Function
The construction port is the base for pre-assembly and construction of the wind farm. Separate locations may be used for feeding foundations and the wind turbines to a wind farm. Location is critical as it affects the time spent in shipment and sensitivity to weather windows.
Who is involved
The construction port services are conducted by specialist suppliers contracted by the developer. Infrastructure investment will be required as there are no ports currently suitable in Ireland.
Key facts
Construction port requirements for a 1 GW project are typically:
- At least 8 hectares suitable for lay down and pre-assembly of product
- Quayside of length 200-300m length with high load bearing capacity and adjacent access
- Water access to accommodate vessels up to 140m length, 45 m beam and 6m draft with no tidal or other access restrictions, and
- Overhead clearance to sea of 100m minimum (to allow vertical shipment of towers).
Large areas of land are required due to the space taken when turbines are stored lying down on the ground.
Sites with greater weather restrictions or for larger scale construction may require an additional lay-down area, up to 30 ha.
Notable differences for floating
The construction port is where the floating substructure and the turbine are assembled. Inbound components are also marshalled and stored. Wet storage areas are required for the marshalling of floating substructures and for marshalling of assembled floating offshore wind turbines.
Construction port requirements for a 1 GW project are typically:
- Minimum of 20 ha suitable for lay down and pre-assembly of turbines
- Minimum of 12 ha of wet storage for storing floating substructures prior to final assembly, and for storing assembled floating offshore wind turbines prior to tow-out
- Quayside length of around 500 m with load bearing capacity ranging from 40 to 100 tonnes/m2 and adjacent access
- Quayside water depth of between 12 and 20 m to accommodate the draft of floating substructures and semi-submersible transport vessels
- Water access to accommodate delivery vessels for floating substructures and turbine components. These are up to 160 m length, 45 m beam and 6 m draft with no tidal or other access restrictions
- No air draft restrictions, to allow tow-out of assembled floating offshore wind turbines with tip heights of about 250 m, and
- As close as possible to the installation site to minimise the time to tow-out and sensitivity to weather windows.
Wet storage is required to temporarily store floating substructures delivered to the construction port before final assembly with the turbine at the quayside. This storage can also be used prior to tow-out of the assembled floating offshore wind turbines with seafaring AHVs.
Separate ports may be used to fulfil the functions of a construction port for the floating offshore wind turbine, the mooring system and the cable system.
Different construction ports may be used to feed floating substructures and wind turbines, separately, to a wind farm if new methods are introduced for final assembly of turbines directly onto moored floating substructures at site. This would require semi-submersible or capable monohull heavy lift vessels to install the turbine as site water depths are not suitable for jack-up installation vessels.
