This is the final versionFloating offshore wind turbines are an emerging source of marine renewable energy, in deep water offshore locations, with minimal visual impact from the shore. The presentation reviews the installation methods for floating wind types such as barges, Spars, semi submersibles and TLPs and offers suggestions for improvements.
 
This floating wind presentation will be useful for stakeholders in the offshore wind engineering sector who are offering installation solutions for floating wind installations. The overview of the installation challenges for different substructure types will provide important information to developers of floating wind

Crowle, A

Thies, PR

This is the author accepted manuscriptFloating offshore wind turbines are an expanding sector within renewable power generation, offering an opportunity to deliver green energy, in new areas offshore, in deep water. The installation engineering of floating offshore wind turbines is important to minimize schedules and costs. This presentation investigates the construction and installation challenges for the various floating offshore wind types, namely barges, semi submersibles, Spars and TLPs  Specifically tailored design for construction and installation includes expanding the weather window in which these floating substructures can be fabricated, transported to and from the offshore site and making mooring and electrical connection operations simpler. The simplification of installation methodology will reduce time spent offshore and minimize risks to installation equipment and personnel

Open Research Exeter

Cornish Institute of EngineersFLOATING OFFSHORE WIND TURBINES -INSTALLATION METHODS13th APRIL 2023ALAN CROWLE*   Professor P.R. THIES *ac1080@exeter.ac.ukBoth University of Exeter, Renewable Energy Department1Title to go hereBody copy to go here2Ref[15]FloatingTitle to go hereBody copy to go here3INDEX1. Safety Moment2. Size, vessels and deployment3. FOWT Types4. Semi submersibles5. Spars6. Barges7. TLP8. Turret mooring9. Turbines10. FOWT challenges11. Research work12. Conclusions13. Abbreviations14. References15. QuestionsTitle to go hereBody copy to go hereMiss ballasting, Ref [27].Title to go hereBody copy to go hereRecovery, Ref [27].Title to go hereBody copy to go here6SIZE, VESSELS, DEPLOYMENTTitle to go hereBody copy to go here7Ref[5]YARD, HTV For Windfloat Semisubmersible27mTitle to go hereBody copy to go here8Ref[5]TUG and Cable Layer For Windfloat SemisubmersibleTitle to go hereBody copy to go here9AREA FOR 3 TOPSIDES, Ref[26] 3 * 8MW TURBINES9 BLADES3 NACELLE-GENERATORS3 HUBS Title to go hereBody copy to go here10Type Deployed Substructure MW No TotalMat rial Built each off GWIn placeSemi Portugal steel Spain 5 3 0.015Semi Scotland steel Spain 9.6 5 0.048Spar Scotland steel Spain 5 5 0.025Stiesdal Norway steel Denmark 2 1 0.002Pivot X1 Portugal steel Portugal 2 1 0.002Ring barge France concrete France 1 1 0.001Ring barge Japan steel Japan 2 1 0.002Pivot barge Spain concrete Spain 1 1 0.001Spar(3/11) Norway concrete Norway O-G 9 3 0.027Total 21 0.123Title to go hereBody copy to go here11Type Deployed Substructure MW No TotalIn place Material Built each off GWconstructionSpar Norway concreteNorway to power Oil and Gas 9 8 0.072TLP France steel France 8 3 0.024Total 11 0.096By the end of 2023 32 0.219Ashore % 55To Power Oil&Gas % 45Project Where Being MW No TotalPlanned each off GWBy 2035 USA West coast 15 2333 35By 2035 Scotwind Scotland 15 1000 15By 2035 INTOG Scotland Oil and Gas 15 333 5By 2030 Erubus Wales 15 25 0.375By 2028 Wave Hub Cornwall 8 4 0.032By 2035 Celtic Sea 5Title to go hereBody copy to go here12TYPESDeployed FOWT 2 barges 5 spars (11 more under construction for Oil and Gas) 8 semi submersibles 1 submerged ballast 2 pivot buoy 0 TLPs   (3 under construction)Fixed bottom 4,000+ Monopiles (limit 50m)   (China has the most deployed) 300+ Jackets  (limit 75m)Reasons for low deployment FOWT high capital costs (CAPEX) FOWT high operating costs (OPEX) In UK still shallow water available for fixed structures Lack of ports for construction Laydown area for components  Title to go