Pressure Harvesting - from ocean depths

[Quantum Quack]

You can't you are driven by an unfortunate ego that closes all comprehension of the motivation that drives a simple man.
Alex

I'll see what the site moderators have to say before I respond to you any further. Sorry about that...

 

[Xelasnave.1947]

I'll see what the site moderators have to say before I respond to you any further. Sorry about that...

Tell the teacher.. great..anything to avoid doing the decent thing. No apology. You define your position clearly. You have wronged me and two others yet you will not, can not apologise.
You reject physics on a science site so do your best and suffer the consequences.
Your only hope is to apologise to those people your casually insulted with terrible allegations.
They won't go away.
Appologise.
Alex

 

[Write4U]

One of the reasons I started this thread with the title as I did is because Google will pick up on it.
Google "pressure harvesting from ocean depths". (Page 1 item 2)
Renewable energies as you know are all the rage at the moment and should draw some new members or at least viewers to sciforums. Guess you might end up famous... lol

Yes QQ, this is what I have been discussing all this time. The problem is that you (and others) are interpreting the article incorrectly, most likely due to a translation problem from German to English. I'm Dutch, sitting in between and have drawn attention to the translation errors.

The error lies in the assumption that the tanks are used as the "head water" of the system and the ocean is the "tail water" of the system.

Tailwater
Tailwater refers to waters located immediately downstream from a hydraulic structure, such as a dam, spillway, bridge or culvert. Wikipedia

This introduces a fatal flaw in the description of the actual design.
In context of "high pressure energy harvesting" there is only one candidate that offers high pressure and that is the ocean itself. Therefore, the ocean is the head water and the tanks are the tail water. Once this principle is accepted the entire system becomes as clear as a bell.

I you read the published analysis of the illustrated system, you will find there is no mention of any air compression at all, anywhere. There is an "air vent" in order to avoid the creation of a vacuum while evacuating the water from the tanks, but this passive vent is not used to pressurize anything.

The process consists of a transfer of high pressure ocean water (the head water) to low pressure (empty) tail water tanks at a depth from between 400-800 meters, but IMO the system would work at just about any depth over 50 meters. It does for submarines. When a submarine "floods" its ballast tanks to dive it is in fact transferring water from a high pressure environment to a low pressure pressure reservoir (the ballast tank). We've all heard the cry "dive, dive, dive" when a submarine is ready to "flood" it's empty ballast tanks. This process does not require pumping . The sub's displacement is sufficient to surround the hull with high pressure water.

As I noted, if one places a generator in the path of the inrushing water, one could theoretically generate electricity until the ballast tanks are filled with water. But a submarine has no use for that purpose.

In the illustrated submarine electric generator system we have placed a generator in the path the flooding water which can generate electricity during the flooding of the tail water tanks.
When those tanks are filled with water, we can the reverse the turbine to pump out the water to restore a "low pressure" reservoir ready to be flooded again and generate electricity in the process. It becomes a cycle of "flooding the empty tanks and generating electricity, transmitted to the surface grid" and "pumping filled tanks until empty, using some electricity from the surface grid". The result is a net gain, due to the exploitation of a naturally existing "high pressure environment" and energy potential at the ocean bottom.

On dry land we use height and gravity to exploit a free energy potential to generate electricity from kinetic water energy.

The system does not use high pressure air to "blow" the water out of the tanks (like a submarine), it uses the reversible turbine to pump out the water (slow but energy efficient), in order to empty the ballast tanks from water and create a low pressure reservoir, ready to be flooded and generate electricity in the process of flooding the tanks.

That is the only difference between how a military submarine does it for speed and how this electricity generating system does it for efficiency and cost saving.

 

[Quantum Quack]

Yes QQ, this is what I have been discussing all this time. The problem is that you (and others) are interpreting the article incorrectly, most likely due to a translation problem from German to English. I'm Dutch, sitting in between and have drawn attention to the translation errors.

The error lies in the assumption that the tanks are used as the "head water" of the system and the ocean is the "tail water of the system.
But in context of "high pressure energy harvesting" there is only one candidate and that is the ocean itself. Therefore, the ocean is the head water and the tanks are the tail water. Once this principle is accepted the entire system becomes as clear as a bell.

