At the moment the prototype plant, located on the banks of the Oslofjord, generates just 4 kilowatts – enough to power an electric kettle, which is exactly what was done at the grand opening graced by Her Royal Highness Crown Princess Mette-Marit of Norway. The owner plans to test the technology to pave the way for an industrial scale plant to be constructed in a few years.

Both Statkraft and Norwegian officials are optimistic about osmotic power, saying its potential is huge. Such plants can be built anywhere where fresh and sea water mix, namely on every river running into a sea. The company estimates that salinity power could eventually provide around one tenth of Norway's electricity needs. The only waste product of an osmosis power plant is “brackish” (slightly salty) water. And it is renewable too.

However, scaling up the technology while making it economically feasible may prove difficult, skeptics say. Membranes for osmosis applications are still quite expensive, and it may take a dozen years before the prices drop low enough for power generation. Also, membranes can get clogged quickly by microscopic algae and dirt particles from rivers, which would degrade the plant’s efficiency.