H2 from seawater 7

[thorangle]

Why can't you place two electrodes in seawater, place a voltage source across the electrodes and produce hydrogen and oxygen?

 

[macroscopic]

Oh yeah, almost forgot.

Flow Batteries.
Like a reversible fuel cell but use a oxidation reduction process with Vanadium or other fluids.. actually have a lot of potential for the future. Sometimes called Vanadium Redox batteries. Very cool.

 

[macroscopic]

I have a question for people:

Does anyone know specifics about splitting sea water?

Does it really need to be purified first in a seperate step?

Does anyone know specifics about what needs to be done or any references I can find? I NEED to design a system to store electric energy by electrolyzing sea water..

There don't seem to be any electrolysers that work on seawater...

I guess the choices are to distill the water, or use reverse osmosis...then electrolysis.. is this the simplest way to do it?

 

[HydroScope]

did you not read the early threads of this tread check out moltenmetal Nov 12, apart from that??

 

[macroscopic]

yeah, I read those posts but am still not clear on it.

Does the statement: " If you want hydrogen and oxygen, you'll need a different electrolyte." mean that in order to split seawater for hydrogen, the salt in ocean water must be removed, and a different electrolyte must be added?

An electrolyte isn't added to water before it goes into an electrolyzer (as far as I know) so I'm not sure what that means....

are there any electrolysis units that directly extract hydrogen from seawater, or is it always a multi-step system? From what I have found, it always needs to be purified first. I guess this is because the electrodes will corrode or get poisoned if they are in direct contact with ocean water which is impure.. So even though electroloysis might be near 90 percent efficiency, once you inlude the energy required for water purification, this would potentially be much lower.


I am really thinking flow batteries are the energy storage system to watch. Because of the fact that you can scale them up by just adding more electrolyte, which is stored in tanks. They can be charged and discharged fully with no degradation, and especially with the Vanadium REDOX type, there is no crossover membrane crossover pollution problems, since the negative and positive side are both just different oxidation states of the same material. These systems can be cycled thousands of times and keep coming back for more. They are also up to 90 percent round trip effiency

 

[moltenmetal]

In a mixed cell, chloride in the seawater will be electrolyzed to produce chlorine, then hypochlorite, then chlorate, then perchlorate... If you want to produce hydrogen and oxygen, you need to remove the chloride and replace it with another ion.

The nature of the ions in the electrolyte, and the electrochemical side reactions they undergo, determine to a large degree the efficiency of any electrolyzer you might want to build.

In theory, you don't need to add electrolyte to a continuous electrolyzer if you choose one which is stable. All you do is add fresh PURE water to an initial charge of electrolyte which remains in the cell. However, just like in distillation, any impurities in the water will accumulate in the electrolyzer, requiring ultimately a bleed stream and an electrolyte replenishment stream if you want to run a continuous electrolysis process.

 

[garbage]

Under Sea desalination plant producing electrolytic H2, O2, pure water powered sfloating solar panels. Is this economically feasible both technically & distribution wise using under water pressures?

 

[agent007]

What do you gents think of the video at this link?

http://www.spiritofmaat.com/archive/watercar/h20car2.htm

Bruce Toski

Bruce Toski
ASE Master Certification
Automotive Instructor