I you read the published analysis of the illustrated system, you will find there is no mention of any air compression at all, anywhere. There is an "air vent" in order to avoid the creation of a vacuum while evacuating the water from the tanks, but this passive vent is not used to pressurize anything.

The process consists of a transfer of high pressure ocean water (the head water) to low pressure tanks (the tail water) at a depth from between 400-800 meters, but IMO the system would work at just about any depth over 50 meters. It does for submarines. When a submarine "floods" its ballast tanks to dive it is in fact transferring water from a high pressure environment to a low pressure pressure reservoir (the ballast tank). We've all heard the cry "dive, dive, dive" when a submarine is ready to "flood" it's empty ballast tanks. The sub's displacement is sufficient to surround the hull with high pressure water.

As I noted, if one places a generator in the path of the in rushing water, one can generate electricity until the ballast tanks are filled with water.

Have you discovered any other systems that exploit high density ocean pressures during your net searching?

In the illustrated submarine electric generator system we have placed a generator in the path the flooding water which can generate electricity during the flooding of the ballast tank. We can the reverse the turbine to pump out the water to create a "low pressure" reservoir ready to be flooded again and generate electricity in the process. It becomes a cycle of "flooding the empty tanks and generating electricity, transmitted to the surface grid" and "pumping filled tanks until empty, using some electricity from the surface grid". The result is a net gain, due to the exploitation of a naturally existing "high pressure environment" and energy potential at the ocean bottom.

On dry land we use height and gravity to exploit a free energy potential to generate electricity from kinetic water energy.

The system does not use high pressure air to "blow" the water out of the tanks (like a submarine), it uses the reversible turbine to pump out the water (slow but energy efficient), in order to empty the ballast tanks from water and create a low pressure reservoir, ready to be flooded and generate electricity in the process of flooding the tanks.

That is the only difference between how a military submarine does it for speed and how this electricity generating system does it for efficiency and cost saving.

Thanks for you post.
It is indeed a good candidate for deep ocean pressure exploitation. IMO.
However I do question it's declared efficiency but this is only an intuitive observation and not based on empirical evidence or math. Suffice to say if I had the skills I would probably do an energy cycle work out to find whether the 80% is founded or not. I guess I shall have to give them the benefit of the doubt as to this detail and as it appears to make perfect sense logically I am pretty happy about it all at this stage.

There is also one other thing that raises the eyebrow.
That is when I googled for other reasons I stumbled upon an article that claimed this system (using the very same image graphic) was by a Norwegian based research company and not German as has been suggested..To me this discrepancy is not so very important but I will go look for it again if you need it.

 

[Quantum Quack]

You fool.

Now you have to be trolling.

You know it is bewildering how people can get so upset when someone fails to agree with their position. They seem to take it as an insult and get angry and post stuff like the above.
The reason why the system I am suggesting as a contender for this thread doesn't breech the energy conservation laws is really simple but hard to see.
Yet I am being called a fool, a troll, and need to apologize for not agreeing with nonsense just because I am fortunate enough to see what others do not see.
There is no free ride in the system I propose and yes Potential energy can be extracted over and over again with out depletion of the oceans pressure because we add pressure to start with by way of displacement during every cycle...
The very same reason applies to Writ4u's candidate. When the tank is emptied the displacement increases and again it does not deplete the pressure of the ocean because it is added to start with every time it cycles.
Thus PE can be extracted with out cost to the ocean.
So perhaps before you label someone a fool or a troll because they genuinely disagree with you, you could seriously consider your own wisdom...or lack thereof.

 

[Quantum Quack]

Write4U,
Have you discovered any other candidates for this thread in your net searching?
I haven't found any others that produce usable energy, although I must admit I haven't been that thorough...

 

[Write4U]

Write4U,
Have you discovered any other candidates for this thread in your net searching?
I haven't found any others that produce usable energy, although I must admit I haven't been that thorough...

Not in-depth..... (pun intended).
This system seems so elegantly simple and with a somewhat similar functional military history that I cannot imagine a more efficient way of using ocean water pressure, except for "tidal pressure", which actually does provide a completely free reversible electricity generation potential both ways, without any pumping required at all . There is a natural 6 hour turn around of kinetic energy provided by the ocean's tidal function.

But that requires specific tidal areas which are not abundant, whereas the submarine electric generator system is basically useable everywhere where there is a marginally deep bottom with sufficient water pressure to produce a functional kinetic force from high pressure to low pressure.

