O&M ports provide facilities from which long-term O&M activities are carried out – such as jetties or quaysides for CTVs and SOVs, warehouses, workshops and offices – and which support major repairs.

What it costs

About £180,000 per annum for a 450 MW floating offshore wind farm.

Who supplies them

Any port with the necessary facilities, located within a suitable distance of the floating offshore wind farm, could become an O&M port. Aberdeen and Peterhead are the first in the UK used to support floating offshore wind farms, which service Kincardine and Hywind Scotland respectively.

There are expected to be a smaller number of major repair ports as these have more specific requirements. The Port of Nigg, for example, has suitable facilities and is well-located to support floating ScotWind projects.

The Port of Peterhead which is being used as the operations and maintenance port for the Hywind Scotland project. Image of Peterhead Port courtesy of Camtech Engineering. All rights reserved.
The Port of Peterhead which is being used as the operations and maintenance port for the Hywind Scotland project. Image of Peterhead Port courtesy of Camtech Engineering. All rights reserved.

Key facts

O&M ports for floating offshore wind farms are expected to be similar to those for fixed, whether using CTVs or SOVs.

Typically, wind farm owners look to use the nearest port that meets its specifications to minimise transfer times and reduce the risk of time being lost due to bad weather. Nevertheless, owners typically competitively tender the contract for the provision of port services. For wind farms further from shore, the use of offshore accommodation and other facilities (possibly shared with other wind farms) becomes more attractive.

Port location is critical. Far from shore port requirements differ from a wind farm that is operated using CTVs and workboats only.

Tow-to-port maintenance almost always requires a different port as ballasted semi-submersible floating substructures have drafts of 15 to 20 m. A construction base port for floating offshore wind projects could have the depth requirements and facilities to do this work, such as quaysides and cranes (see I.8 for further information).

If suitable O&M ports are not available for floating offshore wind, floating offshore wind turbines need to be moored in storage areas outside of the O&M port and serviced using a jack-up crane vessel.

Safe means of transfer onto vessels is needed. This often requires the installation of pontoons to ensure a level access route in all tidal conditions.

Each support vessel needs a berth of up to 30 m. A 450 MW wind farm may require the operation of two or three vessels, depending on the distance from the wind farm to shore and the maintenance strategies chosen, although up to five berths may be specified in order to provide capacity for peak periods. Uninterrupted access requires the availability of a non-drying harbour with minimal tidal restrictions.

O&M port facilities required include:

  • Jetties for CTVs, with approximately 35 m per CTV, depending on the size of CTV used, and a minimum draft of 3 m, often with 2 t SWL telescopic boom jetty cranes
  • Quaysides for SOVs, with approximately 100 m quayside per SOV and minimum draft of 7 to 8 m.
  • Warehouses for spare parts
  • Workshops for work such as sorting equipment brought back from site, kitting of parts and equipment to go to site, and minor refurbishment
  • Office buildings to house the operations control centre and other project operations staff, and
  • Convenient access for O&M technicians.

Ideally all ports would be as close as possible to the floating offshore wind farm. In practice they are generally:

  • O&M ports using CTVs: generally, within 40 km.
  • O&M ports using SOVs: generally, within 200 km.
  • Repair ports: could be a long way from the wind farm site but are expected to be used infrequently.

What’s in it

Guide to a Floating Offshore Wind Farm