INF/TE/SSD/W/26/Add.1  
 
 
23 May 2023 
(23-3525) Page: 1/42 
  
  
  Original: English  
 
  
TRADE AND ENVIRONMENTAL SUSTAINABILITY STRUCTURED DISCUSSIONS  (TESSD)  
COMMUNICATION  FROM THE UNITED KINGDOM  
Addendum1 
The following communication, dated 23 May 2023, is being circulated at the request of the delegation 
of the United Kingdom.  
 
_______________  
 
OFFSHORE WIND ENERGY  
Technical paper by the United Kingdom  
ANNEX I.  
VALUE CHAIN DIAGRAMS  FOR OFFSHORE WIND ENERGY  
Value chain diagrams – key: 
 
Chevron 
Colour  Meaning  
  Activity or process involved in the 'Development and project management ' 
stage of an offshore wind farm 's lifecycle. In the delivery of a service, this 
represents a sub -stage of service delivery. In th e delivery of a good (whether it is 
an input, intermediate, or final good), this represents a manufacturing activity or 
production process.  
  Manufacturing activity or production process involved in either the manufacture or 
assembly of a wind turbine  
  Manufacturing activity or production process involved in the manufacture, 
assembly, or installation of an offshore wind farm 's balance of plant equipment  
  Manufacturing activity, production process, or installation process involved in the 
final installation and commissioning  of an offshore wind farm  
  Manufacturing activity, production process, or installation process involved in the 
'Operation, maintenance and service ' stage of an offshore wind farm  
  Activity or process involved in the 'Decommissioning ' stage of an offshore wind 
farm's lifecycle  
  Input product, intermediate product, final product, or a service deliverable in any 
stage of an offshore wind farm 's lifecycle  
 
  
 
1 This Addendum supplements the paper titled "Offshore Wind Energy – Submission of Information to 
trade and Environmental Sustainability Structured Discussions (TESSD) from the United Kingdom", 
INF/TE/SSD/W/26 . INF/TE/SSD/W/26/Add.1  
 
- 2 - 
 
  Contents  
I.1.  DEVELOPMENT AND PROJECT MANAGEMENT  ................................ ............................  3 
I.1.1.   Development and consenting services  ................................ ................................ ..........  3 
I.1.2.   Environmental surveys  ................................ ................................ ...............................  4 
I.1.3.   Resource and metocean assessment  ................................ ................................ ............  6 
I.1.4.   Geological and hydrographical surveys  ................................ ................................ .........  8 
I.1.5.   Engineering consultancy  ................................ ................................ .............................  9 
I.2.  Wind Turbine  ................................ ................................ ................................ .............. 10 
I.2.1.   Nacelle  ................................ ................................ ................................ .................... 10 
I.2.2.   Rotor  ................................ ................................ ................................ ...................... 12 
I.2.3.   Tower  ................................ ................................ ................................ ..................... 14 
I.3.  Balance of plant  ................................ ................................ ................................ .......... 16 
I.3.1.   Cables  ................................ ................................ ................................ .................... 16 
I.3.2.   Turbine foundation  ................................ ................................ ................................ ...17 
I.3.3.   Offshore substation  ................................ ................................ ................................ ..18 
I.3.4.   Onshore substation ................................ ................................ ................................ ...19 
I.3.5.  Operations base  ................................ ................................ ................................ .......20 
I.4.  Installation and commissioning  ................................ ................................ ..................... 21 
I.4.1.   Foundation installation  ................................ ................................ .............................. 21 
I.4.2.   Offshore substation installation  ................................ ................................ .................. 23 
I.4.3.   Onshore substation construction  ................................ ................................ ................ 24 
I.4.4.   Onshore export cable installation ................................ ................................ ................ 25 
I.4.5.   Offshore cable installation  ................................ ................................ ......................... 26 
I.4.6.   Turbine installation  ................................ ................................ ................................ ...27 
I.4.6.1.   Commissioning  ................................ ................................ ................................ ......28 
I.4.7.   Construction port  ................................ ................................ ................................ .....29 
I.4.8.   Offshore logistics  ................................ ................................ ................................ ......30 
I.5.  Operation, maintenance and service  ................................ ................................ .............. 31 
I.5.1.   Operations  ................................ ................................ ................................ .............. 31 
I.5.1.1.   Training  ................................ ................................ ................................ ............... 31 
I.5.2.   Maintenance and service  ................................ ................................ ........................... 35 
I.5.3.   Balance of plant maintenance and service  ................................ ................................ ...36 
I.6.  Decommissioning  ................................ ................................ ................................ ........ 37 
I.6.1.   Turbine decommissioning  ................................ ................................ .......................... 37 
I.6.2.   Foundation decommissioning  ................................ ................................ ..................... 38 
I.6.3.   Cable decommissioning  ................................ ................................ ............................. 39 
I.6.4.   Substation decommissioning  ................................ ................................ ...................... 40 
I.6.5.   Decommissioning port  ................................ ................................ .............................. 41 
I.6.6.   Reuse, recycling or disposal  ................................ ................................ ....................... 42 
 
