Situated on the scenic banks of the Oslo fjord in southern Norway, the world’s first prototype osmotic power station came online this week. The new plant generates electricity using osmosis, which occurs whenever two solutions of different concentrations meet a semi-permeable membrane. The spontaneous passage of water from dilute to concentrated solutions through the membrane generates a pressure difference that can be manipulated to generate power.

The prototype plant uses salt and fresh water, which are siphoned from near the point where they meet at the mouth of the fjord. The two liquids are pumped to either side of the membrane, where osmosis creates the pressure used to drive a turbine and generate electricity.

Statkraft, the renewable-energy giant running the project, estimates the total global potential of osmotic power to be in the realm of 1700 terawatt-hours per year – roughly 10 percent of the world’s total current electricity consumption.

Many of the world’s major cities sit on river estuaries, which could potentially make osmotic generation an ideal power source. Unlike solar power and wind, osmosis can provide a continuous source of power, although seasonal river-level changes do cause some fluctuations.

With the Copenhagen climate summit rapidly approaching, the hunt is on for ways of producing electricity that do not emit greenhouse gasses into the atmosphere. In theory at least, osmotic power seems to fit the bill. It is renewable, emission-free, and works in any weather. One major issue is coming up with a membrane of exactly the right thickness, capable of withstanding huge pressures that does not constantly get clogged up with salt.

Advocates say that osmotic technology has virtually unlimited potential, but skeptics question the feasibility of this type of power generation due to its extraordinary expense. Some experts say that tidal power is more promising as a possible solution to the world’s energy crisis.

The project has been under development since 1997, and Starkraft hopes to achieve commercial status with the osmosis generator between 2015 and 2020. The test project has taken a total of 100 million crowns (10.7 million U.S.) in the project since its inception, in addition to 50 million crowns it received from Norwegian and EU funds.

View a previously written post by Mouli Cohen about energy