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Osmotic Power Plant. By Cosmina Herţog. Why osmotic power?. emissions free renewable unlike wind or solar power - works whatever the weather. Osmosis.
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Osmotic Power Plant By CosminaHerţog
Why osmotic power? • emissions free • renewable • unlike wind or solar power - works whatever the weather
Osmosis • the movement of solvent molecules through a permeable membrane into a region of higher solute concentration, aiming to equalize the solute concentrations on the two sides. • describes a physical process in which any solvent moves, without input of energy • it does use kinetic energy and can be made to do work • net movement of solvent is from the less concentrated (hypotonic) to the more concentrated (hypertonic) solution, which tends to reduce the difference in concentrations. • can also be explained using the notion of entropy from statistical mechanics When equilibrium is reached, water continues to flow, but it flows both ways in equal amounts.
November 24, 2009 the world's first osmotic power plant with capacity of 4 kW opens in Tofte, Norway. • “The sun shone through the windows, the bass rumbled through the speakers and Crown Princess Mette-Marit enjoyed the world’s first cup of tea made using osmotic power.”-quote from the company’s website
The plant had cost about $8 million to build and about $20 million into research on osmotic power. • Generating up to 4 kilowatts of electricity for the grid. • The plant is modular and consists of 66 pressure pipes with rolled-up membranes on the inside. • Holds a total of 2000 m^2 of membranes. • The membrane efficiency was less than 1 watt per sq. meter corresponding to 10 l of H2O flowing through the membrane per second, and at a pressure of 10 bar • The goal is to reach 5 watts.
Facts • How does osmotic power works? When freshwater and seawater meet (river/sea) through osmosis the membrane will allow the fresh water to flow through creating a pressure on the seawater side that can be used to drive a turbine. The pressure is 12 bar or the equivalent of 120m waterfall. • What will a full-scale power plant look like? The size of a football stadium could have a capacity of 25 MW, which would require 5 million sq. meters of membrane. The plant could produce 166 GWh of electricity per year – enough to supply 30 000 European households. • How much water is needed for a full-scale plant? To achieve an output of 1 MW, one cubic meter of freshwater (per second) must be mixed with two cubic meters of seawater at 12 bar. This means that a typical 25 MW plant will need 25 m3 of freshwater and 50 m3 of seawater per second.
Possible negative environmental impact • The main waste is brackish water (sudden drops or spikes of salinity in an aquatic environment may result in low density of animals and plants due to intolerance of sudden severe salinity changes) Problems to consider • The cost of the membrane has been an obstacle. • An investment in osmotic power must consider future upstream use in the long-run. Example-rivers running dry from overuse (agriculture, dams and industry) that end up not reaching their delta where the plant will be built (e.g. Yellow River, Indus River, Colorado River)
Bibliography • http://www.statkraft.com/presscentre/news/2009/the-worlds-first-osmotic-power-plant-opened.aspx • http://ngm.nationalgeographic.com/2008/05/china/yellow-river/larmer-text/2 • http://www.thenatureanimals.com/2012/03/8-mighty-rivers-run-dry-from-overuse