Since the demand for renewable energy sources on a global scale has increased substantially over the past few years, a great number of businesses have made investments in this industry and are doing their utmost to make additional developments and discoveries in the field of wind energy. Wind farms, both onshore and offshore, are considered to be key contributors to the production of sustainable energy because they offer significant benefits, including a reduction in the negative effects on the environment and the production of harmful gases. The purpose of this thesis was to analyse and explore the lifecycle activities of a wind farm, in order to determine the failure modes, failure effects, and failure consequences of the critical components, as well as the strategies that can be used to counteract these failures. As many wind farms are reaching their end of life, so this thesis also focused on the techniques and strategies that can be done before dismantling, The thesis also includes a reliability analysis, failure mode effect and criticality analysis of generator and gearbox of wind turbine, and also lifecycle cost analysis of an offshore wind farm. These studies improved our knowledge of offshore windfarm operations, maintenance strategies and give a brief information about cost reduction techniques. Several steps from maintenance strategies based on NORSOK Z-008 and ISO-14224, as well as knowledge gained from research papers and interviews with engineers in moreld, were implemented to achieve the goals of this thesis.