hereBody copy to go here13Monopile      Jackets             Semisubmersible         TLP                     SPAR(<50m)           (<70m)                   (>60m)                  (>100m)           (>90m)Ref[15]FIXED vs FLOATINGTitle to go hereBody copy to go here14INSTALLATION CONSTRAINTSBarges: Low freeboards Tow out motions highSemi submersible: High steel weight 10m to 15m water depth adjacent to fit out quaySpars Deep sheltered water, (70m plus) required for fit out Not possible to return to port for heavy maintenanceTLPs Low or negative intact stability during tow out Very complicated moorings, weather restricted during installation Not possible to return to port for heavy maintenanceTitle to go hereBody copy to go here15SEMI SUBMERSIBLETitle to go hereBody copy to go here16LIFTING NACELLEBY ONSHORE CRANE AT THE FIT OUT QUAY, ref[5]Large onshore craneNacelle and HubSubstructureTitle to go hereBody copy to go here17LIFTING NACELLE-HUBBY ONSHORE CRANE AT THE FIT OUT QUAY, ref[5]People needed to make the connection between nacelle and towerTitle to go hereBody copy to go here18Lifting blades by onshore crane atthe fit out quay, Ref[5]Large onshore craneBlade handling toolSubstructureTitle to go hereBody copy to go here19Lifting Blades By Onshore Crane AtThe Fit Out Quay, Ref[5]Title to go hereBody copy to go here20LIFTING BLADES BY ONSHORE CRANE ATTHE FIT OUT QUAY, Ref[5]May need temporarybuoyancy or air bags toreduce draftTitle to go hereBody copy to go here21WET STORAGE, REF[5]Temporary Mooring PilesHarbour TugFOWTTitle to go hereBody copy to go here22WINDFLOAT, REF[5], OFFSHORE PORTUGAL Fender  Onshore crane for nacelle/bladesTitle to go hereBody copy to go here23WINDFLOAT, REF[5], OFFSHORE CROMARTYPotential fit out port BladesNacelleTowerOcean going tugsHarbour tugTitle to go hereBody copy to go herePORT TALBOT PROPOSALTowers, Nacelles Blades           Out-fit        Wet-Storage(15.8m LAT)          Tow-outFabrication  Assembly  Loadout onto submersible barge4/17/2023 24Title to go hereBody copy to go here25WISON (China) SEMI SUBMERSIBLE, ref[2]Substructure(for 5MW)91m long91m wide31m depthSPMT TrailersSubmersible BargeHarbour Tug Title to go hereBody copy to go here26CONNECT MOORINGS    Ref[2]Mooring lines(3 per column)Moorings beingtensionedTugger linesTitle to go hereBody copy to go here27SPARTitle to go hereBody copy to go here28EQUINOR, REF[4], TAMPEN Equinor’s 88MW Hywind Tampen proj ct in Norway, which is to become the world’s first floating wind farm supplying renewable power to offshore oil and gas installations. Loading solid ballast into the base.Title to go hereBody copy to go here29HYWIND TAMPEN, ref[4]Onshore craneLifting bladesTitle to go hereBody copy to go here30HYWIND TAMPEN, ref[4]Title to go hereBody copy to go here31HYWIND TAMPEN, ref[4]Subsea 7 has laid the first subsea cables in the water for the 94.6 MW Hywind Tampen floating wind farm offshore Norway.Title to go hereBody copy to go here32BARGETitle to go hereBody copy to go here33BARGE, ref[11]Concrete substructure                       Crane for outfittingTitle to go hereBody copy to go hereTLPPossible Installation Methods34Title to go hereBody copy to go hereTLP TEMPORARY BUOYANCY Ref [9]35Tow out with temporary buoyancy Remove temporary buoyancy afterConnecting tendonsStiesdal  TLPTitle to go hereBody copy to go hereTLP Install Crane Vessel36Bluewater  Tugs   Active Heave Compensation Of Hook of DP2 crane vesselRef [10]Title to go hereBody copy to go hereSBM    Ref[23] 37Tension Leg Platforms (TLPS) Title to go hereBody copy to go herePROVENCE GRAND LARGE, July 2022, ref [23]Eiffage Métal’s site in Fos-sur-Mer,where the assembly of thestructures is beingcarried out by theFrench companyand Smulders,its Belgium-basedsubsidiaryTitle to go hereBody copy to go hereSBM    Ref[8] 39Tow out shallow draftLarge 2nd moment of waterplane areaTension (chain)tethers, ballast downand re-tensionTitle to go hereBody copy to go hereBLUE SATH PIVOT BUOY TURRET MOORING40Title to go hereBody copy to go hereBLUE SATH   Ref[12]41DemoSATH mooring, anchoring and quick connect solution is set for the 2MW turbine.Maersk Supply Service