New Models for Maintenance of Offshore Wind Farms

Kristian R. Petersen

Research output: ThesisPh.D. thesis


Operations and maintenance (O&M) processes are important for keeping offshore wind turbines in operation. Costs related to such activities constitute approximately 30% of the lifetime cost of an offshore wind farm project. Currently, the offshore wind energy industry has shown a rapid increase in new installations, even though national subsidies ensure the return on the investment. Research seems to have focused mainly on the installation of new wind farms, an research on O&M has been deemed to be in its early phases. A study of literature showed that in order to properly manage the O&M of an asset, it is important to consider three decision-making perspectives: short-term operational, medium-term tactical, and long-term strategic. However, the main focus has been on day-to-day operational issues, which leaves no room for longer-term thinking. Through three research projects, one on each of the O&M decision-making perspectives, this study focused on how considering the short-, medium-, and long-term perspectives can support the cost of energy reduction for the offshore wind energy industry. For the short-term operational perspective, a case study on lean and modularisation was conducted. First, how lean can be instituted in an offshore wind farm was investigated. The research included investigations of how lean has contributed to the reduction of scheduled maintenance time as well as the increase of wind turbine availability. Based on field studies, seven types of O&M wastes related to offshore wind turbines were defined, from which findings from the case study on lean were analysed. In this analysis it is identified that Modularisation involving maintenance resources and tasks can be used to streamline operations and maintenance processes further. For the medium-term tactical perspective, a Reliability-Centred Maintenance analysis was performed on an electrical system in an offshore wind turbine in order to investigate how this concept can be used to develop tactical maintenance strategies for an offshore wind farm. From the analysis, two new maintenance strategies for a specific component that was causing a large amount of downtime were identified. Further analysis with the Reliability-Centred Maintenance concept helped determine the most appropriate maintenance strategy. In the final perspective, long-term strategic decisions were the focus. Asset Management and especially Asset Life-Cycle Management were studied using a case study. The case study analysis was used to generate strategies to help managers perform maintenance more proactively and to prepare the management of the offshore wind farm turbines for the future. Existing literature on Asset Life-Cycle Management has shown that such approaches should be multidisciplinary; however, previous attempts have mainly considered technical and economic aspects of the operation of assets. Thus, a truly multidisciplinary approach that includes technical, economic, customer, compliance, and organisational aspects was developed. The approach was tested on an offshore wind farm. The findings showed that the approach can help the asset owner identify possible future events that influence the assets both negatively and positively. Evaluating the events in a life-cycle plan may reveal how the asset owner can mitigate negative events, which can enable futureproofing of assets.
Original languageEnglish
Place of PublicationOdense, Denmark
Print ISBNs978-87-93192-83-6
Publication statusPublished - 24. Feb 2016


  • Offshore Wind Energy
  • maintenance
  • O&M
  • strategic maintenance
  • tactical maintenance
  • operational maintenance


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