Due to the growing demand for offshore wind energy and the increasing wind turbine sizes, a shortage of capable installation vessels is anticipated by 2024. Consequently, the utilisation of heavy-lift vessels, previously not employed for bottom-founded or floating offshore wind turbine installations, may become imperative to realise the offshore wind project pipeline. Therefore, this study analyses the technical and economic feasibility of installing floating wind turbines with the largest construction vessel in the world named the Pioneering Spirit. For this, the concept development stage of the systems engineering method was applied, consisting of three successive phases. Firstly, in the Needs Analysis phase, valuable insights regarding the operational environment were obtained, resulting in operational requirements for the concept design. Secondly, in the Concept Exploration phase, these requirements were used for generating multiple alternative concept options after which the most promising concepts were selected for further analysis through a trade-off analysis. Lastly, in the Concept Definition phase, the technical feasibility, workability and economic feasibility were evaluated for the selected concepts. The technical feasibility was assessed by creating storyboards for the different installation procedures, determining the stability of the barge named the Iron Lady for different load cases and providing technical descriptions of performed operations and required equipment. Furthermore, the workability was estimated by comparing statistical wave and wind data with the environmental limits for various operations obtained through literature, previous projects and a motion analysis model. Subsequently, with the storyboards and workability results, the economic feasibility was determined with a model that included estimations of the vessel and fuel costs for constructing a reference wind farm located at a variable distance to shore. Ultimately, it was found that Spar- and TLP-type floating wind turbines are of most interest for the concept design and that the Pioneering Spirit is in principle capable of installing the corresponding pre-assembled foundations and wind turbines relating to a capacity of 15 megawatt with a single-lift operation. Furthermore, this research gives valuable insights that extend beyond the initial scope of this paper. Since the performance implications of the selected concepts related to the workability assessment and economic feasibility study can directly be linked to specific design choices and limitations. This, in combination with the exploration of floating wind turbine installation with alternative lifting equipment, can be used to provide recommendations for future designs of purpose-built vessels in this sector. Finally, the methodology used in this study could be applied to evaluate the feasibility of other potential concepts for deployment in this area.

The maritime industry faces a lot of uncertainty, and the energy transition has only increased this uncertainty. Ships will probably have to be converted to an alternative fuel during their lifetime and methanol seems to be the fuel with the most potential for offshore ships. By preparing for this, Design-for-Conversion to methanol, the costs of changes can be significantly reduced with only minor investments during the new building phase. The added design preparations pay for themselves only if they are being used in the future. However, due to large uncertainties, it is unclear whether a ship is actually converted to methanol in the future. Therefore, an answer had to be found to the main research question: How to determine the value of Design-for-Changeability under uncertainty to find the optimal DFC level when preparing for conversion to methanol?

From the literature is concluded that Design-for-Changeability principles can help to deal with uncertainty during a ship's lifetime. Moreover, Real Options Analysis is selected from the literature, as a method to deal with decisions and uncertainty when designing for conversion to methanol. By means of a combination of these methods, a methodology is established which is used in a case study.

In the case study, it was found that waiting with the execution of conversion to methanol results in decreasing added value of Design-for-Conversion. Moreover, it was found that the Discount Rate used for Net Present Value calculation significantly impacts the choice of whether to prepare a ship for methanol. It can be concluded that an instigator is needed so that ships are converted to methanol. Two instigators have been researched, a carbon pricing measure and a ban on harmful emissions. It can be concluded that a carbon pricing measure is only effective if the right price is established, while a carbon ban is highly effective as ships are converted instantly.

The combination of methods, the Design-for-Changeability principles together with a Real Options Decision Tree, provides a suitable framework to quantify the impact of Design-for-Conversion to methanol under uncertainty.