completed the installation of six mooring lines (comprised by hybrid lines of chain and fibre rope) and six drag anchors with Maersk Mariner.Once loaded, the vessel left the Port towards the installation site at test area where the elements’ connection and laying took place. The lines will be recovered from the seabed for a plug and play connection.Title to go hereBody copy to go hereBLUE SATH   Ref[12]42Large onshore craneTitle to go hereBody copy to go hereBLUE SATH   Ref[12]43Submersible bargeTitle to go hereBody copy to go hereBLUE SATH   Ref[12]44Turret mooringTitle to go hereBody copy to go hereBLUE SATH   Ref[12]45Pivot Buoy Turret mooringTitle to go hereBody copy to go hereTURRET46Floating Offshore Wind Turbines with turrets. Electrical swivels must be capable of transferring uninterrupted high power while offering significant protection in hazardous areas. Ref [25]Title to go hereBody copy to go hereDESIGNS FOR PIVOT BUOYTURRET MOORING47Title to go hereBody copy to go hereHEXICON TWIN FLOATER TURRET Ref[8]48Turret, with fixed moorings and electrical swivel.                          Turbines fixed. Title to go hereBody copy to go hereHEXICON FOR WAVE HUB Ref[8] 49Using 8MW MING Turbines Each blade length 85m Each 173m diameter Each nacelle 420 tonnes Nacelle above water 120mSubstructure (approximate) Length hull 120m Width hull 80m Overall dimensions Length 280m Height 204mTitle to go hereBody copy to go hereTRIVANE, TURRET MOORING    Ref[7]Model test University of Plymouth scale 1/5050Turret mooringTitle to go hereBody copy to go hereTRIVANE, TURRET MOORING    Ref[7]51Turret mooringTrivane at 6 metre draftfor Assembly and TowTrivane operating offshore at  20 metre draftTitle to go hereBody copy to go herePIVOT BUOY  (X1Wind) For Canary Islands Ref[8]52Turret mooringTitle to go hereBody copy to go hereMOORING53Title to go hereBody copy to go here54Catenary                           Taut / Semi-Taut                         Tendon linesMOORING TYPES, ref [16]Source: Trubat Casal, P. (2020). Station keeping analysis and design for newfloating offshore wind turbines.Title to go hereBody copy to go here55ANCHOR TYPES, ref [17]Title to go hereBody copy to go here56CABLES, ref [18]Inter Array Cable (IAC)• Between Wind Turbines• MV 66kV• 3-core AC• Dynamic and Static cableExport cable• From substation to shore/O&G facilities• HV 132 345 kV cables, 3-core AC• HV320 kV single core DCTitle to go hereBody copy to go here57TURBINESTitle to go hereBody copy to go here58BLADE HANDLING, ref[13]Title to go hereBody copy to go hereAIR DRAFT   Ref[13]TURBINE CAPACITYBLADE LENGTHHUB HEIGHTTOTAL HEIGHT LOCATIONMW m m m2 43.3 68.8 113.23 52.8 80.1 133.95 67.6 97.4 166.26 73.8 104.6 179.88 84.9 116.3 202.6 Hywind Tampen9.6 92.7 124.1 218.3 Kincardine10 94.6 126.1 222.211 99.1 130.6 231.212 103.3 135.8 241.7 Dogger Bank13 107.4 140.4 250.9 Dogger Bank14 111.4 145.4 260.715 115.2 150.2 270.3 Germany16 118.8 154.3 278.6 China17 122.4 157.9 285.718 125.8 161.8 293.619 129.1 165.1 300.320 132.4 168.9 307.8ABOVE WATER59Title to go hereBody copy to go hereTURBINE WEIGHTS Ref[13]60Title to go hereBody copy to go hereTURBINE SIZE    Ref[13] 61Title to go hereBody copy to go here62FOWT COSTSCost comparisons:Fixed offshore wind is more expensive than onshore windFloating wind is 50% more expensive than fixed offshore windFloating wind maj r maintenance very expensiveTypesNumerous technologies. No clear winning concept yet. Semi-sub in steel is the better short-term solution.Uncertainties;• Insurability will be important factor for projects seeking finances • Supply Chains need commitments from Developers to invest in facilities.• No reliable CAPEX references available yet.• No O&M references for business cases.