| dc.description.abstract | Operation and maintenance of floating wind turbines are a major cost and account for approximately 20% of the cost of a floating wind turbine over its lifetime. Since floating wind turbines are relatively new in the market, there is little information available on how to perform the operation and maintenance of an offshore wind farm. Floating wind is a market that is constantly evolving and is a focus area in Norway as well as in other countries. This assignment looks closer at the subsea maintenance work that needs to be carried out on the new Utsira Nord park that will be completed in the coming years. It also looked at the time it takes to carry out such an inspection in order to establish a basis for calculating the cost.
Interviews with key personnel in the offshore wind industry, literature searches, and close collaboration with DeepOcean indicated that inspections to define deviations would be the method used rather than planned maintenance work. The inspections would be used to provide an overview of the components under water and then assess whether to carry out repairs or maintenance work. The assignment therefore took a slightly different turn than planned, with a checklist for inspections and a time frame for how long an inspection of a wind turbine would take.
Inspection intervals for floating wind parks were set at every two years, during which a general visual inspection of all components located underwater would be carried out. If deviations are found during the general inspection, a more specific inspection or possible repair would need to be considered. To inspect all components underwater, it will take about 62 hours per turbine, excluding mobilization and demobilization of equipment on the vessel. If an inspection is to be carried out on a single wind turbine, this will include mobilization and demobilization and will cost 5.625.000NOK. If multiple wind turbines are taken while the boat is already mobilized in the field, it will cost 2.583.333NOK per additional wind turbine.
Through data collection and interviews, it was clear that new technological solutions such as autonomous boats and underwater drones would create a great advantage for efficiency and cost-effectiveness for floating wind parks. Sensors could also be used so that there is an overview of the condition and then the windfarm can be less dependent on visual inspection. | |