The fundamental trick is to construct an efficient functional system that uses the kinetic force of flowing water to drive an electric generator.

Theoretically this could be used for generating electricity from 12V DC to 240 volts AC, just like a home generator that uses a gasoline engine or windmill to drive the generator on the surface.

There is lot of flowing water, which we use, but there is also deep water pressure which is rarely used commercially.

 

[Write4U]

From the original link;

But aside from the river sized opportunity, smaller scale is ripe with opportunity too. A portable turbine model is estimated to cost around $2000. The canal-sized turbine, which will have two sizes, ranging from 2 kW to 10 kW, would cost $20,000 and $40,000. Price of the waterfall turbine, which is supposed to have a modular design in two sizes, is yet to be determined as it is still in the development stage. Although these turbines are not big energy generators, they are quite low cost and easy to install, they are definitely a better substitute for producing electricity than just letting all that water just “run down hill”.

https://newenergyandfuel.com/http:/newenergyandfuel/com/2012/02/17/pumping-back-some-power/

 

[exchemist]

You know it is bewildering how people can get so upset when someone fails to agree with their position. They seem to take it as an insult and get angry and post stuff like the above.
The reason why the system I am suggesting as a contender for this thread doesn't breech the energy conservation laws is really simple but hard to see.
Yet I am being called a fool, a troll, and need to apologize for not agreeing with nonsense just because I am fortunate enough to see what others do not see.
There is no free ride in the system I propose and yes Potential energy can be extracted over and over again with out depletion of the oceans pressure because we add pressure to start with by way of displacement during every cycle...
The very same reason applies to Writ4u's candidate. When the tank is emptied the displacement increases and again it does not deplete the pressure of the ocean because it is added to start with every time it cycles.
Thus PE can be extracted with out cost to the ocean.
So perhaps before you label someone a fool or a troll because they genuinely disagree with you, you could seriously consider your own wisdom...or lack thereof.

But emptying the tank requires energy input from somewhere, because you are pushing back the ocean against the pressure it exerts. When you say "there is no free ride" you are quite right. And that's why.

So then, how do you think you can extract potential energy "without cost" from the ocean?

 

[billvon]

Actually they flood the tanks with high pressure water to descend!

No such thing as high pressure water. Water is incompressible. They release the air in the tanks (or pump it back into storage) and that allows water to flood the ballast tanks.

If they put a generator in that in-flow path they could generate electricity while descending. Neat, huh?

If you learn basic thermo, you'd understand the stuff you are guessing about. Neat, huh?

 

[billvon]

No I haven't made a mistake. Pressure is in fact considered as energy.

OK then do the math. I have 1000psi. How much energy do I have?

 

[Write4U]

No such thing as high pressure water. Water is incompressible. They release the air in the tanks (or pump it back into storage) and that allows water to flood the ballast tanks.

Did I say compressible? Why don't you think about what I actually post instead of your kneejerk rejection. Perhaps consult Wikipedia on occasion. There is a difference between pressure and compression.

As nouns the difference between compression and pressure
is that compression is an increase in density; the act of compressing, or the state of being compressed; compaction while pressure is a pressing; a force applied to a surface.

Have you ever scuba dived, or had the bends?

The bends, also known as decompression sickness (DCS) or Caisson disease, occurs in scuba divers or high altitude or aerospace events when dissolved gases (mainly nitrogen) come out of solution in bubbles and can affect just about any body area including joints, lung, heart, skin and brain.

I wonder why all that decompression is necessary after a deep dive, if there is no such thing as high water pressure at great depth. Did you know that the most dangerous depth is 33 feet from the surface? You know why?

Because 33 feet of salt water exerts 1 atmosphere, the absolute pressure at 33 feet is 2 atmospheres. Pressure continues to increase by 1 atmosphere every 33 feet.

At 33 ft the pressure doubles relative to the surface atmoshpere and the air in your lungs expands to twice its size unless you learn to exhale while ascending. If you don't, you get the bends , which can kill you!

If you learn basic thermo, you'd understand the stuff you are guessing about. Neat, huh?

You don't know what you're talking about. No wonder that you are unable to grasp the principles involved in the submarine electric generator system that we are examining. You're not reading what I post.

 

[Neddy Bate]

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.