• Volatility of raw material costs, inflation, financing uncertainties.Title to go hereBody copy to go here63PORTS - SUPPLY CHAIN (Ref [19]) 15MW turbine• Complete size of a given floater is around: 100 x 100 x 25m • Complete weight of steel floater is around: 2,500 ~ 4,000 tons• Addition weight of moorings 1000tonnes in 100m of water• Complete weight of a concrete floater is around: 17,000 –27,000 tonsThe port infrastructure should account for• Strong Bearing capacity for storage and assembly of components• Bearing capacity of 25-50 tonne/sqm for WTG assembly operations• Quay length of 500 meters • Draft at quay and along channel should be no less than 10-12 metersTitle to go hereBody copy to go here64ELECTRICITY GENERATIONTitle to go hereBody copy to go hereGB ELECTRIC 2022, Ref[21]65Generation by type             GW        %Fossil fuels 13.2 43.7Renewables 10.5 34.9Other sources 6.8 22.7Generation by sourceCoal 0.42 1.4Gas (orange0                    12.74 42.3Solar 1.40 4.7Wind (light green)              8.72 29.0Hydroelectric 0.38 1.2Nuclear 4.92 16.3Biomass 1.61 5.4Other 0.30 1.0Imports and exportsBelgium 0.04 0.1France −1.02 −3.4Ireland 0.03 0.1Netherlands   0.17 0.6Norway 0.37 1.2StoragePumped storage               0.01 0.0Title to go hereBody copy to go here66Title to go hereBody copy to go here67Globally Floating Offshore Wind will grow from a low 15 km2 today to more than 33,000 km2 by 2050.Floating windToday                                         0.1GWPredicted 2027     world             8.3GW Predicted 2050     world         250.0GW  (16,000 of 15MW turbines)WORLD FLOATING WIND Ref[1]Title to go hereBody copy to go here68CUMULATIVE FLOATING WIND Ref[22]Title to go hereBody copy to go hereFOWT Challenges   Ref[20]69a. To reduce FOWT costs, sustained mass production is neededc. Commercial FOWT will use >15MW turbines d. Probably visual impact when fitted out inshore.e. Spar and TLPs to stay offshore for in place major maintenance Title to go hereBody copy to go here70Port With Manufacture Ref[28]Title to go hereBody copy to go hereFUTURE WORK 71Floating wind will be an important component in the offshore wind industry’s future. In some markets – such as Spain, Japan, Norway, West Coast of the U.S. and island communities – there is limited shallow water and so floating wind is a potential solution.In other markets, floating wind will be used more once we run out of sites that can accommodate fixed-bottom wind turbines.It will take time to scale up production of floating wind components.Title to go hereBody copy to go hereRESEARCH WORK  Shipyard requirements for mass production Fit out quay requirements (strength of quay wall and water depth and available cranes) Tow out and installation of TLPs Heavy maintenance offshore of Spars and TLPs72Title to go hereBody copy to go hereCONCLUSIONS 73To facilitate the installation process and minimize costs, the main installation aspects have to be considered: >  Floating offshore wind turbine type (substructures different)>  Shipyard location>  Distance from the shipyard to the fit out port distance  Distance from fit out port to offshore wind farm site (3 day tow)>  Minimise weather downtime during installation >  Number of anchor handling vessels (3 or 4)> Whether an offshore crane vessel is required (TLP)Title to go hereBody copy to go here74THANK YOU FOR YOUR ATTENTIONANY QUESTIONSEmail ac1080@Exeter.ac.ukTitle to go hereBody copy to go here75ABBREVIATIONSFOWT       floating offshore wind turbineHTV           heavy transport vesselKm            kilometreM              metreSPMT        self propelled modular transporter (trailer)T               (metric) tonnes WTG         wind turbine groupTitle to go hereBody copy to go here76REFERENCES1. ‘www.dnv.com, accessed 28 April 20222. ‘www.wison.com, accessed 28 April 20223. ‘www.menon.no, accessed 28 April 20224. ‘www.equinor.com, accessed 28 April 20225. ‘www.principlepower.com, accessed 28 April 20226. ‘www.saipem.com, accessed 28 April 20227. ‘www.trivane.com, accessed 28 April 20228. ‘www.hexicon.eu, accessed 28 April 20229. ‘‘www.deme.com’, accessed 16th Feb. 202210. ‘www.xwind.com accessed 1st June 202211. ‘www.bw-ideol.com, accessed 19th June 202212. ‘www. saitec-offshore.com, accessed 28 April 202213. ‘www.vestas.com, accessed 28 April 202214. BSEE, Bureau of Safety and Environmental Enforcement (USA), 202215. US Department of Energy, 2023, Josh Bauer/NREL16. ‘www.ibedrola.com , 202317. ‘www.vrhof.com, and ‘www.aecton.com 202318. ‘www.NREL.com, 202319. ‘www.bluefloat.com, 