Offshore wind stands as a crucial contributor to generating clean, renewable energy, but the limited availability of shallow water locations restrains the potential of bottom-fixed wind. To unlock the vast wind energy potential in deeper waters, a substantial reduction in the Levelized cost of energy (LCOE) of floating wind technology is necessary. Tension leg platform (TLP) floating offshore wind turbines (FOWTs) offer significant cost-saving potential, positioning them as a promising solution. However, achieving cost-effective installation of TLP FOWTs poses significant challenges. In the existing literature, this remains relatively undressed with only two studies focusing on this subject, providing partial solutions

The overachieving goal of the thesis is to address this challenge by conducting an in-depth design space exploration (DSE) of an innovative special-purpose installation vessel along with a robust installation method, offering a cost-effective solution. Floating wind represents a yet-to-be-explored market, presenting design challenges associated with managing uncertainties in operational conditions and TLP designs it intends to commission. The research is conducted within the framework of systems engineering.

During the literature phase, a needs analysis is performed to establish design requirements. The installation vessel must be capable of transporting future fully assembled TLP FOWTs. These include 20 MW wind turbines, three-legged TLPs, and an innovative TLP design with one foldable leg for efficient stacking onboard. The DSE model comprises a two-step design approach and a design evaluation based on scenario modeling. The first design step explores radically different designs using an exploration approach integrated with morphological mapping. A trade-off analysis led to the Windchanger concept featuring an installation deck (ID) integrated with the stern design, employing a winch system for FOWT lowering and recovery. In the second design step, this concept is subjected to further exploration through a parametric model, including generating the hull surface for extensive stability calculations. The key factors for scenario modeling comprise the distance to the port, the operational area, and the TLP design. By evaluating the cost-effectiveness and installation duration in each scenario, the goal is to gain insights into the optimal design ranges. This serves as the basis for establishing a design decision framework to manage the considered uncertainties.

The results of this research offer valuable insights into both the technical feasibility and the cost-effectiveness of the Windchanger concept, facilitating optimal design decisions. The model enables evaluation across diverse scenarios to identify the most suitable design within predefined parameters. This is showcased by assessing performance in two operational areas: the North Sea and the U.S. East Coast. The optimal design ranges derived from these analyses can guide further development of the Windchanger Concept, highlighting that a transport capacity of 2 emerges as the most cost-effective option based on the scenarios evaluated.

Introducing a new installation solution necessitates benchmarking against existing methods to ensure cost-effectiveness and feasibility. The results reveal that TLP foundation costs are approximately 40 percent lower than other floating foundations, confirming the anticipated cost-saving potential. Installation costs represent only a fraction, ranging from 0.5% to 1% of foundation costs, emphasizing the importance of robustness and installation time in cost-effectiveness. The model demonstrates that the Windchanger concept outperforms other TLP installation methods, with lower installation costs per FOWT and a significantly higher number of yearly installations. These findings underscore the Windchanger concept's robustness and cost-effectiveness, potentially leading to a substantial reduction in the LCOE of floating wind.