Decision variables for floating offshore wind farms based on life-cycle cost: The case study of Galicia (North-West of Spain)

Despite the fact that offshore wind energy will tend towards the floating technologies their economic impact has not been practically evaluated yet. In this context, the aim of this article is to characterize the possible economic alternatives which can be considered in the life-cycle of floating offshore wind farms based on their life-cycle costs. Several groups of variables have been considered for determining these alternatives: wind turbines, floating platforms, mooring system, anchoring process, kind of seabed, electric system, installation, shipyard and maintenance. The method proposed has been applied to the case of the North-West coast of Spain (Galicia region). For this case test three different platforms have been analyzed: Tensioned Leg, Spar and Semisubmersible platforms. Results, which are presented by using maps of the area, conclude that offshore substation, string electric configuration and "tree fall" decommissioning method are the best options for minimizing the costs. In addition, the installation method will be conditioned by the type of floating platform and mooring material, whereas the disposition and anchor decisions are dependent on the geographic location. Results show how the methodology proposed is useful to characterize economically the life-cycle of a floating offshore wind farm.