202320. ‘www.mainstreamrenewablepower.com, 202321. ‘www.iamkate.com, 202322. ‘www.energy.gov, 202323. ‘www.sbm.com, 202324. ‘www.floatingwindfarm.weebly.com, 202325. ‘www. everaxis.com, 202326. ‘www.roll-group.com, 202327. ‘www. Fukushima-Forward.jp, 202128. ‘www.moffatandnichol,.com, 202329. ‘www.jmu.jp, 2023Title to go hereBody copy to go here77ABSTRACTInterest in floating offshore wind farms in deep waters is increasing, as an option for marine renewable energy. Existing floating  wind projects demonstrate the feasibility of future commercial floating wind farms. To boost the competitiveness of floating offshore wind energy, it is important to identify the major cost drivers during the lifecycle, including the installation phase. Costs will be considered in the presentation into the optimum use of installation vessels. Each type of floating substructure types exhibit quite different characteristics during transportation and installation.This presentation is a review of the state-of-the-art technical aspects of floating offshore wind turbine installation for different substructures types. An overview is first presented introducing the classification of floating offshore wind turbines, installation vessels, rules and regulations, and numerical modeling tools. Various installation methods and concepts for floating offshore wind turbines are critically discussed, including cable installation, wind turbine substructures and components. Opportunities and challenges of the installation methods of floating offshore wind turbines are identified. Future developments in technical areas are envisioned in loadout, topside fit out, ocean tow and offshore installation are discussed. This review aims to guide research and development activities on floating offshore wind turbine installation.Title to go hereBody copy to go here78Ref[14]Title to go hereBody copy to go here79Title to go hereBody copy to go here80QuestionsQ1.    Why is floating wind so important?A1.    It is important for climate change that as much electricity as possible is produced from renewable resources, floating wind being one of them.Q2.   How do you expect existing floating construction equipment to be used for floating wind installation?A2:    Large crane vessels such as those operated by Heerema and Saipem will have a part to play in construction of TLPsQ3.    How can heavy maintenance be carried on during operation of Spars and TLPs?A3:    Large crane vessels such as those operated by Heerema and Saipem will have a part to play in the heavy maintenance of TLPs and Spars, but will need to fitted with active heave compensation.Title to go hereBody copy to go here81Q4.    What new marine vessels are required to install floating wind turbines?A4.     Larger anchor handling tugs which can transport several sets of mooring components and then install them.Q5.      What changes are required in fit-out ports for the inshore construction of floating wind?A5.      The port needs to be within in 3 days sailing time of the offshore wind, at about 3knots maximum, i.e. about 200 nautical miles. A strong quay capable of  supporting large mobile cranes. Also water depth alongside the quay of over 0m at low tide is required.Title to go hereBody copy to go here82Ref [4]Q6.    How is the cost of floating wind turbines expected to reduce?A6.     See the Equinor estimates of future floating wind.Title to go hereBody copy to go here83Q7.    Can old oil rigs be used for floating wind?A7.    There may be a role for jack ups to be converted into floating port construction vessels. ClassNK has issued an approval in principle (AiP) for the conversion plan of the medium-sized self-elevating platform (SEP) vessel (pictured) for the installation of large wind turbine on a semi-sub floater in port, re[]

Floating offshore wind turbines - Installation methods

