TOFTE, Norway — Norway unveiled the world's first osmotic power plant on Tuesday, harnessing the energy-unleashing encounter of freshwater and seawater to make clean electricity.

"While salt might not save the world alone, we believe osmotic power will be an important part of the global energy portfolio," the head of state-owned power group Statkraft, Baard Mikkelsen, told reporters.

Statkraft, which claims to be the biggest renewable energy company in Europe, is running the osmotic power plant prototype in a former chlorine factory on the banks of the Oslo fjord, about 60 kilometers (37 miles) south of the Norwegian capital.

Osmotic energy is based on the widespread natural phenomenon of osmosis, which allows trees to drink through their leaves and plays on the different concentration levels of liquids.

When freshwater and seawater meet on either side of a membrane—a thin layer that retains salt but lets water pass—freshwater is drawn towards the seawater side. The flow puts pressure on the seawater side, and that pressure can be used to drive a turbine, producing electricity.

The point of osmotic power is "to use power not against nature but with nature," summed up Sverre Gotaas, in charge of innovation and growth at Statkraft.

Contrary to other renewable energy sources such as wind and solar power, osmotic power produces a stable electricity flow regardless of weather conditions.

Osmosis has been used by industry to desalinate seawater, but Statskraft's prototype at Tofte marks the first time it has been used to produce energy.

Inaugurated Tuesday by Norwegian Crown Princess Mette-Marit, the plant will for now produce just enough electricity to power a coffee-maker.

But it could prove to be a great potential clean, environmentally friendly power source.

"It has very, very limited environmental consequences. It's only positive and it can be used in many places," Frederic Hauge of environmental organization Bellona told AFP, adding the development of osmotic power was "very exciting."

Because they produce energy from the encounter of freshwater and seawater, osmotic power plants could be installed almost anywhere where rivers flow into the ocean.

"Even countries that do not have oil, coal, or mountains will be able to produce their own energy," Rasmus Hansson, the head of the World Wildlife Fund in Norway told AFP.

"It is very nice when industry imitates nature," he added, lauding the decision by Statkraft and various Norwegian organizations to invest around 150 million kroner (17.9 million euros, 26.8 million dollars) of their own money in a "revolutionary technology."

According to advocates of the technology, an osmotic energy plant could be constructed near a water source, with an office building or shopping center built on top.

"We could imagine a plant in the basement of a shopping center, instead of a parking garage," Gotaas said.

The worldwide potential of osmotic energy is estimated at 1,700 terrawatt hours (TWh) per year, equivalent to half of the European Union's energy production.

But before osmotic energy can be profitable, a more energy-efficient membrane will need to be developed—a process that is being keenly watched by NASA which could use the technology for its space stations.

The most efficient membranes currently produce three watts per square meter, while a commercially viable one must produce five watts.

"This is possible, we believe in these figures," Gotaas said.

Statkraft hopes to start building the first commercial osmotic power plant, which would have a 25-megawatt capacity, enough to provide about 10,000 households with electricity, in 2015.