half baked ocean depth pressure scheme

[timewarp]

Someone with a better grasp of physics than my own may be just what I need. Simply knowing if friction losses in what I have in mind are higher than the amount of power that could be produced would tell me all I really need to know whether or not there is any potential in my idea.

The concept is to use the pressure of deep water to compress air, which would be returned to the surface where electricity could be generated from the compressed air. What I have in mind is to use something like a conveyor belt to squeeze a flexible hose (something like fire hose), trapping a "pocket" of air that the conveyor can take down to the depth needed to get the best working pressure for the system. The flexibility of the hose would allow the air to be compressed within the hose, and the "conveyor" would be needed to trap the air against flowing backwards up the hose. The compressed air would be collected in rigid pipe at the bottom, and piped back to the surface for air driven motors to use on generators.

Sorry, I really should have a sketch to send along to maybe make the idea a bit clearer. If the potential energy of the compressed air is higher than the friction losses from the conveyor system, maybe there is some potential there. It's an idea that's been in my head for years, but until the internet made it easier to find other people that may be able to help me with the engineering/physics, the idea hasn't gone anywhere.

[hansvonlieven]

G'day timewarp,

There is more than friction losses involved here. In order to transport an air filled container of some sort to the ocean floor you must also overcome buoyancy. At sea level the air would take up a considerable volume, which decreases as the container sinks. The displacement of water caused by the air container at the start up would create buoyancy. Try pulling a balloon down to any depth and you get an idea how much power is required to do so. I haven't done the maths on this but my estimate is that there is no gain.

An interesting idea nevertheless that I have not heard expressed anywhere.

Keep trying

Hans von Lieven

[sm0ky2]

it requires more energy to overcome the bouyancy than can be retrieved by decompressing the air.

it is FAR more efficient to compress the air using a standard compressor.

no gain to be had by this sort of thing....

[hansvonlieven]

LOL smoky, I love those simulcasts 

Hans

[CARN0T]

Hi, Timewarp,

Wait a minute, what if you don't have to pay to put the "air" at the bottom of the ocean?  Then you get all sorts of power out, right?  If you could generate a lot of small bubbles in the water, they would pump water upward as they rose-- that's a great water pump in itself.  Or, you can harness the high pressure of the "air" as you intended.  What are the possibilities for this "air"?

Let's see-- the deep ocean is at about 4 degrees C.  Is the water saturated with any gas?  If so, warming the water reduces gas solubility, causing bubbles to form.  If you make a closed loop of pipe that draws down warm surface water, with a heat exchanger at the bottom, then the loop might be self-powering.  Maybe.  But the water probably doesn't have a suitable gas unless--

Methane.  People are worried that at any moment, the ocean depths might warm up enough to release methane that is stored there.  The oil companies are like wolves smelling blood over this one.  They want to mine the methane and test operations are going on as we talk. The methane is stored on the ocean floor as "methane hydrate," a compound with water that is very unstable.  Just a little warming and it converts to a gas and wants to bubble up. 

Recent scientific reports indicate that the shallow sea shelves along the coasts of the Arctic Ocean are already beginning to "off-gas" methane from the sea floor.  But deep methane occurs almost everywhere in the oceans.

That was fun, but let's try one more time.  The deep ocean floor is a carbonate ooze.  That's how limestone forms.  What if a little acid got into that ooze?  CO2 would be released.  Again, if you primed a loop carrying acidic water from the surface, it might be self-powering.

I know these are half-baked answers, but that's just perfect here, right?

Ernie Rogers