Offshore Floating Wind is finally emerging as a promising source of Renewable Energy, but the Industry still faces important challenges. Among these, the impact the floater's motions have on the product life-cycle performance still requires evaluation and validation. In this sense, the industry has struggled to define an approach that minimizes the Levelized Cost of Energy (LCOE). The reasons for this, among others, are that each floater typology induces different motions on the nacelle equipment, each metocean site conditions are different, and the wear at the nacelle depends on the turbine model and manufacturer. Hence, the industry recommendations have so far usually limited the maximum longitudinal accelerations at the nacelle to 0.3-0.4g, and the maximum roll-pitch combination is set below 10°.

The induced motions add dynamic loading, wear down the mechanical equipment, produce fatigue damage on the structural members and are a source of potential downtimes, due to machine failures or simply due to unacceptable accelerations at the nacelle. Therefore, the different components of the turbine should be reinforced, increasing the CAPEX; or the maintenance and repair activities with its associated costs should increase; being both a possible combination.

The purpose of this paper is to analyze the different costs items associated with more or less conservative approaches with regards to the motions at the nacelle highlighting the combination of accelerations, operational weather windows, construction and maintenance strategies that can lead to the optimum LCOE.

Several response spectra of accelerations at the nacelle will be obtained for two different floaters, namely; a spar and barge preliminary sized for the DTU-10MW reference wind turbine. The effect of the turbine controller on the motions is not considered. For different acceleration cutoff values, the energy produced is estimated.

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