International Journal of Advances in Engineering & Technology, Dec., 2024. ©IJAET ISSN: 22311963 631 DOI: 10.5281/zenodo.14823887 Vol. 17, Issue 6, pp. 631-645 COST-EFFICIENT OPTIMIZATION OF SYNTHETIC MOORING SYSTEMS WITH POLYMER SPRINGS FOR 15 MW FLOATING WIND TURBINES IN SHALLOW WATERS Salvatore Verde 1 , Eduardo Nobre Lages 2 1 Professor, Universidade Federal de Alagoas, Delmiro Gouveia, Brazil salvatore.verde@delmiro.ufal.br 2 Professor, Universidade Federal de Alagoas, Maceió, Brazil enl@ctec.ufal.br ABSTRACT The deployment of larger wind turbines has significantly reduced energy costs but has also introduced new challenges for installations in intermediate water depths (50–150 m), where efficient mooring systems are critical. While traditional chain catenary arrangements and polyester-based solutions are widely used, they often fail to adequately mitigate peak loads or maintain platform pitch control, particularly under extreme environmental conditions. Nylon has emerged as a promising mooring material due to its inherent elasticity, which effectively reduces peak loading. However, its use can lead to increased platform pitch and may raise concerns about long- term fatigue performance. To address these issues, recent optimization frameworks have focused on hybrid nylon- chain systems, fine-tuning parameters such as line length and diameter. The integration of Load Reduction Devices (LDRs), tailored in length, target load, and stiffness, further enhances mooring performance by mitigating peak loads and fatigue damage while preserving platform stability and compliance. In this study, an LDR-nylon- chain mooring system was optimized to minimize both LDR length and target load across various platform radii. The resulting configurations achieved substantial cost reductions without compromising motion performance requirements. Minor adjustments were required to ensure compliance with tension limits, and subsequent analyses revealed pronounced peaks in the system’s power spectrum—attributed to the LDR’s low damping characteristics—thus highlighting an area that warrants further refinement. Overall, this work provides valuable insights for designing cost-effective and reliable mooring systems in shallow water environments, thereby advancing safe and economical floating wind technology. KEYWORDS: Floating wind turbine, Mooring systems, Nylon rope, Genetic algorithm optimization, Spring polymer. I. INTRODUCTION As governments worldwide aim for net-zero emissions by the mid-21 st century, the renewable energy sector continues to expand into offshore areas with floating offshore wind technology, highlighting the pivotal role of wind energy. Offshore wind capacity currently stands at 64.3 GW, representing 7% of global wind energy. The Global Wind Energy Council (GWEC) forecasts an increase of over 380 GW by 2032, reaching a total capacity of 447 GW [1]. For instance, Brazil's Offshore Support System [2] manages areas with a potential of 700 GW in waters up to 100 m deep [3], where floating offshore wind turbines (FOWTs) are favoured over fixed-bottom designs. FOWTs are connected to the seabed using mooring lines and anchors. Increasing turbine sizes is essential for cost reduction; however, this scaling poses challenges to floating structures and mooring systems. The costs associated with mooring systems largely depend on two main factors: the minimum breaking load (MBL) of the mooring lines and the anchor’s capacity to withstand extreme peak loads. Reducing these loads involves decreasing system stiffness or increasing compliance, which can be achieved through geometric means (e.g., catenary chains) or elastic means (e.g., taut synthetic ropes).