all images: Statkraft
If you haven't heard of osmotic power, you're very much forgiven. Though Norway's Statkraft has been researching the technology -- which generates power by exploiting the hydrostatic pressure created when fresh water passes through a special membrane into salt water -- since 1997, only now has the world's first osmotic power plant prototype been opened:
Commercial Power Plant Still a Few Years Off
In its press release touting the event Statkraft says the prototype plant at Tofte (an hour south of Oslo) will have a "limited capacity" -- 2-4 kilowatts initially with plans to increase it to 10 kW -- and aims to construct a commercial osmotic power plant "within a few years' time."
Currently the membrane efficiency of the plant is less than 1 watt per square meter, but membranes will be installed to increase that to 2-3 watts after the plant has been operational for a while. The goal is to increase that to 5 watts per square meter, which is pretty much the break-even point for the technology.
The pressure created through the membranes (coiled in those tubes) is used to turn a turbine and generate electricity.
25 MW Would Be Size of Sports Stadium
Should this all pan out, Statkraft envisions a 25 MW commercial osmotic power plant being about the size of a football stadium (as in soccer, not the US game where you rarely actually touch the ball with your foot...). That would require five million square feet of membrane and could generate enough power to supply 30,000 homes.
50% of Europe's Power Could Be Supplied... If the Technology Gets There
Statkraft estimates that Europe has an osmotic power potential of 180 TWh annually, or about 50% of current power production in the EU. Globally that increases to 1600-1700 TWh annually, but frankly perhaps the focus should be on getting the technology cost-effective and able to run something greater than an electric tea kettle before touting its global potential.