They've already developed a way to make fuel out of sea water to use in existing Navy ship engine designs. They figure in about 10 years they'll have figured out how to up-scale the process for on-board use. Then the fleet won't be hindered by needing tankers to re-fuel from.
http://www.geek.com/science/game-changi ... l-1590495/
Just google "Navy sea water fuel" for more info.