   
  INF/TE/SSD/W/26/Add.1  
 
- 3 - I.1.  Development and project management  
I.1.1.   Development and consenting services  
Development and consenting covers the work needed to secure consent and manage the development process through to financial c lose. 
 
 
 
  
Development and Consenting servicesEnvironmental Impact AssessmentsHabitual regulations assessmentEnvironmental StatementResidual impactsMitigationSite-Specific impactsAssessmentScoping 
  INF/TE/SSD/W/26/Add.1  
 
- 4 - I.1.2.   Environmental surveys  
To determine the environmental impacts, a full suite of environmental surveys of the wind farm location and its surroundings is undertaken. These surveys 
establish the baseline for the assessment and allow impact modelling to be undertaken.  
 
• Benthic environmental surveys:  Benthic studies survey species that live on the sea bed and in sediment. The survey data and analysis is used to 
define areas of similar environmental conditions on the sea bed and to inform habitat and species impact studies.  
• Fish and shellfish surveys:  establish what species a re present in the water column within the proposed wind farm site and surrounding areas. The 
resulting data is used to inform impact analysis and reporting.  
• Ornithological surveys:  establish the presence and behaviour of birds within the wind farm boundary  and surrounding areas. The data from these 
bird surveys is used to establish the risks to birds that a wind farm may pose.  
• Marine mammal surveys:  establish the diversity, abundance, distribution and behaviour of cetaceans (including porpoises, dolphins an d whales) 
and seals within the wind farm boundary and surrounding areas. Surveys are typically undertaken monthly for at least two year s to establish how 
these variables change across seasons and between years. The data from these surveys is used to establ ish the potential impacts to marine mammals 
that a wind farm may pose.  
• Onshore environmental surveys:  consider the potential ecological impact that cable -laying and onshore substations may have on the onshore 
environment.  
• Human impact studies:  assess the i mpact that a proposed wind farm may have on the community living in and around the coastal area near the 
wind farm.  
   
  INF/TE/SSD/W/26/Add.1  
 
- 5 -  
 
 
Environmental Surveys
Onshore environmental 
surveysOrnithological environmental surveysImpact models and reports
Fish and shellfish 
surveysImpact models and 
reportsLaboratory analysesSpecies identification 
and counting
Benthic environmental surveysImpact models and reports
Reporting
Data analysis
SurveyingHuman Impact Studies
Consultation
SurveysMarine mammal environmental surveys
Impact models and reports
Species identification and counting
Offshore ornithological and mammal 
surveyingImpact models and reports
Species identification and countingImpact models and reports
Species identification and counting
Offshore ornithological and mammal 
surveying
Experienced and 
qualified crewVessels and aircraftLaboratory analysesSpecies identification and 
counting
Species identification and counting
Many of above services likely 
CPC (2.1) 83931 –
(Environmental consulting 
services) 
  INF/TE/SSD/W/26/Add.1  
 
- 6 - I.1.3.   Resource and metocean assessment  
A resource and metocean  assessment is carried out to provide atmospheric and oceanographic datasets to inform the engineering design of a wind farm, the 
potential future energy production, and to fully describe the likely operating conditions at the proposed wind farm location.  
 
