Integration methods for floating offshore wind farms

Abstract

The amount of floating offshore wind farms under development has drastically increased over the past years as the technology becomes viable for pre-commercial and commercial scale projects. Projects of this size require a streamlined, efficient production of the complete floating offshore wind turbine (FOWT), not only for manufacturing the floater but also for assembling the complete system. Most assembly tasks could, in theory, take place in a port, which is generally preferred, but most ports do not have the sufficient port infrastructure to perform those tasks, while the required infrastructure upgrades are very expensive. This is a significant challenge for smaller-scale, first-mover floating wind farms, which do not have sufficient units to justify those substantial investments for the assembly. To overcome this issue, a jack-up type wind turbine installation vessel could be used nearshore to integrate the wind turbine on the floating unit. This would ensure the realisation of the project without major infrastructure investments. At the same time, it could utilise the sheltered area's advantages and be a kick-off for large-scale projects in the region.

This proposed concept has so far not been investigated in academic research. Therefore, this thesis aims to create a general understanding of the system and its characteristics. Based on the example of Port Talbot in the UK, it should be examined how the concept can be implemented in a location. Furthermore, a response analysis of the system is done in SIMA for the single blade installation to understand which motions characterise the integration task and which environmental conditions limit the operation. Those operational limits are then implemented in a Python model of the complete integration sequence to conduct an operability analysis which should also give estimates for the required installation time and costs of the system when subject to wind and wave loads. Based on the findings of those studies, the technical and economic feasibility of the concept should be investigated.

The study has found that the wave-induced floater motions are mainly governing the systems motions during the single blade installation, which leads to very strict operational limits for the waves during the mating procedure. The technical feasibility of the proposed system is given if it is not subject to large tides and if a sufficient control mechanism is implemented for the installation. The operability analysis has shown that the system can be economically feasible if smaller projects should be implemented. For large projects, it is likely more feasible to invest into the port infrastructure.