A voltage question

andywelik
andywelik Registered Users Posts: 2
in Solar Beginners Corner #1
Could somebody here tell me how many volts are minimally needed to split water into O2 and H2?

I ask it because I want to use solar power to split water into O2 and H2. Is sea water suitable for splitting?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: A voltage question

    You're talking about the process of electrolysis. Technically it requires enough Voltage to overcome the resistance of the electrolyte used. Pure water doesn't work very well. Sea water would be an electrolyte, although in its raw form an inconsistent one (meaning the results will also be inconsistent for a fixed process).

    Wikipedia is your friend: http://en.wikipedia.org/wiki/Electrolysis_of_water

    Don't expect this to be a process of much value; as with all energy transformations you put more in than you get out.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,590 admin
    #3
    Re: A voltage question

    I guess it takes around 4-5 volts minimum to electrolyze water. Sea water can be converted just fine (salt, or other additive is needed to make the water more conductive).

    Why do you want to do this? In general, lead acid batteries are more efficient to store energy (as electricity). And to build "fuel cells" to (relatively) efficiently convert Hydrogen+Oxygen back into electricity usually uses platinum or other expensive catalysts.

    And Hydrogen is pretty dangerous to work with (explosion, hydrogen embrittlement of steel/other metals used for piping/pressure vessels).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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