• The structure:  provides the mounting for the meteorological and metocean, sensors and auxiliary systems plus safe access for personnel.  
• Sensors:  provide data on meteorological and oceanographic conditions at the site of interest. Data loggers provide data  storage, processing and 
remote communications capability.  
• Maintenance:  Offshore wind and metocean systems will require maintenance, including inspection, cleaning and refuelling (where diesel gene rators 
or hydrogen fuel cells or similar are used).  
  
 
   
  INF/TE/SSD/W/26/Add.1  
 
- 7 -  
 
 
 
Resource and metocean assessmentStructure Sensors MaintenanceAssembly/ConstructionFoundation
Platform
Mast
Buoys
Assembly/ConstructionMeteorological sensors
Anemometers
Metocean sensors
Dataloggers
Access vessel
Maintenance personnel
Equipment and consumablesHS 730820
HS 8907
HS 901580
CN 9015802000
HS 903180
HS 902580
HS 847190
HS 890110 
  INF/TE/SSD/W/26/Add.1  
 
- 8 - I.1.4.   Geological and hydrographical surveys  
Seabed surveys analyse the sub seabed environment of the proposed wind farm site and export cable route to assess its geologi cal condition and engineering 
characteristics. The data collected is utilised in a wide range of engineering and environmental studies through the design and development phase.  
 
 
 
Geological and hydrological surveysGeophysical Surveys Geotechnical Surveys Hydrographic SurveysGeophysical survey 
vesselsSpecialist crew
Survey and 
analysis 
equipment
Geotechnical survey 
vesselsSpecialist crew
Survey and 
analysis 
equipmentVessels
Crews
Survey 
equipmentHS890110
HS901580
HS901580
HS901580
HS890110
HS890110 
  INF/TE/SSD/W/26/Add.1  
 
- 9 - I.1.5.   Engineering consultancy  
Front -end engineering and design (FEED) studies address areas of wind farm system design and develop the concept of the wind farm i n advance of procurement, 
contracting and construction. Earlier on in the process, pre -FEED studies are used to develop an ou tline concept of the project for the purposes for defining the 
consent envelope and to inform environmental impact studies. The FEED study is continually refined through the development pr ocess and is ultimately used to 
frame and process substantial engine ering and procurement decisions.  
 
 
 
  
Engineering and ConsultancyOperational strategyInstallation MethodsHealth and Safety PlanningInterface ManagementElectrical design strategyFoundation type selectionTurbine selectionLayout design and optimisation 
  INF/TE/SSD/W/26/Add.1  
 
- 10 - I.2.  Wind Turbine  
The turbine converts kinetic energy from the wind into three -phase AC electrical energy.  
 
I.2.1.   Nacelle  
The nacelle supports the Rotor and converts the rotational energy from the rotor into three -phase AC electrical energy.  
 
• Bedplate:  supports the drive train and the rest of the nacelle components and transfers loads from the rotor to the tower.  
• Main bearing:  supports the rotor and transfers some of the rotor loading to the nacelle Bedplate.  
• Main shaft:  transfers torque from the rotor to the gearbox or, for some direct drive designs, the generator. It is supported at the rotor  end by the 
main shaft bearing and at the other end either by the gearbox / generator or separately mounted bearing.  
• Gearbox:  converts rotor torque at a speed of 5 -15 rpm to a speed of up to about 600  rpm for a medium speed gearbox and 1500  rpm for a high -
speed gearbox for conversion to electrical energy by the generator.  
• Generator:  converts mechanical energy to electrical  energy.  
• Power take -off: receives electrical energy from the generator and adjusts voltage and frequency for onward transfer to the wind farm distribu tion 
system.  
• Control system:  provides supervisory control (including health monitoring) and active power a nd load control in order to optimise wind turbine life 
and revenue generation, while meeting externally imposed requirements.  
• Yaw system:  orients the nacelle to the wind direction during operation.  
• Yaw bearing:  connects the nacelle and tower, enabling the yaw system to orient the nacelle to any wind direction during operation.  
• Auxiliary systems:  facilitate ongoing unattended operation of the wind turbine for the vast majority of the time, and support planned maintenanc e, 
which typically should be only on an annual basis.  
• Nacelle cover:  provides weatherproof protection to the nacelle components pl us support and access to external components such as coolers, wind 
measurement equipment and lighting protection devices.  
• Small engineering components:  make up the rest of the nacelle assembly.  
• Structural fasteners (either bolts or studs):  are used in a ra nge of critical bolted joints, for example connecting rotor to main shaft, main bearing 
housings to nacelle bedplate and yaw bearing to the underside of nacelle bedplate.  
• Condition monitoring systems:  provide additional health checking and failure predicti on capability.  
   
