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New plant produces energy by mixing fresh water and sea water

30/11/2009

World's first osmotic plant opens, but commercial version will not be available for several years.

European renewable energy producer Statkraft this month opened the world's first power plant generating energy by mixing fresh water and sea water in Norway.

The energy is based on the natural phenomenon of osmosis, the transport of water through a semi-permeable membrane.  When fresh water meets salt water, substantial amounts of energy are released, which can be used to generate power.

At the osmotic power plant, fresh water and salt water are guided into separate chambers, divided by an artificial membrane. The salt molecules in the sea water pull the fresh water through the membrane, increasing the pressure on the sea water side. The pressure equals a 120 metre water column, or a significant waterfall, and can be used in a power generating turbine.

The plant is the culmination of more than a decade of research by the company into osmotic power generation. The prototype will have limited production capacity and is intended primarily for testing and development, but Statkraft aims to be able to construct a commercial osmotic power plant within a few years.

Osmotic power plants can, in principle, be located wherever fresh water runs into the sea; they produce no noise or polluting emissions and they can be integrated into existing industrial zones, such as the basements of industrial buildings. The global potential of osmotic power is estimated to be 1,600-1,700 TWh per annum, equivalent to 50 per cent of the EU's total power production.

Statkraft chief executive and president Bard Mikkelsen said: "New solutions to meet the climate challenges might be closer than we expect, which makes me confident that the future looks bright".