60 ARTICLE / MAKALE as infrastructure, topography and natural environment. During operation, membranes are cleaned regularly in order to maintain their performance. The cleaning agents are similar to those that are used in drinking water plants and are non-toxic and environmentally friendly. The cleaning agents will be recycled in the plant to reduce cost and emissions. in this way it is possible to avoid harmful emissions during the life cycle of the plant. Considering its CO2-free power production and compact size the environmental performance of osmotic power would be very good compared to most renewable energy sources. Economics For a commercial company like Statkrart SF it is absolutely essential that technology development provides new attractive business options. Starkraft has a vision or being a European leader in environmentally friendly energy and the efforts to develop salinity power is part of that strategy. As of today the company is the second largest hydropower producer in Europe and involved in several large wind power developments. Compared to other renewable energy sources, like hydropower, biomass and onshore wind power where the best sites and resources already are developed, osmotic power has a large unexploited potential that is fairly easily accessible. The energy production is stable and predictable, and unlike wind power and solar energy osmotic power plants can be designed to operate as base load power suppliers. Given its excellent environmental performance and CO2-free power production osmotic power should qualify for green certificates and other supportive policy measures for renewable energy. Assuming realistic membrane performance and cost data, this form of power generation could be competitive with other emerging renewable energy sources such as off-shore wind power and biomass power generation. Provided the successful commercial development of osmotic power, the demand for membranes will increase substantially compared to present global production capacity and the construction of power plants will sustain a massive expansion of the membrane industry over a period of several decades. For each MW of generating capacity about 200 - 250 000 m2 of membrane will be required. Osmotic power would then contribute both to security of energy supply, profitable green power production and the strengthening of several industries. Current work and objectives in 2001 Statkraft SF together with ICT-POL of Portugal, SINTEF of Norway, GKSS-Forschungszentrum of Germany and Helsinki University of Technology of Finland joined forces in a 3.4 million Euro European Union research project with the objective of developing suitable membranes for PRO power. The partners are making steady progress in membrane performance and the objective of finding a membrane suitable for competitive power production seems within reach. Although traditional reverse osmosis membrane materials are thought to be functional alsa in ENERJİ & KOJENERASYON DÜNYASI osmosis, a significant effort is necessary to develop membranes and analyze their performance in this new appli cation. A major goal of the project is to develop a membrane that has a power production capacity equivalent to 4 W/m2 or more. This is a very ambitious goal and represents a many-fold increase in power density compared to previously tested membranes. The membranes should alsa have a low production cost and a long lifetime in order to sustain competitive power production in the PRO plant. The membrane is packed into compact modules which are placed inside pressure vessels. The design of such modules is essential for the efficient utilization of the power generation capacity of the membrane. Furthermore the partners will perform a feasibility study to establish the technological and economic potential for salinity power in a global renewable energy scenario. The research project headed by Statkraft is the only major research activity in osmotic power exploitation world-wide. The efforts of this world leading consortium are expected to establish the necessary theoretical and practical know-how at a pre-engineering level for the future commercialization of the technology. Even if membrane development is expected to continue for several years to come, the present efforts will establish the competitiveness and performance of a PRO power plant in operation. Progress to date Prototype membranes with high power production capacity have been produced. Simple experimental tesis show that the best membranes have a potential for specific power well above the progress plan and the prototypes arc better than any other membrane of this type. Experimental and theoretical analysis of membranes and membrane performance have not identified any fundamental obstacles for further increase in membrane performance and it is reasonable to assume that the membrane performance objective can be achieved in the near future. On the 6 June 2003 Statkraft and research partners opened the first osmotic power testing facility in the town Sunndolsora on the Norwegian west coast. in the initial phase the laboratory is being used for small scale resting of membrane samples in natural non-purified river water and seawater while scale up for testing of real size modules will commence within the next months. The opening of the field lab demonstrates Statkraft and partners commitment to the development of this technology. Although significant challenges remain before the technology is commercially available the progress over the lası few years has been impressive and encouraging. Continued efforts in membrane development must be followed by confirmation performance in long term testing under real operating conditions, then follows progressive scale-up to pilot plant dimensions before the first semi-commercial units can be built. Provided progress continues at the present rate and hearing in mind typical development schedules for similar technologies, market introduction of osmotic power technology can be expected in about 5 to 1 O years. Source: REFOCUS 11/12 2003
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