Offshore wind energy continues to be a key technology towards the generation of electricity from renewable energies. Turbine dimensions are becoming larger and larger, and the turbines are installed at greater distances from the coast and in deeper waters. This leads to more and more wind farms being built with so-called floating foundation structures. This paper investigates the advantages and disadvantages of conventional and floating installation concepts using simulation studies. The findings show that the floating concepts in certain constellations require less installation time than conventional concepts.
Offshore wind energy is highly important for a climate-neutral future. Worldwide, around six gigawatts of nominal capacity were installed offshore in 2020 (Global Wind Energy Council 2021). In this context, the turbine dimensions are becoming larger and larger (e.g., Wieser and Bohlinger 2018). Moreover, turbines are partly installed at greater distances from the coast and in deeper waters (Hau 2016). These trends lead to the situation that, in addition to the conventional installation concept with an installation vessel and fixed foundation structures, more and more wind farms are being built with so-called floating foundation structures (Liu et al. 2016; Jiang 2021). In this concept, the wind turbines can be installed on the floating foundation in the harbor and then sailed to their target position by a tugboat. There they will be anchored to the seabed.
Depending on the installation scenario, the different concepts have advantages and disadvantages. In the conventional concept, relatively little harbor space is required, and the restrictions in terms of wind and waves are mainly relevant for installing the turbine at sea. However, installation vessels are significantly more expensive compared to tugboats used for installation with floating foundation structures (Global Renewables Shipbrokers 2020). In addition, current studies show that installation vessel availability could become a bottleneck for future installation projects if the present developments continue (Durakovic, 2020). In contrast, installation with floating foundation structures requires more harbor space and more personnel in the harbor. Harbors only provide a certain area for heavy-duty operations that cannot be extended at will. Similar to the availability of installation vessels, current studies show that the noted trends might result in insufficient capacity (Oelker, 2020). This could become more severe if the share of floating installations increases. In addition, the restrictions in terms of wind and weather are also relevant for the transport route. In conclusion, future projects will need to render in the beginning the decision on following a conventional or a floating installation concept, i.e., assembling the turbine on- or offshore, based on their actual characteristics and the availability of resources.
