Via EcoGeek.org by Philip Proefrock on 30-11-2009
Solar. Wind power. Wave power. Geothermal. Tidal power. If you’re a regular EcoGeek reader, you’re probably pretty familiar with the different major power generating alternatives to the burning of non-renewable fossil materials. But still, osmotic power generation is likely something you haven’t heard of before. Your first question is likely ‘How do you use osmosis to generate electricity?’
Osmosis is a process whereby water with two different concentrations of solution (in this case, salt) is separated by a semi-permeable membrane. Fresh water is able to pass through the membrane to the salt water side, but salt water cannot cross back in the other direction. This causes an increase in pressure on the salt water side, and this pressure difference is used to run a turbine which produces electricity.
Statkraft, a Norwegian renewable power company, has begun operations to use this process to generate electric power. The test facility, opened this week in Norway, is just a small demonstration plant which will produce only a few kilowatts of power. However, by 2015, Statkraft expects to be producing 25 megawatts of electricity by osmotic power.
Since the osmotic process requires a great deal of freshwater to function, we can forsee some serious problems for this system in the many parts of the word where the availability of fresh water is limited. The osmotic process also produces waste water that is saltier than freshwater, but not as salty as seawater, and the discharge of large quantities of this brackish water could be detrimental to local aquatic ecosystems.