After wind, sun, currents and tides, a company is preparing to make clean electricity by harnessing another natural phenomenon, the energy-unleashing encounter of freshwater and seawater.

Taking a step further in the planet's hunt for clean power, Norway is to unveil on Tuesday the world's first prototype of an osmotic power plant on the banks of the Oslo fjord.

The project is small-scale but could prove the great potential of osmotic energy.

Boosting the amount of energy obtained from water

The principle of generating blue energy by reverse electrodialysis

The energy generated in places where fresh water and salt water meet is known as blue energy. This is a relatively new but highly promising renewable energy source. Piotr Długołęcki of the University of Twente and the Wetsus centre of excellence for sustainable water technology has further refined the method that is most commonly used to generate blue energy in the Netherlands. This method produces three to four times as much energy as previous processes.