Sanford University have developed a system where countries blessed with seawater and freshwater (e.g. islands like Britain, Japan, ) will never need dangerous Nuclear Energy!
You simply borrow water from a river, send it to a battery in which seawater is also being used to generate power, and then return the fresh water to the river. In fact the water needn't be all that clean. You could do it with other neutral water. The university's model is more than 70% efficient but with more development a figure of over 80% is easily reachable.
In fact the system could provide 13% of the world's energy!