Earlier quoted context omitted.
If I were building a desalination plant I'd put the generator on site - why waste money on transmission losses? Natural gas generators are clean enough that I don't think it would be a big problem putting one by the ocean.
Do you know how much energy is required to evaporate the amounts of water necessary for urban consumption?
And even the old ones that do use evaporation, recapture the energy, so you really only need to evaporate the water once, other than losses.