Recently, a team of researchers from Switzerland and the United States built a new kind of osmotic power generator that vastly outperforms any that came before. In their version, one side of the tank contains a higher concentration of seawater ions than the other side of the tank. The membrane, which is just three atoms thick, features a single opening through which only positive ions can pass. An electrode connects the two sides. When positive ions squeeze through the membrane, their electrons transfer to the electrode, producing a current.