漂浮式海上风电接入策略与考量

Public SummaryReport Author:Jo Dahle and Ben MoverleySmith Date:18/07/2025 DISCLAIMER Whilst the information contained in this report has been prepared and collated in good faith,ORECatapult makes no representation or warranty (express or implied) as to the accuracy orcompleteness of the information contained herein nor shall we be liable for any loss or damageresultant from reliance on same. EXECUTIVE SUMMARY Floating offshore wind (FOW) developers are anticipating a significant increasein floating offshorewind deployment overthe next decade; the first commercial-scale floating wind farmisset to bebuilt starting in 2029[1]witha UK goal of 5 GW of floating wind by 2030[2]. The influx of largeturbines increases thedemandonoffshore construction and maintenance activities. A key aspect toensure reliable maintenance is safe and effective transfer for technicians from shore onto turbines.However, there are concerns regarding transfer safety,optimal transfer method, andlack ofstandardisation. This project aims to better understand different access methods, focusing on: •Crew Transfer Vessels (CTV),•Service Operational Vessels (SOV) with Daughter Crafts (DC),•SOV with a Walk-to-Work (W2W) gangways,•Helicopters. The project began with a review of each method using currently available literature and stakeholderengagement. Next, different access methods were assessed using the OrcaFlex modelling software.Finally,logistical modellingmeasuredimpacts of various access limitations on key performanceindicators (KPIs). Work Package 2: Review of FOW Access Methods Across all methods, prioritywas given to the distance from shore, the length of the maintenancecampaign, and technicians’ safety when determining which method to use to carry out transfers.SOVwith W2W gangways have the highest expected use, despite the high cost, as the design has thehighest accessibility limits and teams allowing for rotating shifts enable longer working hours.CTVsand DCs are similar in access design, and CTVs are expected to be limited by the distance of theturbines offshore, andused in farther distances for necessary individual repairs. Helicopters areexpected to be rarely used, and restricted by the weather limits of the vessel used to preventtransferees being stranded. Exceptions for thisincludeemergency transfer, especially in conditions ofsea recovery, which is easier with helicopters than with SOVs. Most substructure designs are notexpected to be able to winch onto the nacelle, further limiting helicopter use. Across all fourmethods, therewere concerns regarding relative motion, maintaining contact, and lack ofregulations. Several developers emphasised the importance of sharing findings across industries,including learning from fixed wind and oil and gas (O&G). Increasing accessibility is an industry priority for ensuring consistent and reliable maintenance plans.Keyuniversal methods for increasing access include: •Increasing the number of landing points onto the turbine;•Positioning the vessel into prevailing sea conditions;•Minimising turbine motion, thereby limiting relative motion between turbine and vessel. WP3: Analysis of FOW Turbine and Vessel Relative Motion In this work package, access to FOWTs is investigated via numerical modelling in the softwareOrcaFlex. Methodologies to model access by: (a) Helicopter, (b)CTV,and (c)SOV with a W2Wgangwaywere developed. These methods were then applied to models of a bottom fixedfoundation, a FOWT on a semisubmersible foundation and a FOWT on a tension leg platform (TLP)foundation. The transfer method was then assessed in environmental conditions which arerepresentative of the locations where FOWFs are likely to bedeployed. Broadly, the results show a reduction in access for the semisubmersible foundation compared to theTLP and bottom fixed foundations, which have very similar levels of accessibility. This is particularlytrue when considering access by helicopter, where a nacelle motion limit of 4m was applied based onhoist landing area standards.This motion limit was exceeded in all sea states with significant waveheight (Hs) higher than 1.5m for the semisubmersible, and in lower Hs conditions with low wavepeak period (Tp). By contrast, the nacelle on the TLP did not exceed this limit in any of theenvironmental conditions considered (Hs up to 2.5m, and Tp up to 14s). Access via CTV was also more limited for the semisubmersible foundation. Figure i shows acomparison of CTV accessibility for the foundations and sea conditions considered, when the wavesare from the direction of the foundation. The lower semisubmersibleaccessibility is likely due to theheave response of the foundation. This increases the relative vertical motion of the vessel andfoundation, leading to increased slipping of the CTV fender against the landing area. As shown, theTLP has accessibility very similar to that of the fixed foundation, which is likelydueto the limitedheave motion ofTLPs. Access by SOV is