Challenges in Shared Anchor Concept for Deep Water Floating Offshore Wind Turbines

Abstract About two-thirds of the US offshore wind potential lies in the deeper waters. To effectively utilize this potential, it’s crucial to optimize the anchoring systems of floating wind platforms. The concept of shared anchoring, where multiple turbines are anchored together rather than individually, is a novel approach being actively explored now. This concept is believed to be cost-beneficial given the reduced number of anchors and its related costs. In our paper, we examine the practicality of shared anchors on a commercial-scale wind farm considering various parameters, including layout design, anchor forces, Annual Energy Production (AEP), Capital Expenditures (CAPEX), Operating Expenditure (OPEX), and the Levelized Cost of Energy (LCOE). The analysis is conducted for a site with a water depth of 850 m using 15MW turbines on semi-submersible platforms. We investigate a honeycomb-shaped layout where platforms are moored by hybrid chain-polyester-chain taut mooring lines to shared anchor piles. Our findings indicate that the honeycomb layout leads to a reduction in AEP compared to an optimized layout with individual anchors. Preliminary results show that the vertical forces on shared anchors are significantly higher than those on traditional individual anchors. This increase in force impacts CAPEX, leading to minimal cost savings for the evaluated location. Despite ongoing research anticipating benefits from shared anchoring, our study suggests that the overall cost benefit of shared anchors for the specific scenario is marginal. Through this case study, the paper will provide insight on which parameters influence the conclusion, and under what conditions shared anchors could be beneficial.