A better version would be to connect the free end of the hose to a tank (mounted above the surface of the water), and put a check valve there so that no pressure from the tank can ever come back down the hose. Now put your thumb over the other end of the hose, swim to the bottom, and take your thumb off the hose. The water pressure will push water up into the hose, forcing air into the tank. Swim back up to the surface, disconnect the hose from the check valve/tank and then pull the hose up so that the water empties out of it back into the pool. Reconnect the hose and repeat. You get a tank of compressed air, but you also get tired expending all of that energy yourself.

An even better version would be to fill a ship with heavy rocks, and take it out to sea. Now do the same routine with the hose, check valve, and tank, except instead of swimming you just have to pick up a heavy rock and throw it over the side of the ship with the hose attached. Use a wireless signal to open the end of the hose, and to disconnect the hose from the rock at the end of the process. You will still get a tank of compressed air, but you also still get tired, because you have to pick up the rocks and put them in the ship, and you also have to pick up the rocks to thrown them overboard, and you have to pick up the hose to drain the water out of it. So ultimately you decide to use pneumatic devices to lift the rocks & hose, and you find that you use up all of the compressed air that you harvested just to move the rocks, so you end up right back where you started. Actually you end up worse off, because the energy losses to friction in the pneumatic devices, compression of the hose while under water pressure, and other factors all conspire to ensure that you end up harvesting less energy than you put into it. That is why there is no system from which energy can be obtained endlessly, (except those generated by our sun, which seems to be an endless energy source, but in the end, even the sun will not last forever).

 

[Write4U]

They release the air in the tanks (or pump it back into storage) and that allows water to flood the ballast tanks.

An emergency main ballast tank blow is a procedure used aboard a submarine that forces high-pressure air into its main ballast tanks. The high-pressure air forces ballast water from the tanks, quickly lightening the ship so it can rapidly rise to the surface (positive buoyancy).

As the submarine dives, the ballast tanks are flooded with water and the air in the ballast tanks is vented from the submarine until its overall density is greater than the surrounding water and the submarine begins to sink (negative buoyancy). A supply of compressed air is maintained aboard the submarine in air flasks for life support and for use with the ballast tanks.

https://science.howstuffworks.com/transport/engines-equipment/submarine1.htm

OK, is all this clear now? Can we agree that we both have a general idea of how submarines dive and ascend? And can you please stop with your air of superiority as if you have nothing to learn?

And I already know your response......(the last quoted paragraph)......

 

[DaveC426913]

The relevancy of scuba diving to this topic is zero. The mechanisms we are talking about do not involve dissolved gasses in tissue.

At 33 ft the pressure doubles relative to the surface atmoshpere and the air in your lungs expands to twice its size unless you learn to exhale while ascending. If you don't, you get the bends , which can kill you!

This is false.

I am a diver; you are not.

You won't learn how the world works from Wikipedia. And you sure won't bamboozle us.

So, you really should avoid saying things like this:

You don't know what you're talking about.

And this:

No wonder that you are unable to grasp the principles involved in the submarine electric generator system that we are examining.

As xelasnave has pointed out, you have a history of pretending to know more than you do, and you think the rest of us can't see that you don't know. This torpedoes your credibility.
Stop doing this. Stick to what you know.

 

[Write4U]

The relevancy of scuba diving to this topic is zero. The mechanisms we are talking about do not involve dissolved gasses in tissue.
This is false.

I know, I cited only expansion of the air in the lungs. The bends is expansion of Nitrogen bubbles in the blood. I cited the lungs as an immediate result during ascending too fast without exhaling.

I am a diver; you are not.

Well, I have dived to 100' depth in Lake Havasu, accompanied by two ex-UDT divers. I experienced nitrogen narcosis which is a very disconcerting experience and prompted me to learn a few things about SCUBA diving, OK?

You won't learn how the world works from Wikipedia.

When I claim I have been there and experienced it I am not lying.

So, you really should avoid saying things like this:..... And this:.....

Well, that was in response to a prior insult directed at me.

As xelasnave has pointed out, you pretend to know more than you do, and you think the rest of us can't see that you don't know. This torpedoes your credibility.

I took Alex's compliment as an honest expression. I know he is not prone to sarcasm. When I learn something new from anybody, I also express my gratitude with a "like".

I have never claimed superior intellect over anyone. I am old enough and experienced enough to know my limitations. By the same token I also know my strengths and insights.

