Areva Wind offers a range of service packages depending typically on the wind farm’s distance to shore and the number of turbines deployed. The company’s Onshore Service Concept accommodates service technicians and a complete spare parts stock. Every intervention starts from the onshore service base working out of a nearby harbour and airport.
For wind stations located at a medium distance from shore and with a medium turbine count, Areva’s Partly Equipped Substation Model comes into play. Part of the spare parts stock is shifted to the offshore substation, which also has temporary and emergency accommodation facilities. When an intervention is needed, two intervention teams will travel offshore. One team accesses the turbine for fault clearance, while the other waits on the substation in case another operation is necessary. This model ensures fast reaction times and reduced transport costs, Areva says.
For wind stations far from shore and with a larger number of turbines, Areva offers its Fully Equipped Substation Model, whereby the complete onshore facility is shifted offshore, with the aim of eliminating expensive and time-consuming travel. This model will be used for the 80-turbine Global Tech I wind farm, which is 110km from Germany’s North Sea coast. The company plans to use a floating hotel for offshore service staff. After testing this at the Alpha Ventus wind farm, the company says it is in the process of selecting the right vessel. It says the vessel will need capacity for 60 service technicians for scheduled annual maintenance.
The benefits of a floating hotel vessel located within the wind farm throughout the year are the same as those of the fully equipped substation model. They include the ability to use short weather windows, fast reaction times and low logistics costs. These vessels need to get back to sheltered waters, however, if high waves are threatening.
Cost estimates for offshore turbine O&M are €0.25-0.45 million per turbine per year; this is not Areva’s own figure but the company considers it sensible. The exact cost will depend on, among other factors, contract scope, distance to shore, number of turbines and local regulations.
Areva pinpoints long-term logistics partnerships and synergies among wind farm operators as ways to reduce costs. It has made a framework agreement for helicopter usage spread over different wind farms. Clustering farms could provide an opportunity for joint logistic solutions.
Turbine design is also crucial. Areva’s 5MW offshore machine has 129 redundant components, meaning, it says, that "any operating failures are unlikely to lead to a turbine shutting down completely".
Areva employs 70 service technicians and 40 other staff in offices in Bremerhaven and Emden, the latter being the service base for its six turbines at the Alpha Ventus offshore station. For the moment, the company does not plan to provide offshore O&M to non-Areva projects.