  INF/TE/SSD/W/26/Add.1  
 
- 11 -  
 
 
 
 
 
 
 
NacelleNacelle assemblyBedplatePaintingMachiningLarge SG Iron or 
fabricated steel 
structure
Main bearingAssembly
Main shaftPaintingNon -destructive testingMachiningForged or cast shaft
GearboxAssembly
SensorsLubricansGearsCylindrical, taper and 
spherical roller bearings; 
plain bearingsSG iron castings and 
steel forgings
GeneratorAssembly
High -speed shaft 
couplingSlip rings for doubly 
fed induction 
generatorsSensorsBearingsWindingsCastings
Power Take -offAssembly
CablesSwitchgearTransformerPower converter
Control SystemAssembly and installationSensor 
installation
TachometersThermocouplesStrain gaugesPower metersLoad cellsAccelerometers
Power metersLoad cellsAccelerometers
Strain gaugesPower metersLoad cellsAccelerometers
ThermocouplesStrain gaugesPower metersLoad cellsAccelerometers
TachometersThermocouplesStrain gaugesPower metersLoad cellsAccelerometers
Safety and Emergency 
systemsControl system 
hardwareControl panels
Yaw System
Assembly
SensorsYaw brakesYaw motors and 
associated gearboxesYaw bearing
Metal sprayed and/or painted finish
Assembly
Surface finishing
Hardening
Machining
Forged ringsMachining
Forged ringsHardening
Machining
Forged rings
GreaseSealsCages or spacersBalls
Cages or spacersBalls
SealsCages or spacersBallsNacelle Auxiliary systems
Assembly
Internal service craneUninterruptible Power SupplyFire protectionAnemometryCoolingRotor lockBrakeNacelle Cover
Assembly
Post -assembly auxiliary systemsBuilt -in auxiliary 
systems
Maintenance support 
features
Fibreglass or steel 
constructionInstallation of small engineering 
components
Lighning conductorsOther fixed maintenance aidsHose handing systemsCableDrip traysFlooringGuards
Small fastners
Other accessories and 
consumables used during 
assemblyStructural fasteners
AssemblyBolts
Studs
NutsCondition monitoring 
system
Assembly and 
installation Sensors
Condition 
monitoring 
hardwareHS 730890
CN 7308909811
CN 7308909890HS 732690HS 848299HS 848250HS 271019
HS 401693
Main bearingAssembly
Forged rolled ringRolling elementsRolling element 
supportLubricants and sealsSG iron bearing 
housingCN:
84833032
CN 84831021HS 903180HS 2710HS 848340
Possible HS:
848220
848230
848250
848280HS 732599HS 848360HS 850300HS 903180HS 8482HS 854411HS 7326HS 8544HS 8537HS 8504HS 850440HS 854370HS 853710HS 902920HS 902580HS 8533HS 902830HS 842390HS 903190
HS 850231
CN 8502310085HS 841280
HS 8503?
HS 841290
HS 903180HS 732690
HS 732611
HS 732690
HS 73??
HS 401693
HS 271019
HS 870830
HS 8503?
HS 841989
HS 902680
HS 842410
HS 850440
HS 842691
HS 7109
HS 730890
HS 732399
HS 8544
HS 853540
HS 741533
HS 741533
HS 741533HS 830890
HS 903180
HS 903180HS 730290? HS 848310 HS 848340 HS 850231 HS 848360 HS 854370 
  INF/TE/SSD/W/26/Add.1  
 
- 12 - I.2.2.  Rotor  
The rotor extracts kinetic energy from the air and converts this into rotational energy in the drive train.  
 
