The New York Times
The world’s first osmotic plant opened today in Tofte, Norway, harnessing the saltiness of the sea, along with freshwater, to produce electricity through a polymer membrane.
The project, run by Statkraft, a Norwegian renewable energy company, is a tiny pilot, generating up to 4 kilowatts of electricity for the grid — or roughly enough to run a coffee maker.
But while Stein Erik Skilhagan, the vice president of osmotic power at Statkraft, acknowledged that the project marked a small start, he said that he hoped to develop it quickly. The concept, according to a question-and-answer page on Statkraft’s Web site, holds the potential to provide half of Europe’s power and is a baseload resource that could run all the time.
“We really need to increase the speed to bring this technology into the market,” Mr. Skilhagen said. “We should do this much faster than we did with solar power and wind power.”
The concept of osmotic power was thought up by an American professor, Sidney Loeb, in the 1970s. Mr. Loeb passed away last year.
As explained on Statkraft’s Web site, the process works in the following way:
Freshwater and saltwater are channeled into separate chambers, separated by an artificial membrane. The salt molecules in the seawater draw the freshwater through the membrane, causing the pressure on the seawater side to increase. This pressure is equivalent to a water column of 120 meters or, in other words, quite a significant waterfall. This pressure can be used in a turbine to make electricity.
The concept has been little explored since the 1970s — until now. Part of the reason, in addition to a growing push for renewable energy, has to do with membrane technology, Mr. Skilhagen said.
“The first membranes were really bad and really expensive,” he said. Now, partly due to their extensive use for reverse osmosis in desalination plants, the membranes, which are made from different kinds of polymers, have improved, he said.
Mr. Skilhagen said that the plant had cost about $7millon to $8 million to build and that Statkraft has put about $20 million into research on osmotic power. The concept has also received backing from the Norwegian government and the European Council, he said.
Research into osmotic power is also happening in the United States, according to Mr. Skilhagen, including at the University of Kentucky, Virginia Tech and the University of Texas.
Rick Stover, the chief technology officer of Energy Recovery, a California-based technology company that made the pressure exchangers for the Norwegian plant, said that the technology could theoretically be applied “wherever like a river comes close to the ocean.”
But it might also fit well near existing desalination plants, Mr. Stover suggested, because seawater from those plants is extremely salty, with two times the osmotic potential of regular seawater.
In addition, he said, if a wastewater treatment plant were near to the desalination site, an osmotic power plant could put a membrane between the salty seawater from the desalination plant and the treated freshwater from the wastewater plant.
That is clearly a long way off from a pilot that can power a coffee maker. Nonetheless, Mr. Stover said, “We’re really proud to be part of this ambitious pilot plant.”