May 30 2013

OWC Desalinator

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In our world today over 780 million people lack access to clean drinking water. That’s approximately one in nine people This staggering statistic has spurred the development of desalination plants, however most are very expensive, over $300 million and consume large amounts of energy because of the high temperatures for evaporation or high pressure for reverse osmosis needed.  Research conducted in England at the University of Southampton is investigating the use of ocean power based on the oscillating water column create high pressure at a much lower cost. Their proposed desalination system can stand completely alone, meaning it needs no connection to the grid. Its brilliance lies in its simplicity. Only needing a pump, created by the oscillating wave column, and a WaveCatcher, where the water pressure is intensified for reverse osmosis. The WaveCatcher creates 6MPa of pressure, the necessary amount for reverse osmosis.


Reverse osmosis process using a semipermeable membrane

diagram 2

OWC Desalinator Design


The OWC converts the kinetic energy of the wave into potential energy by increasing the height of the water (PE=mgh). Normally, OWCs adjust the air in the compression chamber to  maximize resonance, however in this case for simplicity sake the stiffness of the air spring can be adjusted by  altering the angle of the output duct. This simplification differentiates the device from blueWAVE OWC desalinator because it significantly reduces cost and makes use of the device more attainable in developing nations. To decrease friction, the experiment tested multiple diameters for the pump until finding the optimal distance. A resonance control device can increase the incident wave height by up to five times the original height. On average, the amplification factor is “betweeen 2.5 and 4 time[s] the incident deep water wave height,” which dramatically increases the water pressure and amount filtered. Future studies look to capture incident waves of varying periods via a “Pan-flute array of pumps.”This development would ensure maximal efficiency throughout all seasons of the year. Unfortunately, despite the study’s focus on reducing cost, it fails to state what the proposed cost for the designed desalinating device would be and how many gallons it would desalinate.


Magagna, D., Stagonas, D., Warbrick, D., Muller, G., 2009, Resonating wave energy converter for delivery of water for desalination and energy generation, the School of Civil Engineering and the Environment of the University of Southampton, p. 393-399.



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