Design and global analysis of two floating wind turbines in a shared mooring line configuration

Shared mooring configurations for floating offshore wind turbines (FOWTs) offer a promising solution to significantly reduce the overall costs of wind farms. This study presents a detailed framework for analyzing FOWTs utilizing a shared mooring line configuration. A case study involving two 5-MW CSC FOWTs connected by a single shared mooring line is selected. First, excursion circles are used to characterize platform offsets for the shared mooring line system (SM) under steady wind loads from all directions. Next, dynamic responses—including platform motions, wind turbine tower bending moments, and mooring line tensions—are evaluated for the SM under irregular wave and turbulent wind conditions corresponding to a 50-year return period, while accounting for the full directionality of environmental loads. The results are benchmarked against those of an individual mooring system (IM). The analysis confirms the viability of the SM configuration, with only a 5 % increase in the maximum mooring line utilization factor compared to the IM. However, the SM exhibits significantly larger horizontal offsets, with the maximum offsets of the FOWTs more than double those observed in the IM. When the wind turbines are operational, the higher mean surge offsets in the SM lead to increased mean tension levels, making the anchor line tensions more sensitive to wave-frequency excitations. Despite these challenges, the SM configuration demonstrates strong economic potential, achieving an estimated 20 % reduction in mooring costs compared to the IM.