Offshore wind energy has been considered as one of the best solutions among renewable energy sources for reducing dependence on conventional energy such as fossil fuels. However, the cost is still the major obstacle in expanding offshore wind energy comparing to other renewable energy sources. In order to address this obstacle and make offshore wind energy become more competitive in energy market, an effective solution is enhancing the efficiency of maintenance activity to reduce maintenance cost that contributes a large portion to total life cycle cost of offshore wind systems. In this study, an optimal approach for executing maintenance activities at offshore wind systems is proposed. Firstly, deterioration process of offshore wind system is analyzed through component’s reliability with respect to the effect of previous maintenance activity. After understanding the condition of wind system’s components, a maintenance scheduling and vessel routing approach is proposed with the aim of minimizing maintenance cost while ensuring the system’s reliability. Maintenance schedule in this study is formulated dynamically for single component, multiple components of a wind turbine, multiple wind turbines and multiple types of wind turbine under a variety of influential factors. To improve the robustness and accuracy of proposed approach, a numeral example with information from Taiwan is investigated. The experimental results show that by applying the proposed approach, maintenance duration can be reduced 24%-56%, vessel traveling distance also saves in a range of 52.50%-62.40%, which leads maintenance cost saving up to 15.15%-29.23%. Such that total maintenance cost is consequently obtained at optimal level.

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