Evaluating operational strategies for the installation of offshore wind turbine substructures

The construction of offshore wind farms requires solving more and more complex logistical problems due to the increasing sizes of turbines and changing environments. In particular, the installation of substructures requires attention due to their significant impact on capital expenditures and the limited literature and guidelines available. In this paper, we develop a decision support tool consisting of a discrete-event simulation that allows for comparing strategies for the installation of offshore wind turbine substructures in terms of time and costs. We identify several combinations of transportation and installation strategies for monopile and for jacket substructures. The differentiation is based on the deployed vessels and the installation sequence of the components. The strategies are applied to the case of a wind farm in the North Sea. For both substructure types, we find that strategies involving a second installation vessel result in the shortest installation times, and those in which the installation vessel(s) take(s) care of both transportation and installation result in the lowest costs. Additionally, we quantify the performance increases as a result of a reduction of the most prominent bottlenecks and the sensitivity of the project performance to the start date. Finally, the results are discussed in relation to future market and technological developments in the field.