Conference:Marine Construction Engineering Deepwater DevelopmentNovotel London West, Hammersmith, London, W6 8DR, UK12th to 14th April 2022FLOATING OFFSHORE WIND TURBINES INSTALLATION METHODSBy Alan Crowle*1 and Professor P.R. Thies1 *Email: ac1080@exeter.ac.uk1 University of Exeter, College of Engineering, Mathematics and Physical Sciences, Renewable Energy Group, Penryn Campus, Treliever Road, TR10 9FE, UKvINTRODUCTIONFloating offshore wind turbines are an emerging source of marine renewable energy, in deep water offshore locations, with minimal visual impact from the shore. The presentation reviews the installation methods for floating wind types such as barges, Spars, semi submersibles and TLPs, Ref[1].MAIN FOWT TYPES      Ref[2]FOWT TYPE BARGE SPAR SEMI SUBMERSIBLE TLPNo. in operation 1 concrete 1 steel 5(straight)                             1(Submerged keel)8 Windfloat                                1 WisonNoneAdvantages Small draft so can be moored in many ports for fit outGood intact stability during tow outGood intact stability during tow outSmall area of moorings on the seabedDisadvantages a. Long mooring lines                                    b.   Small freeboard so weather restricted during towouta.    Deep draft, 70 to80m means fit out needs to take place in sheltered deep water e.g. Norwegian Fjords   b.   Long mooring lines    c.   Requires solid ballast specific gravity 2.5 to 4.0 t/m3                                     d.    Long mooring lines                 e. Requires large crane vessel or spacer barge with crawler crane for turbine installation inshorea.   High substructure weight                                     b.   Long mooring linesa.  Very low intact stability during tow out                     b.   Turbine is in the centre  so reducing crane capacity during turbine fit out                                             c. Installation on tethers is weather restricted and time consuming                                          d.  Drag anchors not possible                            e. May need temporary buoyancy for towoutf. May need crane vessel to assist offshore mooring connectionSURVEYSSurvey are required for the export cable route and offshore wind farm Metocean Geophysical including water depths Geotechnical  Shifting seabed UXO Grapnel dragged along the cable export cable route AUV with LIDAR Looking for: Wrecks Lost fishing gear Pipelines Cables electric, TelecommsGEOPHYSICAL  SURVEY   Ref[3]Dedicated vessels map the characteristics of the seabed and bedrock to assess the conditions around the wind farm site and the potential export cable locations.Accurate measurements aremade of the bathymetry GEOTECHNICAL SURVEY   Ref[3]The detailed site geotechnical  investigations include, downhole cone penetration testing (CPT), seismic cone penetration testing (SCPT), ENVIRONMENTAL  SURVEY   Ref[12]  Bird migration Fisheries Surveys Fish spawning studies Plankton Surveys Fish behaviour surveys Electronic monitoring and sampling of fish toevaluate their behaviour in regards to sub-sea power cables Surveys to investigate the behaviour of fishspecies during offshore piling activities Sampling survey to examine the behaviourof fish species in regards to unburied sub-sea pipelines Commercial fishery mitigation andmanagement surveysMETOCEAN SURVEY   Ref[3]  Habitat mapping and marine mammal monitoring  Metocean measurement Real-time ocean current profiling  Integrated real-time buoy monitoring systems Derivation of metoceanstatistics for installation, operational and design supportMETOCEAN SURVEY   Ref[4]The long term measurements include: Wind speed Wind direction Wave height Wave period Wave direction Tide heights Tidal current speed Tidal current directionROUTE CLEARANCE    Ref[11]Route clearance is required ahead of site preparation and cable installation. The assets to swiftly, accurately and safely remove boulders, old cabling and other debris and obstacles from all compositions of seabed, include:•Pre-Lay Grapnel Runs to remove surface debris (including fishing nets, redundant wiring and ropes) from the cable route, creating a clear path for the submerged plant and burial vehicle during trenching.•Removal ofout-of-service cables found within the installation corridor to create a clear and safe passage for new cable installation.