Quantcast

Sierra Magazine: Explore, enjoy and protect the planet.
River + Ocean = Electricity - Sierra Daily
Find us on Facebook Follow us on Twitter Contact Us

March April 2014

Read the latest issue of Sierra

« Fossil Fuels Are Cheap | Main | Can a Wind Farm Float? »

Sierra Daily

Apr 20, 2012

River + Ocean = Electricity

Osmotic 4075064934_c871173026

Tapping the power potential of the difference in salinity between fresh water and salt water could supply electricity for 520 million people, according to research funded by the Environment and Water Industrial Development Council of Singapore. Pressure-retarded osmosis (PRO) is an alluring process because it is available anywhere fresh water and salt water meet: Less-concentrated fresh water naturally wants to mingle with more-concentrated salty water. When the fresh water is run through a semi-permeable membrane, pressure from the flow can be tapped to drive a turbine that generates electricity—with no carbon dioxide emissions.

The Norwegian renewable-power company Statkraft has operated a prototype PRO facility near Oslo (at left) since 2009. By 2015 the facility is expected to produce 25 megawatts, the equivalent of a small wind farm.

Researchers Menachem Elimelech and Ngai Yin Yip calculate that the target of a half-billion customers could be reached by relying on one-tenth of the world’s river water flow. They note that the same amount of electricity produced by a coal-fired power plant would release over one billion metric tons of greenhouse gases annually. 

Photo by Statkraft.

Blog photo   HS_ReedMcManus (1)Reed McManus is a senior editor at Sierra. He has worked at the magazine since Ronald Reagan’s second term.  For inspiration, he turns to cartoonist R. Crumb’s Mr. Natural, who famously noted: “Twas Ever Thus.” 

User comments or postings reflect the opinions of the responsible contributor only, and do not reflect the viewpoint of the Sierra Club. The Sierra Club does not endorse or guarantee the accuracy of any posting. The Sierra Club accepts no obligation to review every posting, but reserves the right (but not the obligation) to delete postings that may be considered offensive, illegal or inappropriate.

Up to Top