer has less pressure

also when he breaks it down to two columns of water i don't think this is a good way to describe it because the compressed molecules are pushing back in every direction so i believe if i can shelter enough area from the downward pressure above and channel it that it should naturally create a lower pressure for the molecules to push in from every direction