Norwegian state-owned electricity company Statkraft AS, which is particularly active in the renewable energy sector, has been researching the potential of osmotic power for more than 10 years. Statkraft developed the prototype plant with the help of backing from Enova SF, a public enterprise owned by the Royal Norwegian Ministry of Petroleum and Energy.
The prototype plant will enable Statkraft to gain a clearer picture of translating the technology into a commercial-scale plant. Statkraft sees the prototype as a necessary step in the realization of the full potential of the technology.
The basic principle of an osmotic power plant is based on the natural process known as osmosis, which is the transport of water through a semi-permeable membrane.
Such a membrane separates fresh water and seawater in the osmotic power plant. The salt molecules in seawater draw fresh water through the membrane, producing pressure on the seawater side of the membrane.
Despite the simplicity of the process, the pressure generated by the movement of fresh water through the membrane is enough to produce significant energy. The power source is entirely free of emissions, noise and pollution. An osmotic plant can, in theory, be located wherever fresh water runs into the sea. Plants can also be located underground if desired, such as in building basements or underneath public parks. A plant the size of a football stadium has the potential to provide electricity for about 10,000 homes.
The Norwegian prototype has been constructed at a pulp mill operated by Södra Group at Tofte, taking advantage of good supplies of fresh water and seawater and the existing plant infrastructure.
The osmotic principle was first brought to the attention of Statkraft in the 1990s by the research group SINTEF Group, Scandinavia's independent research organization. The prototype plant has been developed in cooperation with research and development organizations in many countries and has attracted attention both within Norway and overseas.
The potential for osmotic power as a source of clean, renewable energy is impressive. The global potential has been estimated at about 1,600 terawatt-hours (TWh), with the figure for Europe close to 200 TWh. For Norway alone, the estimate is that 12 TWh could be generated by osmotic power, representing about 10% of Norway's current power production.