Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Simulative comparison of installation concepts for offshore wind farms
1

Stephan Oelker1,*, Abderrahim Ait Alla1, Daniel Rippel1 and Michael Freitag1,2

BIBA – Bremer Institut für Produktion und Logistik GmbH at the University of Bremen, Bremen, Germany
2University of Bremen, Faculty of Production Engineering, Bremen, Germany

structures requires more harbor space and more personnel in the harbor.
Harbors only provide a certain area for heavy-duty operations thatcannot be extended at will. Similar to the availability of installation
vessels, current studies show that the noted trends might result ininsufficient capacity (Oelker, 2020). This could become more severe if
the share of floating installations increases. In addition, the restrictionsin terms of wind and weather are also relevant for the transport route.
In conclusion, future projects will need to render in the beginning thedecision 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.
This article proposes a simulation study to analyze which concept ismost favorable for a specific scenario to support this decision. The
simulation considers the influence of two concepts resulting fromdifferent parameters settings. Parameters are, for example, the numberof tugboats. The aim is to investigate the impact of the number oftugboats on the installation time. The simulation study applies different
objective metrics, for example, the duration of the operation and theutilization of resources to assess the simulation results. The simulation
proved to be a useful tool to assist the planner of offshore wind farmprojects as it allows planning, the identification of bottlenecks, and theselection of the best possible installation concept for the individual
scenario (Niemann, 2006).

ABSTRACT
Offshore wind energy continues to be a key technology towards thegeneration 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 andmore 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.

KEY WORDS: Offshore Wind Energy, Installation, Floating
Foundation Structures, Simulation Study.

INTRODUCTION
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 andBohlinger 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, thewind turbines can be installed on the floating foundation in the harborand then sailed to their target position by a tugboat. There they will beanchored to the seabed.
Depending on the installation scenario, the different concepts haveadvantages and disadvantages. In the conventional concept, relatively
little harbor space is required, and the restrictions in terms of wind andwaves are mainly relevant for installing the turbine at sea. However,installation vessels are significantly more expensive compared totugboats 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

STATE OF THE ART
While most of the literature on offshore wind farms focuses on theoperations and maintenance phase (Vis and Ursavas, 2016), several
authors have also turned their attention to the installation phase. The
current literature proposes several models to schedule or evaluate
installation projects using mathematical or simulation-based
approaches.
Among the simulation-based approaches, two articles assess theinfluence of installation concepts. Ait Alla et al. (2017) compare theconventional installation concept with feeder concepts as a possible
new form of installation concept. Vis and Ursavas (2016) assess theefficiency of different pre-assembly concepts, where they assumed thatparts of the top-structure are already assembled within the base port. Asa result, the authors note that pre-assemblies selection highly depends
on the project, port, and turbine characteristics. Most other approaches
focus on the conventional installation concept and evaluate different

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