Hydrogen Storage

Is it possible/feasable to use the pressue of water of the ocean to store hydrogen in a cannister type system? The idea is to replace the
expensive system of presurizing Hydrogen gas by conventional means with the pressure of seawater at great depths of up to 1000metres and of course retrieve the cannisters to the surface.
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Dear Sugna41:

Yes. It will be slightly more efficient than conventional means, since it could be isothermal compression. Unfortunately then you also have the friction losses of moving a compressible container to depth, and figuring out how to retain its shape upon allowing it to surface.
Stick with methane clathrates.
David A. Smith
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Possible, yes. Cost effective no. At 1000 meters you only get about 1400 psi. Hydrogen storage is much more, (depending on the system).
Let's say you have a compressing system, this system has a canister full of Hydrogen, to be compressed, it's 1 cubic meter (Hydrogen volume), and weighs 100 kilograms. You have a counter weight also 100 kilograms, and the same density as your compressor, but incompressible. There is a pulley at the surface, and one on the bottom of the ocean. To compress Hydrogen, fill, lower, and return to the surface. Sounds like you need a very small motor to overcome friction, right? Nope, As you lower the compressor, Hydrogen is compressed, the volume of the device gets smaller, less bouyant. At 1000 meters, that 1 cubic meter is now .01 cubic meter. When you try to lift the compressor, it is like lifting .99 cubic meters of water, because of the decreased bouyancy. (.99 cubic meters of water x 1000 meters = a lot of power.) Dave
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wrote:

The reason why I ask is certain places where ocean depths are this great, there is also large wave action. Should an efficient method be found to cature the energy of waves and store it as hydrogen or another form, then these cannisters could be used to fuel ocean going vessels instead of fossil fuels such as diesal oil. With 30 000 vessels on the ocean in any one given day, the reducton in carbon would be significant and if it could compete with oil based fuels in dollar terms then it may prove to be an alternative to present day propulsion. Trying to supply electricity to a shore based consumer market is very difficult with the distances involved and technology needed to satisfy the consumer demands put upon the grid but supplying cargo vessels with an alternate fuel may prove to be easier and in the long term, a provide a greater reduction in Carbon. The idea if implimented could make Hydrogen availible on demand and with advanced orders to the marine industry world wide.
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Dear Sugna41:
...

Not at this depth no. Where there are changes from very deep to fairly shallow, yes.

You'd be getting the hydrogen from... water right? You'd be getting it by some form of... electrolysis right? Is there anything that says you cannot do the hydrolysis at 1000m down?
...

Biodiesel from plankton. No potential loss of hydrogen to space, in case of a leak.
David A. Smith
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wrote:

I need to clarify some points. The WEC would generate electricity from surface ocean waves and there would have to be electrolysys at the bottom where pressure is high. An umbilical cord from surface WEC farm to the bottom would connect the two seperate but dependant parts of the operation. The pressure already availible from the water colum could be utilized to store the hydrogen and retrieving the cylinders to the surface would also have to be considered. Here is a useful site which is a good indicator of where the major wave action is located.http://www.oceanweather.com/data /
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Dear Sugna41:
...

OK so far. Electrolysis of seawater generates hypochlorite ion, bromate ion, hydroxyl radicals, and free chlorine. The hypochlorate ion and free chlorine are toxic to aquatic life, but are also salable chemicals (used in municipal water treatrment). The hydroxyl radical will raise the pH to toxic levels. You will need to have a forced positive flow from the site of electrolysis, prevent life forms from entering, and bring these chemicals to the surface for collection and / or neutralization.

A dumb waiter system would work for the containers, since they weigh about the same once they are water-filled.
You'd be money ahead to simply store the wave energy as compressed air, stored under a submerged "cup", and released during periods of low wave activity through a turbine or air motor. Or store the energy into heating salts...
David A. Smith
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Osmosis could be used to filter out pure water elimanating the problems with impurities.. At these pressures, it should work well.
Electrolisys would produce the Hydrogen and the Oxegen could then be expelled into the surrounding water. From the studies I have read, linear generators are proving to be the most efficient method of capturing energy from waves and converting it directly into electricity. The problem is uncertainty for marketing and that is the reason for the hydrogen production. Also where the maximum wave activity occurs, it is far from coasts but some areas are in the busy shipping lanes where ocean going vessels could use these strategic areas as refueling stations.
I know it is a far fetched idea but right now I am think of a prototype to capture energy from ocean waves but with grid connections and the distances involved, selling the electricity will be difficult. With the price of oil sky rocketing, shipping companies are looking under every rock for savings and alternative fuels. Ocean going vessels are also one of the largest producers of carbon emmisions and with carbon emmisions there aren't any winners. Some of them could be convinced to try this method providing it is economical and reliable. I'll keep post up to date if any developments come about
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Dear Sugna41:
wrote:

No, fouling is a serious problem. You don't really need much more that a screen with wiper at the suction (deep) end.

You don't get oxygen when you electrolyze seawater, as I said. Ionic chlorine is too readily available, so you get the species I mentioned. The oxygen stays bonded to the other hydrogen.
http://adsabs.harvard.edu/abs/1975hyen.proc..417W
You just killed all the aquatic life.
David A. Smith
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wrote:

Ok there will be problems with this system. May not be possible to produce hydrogen with such a system. I was thinking of producing Hydrogen from pure water which would be produced from a reverse osmosis system but that in itself isn't availible as such and producing it may cause problems and use to much energy.
Maybe difficult to store the energy in useful form. Il have to look at other methods but ty anyway. All a process of design. Explore all problems and options. storing the energy in a usefull and readyly availible form could prove difficult but I do have a small shipping company who is interested in the idea and now if I can get it to work....
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wrote:

At these depths, there is very little energy available for lifeforms unless they are near undersea vents, so there is little life to kill

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With a reverse osmosis system the pressure would be availible at these depths for the intake but it would have to be lowered at the outlet- the energy would have to applied in the reverse side. Reverse osmosis could supply more than enough filtered pure water for electrolysis of water and maybe it would be a better system to store both the Hydrogen and Oxegen for use in fuel cells when needed for propulsion? The pressure for compressing the gasses would be from the water colum. As for fowling, there isn't any algea at these depths but there is some coral and other forms. Getting the cylinders to the surface could pose problems.
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Dear Sugna41:
...

There used to be little available *oxygen*, not "energy".

Use seawater, generate the hydrogen at depth, have the other electrode some distance up the duct that will draw the chlorine compounds to the surface, to be harvested.

Deep sea fouling will be a problem, as I said.

Dumb waiter. Bring one up at the same time you lower a replacement. Minimum power if you are not in a hurry.
David A. Smith
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