Norwegian utility Statkraft said October 3 it would build the world’s first prototype osmotic power plant in 2008, using osmosis to create water pressure that drives a hydropower turbine.
Osmotic power uses the process of osmosis, the movement of water across a partially permeable membrane. In an osmotic power plant, sea water and fresh water are separated by a membrane. The sea water draws the fresh water through the membrane, increasing the pressure on the sea water side. The increased pressure is used to produce power.
Statkraft said the 2- to 4-kW project would be built at a plant of paper pulp manufacturer Sodra Cell Tofte at Hurum in Buskerud, Norway. It said the seaside site would provide fresh water and sea water as well as a link to established infrastructure.
The utility said the global technical potential for osmotic power production is estimated at 1,600 terawatt-hours, including 200 TWh in Europe and 12 TWh in Norway, or 10 percent of Norway’s current power production.
Statkraft, which has been studying osmotic power since 1997, said its decision to develop the Hurum project will boost its investment in the technology to 100 million kroner (US$18.43 million).
“Osmotic power is a very promising technology in which we are global leaders,” Statkraft Chief Executive Bard Mikkelsen said. “It is clean and emission-free, and could become competitive within a few years.”
The �pressure retarded osmosis� process can increase pressure to a theoretical maximum of 26 bars, Statkraft said, which it said is the equivalent of a water column 270 meters high.
In practice it said, one-third of the flow produced would run through a turbine-generator and be returned to the sea. The other two-thirds would return to the pressure exchanger to pressurize the feed of seawater. It said to optimize a power plant, the typical operating pressure is in the range of 11 to 15 bars, equivalent to a head of 100 to 145 meters in a hydropower plant.