Basically pointing out, once again, that it really is a question of price, not of availability. Cheaper energy would make this more doable. And water has been proposed as a transfer medium for value from photovoltaic arrays (they desalinate water by cracking it into hydrogen and oxygen, which then gets recombined to produce local energy and exportable potable water. Only makes sense if you are willing to pay more for the water.

That said, the ability of graphene to desalinate water is something I think should get more investigation than it does. See (http://cleantechnica.com/2015/04/03/methane-rescue-new-energ...) for example.