Externet Posted June 19, 2014 Posted June 19, 2014 Could this often ignored, abundant metal provide an energy source as hydrogen with economical sense ? Is its production too much energy demanding as to discard its potential ? Is there a specific voltage or method that could collect only calcium ions from seawater without other cathodic deposits ?
Enthalpy Posted June 23, 2014 Posted June 23, 2014 Hi externet! Because calcium metal reacts with water, extraction by electrolysis can't be made in water. You would have to dry the salt mixture first, then possibly electrolyze the melt. In seawater, sodium is more abundent, and may be more interesting than cacium. Calcium compounds are usually obtained from limestone instead. You want to produce hydrogen that way? Several attempts exist to store a metal and produce hydrogen when and where needed to feed fuel cells. One is aluminium, doped with gallium to promote corrosion. Though, I expect it's better to use the metal in an electrochemical cell directly, rather than convert it to hydrogen, where potential is lost as heat. Calcium weigh 40g for two electrons, that would be equivalent to 2g of hydrogen. Magnesium looks a bit better, lithium is too scarce for some uses. The big question is: how light (and safe and convenient!) can be the storage of hydrogen.
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