Statkraft plans to build a 'Stage II' pilot osmotic power plant next year as part of its R&D investment in new membrane technology, and is looking to scale-up tests further in the next two to five years, IWP&DC has been told.

The Norwegian electric utility will have invested approximately NKr100M (US$18.5M) on Stages I & II of the osmotic power R&D work by the time the new plant is built and operated for the planned two-year trial, a spokesman said. But the trial equipment is as yet very small in power capacity terms, the ‘Stage I’ kit being described as being as big as a car battery and tested over 2004-6, and the ‘Stage II’ plant planned to be only 2-4kW.

Primarily, the R&D efforts are to advance the membrane technology and not scale up capacity at present, said the spokesman. The patented membrane system is based on a combination of rubber, fibre and other materials. Further details were not immediately available.

The osmotic power system is based on the actions of fresh water and sea water: they diffuse, unless a boundary is placed that establishes a pressure gradient, in effect letting the fresh water ‘press’ on a flexible membrane and hence on the sea water. By having the sea water held in defined channels, the exerted pressure results in some exit flow, and with this action on sufficient numbers of channels the cumulative flow could be used to generate power, the spokesman said.

He added that the work was yet to be done on how the flow would be utilised to generate power, and the type of turbine that could prove effective.

In a statement, Stakfraft said the global technical potential for osmotic power production is estimated at approximately 1600TWh globally of which 200TWh is in Europe, including 12TWh in Norway – equivalent to 10% of present electricity production.

The R&D is supported by The Research Council of Norway. In total, the osmotic power research work has been underway for a decade, Statkraft said.