According to a new analysis the point where a river flows into the ocean, the river mouth, could generate enough electricity to support over half a billion people. The process is called pressure-retarded osmosis (PRO). It was examined for its power-generation potential by Ngai Yin Yip and Menachem Elimelech from the Department of Chemical and Environmental Engineering at Yale University in the most recent edition of the journal Environmental Science & Technology.
They state that enough electricity could be generated by tapping only one-tenth of the global potential of PRO. They also note that it would require no fuel to run, is sustainable, and would release no carbon dioxide.
PRO exploits the difference in saltiness between the freshwater river and the saltwater ocean. According to the American Chemical Society, “in PRO, freshwater flows naturally by osmosis through a special membrane to dilute seawater on the other side. The pressure from the flow spins a turbine generator and produces electricity.”
Following the first prototype pressure-retarded osmosis plant being established in Norway in 2009, the researchers set out to better calculate the actual contribution to future energy needs under real-world conditions of a PRO system.
Source: American Chemical Society