• Blades: capture the energy in the wind and transfer torque and other unwanted loads to the drive train and rest of the turbine.  
• Hub:  connects the blades to the main shaft.  
• Blade bearings:  enable adjustment of blade pitch angle to control power output from the turbine, minimise loads and start/stop turbine as req uired.  
• Pitch system:  adjusts the pitch a ngle of the blades to control power output from the turbine, minimise loads and start/stop turbine as required.  
• Spinner:  provides environmental protection to the hub assembly and access into the hub and blades for maintenance personnel.  
• Rotor auxiliary systems:  may be incorporated to lubricate bearings and provide condition monitoring and advanced control inputs.  
• Fabricated steel components:  often required to stiffen the blade bearing support and provide a connection for hydraulic pitch system actuators.  
 
   
  INF/TE/SSD/W/26/Add.1  
 
- 13 -  
 
 
 
  
RotorRotor assemblyBlades Hub casting Structural fastenersAssemblyStructural composite 
materialsAssembly
ConsumablesClosed -cell foam or 
balsa bulk fillAdhesiveEpoxy or polyester resinCarbon fibreFibreglass
Epoxy or polyester resinCarbon fibreFibreglass
Blade rootAssemblyComposite 
structureMetal inserts
Composite 
structureMetal inserts
Environmental 
protectionAssembly
Data captureMetal or ceramic 
insertsTapeLightning conductor 
arrangementLightning receptors
PaintingMachiningNon -destructive testingCasting
Blade bearingsMetal sprayed and/or painted finishAssemblySurface finishingHardeningMachiningForged rings
Surface finishingMachiningForged rings
Machining
Surface finishingHardeningMachiningForged ringsGreaseSealsCages or spacersBalls
GreaseSealsCages or spacersBalls
GreaseSealsCages or spacersBalls
Fibreglass mouldingsFibreglass mouldingsSpinner
Assembly
Fibreglass 
mouldingsFabricated 
steel support 
frameRotor auxiliary systems
Assembly
Automatic 
lubrication 
systemBlade load 
measurement 
systemMaintenance 
support featuresFabricated steel components
Assembly
Surface treatment
Steel fabricationsHydraulic pitch system Electric pitch system
Assembly Assembly
HosesAccumulatorsManifold blocksRotating unionHydraulic actuatorsPower pack
Electrical slip ringsPosition sensorsBattery chargersBatteriesElectrical panelsGearboxesMotorsOR
HS 3921?HS 350691HS 390730
Or HS 390791HS 681511HS 7019HS 8209?HS 847150?HS 820900HS 300510
HS 853540
HS 732690HS 271019HS 401693HS 73??HS 732611
HS 732690
HS 741533
HS 848049 HS 730890Possible codes:
841381
847989
8481
850300HS 903180
HS 730890
HS 8501
HS 870840
HS 841290?
HS 8537
HS 8506
CN 
8504405510
HS 9032?
HS 902680
HS 8504?
HS 8579?
HS 841221
Or HS 841229
HS 848790
Or HS 848490
HS 8481
HS 8507
HS 4009
HS 850300?HS 841221? HS 8501? HS 730890 HS 8501? HS 8503?Possible HS codes:
841280
841290 (most likely)
850300
850231
HS 841290 HS 732599 HS 848280 
  INF/TE/SSD/W/26/Add.1  
 
- 14 - I.2.3.   Tower  
The tower is typically a tubular steel structure that supports the nacelle. It also provides access to the nacelle and houses  electrical and control equipment. Also 
provides shelter and storage for safety equipment.  
 
• Steel: the most commonly used material for the manufacture of towers.  
• Tower internals:  provide means of access, lighting and safety for maintenance and service personnel, plus means of transferring hand tools and  
components to the nacelle. They  provide support for control and electrical cables and housing of switch -gear, transformers and other elements of 
power take -off. Tower internals also provide storage for survival equipment. A tuned damper may be located at the top of the tower to ai de dam ping 
of tower and structure resonances.  
   
