Rivers could provide energy for half billion people

Washington, April 19 (IANS) A new genre of power plants, using only a tenth of the global river flow into the oceans, could meet the energy needs of a half billion people, without emitting carbon dioxide (CO2), says a study.

The same amount of electricity, if produced by a coal-fired power plant, would release over one billion metric tonnes of greenhouse gases (CO2) each year.

Researchers Menachem Elimelech and Ngai Yin Yip from Yale School of Engineering and Applied Science explain that the little-known process, called pressure-retarded osmosis (PRO), exploits the so-called salinity gradient, or difference in saltiness, between freshwater and seawater.

The revolutionary process requires no fuel, is sustainable and releases no carbon dioxide (CO2), the main greenhouse gas, the journal Environmental Science & Technology reported.

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, a university statement explained.

The world's first PRO prototype power plant was inaugurated in Norway in 2009.

Scientists are setting out to make better calculations on how much it actually could contribute to future energy needs under real-world conditions.