•Removal and relocation of boulders, using a multi-purpose work class ROVs to clear obstructions from both low and high-density areasUNEXPLODED ORDNANCE Ref[11] RISK MITIGATIONA UXO solution, from initial survey through to subsequent positive explosive ordnance disposal (EOD) on designated targets, using the latest technologies and techniques to deliver results safely, efficiently, and cost-effectively.  Detection, identification, removal and disposal Innovation in disposal including bubble curtain noise attenuation3D  AUV  Ref[22]Hydrography and Geophysics are central to any site investigation or seabed mapping project. Securing accurate and precise 3D data sets to assess, measure, evaluate, document and monitor are important to the success of any underwater program. measure subsea topography, assets and the marine environment are important. From establishing baseline audits to long term documentation and monitoring, the subsea LiDAR SL systems provide touchless, log range – up to 45 meter 3D scans with low impact to the surrounding environmentTURBINESFloating offshore wind turbine, maximum so far    9.6MWFixed offshore wind turbine, on order                  13.0MWTURBINES    Ref[13]BladesHubNacelleTowerTURBINES    Ref[13]BLADE TRANSPORT   Ref[9]NACELLE TRANSPORT   Ref[5,10]STEEL BARGE (2 blades) Ref[19]  BW-IDEOLCompleted-structurewith 2 bladesSheer leg crane vessel used to install tower, nacelle and bladesSteel substructureEQUINOR STEEL SPAR    Ref[21]Semi submersible crane vessel (SSCV) SaipemS7000 , ref[17} lifting the HywindSpar turbineEQUINOR STEEL SPAR    Ref[21]Outfitted Steel Spar,70m draft. Topsides installed by SSCVTemporary moorings for bargeSpar moored to bargeOutfit bargeLarge onshore crane to lift turbineSpacer bargeConcrete substructure, 80m draftEQUINOR CONCRETE SPAR    Ref[21]MOORINGSMOORING TYPES     Ref [14] OFFSHORE ANCHOR TYPES  Ref [15]ANCHORING SYSTEMS     Ref [15] HEXICON TURRET MOORING Ref[16]Turret, with fixed moorings and electrical swivel.                         Turbines fixed. SAIPEM HEXAFLOAT   Ref[17]BladesNacelle/hubTowerSubstructureSubmergedPendulumTension MooringDynamic cable Body copy to go hereSBM    Ref1[8] 30Tow out shallow draftLarge 2nd moment of Water plane areaTension (chain)tethers, ballast downand re-tensionTLPVariableDraftSTIESDAL OPTIONS   Ref[19]TetraSub:semisubmersible TetraTLP: Tension Leg TetraSpar:SparTLP Requires temporary buoyancyfor the tow out and mooring connectionSpar uses suspendedballast weight for inplace intact stabilitySEMI SUBMERSIBLE INSTALLATIONLOADOUT  Ref[5]  (Offshore China) SubstructureLength 91mWidth 91mDepth 31mBraceColumnHeave plateON SUBMERSIBLE BARGE    Ref[5]SubstructureSPMT TrailersSubmersible BargeHarbour Tug TOW OF SUBSTRUCTURE   Ref[5]SubstructureHarbour tugOcean going tugLIFTING TOWER SECTIONS Ref[5]Tower on cornerTo maximise onshore cranecapacityTOWOUT STRUCTURE Ref[5]Tower on cornerTugger linesTowing bridleHarbour tugOcean tugCONNECT MOORINGS    Ref[5]Mooring lines(3 per column)Moorings beingtensionedTugger linesDYNAMIC CABLE Ref[5]DYNAMIC CABLE CONNECTION Ref[5]BladesNacelleTowerSubstructureCable lay vesselCONCLUSIONSTo facilitate the installation process and minimize costs, the main installation aspects have to be considered: >  Floating offshore wind turbine type (each substructure is different)>  Inshore vessel requirements (inshore floating crane)>  Shipyard location can be anywhere in the world>  Blade and nacelle manufacture can be anywhere>  Distance from fit out port to offshore wind farm site (3 day tow)>  Semi submersible type has least weather downtime during installation >  Number of anchor handling vessels for mooring connection (3 or 4)> Whether an offshore crane vessel is required (TLP)THANK YOU FOR YOUR TIMEDO YOU HAVE ANY QUESTIONS?email ac1080@Exeter.ac.uk1. ‘www.principlepower.com, accessed February 20222. ‘www.deme.com’, accessed 16th Feb. 20223. ‘www.fugro.com’  accessed 17th Feb. 20224. ‘www. Eolos.com’  accessed 17th Feb. 20225. ‘www.myse.com.cn 6. ‘https://www.world-energy.org/article/21889.html  video of Chinese floating offshore wind turbine7. ‘https://www.world-energy.org/article/18936.html  video of floating offshore wind