Osmotic power or salinity gradient power is the energy available from the difference in the salt concentration between seawater and river water. Two practical methods for this are reverse electrodialysis (RED) and pressure-retarded osmosis. (PRO). Both processes rely on osmosis with ion specific membranes. The key waste product is brackish water. This byproduct is the result of natural forces that are being harnessed: the flow of fresh water into seas that are made up of salt water.
The technologies have been confirmed in laboratory conditions. They are being developed into commercial use in the Netherlands (RED) and Norway (PRO). The cost of the membrane has been an obstacle. A new, cheap membrane, based on an electrically modified polyethylene plastic, made it fit for potential commercial use. Other methods have been proposed and are currently under development. Among them, a method based on electric double-layer capacitor technology. and a method based on vapor pressure difference.
The world's first osmotic power plant with capacity of 4 kW was opened by Statkraft on 24 November 2009 in Tofte, Norway. This plant uses polyimide as a membrane, and is able to produce 1W/m² of membrane. This amount of power is obtained at 10 l of water flowing through the membrane per second, and at a pressure of 10 bar. Both the increasing of the pressure as well as the flow rate of the water would make it possible to increase the power output. Hypothetically, the output of the SGP-plant could easily be doubled.
Read more about Osmotic Power: Basics of Salinity Gradient Power, Efficiency, Methods, Possible Negative Environmental Impact
Famous quotes containing the words osmotic and/or power:
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