Removal or making safe of the infrastructure of a floating offshore wind farm at the end of its useful life, plus disposal of equipment.

What it costs

About £66 million for a 450 MW floating offshore wind farm (gross, excluding any resale value of equipment removed).

Who supplies them

Contractors will be similar to those used for installation.

It is likely that other offshore operators will also enter the space, including firms with offshore oil and gas decommissioning experience.

Key facts

At the end of the initial design life of a floating offshore wind farm, there are a number of options:

  • Extend the operational life of existing assets through a programme of risk assessments, inspections, addressing regulatory aspects, and component replacement.
  • Repower the site with new turbines, which are expected to be larger. This requires decommissioning the existing floating offshore wind turbines, mooring lines, and array cables. It could be possible to extend the life of electrical transmission assets.
  • Fully decommission the site.

Properly financed decommissioning plans typically are required as part of planning approval to construct the floating offshore wind farm. In practice, permission is likely to be sought to deviate from decommissioning plans as the sector’s decommissioning techniques mature. The UK Government acts as decommissioner of last resort.

Decommissioning of installed floating offshore wind turbines will require complete removal of the floating offshore wind turbine and its mooring system. The process for decommissioning anchors depends on the technology adopted and its sea bed connection.

For nacelle components, towers, and steel floating substructures the potential for recycling is considerable. There is no established process for recycling composite materials such as those used in the blades. Several manufacturers are developing new composite materials and processes to enable blade materials to be reused.

Careful planning is needed to ensure that hazardous materials, such as the oil used in transformers, are not spilled.

Environmental surveys will typically be required before and after decommissioning, along with post-decommissioning management of the site in line with the Energy Act 2004.

Guide to a Floating Offshore Wind Farm