BuzzSkyline writes: "It's possible to produce energy by simply mixing fresh and salty water. Although chemists and physicists have long known about the untapped energy available where fresh water rivers pour into salty oceans, the technology for exploiting the effect has been lacking. An Italian physicist seems to have solved the problem with the experimental demonstration of a "salination cell" that creates power given nothing more than input sources of salty and fresh water. Apparently the renewable, environmentally friendly energy source is comparable to "each river in the world ending at its mouth in a waterfall 225 meters [739 feet] high." A paper describing the technology is due to be published in an upcoming issue of the journal Physical Review Letters."