Rivers flowing into the sea offer vast potential as electricity source

A new genre of electric power-generating stations could supply electricity for more than a half billion people by tapping just one-tenth of the global potential of a little-known energy source that exists where rivers flow into the ocean. A report on the process appears in ACS’ journal Environmental Science & Technology. Menachem Elimelech and Ngai Yin Yip explain that the process, called pressure-retarded osmosis (PRO), exploits the so-called salinity gradient -- or difference in saltiness -- between freshwater and seawater. 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.