the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Reference Floating Wind Array Designs for Three Representative Regions
Abstract. This work presents the systematic development of three open-source reference floating wind array designs. The designs are tailored to representative site conditions for three regions of the United States: Humboldt Bay off the coast of California, the Gulf of Maine, and the Gulf of America. We adopted existing reference designs for the individual 15 MW turbines, semisubmersible floating platforms, substations, mooring systems, and power cables -- integrating and adapting them as needed for each location. We adapted existing dynamic cable designs to use larger conductor sizes to meet the arrays' power transmission requirements, and we set up redundant mooring systems for each substation. The layout of each array is a uniform grid design optimized to approximately minimize the levelized cost of energy (LCOE) within a square lease area while satisfying spatial constraints. These constraints ensure adequate clearances between adjacent turbines and between underwater components during the layout optimization to prevent clashing and ensure that all components reside within the lease boundaries. Substations are included to allow accounting for intra-array cable costs. They are placed within the uniform grid to maintain the navigability of the arrays. For each feasible layout considered, annual energy production and cable routing costs are calculated and updated in the LCOE objective function. After the optimization, we refined the cable routing with a mix of algorithmic and manual methods to ensure that the cables avoid mooring system components and approach the substation with adequate clearances. We confirmed the suitability of each reference array's layout by comparing the wake losses at each wind heading angle to the wind rose, observing that the optimized layouts largely avoid wake losses in the predominant wind directions. These reference arrays provide open-source baseline designs to enable future research and innovation of floating wind technology at the array scale.
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Status: final response (author comments only)
- AC1: 'Comment on wes-2025-209', Leah Sirkis, 27 Oct 2025
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RC1: 'Comment on wes-2025-209', Anonymous Referee #1, 03 Nov 2025
This manuscript shows the results of a layout optimization exercise for three floating wind turbine sites. The mooring system and initial power cable designs were developed in previous work, such that the present work only addresses the layout optimization. The assumptions are clear and the results are believable given the assumptions and approach, but the scientific contribution of the work is not very clear to me. What research questions does this work address? The novelty of the procedure only seems to be the need for buffer zones which would not generally be considered for a bottom-fixed layout. The procedure for cable routing is also already described in previous work, so it is not very clear to me what is new here.
The premise of the optimization is that a uniform grid layout shall be obtained for a uniform water depth for each location. The procedure assumes that the mooring and cable design are already selected, while only layout optimization is performed here. It is unclear to me how this division can be included in a practical design situation, as the water depth in general will vary throughout the farm and require modifications to the mooring systems. Furthermore, in Fig. 1, it seems that the cable sizes are input to step 4 separately from the cable design in step 3 – aren’t these taken from step 3?
There are also some notable shortcomings in the calculation of both the objective and constraints in the layout optimization. For the objective function, the AEP calculation is very sensitive to the number of wind directions considered, as the authors recognize. It does not appear that the sensitivity to this selection has been assessed for either the optimization process or the final designs. For the fatigue and extreme response criteria, the frequency-domain tool RAFT has been applied. Has the applicability of a linearized tool for 500-year response conditions been assessed? The conditions for linearization are not likely to be met in extreme conditions. Furthermore, the choice of extreme weather conditions, particularly for the GoM/GoA site which is expected to be dominated by hurricanes, deserves a bit more attention. (I have not thoroughly reviewed the reference which provides the background for these choices, but the Hs, Tp, and Uw for the SLC seem a bit low compared to what I might expect in a hurricane-prone area).
The optimization algorithm is described in limited detail. A PSO approach was used, but the number of particles, constraint handling, and convergence criteria are not described.
The writing is generally pretty clear, though it could be a bit less colloquial in some instances (“pulled directly from…”) and tense can vary in some parts of the manuscript. There can also be some confusion between what is meant by “we chose” vs. “the optimizer chose”.
Citation: https://doi.org/10.5194/wes-2025-209-RC1 -
AC2: 'Reply on RC1', Leah Sirkis, 03 Nov 2025
The authors thank the referee for their review and comments. A full response addressing all comments will be provided shortly, but in the meantime the authors would like to clarify that the frequency domain tool RAFT was not used to perform loads analysis for the floating wind turbine and its mooring systems and cables. In previous work, OpenFAST was used for fatigue analysis of the mooring system and extreme loads analysis of both the mooring design and the 300 mm^2 dynamic cable design. In the present work, OpenFAST was used for extreme loads analysis of the 630 and 1000 mm^2 dynamic cable designs. The frequency domain model RAFT was used only to evaluate the floating substation design. It was evaluated in extreme 500-year wind, wave, and current to check the adequacy of the mooring system. The floating substation platform was adapted from other work and its dynamic performance was not the focus of the present work.
Citation: https://doi.org/10.5194/wes-2025-209-AC2
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AC2: 'Reply on RC1', Leah Sirkis, 03 Nov 2025
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RC2: 'Comment on wes-2025-209', Anonymous Referee #2, 05 Jan 2026
Dear authors,
first of all, I would like to apologize for the late review, which was due to a problem with system, as indeed I revised the paper quite a long time ago. Please accept my apologies.
The paper is interesting and will contribute to the research in floating wind, especially in the current context of partial loss of momentum from industry due to the modified economic framework.
Please find below a few comments for your consideration:
1) I see that the paper is registered as a “research article”. While this has no great drawbacks, I invite you to consider switching it to a “Data description” paper since I think this fits better the nature of the study and would put it in a better spotlight. Maybe this can be a topic of discussion with the Editors.
2) Is there any additional info on the real bathymetry in the site and the type of seabed available? You clearly stated that these are not accounted for at this stage, but adding such info (e.g., in the GitHub repository) could be useful to other researchers willing to further optimize the layouts in the future
3) Another piece of information that could be very useful to maximize the future exploitation of this study is represented by more detailed metocean conditions, including waves and wind-wave misalignment. The selected metocean conditions would deserve more attention also in the paper, as they are not addressed in a fully convincing way. If not fully measured, you could reconstruct them using for example the approach proposed in DOI: 10.1088/1742-6596/2385/1/012117
4) Selected cost should be put in context, ideally providing more references and realistic “ranges” of variation of such costs for the time being
Citation: https://doi.org/10.5194/wes-2025-209-RC2
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Reference Array Design Descriptions Leah Hope Sirkis et al. https://github.com/FloatingArrayDesign/ReferenceDesigns
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The visual for Fig. 18 is incorrect. The intended visual is attached to this comment.