Cost Analysis of Multiline Ring Anchor System for Offshore Wind Farm-Paper

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The study evaluates whether multiline ring anchors (MRAs) can reduce foundation costs for floating offshore wind farms by serving several mooring lines with one anchor. It compares MRAs with conventional single-line suction caissons (SCs) and six-line multiline suction caissons (mSCs), using indicative cost estimates for 600 MW farms with 5 MW or 12 MW turbines in soft clay.<br /><br />The analysis covers site investigation, materials and fabrication, transportation, and installation. Scenarios vary turbine capacity, water depth (100 or 300 m), and distance to port (50 or 200 km). The estimates are based on simplified assumptions, including suction installation and assumed vessel rates and operating conditions.<br /><br />The main savings come from fewer anchor locations and the MRA’s lower weight. For the 5 MW scenario, the farm requires 360 SCs but only 60 mSCs or MRAs; for 12 MW turbines, it requires 150 SCs versus 25 multiline anchors. Fewer footprints reduce site-investigation costs to about 17% of SC costs. MRA material costs are about 8% of SC costs, and fabrication costs about 7–8%. MRA transportation costs are approximately 8–12% of SC costs, depending on the scenario and vessel size.<br /><br />MRA installation costs are substantially below those for SCs because fewer anchors are installed, but exceed mSC costs because MRA installation involves additional handling and extraction time. Overall, the results suggest that MRAs’ multiline capacity and high load capacity relative to their weight can reduce capital costs and construction time. The authors emphasize that these are indicative estimates; actual costs depend on site conditions, installation methods, and other project-specific factors.

Keywords

floating offshore wind farms

multiline ring anchors

mooring anchors

suction caissons

foundation costs

capital cost reduction

site investigation

anchor installation

soft clay

indicative cost estimates