Figure 83 Wind turbine decommissioning operations at Utgrunden offshore wind farm, courtesy of Ziton/Vattenfall.
Function
Complete removal and shipment to shore of turbine rotor, nacelle and tower.
What it costs*
Around £105 million for a 1 GW offshore wind farm.
Who supplies them
Turbine installation contractors such as A2Sea/GeoSea (DEME Group), Seajacks and Van Oord Offshore Wind can provide turbine decommissioning.
Likely also other offshore operators will enter the space, including players with offshore oil and gas decommissioning experience.
Key facts
The process will be a reverse of the installation process, such as individual blades being removed, then hub and nacelle then finally tower.
In some cases where it is determined that the remaining life if sufficient, there will be a market for reuse of second-hand components, either as spares for other operating wind farms or possibly for re-installation elsewhere.
Similar lifting frames and arrangements will be used at installation to enable work in the largest envelope of weather conditions. For complex lifting operations, the same level of planning and health and safety management as at installation is required, with the added assessments and method statements to deal with the risks of damaged components or seized interfaces.
In general, the removal process may be quicker than for installation because minor damage to components will be less critical. If components are to be recycled rather than reused, then in some cases less care needs to be taken to preserve the delicate aerodynamic surfaces and the condition of other components, potentially enabling the use of different equipment or enabling operations in a wider operating environment.
Many turbine manufacturers are developing composite technologies that allow blades to be recycled. This will help reduce the impact of their disposal.