Numerical analysis of a floating Airborne Wind Energy farm with a shared-mooring system

Airborne wind energy (AWE) has the potential to complement conventional wind power and accelerate the transition to renewable energy. Realizing this potential will require offshore farm-scale deployments, where mooring systems represent a significant share of capital expenditures. Shared-line mooring concepts have been proposed to reduce these costs; however, floating AWE farms have not yet been studied, and shared-line designs have not yet been commercialized due to the complexity of mooring-induced platform-to–platform interactions. At the same time, taut mooring systems employing synthetic ropes are gaining interest, yet their inherently nonlinear behaviour is often neglected despite its known influence on system dynamics. This study addresses these gaps by numerically investigating the role of nonlinear tensile stiffness in shared-line moorings for floating AWE systems. A fully nonlinear stiffness model, based on industrial rope characteristics, is integrated to capture realistic material behaviour. The dynamics of a nine-platform shared-line farm are compared against a baseline single-device configuration under critical loading conditions, evaluating motions, line tensions, and hourly fatigue damage accumulation rate. Results show that even simple single-mooring configurations experience strong dynamic effects from material nonlinearities, including notable resonance shifts relative to linearized models. In shared-line arrangements, high-frequency load components associated with higher-order harmonics significantly accelerate fatigue damage accumulation. These findings underscore the critical importance of nonlinear mooring modelling in the design and assessment of shared-moored floating renewable energy systems.