turbine8. ‘https://www.offshorewind.biz/2021/12/10/floating-to-fixed-wind-turbine-connection-comes-online-offshore-china-video/9. ‘http://following-the-wind.com/de/2021/05/24/envision-liefert-300-windturbinen-nach-vietnam/10. ‘https://www.offshorewind.biz/2021/06/08/saint-nazaire-nacelles-start-arriving-by-sea/11. ‘www.james-fisher.com accessed 17th Feb. 202212. ‘www.brownandmaymarine.com accessed 18th Feb. 202213. ‘www.ge-wind.com, accessed November 202114. ‘www.intermoor.com,   accessed December 202115. ‘www.vryof.com, accessed 17th Feb. 202216. ‘www.hexicon.eu, accessed 17th Feb. 202217. ‘www.saipem.com, accessed 17th Feb. 202218. ‘www.sbm.com, accessed 17th Feb. 202219. ‘www.bw-ideol.com, accessed 17th Feb. 202220. ‘www.stiesdal.com, accessed 17th Feb. 202221. ‘www.equinor.com, accessed 17th Feb. 202222. ‘www.3datdepth.com, accessed 13th April 202223. ‘www.boskalis.com, accessed 13th April 2022REFERENCESAbbreviation MeaningAHTS anchor handling tug supply   (large towing tugs) AUV autonomous underwater vehicleCSV Construction support vessel FOWT Floating offshore wind turbineROVremotely operated (underwater) vehicleWROV – work class ROVSSCV semi submerrsible crane vessel SPMT self propelled modular transporterNo Question Reply 1How many boreholes are required in the geotechincal survey?Boreholes are required across the whole site because if there is rock in some places and soft mud in other places then  completely different  anchors are required2What about drilled and driven piles installation?Drilled and driven piles work for soft mud, hard mud, sand, soft rock and hard rock. A construction support vessel (CSV) with crane for working in deep water is required for installation. An AHTS is required to lay the mooring line on the seabed.3What about suction piles installation?Suction anchors work in soft mud, hard mud and sand. A construction support vessel (CSV) with crane for working in deep water is required for installation. An AHTS is required to lay the mooring line on the seabed.4What about drag anchors installation?Drag anchors work in soft mud, hard mud, sand and soft rock. Drag anchors can be installed and tensioned with a AHTS. The maximum water depth is about 1500m5What about torpedo anchors installation ?Torpedo anchors work in soft mud, hard mud and sand. A construction support vessel (CSV) with crane for working in deep water is required for installation. An AHTS is required to lay the mooring line on the seabed. The minimum water depth is 100m.But there is limited information on their useNo Question Reply 6Ports for fit out of turbine  onto the substructure?The Cromarty Firth currently has the best existing facilities for fit out of barges and semisubmersibles. It has heavy construction,potential quays fro fit out and has sheltered waters for wet storage.7Typical design life? A typical FOWT design life is 25 years8Major maintenance, blade and nacelles, for the Spar?It is unlikely that Spars can be returned to port, for heavy maintenance, because of the the large water depth required.9Major maintenance, blade and nacelles,  for the TLP?It is unlikely that a TLP can be returned to port because of the difficulty of attaching temporary buoyancy offshore and the complicated moorings. 10Major maintenance, blade and nacelles, for the bargeA barge might be returned to port, for heavy maintenance, if the dynamic array cable is not 'daisy chained'11Major maintenance, blade and nacelles, for the semisubmersible A semi submersible might be returned to port, for heavy maintenance, if the dynamic array cable is not 'daisy chained'12What about demolition of FOWTs.TLPs and Spars will be difficult for demolition and may need offshore crane vessels. The barges and semi submersibles demolition is a reverse of the installation process.CONSTRUCTION SUPPORT VESSEL Ref[23]Dynamic positioning class II or III,ROV Hangar: ROV hangar for 2 x WROV Hydraulic controlled gate 2 x ROV workshops120 t Active heave compensation Offshore knuckle jib crane MOORING USING 3 AHTS Ref[23] and Ref[1]

Floating offshore wind turbines installation methods

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Floating offshore wind turbines installation methods

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