Function
OMS ports provide facilities from which long-term OMS activities are carried out – such as jetties or quaysides for CTVs and SOVs, warehouses, workshops and offices which support major repairs.
Who is involved
The wind farm operator will establish OMS port facilities during the installation process, as many support vessels active during the operational phase will operate from local ports. The wind farm owner will typically occupy quayside facilities, operating on a long-term lease with the owner of the port infrastructure.
Key facts
Typically, wind farm owners will 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 will 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. Port facilities are required to be flexible to accommodate variable demand with maintenance and service campaigns and site activities. Ideally, the warehousing and logistics buildings are close to the quayside to minimise the time loading support vessels. 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.
A 1 GW wind farm may employ up to 100 people onsite, of which about half will be turbine technicians The availability of skilled and experienced technicians is a crucial factor in the successful operation of an offshore wind farm for wind farm owners and operators.
OMS facilities need 24/7 access, 365 days a year. As well as the port facility, operators will use remote land-based support, such as specific engineering advice and support, performance monitoring and 24/7 control room monitoring. Each support vessel will need a berth of up to 30m. A 1GW wind farm may require the operation of between four and seven vessels, depending on the distance from the wind farm to shore and the maintenance and service strategies chosen, although up to 10 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.
OMS 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 OMS technicians.
Notable differences for floating
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.
If suitable OMS ports are not available for floating offshore wind, floating offshore wind turbines need to be moored in storage areas outside of the OMS port and serviced using a jack-up crane vessel.
Ideally all ports would be as close as possible to the floating offshore wind farm. In practice they are generally:
- OMS ports using CTVs: generally, within 40 km.
- OMS 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.
