Parkwind, Heerema Marine Contractors and MHI Vestas have announced plans to use a floating vessel rather than a jack-up to install the wind turbine generators on the Arcadis Ost 1 offshore windfarm
The decision to install the turbines for the German offshore wind project from a floating vessel, rather than a jack-up, as is usually the case in the industry, follows a year-long joint development project between developer Parkwind, shipowner Heerema Marine Contractors and MHI Vestas Offshore Wind, who will supply the V174-9.5MW turbines for the project.
Considering the challenging soil conditions at the Arcadis Ost 1 site – which would have complicated the use of a jack-up which has to lower its jack-up legs to the seabed – Parkwind looked at possible alternatives to conventional installation techniques. In co-operation with Heerema Marine Contractors and MHI Vestas, a floating installation technique was developed.
The project partners said the innovative installation technique has two unique advantages – it avoids the vessel having to establish contact with the seabed, reducing operational risks; and it should significantly reduce the time it takes to install a turbine. This will reduce the levelised cost of energy associated with the project.
The vessel will transport all of the turbine components on deck, including a dummy tower that will provide a stable platform on the vessel on which to assemble the nacelle and turbine blades.
The first step in the installation process will see the wind turbine tower lifted onto a pre-installed foundation. Next, the nacelle will be lifted onto the dummy tower and the blades will be attached.
The completed rotor nacelle assembly will then be lifted from the installation vessel onto the tower.
Parkwind co-chief executive Eric Antoons said, “Taking turbine installation based on a floating vessel from theory to practice is a major step forward for the offshore wind industry.”
Heerema Marine Contractors chief executive Koos-Jan van Brouwershaven said the company used its simulation centre to visualise the process, including crane and vessel controls and environmental conditions.
The shipowner did not indicate which vessel it planned to use for the German project, but in 2018 it completed its first turbine installation project using the dynamically positioned heavy-lift vessel Aegir.
That project saw Aegir install the Delft Offshore Turbine (DOT) on a previously installed monopile using a slip joint connection.
The DOT wind turbine was installed on Eneco’s Princess Amalia offshore windfarm off the coast of IJmuiden, the Netherlands. The turbine was picked up in a single lift by Aegir, direct from the quayside at Sif Rotterdam and transported to the windfarm.
The fully assembled turbine was installed by the vessel in dynamic positioning mode. Installation was completed in less than an hour, which is significantly quicker than installation using conventional techniques.
The company also owns a new vessel, Sleipnir, a new-generation semi-submersible crane vessel with a pair of revolving cranes that can lift 20,000 tonnes in tandem, and has said it sees opportunities for the vessel in the offshore wind and oil and gas sectors.