It actually falls into my undergraduate studies. I had some idea to purify sea water using similar process but in a more massive scale. I talked to my classmate, professor in Qing Hua university and his conclusion is the cost will be higher than reverse Osmosis, which is the currently cheapest. But when used in oil production, it will add huge cost to shale oil production which already costs far more than current oil price even in a place which has everything ready.
If there is any similar low cost sea water Desalination process, China will not need to move water from south to the north.
