DOWEC CONCEPT STUDY; EVALUATION OF WIND TURBINE CONCEPTS FOR LARGE SCALE OFFSHORE APPLICATION

The economics of offshore wind energy may probably be improved by application of very large wind turbines in large wind farms. However a gradual upscale of an existing wind turbine design towards 5 or 6 MW is not as straightforward as it may seem. The goal of the Dutch Offshore Wind Energy Converter (DOWEC) Concept Study is to make an inventory of all wind turbine concepts in order to select the most optimal concept for a 5 to 6 MW offshore wind turbine. In the first phase the DOWEC Concept Study aims at the choice of the optimal wind turbine concept. The wind turbine will not be treated as an isolated system. Designs of different wind turbine concepts will be evaluated as an integral part of the complete large-scale offshore wind farm. All significant properties like the structural loads, the power performance, the system reliability, the costs of the electric infrastructure, maintenance costs and installation costs will be determined for the optimised designs. A quantitative ranking will then be made based on the cost of generated energy. Furthermore qualitative criteria like development risk and market potential will be taken into consideration when finalising the choice of concept. The DOWEC concept study serves as a first design phase. The overall DOWEC development comprises of the design, the construction and the prototype testing. Marine testing of the 5 to 6 MW turbine is planned in 2008. Onshore testing of a 3 MW research and development prototype is scheduled for the end of 2001. This paper describes the approach and the current achievements of the project.