Norway opened on Tuesday the world's first osmotic power plant, which produces emissions-free electricity by mixing fresh water and seawater through a special membrane. Osmotic power, which can be located anywhere where clean fresh water runs into the sea, is seen as more reliable than more variable wind or solar energy. Since many cities are near mouths of rivers, plants could easily connect to existing grids. Osmotic energy is based on the widespread natural phenomenon of osmosis, which allows trees to drink through their leaves and plays on the different concentration levels of liquids. When freshwater and seawater meet on either side of a membrane - a thin layer that retains salt but lets water pass - freshwater is drawn towards the seawater side. The flow puts pressure on the seawater side, and that pressure can be used to drive a turbine, producing electricity. The point of osmotic power is “to use power not against nature but with nature,” summed up Sverre Gotaas, in charge of innovation and growth at Statkraft. Contrary to other renewable energy sources such as wind and solar power, osmotic power produces a stable electricity flow regardless of weather conditions. Osmosis has been used by industry to desalinate seawater, but Statskraft's prototype at Tofte marks the first time it has been used to produce energy. Inaugurated Tuesday by Norwegian Crown Princess Mette-Marit, the plant will for now produce just enough electricity to power a coffee-maker. But it could prove to be a great potential clean, environmentally friendly power source. Osmotic power is one of a number of experimental renewable energy projects betting on a expected climate pact in Copenhagen next month unlocking funding and subsidy schemes that will help develop the technology and slash production costs. State-owned utility Statkraft's prototype plant, which for now will produce a tiny 2-4 kilowatts of power or enough to run a coffee machine, will test and develop osmotic technology. The plant is driven by osmosis that naturally draws fresh water across a membrane and towards the seawater side. This creates higher pressure on the sea water side, driving a turbine and producing electricity. “While salt might not save the world alone, we believe osmotic power will be an interesting part of the renewable energy mix of the future,” Statkraft Chief Executive Baard Mikkelsen told reporters. Statkraft, Europe's largest producer of renewable energy with experience in hydropower that provides nearly all of Norway's electricity, aims to begin building commercial osmotic power plants by 2015. The main issue is to improve the efficiency of the membrane from around 1 watt per square metre now to some 5 watts, which Statkraft says would make osmotic power costs comparable to those from other renewable sources. In developing the membranes Statkraft cooperated with US space agency NASA which is interested in high-tech membranes for recycling water for astronauts. “We're primarily interested in osmotic power membranes for life support applications in future space endeavors,” said Michael Flynn, head of advanced water recycling technology at NASA, which cooperates with Statkraft on membrane development. Flynn said osmotic power would help create a viable market for semi-permeable membranes and drive advances in technology. Statkraft said that when it began researching osmotic power in the late 1990s, membrane efficiency was around 0.01 watt per square meter and latest technology is at 2-3 watts. The plant will change to the more efficient material after system checks. The prototype, on the Oslo fjord and about 60 km (40 miles) south of the Norwegian capital, has about 2,000 square meters of membrane inside dozens of plastic tubes that limit the corrosive effect of salt. Membranes are cleaned daily. Future full-scale plants producing 25 MW of electricity, enough to provide power for 30,000 European households, would be as large as a football stadium and require some 5 million square meters of membrane, Statkraft said. The full-scale model will require 25 cubic meters of fresh water per second, or the equivalent of about 75 bath fulls, as well as 50 cubic meters of sea water. Once new membrane “architecture” is solved, Statkraft believes the global production capacity for osmotic energy could amount to 1,600-1,700 TWh annually, or about half of the European Union's total electricity demand. Europe's osmotic power potential is seen at 180 TWh, or about 5 percent of total consumption - which could help the bloc reach renewable energy goals set to curb emissions of heat-trapping gases and limit global warming. A summit in Copenhagen next month is due to agree on a UN pact to combat climate change by promoting clean energies and a shift from fossil fuels that a UN scientific panel blames for stoking heatwaves, floods, droughts and rising seas. “The fact this plant works indicates that with normal technology development this is fully feasible,” Rasmus Hansson, head of the World Wildlife Fund in Norway, told Reuters. “It has additional advantage of being based on resources that are evenly disturbed throughout the world, but it will take an international agreement to make this type of technology accessible to poorer countries.”
