There are already technologies beyond reverse osmosis in large scale industrial use (and I'm not referring to brine or similar high energy approaches)
Siemens has built a desalination plant in Singapore that works similar to dialysis (mimicking kidneys) and is using a fraction of the energy required for a comparable RO solutions (http://www.desalination.biz/news/print.asp?id=6008).
The key issue with all membrane / filter based desalination solutions still is the lifetime / service requirements of the filters.
Siemens has built a desalination plant in Singapore that works similar to dialysis (mimicking kidneys) and is using a fraction of the energy required for a comparable RO solutions (http://www.desalination.biz/news/print.asp?id=6008).
The key issue with all membrane / filter based desalination solutions still is the lifetime / service requirements of the filters.