Extracting drinking water for domestic use from seawater is not as expensive as made out apparently:

And if the 7kWh/tonne the article talks about came from wind (or, hey, why not wave or tidal?) generation, it would have no carbon footprint nor use any expensive imported fuels.

Desalination is also a process that, unlike most uses of electricity, does not have to be done "on demand" - a large quantity of water can be desalinated while the wind is blowing and used when it is not.

PetraM