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Providing cost effective offshore wind park developments by improved logistics and installation services of present and next generation offshore wind turbines

Ocean Wind Services has developed a semisubmersible crane vessel (SSCV) intended to be used mainly for the renewable energy industry as a wind turbine installation vessel (WTIV). The vessel is equipped with two large heave compensated cranes of 2 x 2500 T capacity (5000 T in tandem lift), allowing for efficient installation of present and future generations wind turbines.

The WTIV will typically remain stationed at the offshore wind farm sites. It will receive wind turbine generator components transported by feeder vessel(s) and transfer them to the WTIVs deck using its heave-compensated cranes.

This approach offers several benefits:

  • Time and cost savings of offshore windfarm developments.
  • Reduction in the required size of marshaling sites, and in some cases, elimination of the need for such sites. Feeder vessel(s) can directly pick up wind turbine generator components from supplier sites, thus avoiding intermediate transfers to marshaling sites along with related lifting and handling operations.
  • Lower fuel consumption during the transportation of wind turbine generator components, resulting in environmental benefits.
  • Simplified load transfer to the WTIV by utilizing its heave-compensated cranes for tandem lift operations when transporting wind turbine generator upper tower sections horizontally.

Wind turbine generator components (tower sections, nacelle, and blades) will be fully assembled onboard the WTIV and then installed as a single unit on top of substructures.

  • This process reduces interaction with substructures from days to hour(s).

The WTIV is equipped with four legs that are deployed to the seabed when installing bottom fixed wind turbines. The weight of the vessel and cargo is mainly supported by the displacement of the WTIV. The legs are only preloaded to take the loads induced by waves.

  • Wave-induced motions eliminated.
  • Minimal disturbance to the seabed.
  • Significant reduction in requirements for seabed survey and preparation.
  • Pinning and recovery of the legs are less weather-sensitive compared to conventional jack-up WTIVs.
  • Eliminates risk of fatal accidents in case of accidental punch-through of jack-up legs.
  • Safe operation in earthquake exposed areas.

The semi-submersible WTIV can also be used for installation of floating wind turbine generators offshore in deep water locations by deploying a 3D compensated handling system of fully assembled tower, nacelle, blades to be positioned/installed on floating substructures.

  • Same logistic benefits as for installation of bottom-fixed wind turbines, as described above.
  • No need for onshore /inshore assembly site with savings on costs and environment.
  • Weight savings on floating substructures.
  • Shorten the windfarm development period and earlier production of electricity.