Removal of the offshore substation and its substructure to shore.
What it costs
About £12 million for a 450 MW floating offshore wind farm.
Who supplies them
Likely to be the same as the offshore substation installers.
Decommissioning plans may define specific requirements for removal of components below the mud line which may then drive the choice or design of offshore substation foundation or floating substructure, and installation methods.
The process is likely to be a reverse of the installation process. Fixed offshore substations will be dismantled using a large vessel. It may prove cheaper to cut the structure into sections to enable a series of smaller lifts that can be undertaken by a lower cost vessel. Floating offshore substations will be towed back to port for decommissioning.
In some cases, there will be a market for reuse of refurbished electrical components.
If the remaining life of the substation, after refurbishment, is sufficient, the substation could be left in-situ and reused for a repowered wind farm of the same capacity.