Jun 02 2010

Osmotic Power

Published by under Student blog entries

This is another example of an offshore renewable energy resource.  Osmotic Power uses salinity to create electricity with zero carbon emissions.  This is based on the fact that water with low salinity levels will move to areas of greater salinity.  To create energy, a membrane that only allows for water molecules to pass through divides a freshwater container and a saltwater container.  The fresh water is naturally drawn towards the saltier side and builds pressure in the salt water container.  This pressure can be released through a turbine that can generate electricity.

Picture: http://osmoticpower.com/index.html

One of the set backs for Osmotic Power (OP) is creating the membrane.  There are similar membranes that exist today and are used in desalinization.  However, these membranes are not suitable for OP.  Another problem is the need for a freshwater source.  Fresh water is already a tough commodity, and the use of OP could further stress this resource.  I was also disappointed to learn that as the fresh water moves across the membrane, it dilutes the salt water and reduces the potential of the system.  This could be solved by pumping more and more seawater but that cuts back on the net energy produced by the system.  It has been proposed to use a pressure exchanger (PX) energy recovery device to exchange the dilute water with seawater.  Apparently PX devices are very efficient (on the order of 98%) and will probably be utilized if OP ever emerges as viable source of energy.

On the positive side, OP is a base load energy resource unlike wind or solar.  A Norwegian company is looking into this technology and claims that 2.6 terawatts (10^12) could be created by OP systems all over the world.  This would most likely be done in areas where freshwater rivers meet the ocean.  This seems like a good idea because there will be a constant supply of freshwater and saltwater.  Another example of taking advantage of resources nearby and localizing energy production.

2 responses so far

2 Responses to “Osmotic Power”

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