The point where a river flows into the ocean, the river mouth, could generate enough electricity to support over half a billion people according to a new analysis.
The process by which a river flows into the ocean is known as 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 note that enough electricity could be generated by tapping only one-tenth of the global potential of PRO, and that it would require no fuel to run, is sustainable, and would release no carbon dioxide. (Note: last year, Stanford researchers cam to a similar conclusion, finding that this renewable energy source could generate 13% of the world’s energy needs at that time.)
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 PRO 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.
Yip and Elimelech conclude in their study that PRO power-generating stations which used only one-tenth of the global river water flow into oceans could generate enough electricity to meet the needs of 520 million people, and all without emitting any carbon dioxide. In comparison, the same amount of electricity generated by a coal-fired power plant would end up releasing over one billion metric tonnes of greenhouse gasses each year!
BRING ON PRO!
Source: American Chemical Society
Image Source: Randen Pederson
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