Illustration text: The principle of osmotic power is utilising the entropy of mixing water with different salt gradients. In the process the water with low salt gradient moves to
the side with the higher salt concentration and creates increased pressure due to
osmotic forces. Given the sufficient control of the pressure on the salt water side,
approximately half the theoretical energy can be transformed to electrical power,
meaning that the operating pressure are in the range of 11-14 bars enabling the
generation of 1MW per m3 per sec fresh water.
2. Current activities.
After the idea of using PRO was developed in the early 70’s, limited effort has been made to bring this technology to a commercial level. There have been some minor studies and testing, but it was not until Statkraft started working with PRO that the development picked up momentum. Since this work started around 1996, research has been focused on designing a suitable membrane for PRO, and at the same time one has worked with system design and several studies of the feasibility of the concept as a commercial source of energy.
The development of an efficient membrane for osmotic power has been the major focus of the efforts made by Statkraft. The current power density of the membrane is approximately 3 W/m2, which is up from less than 0.1 W/m2 a few years back. This research has for most part been done in Germany, Norway and the Netherlands, there are however other groups working on similar topics both in North America and Asia.