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Industrialize Installation

Practice to date, in the offshore wind industry, is that foundation installation is performed mostly with jack ups and to some extent floating crane vessels. The objective of this project was to develop a technical and commercial feasible concept of a multipurpose and self-sufficient dynamic positioned (DP) mono hull installation vessel which was more commercially attractive than current jack ups. This would be achieved by driving down wind farm installation project costs.

A vessel design including all related deck equipment was established based on the requirements that it should be capable of installing complete wind turbines, the jacket foundations and piles based on a pre–piling operation. In this design process special attention was given to the motion behaviour of the pre-assembled offshore wind turbines during transport and their installation offshore. It was concluded that it was not feasible to do this installation operation with a floating mono hull vessel and the vessel design was therefore only focused on the jacket foundation and piling operations. The resulting design, including the required deck equipment, was then reviewed by several parties. Based on the insights gained during this process a design loop for an optimized version was started which incorporated the Mono Pile (MP) type foundations based on the market developments achieved since the start of the project. To find an optimum solution a comparison between floating installation and the jack up installation was made in which motion behaviour, workability, required operational times, CAPEX and OPEX factors where addressed.

The conclusion of the project is that a floating mono hull bespoke design for wind farm foundation installation could compete with jack ups; however, based on the investigated factors the differences are expected to be limited. No convincing differentiators when compared to jack ups presented themselves in the work completed by the project. It is expected that the most decisive factor for wind farm contractors/ vessel owners investing in a bespoke wind farm installation vessel is the ability to install offshore wind turbines which to date is offered by jack ups. Vessel owners expected to invest in a mono hull heavy lift vessel designed with wind farm installation in mind are likely to be operating in specific market conditions or segments and/or with a better fit with respect to company capabilities. The potential saving as per FLOW Offshore Wind Cost Model have been calculated and appear as an average to be well under 0.5 % and then only for wind farm cases with large and heavy foundations.

Lesson learned:

  • Maximizing the number of jackets for a single transport and installation in the offshore wind farm will result in complex and expensive technology. Trading CAPEX for less number of jackets seems more optimal.
  • This floating mono hull installation vessel will likely have similar CAPEX and workability as a class 1 jack up vessel (equipped with a 1200 – 1500 tons crane).
  • Control of vertical load motion is key for pre piled installation of jackets with grout seals. It is expected this is also the case for installing transition pieces with grout seals on mono piles.
  • Control for horizontal sway is required for improvement of workability above currently attainable levels.
  • Mono Pile installation is currently not possible on DP because of required positional accuracy.
  • Because installing wind turbines is currently not possible with a mono hull installation vessel the market position of the potential mono hull owner will need to be different from the owner of a jack up.


Icon Windkracht 14: Industrialize installation

Icon EWEA 2015: Innovative offshore wind installation concepts

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