Still today, over 10% of the world population don't have access to clean water. I'm also curious on how clean the water needs to be to be used with this catalyst. AFAIK, most catalyst conversion need pretty pure water, in which case, we would not only use water, but use _clean_ water, which is even more scare than "dirty" water...
Sea Water (H2O + sea junk) -> H2
Then later when generating electricity:
2 * (H2) + O2 -> H2O (fresh) + energy
Naturally, the resultant H2O can be moved and recycled. I think a catalyst that splits water points towards a potential where we have more fresh water, not less.
Dan Nocera ( http://nocera.harvard.edu ) is very prominent in the water splitting field and has done a calculation in which a volume of an olympic sized pool would need to be split every second to replace all power sources on earth ( https://poptech.org/blog/daniel_nocera_on_personalized_energ... ).
It seems like a lot, but it would presumably be decentralized across many many locations. Additionally, you don't need 24 * 60 * 60 * olympic pool volumes -- you can cycle the same amount of water into/out of a fuel cell in a closed system.
The inland reservoir here is 100 billion liters:
https://www.google.com/maps/@43.8937611,-86.4337261,8900m/da...
It's not very much water.
Hydrogen has a specific energy of 142 MJ/kg [0].
1 water molecule has 2 Hydrogen molecules and 1 Oxygen molcule. Hydrogen has a molecular weight of 1, while Oxygen has a weight of 16 [1][2]. This means that, by weight, water is about 1/9th hydrogen. So 9kg of water should give us 142 MJ worth of Hyrdogen.
Gasoline is about 46 MJ/kg [0], so 3kg of water should give us the equivelent of 1kg gasoline.
Gas has a density of .77 kg/L [3], water has a density of 1kg/L [4]. So 3L of water, should be about 2.31L worth of Gas.
Also, if we keep the water that results from burning hydrogen we may be able to avoid needing to re-purify it.
[0] https://en.wikipedia.org/wiki/Energy_density [1] https://www.google.com/search?q=water+molecular+weight&oq=wa... [2] https://www.google.com/search?q=hyrdogen+molecular+weight&oq... [3] https://www.google.com/search?q=gasoline+density&oq=gasoline... [4]https://www.google.com/search?q=gasoline+density&oq=gasoline...
If you are worried about water shortages, the place to fight that is water intensive farming, on luxury crops.