Optimal Mooring Pattern for a Semi-Submersible FOWT in a Typhoon Environment
Journal
Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE
Part Of
Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE
Journal Volume
7
Start Page
v007t09a010
ISBN (of the container)
9780791887851
ISBN
9780791887851
Date Issued
2024-06-09
Author(s)
DOI
10.1115/OMAE2024-122874
Abstract
The scarcity of suitable shallow waters for fixed-bottom offshore wind turbines has prompted developers to explore deeper waters, albeit with caution due to the significant capital expenditure (CAPEX) associated with Floating Offshore Wind Turbines (FOWTs). A major cost component in FOWTs is the mooring system, a concern exacerbated in regions with the presence of typhoons, necessitating a more robust and therefore expensive 3x3 mooring solution compared to 3x1 in areas such as the North Sea. This study tried to propose a 3x2 mooring arrangement tailored for FOWTs in the typhoon region, offering a potential cost reduction of up to one-third compared to the original 3x3 configuration. To achieve cost savings, an in-depth analysis of spreading angles from 10° to the widest angle of 126° is performed using the pre-tension-diameter vs offset-tension 3D response surfaces technique. The research reveals that, theoretically, a 60° mooring angle minimizes floater offset with the least tension. However, the discrepancy in safety factors between intact and damaged conditions makes grouped mooring a more cost-effective choice. Utilizing the American Bureau of Shipping (ABS) safety factor, a 10° spread angle mooring system's chain cost emerges as roughly one-tenth cheaper than alternative configurations. Additionally, the study explores an innovative V-Share mooring [1], wherein a single pile anchor connects to two different columns via two mooring lines. Depending on the anchoring conditions, it can be the most cost-effective. In conclusion, a 3x2 mooring pattern for a 15MW semi-submersible FOWT in typhoon regions might be theoretically achieved on paper. However, it may not be practically achieved, if the size limit of the manufactured chain is considered.
Event(s)
ASME 2024 43rd International Conference on Ocean, Offshore and Arctic Engineering, OMAE 2024, Singapore, 9 June 2024 through 14 June 2024. Code 203876
Subjects
Cost Optimisation
Floating Offshore Wind Turbines
Floating Wind
FOWT
Minimum Break Load
Mooring Chain
Mooring System
V-Share Mooring
SDGs
Publisher
American Society of Mechanical Engineers
Type
conference paper