And when I am sure of something I will defend it against accusations of ignorance, unless accompanied by hard facts that falsify my position. It has happened in the past, and when I have been proved wrong I have admitted any errors.

But I don't respond well to expressed or veiled ad hominem.

 

[Neddy Bate]

A better version would be to connect the free end of the hose to a tank (mounted above the surface of the water), and put a check valve there so that no pressure from the tank can ever come back down the hose. Now put your thumb over the other end of the hose, swim to the bottom, and take your thumb off the hose. The water pressure will push water up into the hose, forcing air into the tank. Swim back up to the surface, disconnect the hose from the check valve/tank and then pull the hose up so that the water empties out of it back into the pool. Reconnect the hose and repeat. You get a tank of compressed air, but you also get tired expending all of that energy yourself.

An even better version would be to fill a ship with heavy rocks, and take it out to sea. Now do the same routine with the hose, check valve, and tank, except instead of swimming you just have to pick up a heavy rock and throw it over the side of the ship with the hose attached. Use a wireless signal to open the end of the hose, and to disconnect the hose from the rock at the end of the process. You will still get a tank of compressed air, but you also still get tired, because you have to pick up the rocks and put them in the ship, and you also have to pick up the rocks to thrown them overboard, and you have to pick up the hose to drain the water out of it. So ultimately you decide to use pneumatic devices to lift the rocks & hose, and you find that you use up all of the compressed air that you harvested just to move the rocks, so you end up right back where you started. Actually you end up worse off, because the energy losses to friction in the pneumatic devices, compression of the hose while under water pressure, and other factors all conspire to ensure that you end up harvesting less energy than you put into it. That is why there is no system from which energy can be obtained endlessly, (except those generated by our sun, which seems to be an endless energy source, but in the end, even the sun will not last forever).

Actually I just realised that there is no need to cover the end of the hose, you just have to start with a hose filled with air, and connect one end of the hose to a heavy rock, and throw it overboard. The hose fills with water as it descends, and the pressure forces the air from the hose, through the check valve, and into the tank. Now you can use a wireless signal to disconnect the hose from the rock, disconnect the other end from the check valve, and pull the hose back up to empty it. But you still have to load the rocks into the boat, and you still have to pick them up to throw them overboard, and you still have to bring the hose back up so that the water empties out of it. It would be a good science fair project, but your not going to get enough compressed air out of it to even use it to lift the rocks and the hose. And even if you did, then eventually the sea will be filled with the rocks you threw in it, and you will have caused global flooding as the rocks displace the sea onto the shores, lol.

 

[billvon]

I know, I cited only expansion of the air in the lungs.

No, you said "the air in your lungs expands to twice its size unless you learn to exhale while ascending. If you don't, you get the bends , which can kill you!"

This is not only false but dangerous advice. Overexpansion injuries caused by holding your breath on ascent do not cause you to "get the bends." Nor does exhaling during ascent prevent decompression sickness.

Well, I have dived to 100' depth in Lake Havasu . . . I experienced nitrogen narcosis

I would strongly recommend learning about diving safety before doing that again.

 

[Write4U]

No, you said "the air in your lungs expands to twice its size unless you learn to exhale while ascending. If you don't, you get the bends , which can kill you!"

Either can kill you . Your lungs explode or your can get an embolism. They are both deadly, if I recall.

This is not only false but dangerous advice. Overexpansion injuries caused by holding your breath on ascent do not cause you to "get the bends." Nor does exhaling during ascent prevent decompression sickness.

It all depends on the depth and duration of the dive.

At depths greater than 40 metres (130 ft), a diver may have only a few minutes at the deepest part of the dive before decompression stops are needed. In the event of an emergency the diver cannot make an immediate ascent to the surface without risking decompression sickness.

I believe I cited the upper 33 ft as the dangerous part of air expansion in the lungs. At that depth the bends is not an immediate risk, depending on the duration of the dive.

I would strongly recommend learning about diving safety before doing that again.

OK, you win.

Can we get back to the topic under discussion?

 

[Xelasnave.1947]

As xelasnave has pointed out, you have a history of pretending to know more than you do,

I have no problem with Write4U or anyone for that matter, not even QQ although I am disappointed he is unable to apologize. Me..I apologize if I am wrong or if I think I caused offense.
Alex