  INF/TE/SSD/W/26/Add.1  
 
- 15 -  
  
StorageTransportationTowerPaintingShot -blastingFabricationSteel
Steel flanges
Surface finishRollingCuttingSteel Plate
Assembly or installation of tower InternalsPersonnel 
access and 
survival 
equipmentAssemblyFall arresters
Ladders
Elevator
Platforms
Tuned damperAssemblySupport Structure
Liquid container
Damping liquid
Electrical systemAssemblyPower take -off
Control System
Air conditioning
Tower Internal 
LightingAssemblyLuminaires
Low voltage wiring
Cable trays
Emergency backup 
including UPS
CoatingsAssemblyResin
Metal spray
Application equipmentPossible HS codes:
7301
721090
732690
HS 732690
HS 730721
HS 847989?
HS 732690?
CN 73269030
HS 842890
HS 732690
HS 392330?
HS 860900?
HS 290949?
HS 848360
HS 854370
HS 8415
HS 9405
HS 8544
HS 392590
Possible HS codes:
8504?
850440?
8506?HS 3907?
HS 320890
HS 842420CN 7308200011 
  INF/TE/SSD/W/26/Add.1  
 
- 16 - I.3.  Balance of plant  
The balance of plant includes all the components of the wind farm except the turbines, including transmission assets built as  a direct result of the wind farm.  
 
I.3.1.   Cables  
The cables deliver the power output from the wind turbines to the grid.  
 
 
 
HS 760110 HS 260300
HVAC Export cableTests on complete cable lengthsRoutine factory splice testsSample testsCable routine electrical testsCable (and accessories) type testsCable (and accessories) pre -qualification testsCable Core Cable OuterCable 
accessoriesAssemblyConductor
Conductor screen
XLPE insulation
Insulation screen
Lead sheathAl Cu
AssemblyBitumen
Polypropylene 
strings
Steel wire
Interface plug
Hang -off clip
Cable connector, T -Connector
Cable cleats
Cable trays
Cable protection systems
JointsFactory flexible joints
Field rigid jointOR
HS 760429
Or HS7408
HS 853690
HS 390110
HS 392690
Or HS 853690
HS 7804
Or HS 7806
HS 2714
HS 390210
Or HS 392690
HS 7223
HS 854390
Or HS 8544??
HS 853670
Or 843590HS 853590
HS 853890
HS 392590
CN 39259020
HS 8544?
HS 401699
Or HS 391732
HS 39172(1 -9)
HS 854460 
  INF/TE/SSD/W/26/Add.1  
 
- 17 - I.3.2.   Turbine foundation  
The foundation provides support for the wind turbine, transferring the loads from the turbine at the tower interface level (t ypically around 20m above water level) 
to the sea bed where the loads are reacted. The foundation also provides the conduit for the electrical cables, as well as ac cess for personnel from vessels.  
 
 
Turbine foundationFoundation assembly
Monopile
Assembly
JointsFlangeSteel platesJacket
Assembly Steel lattice
Struts
Nodes
Pin piles
Protective coatingTransition pieceAssemblyCrew access system and 
work platformAssembly GuardrailsDeckingSteel 
framework
Internal PlatformsAssemblyDeckingLightweight 
structural 
steel frame
Davit craneFabricationSteelwork
J-tubes, I -tube, or 
monopile entry pointFabricationTubular steel
Corrosion protection
ApplicationPaints and 
thermal metal 
spray coatings
Zinc or 
aluminium based 
sacrificial anodes
Impressed current 
cathodic 
protection systemsScour protection
Installation
Rock or geotextile sand 
containersHS 732690HS 730890HS 732690 HS 730890
HS 730890 HS 730490
HS 84261(1 -9)Possible Codes:
HS 401490
HS 760900
HS 730640
HS 848490
HS 681599
HS 730820
HS 732690
HS 7318??
HS 730110
HS 320890
HS 721090
HS 730791
HS 730799HS 703820 
  INF/TE/SSD/W/26/Add.1  
 
- 18 - I.3.3.   Offshore substation  
Offshore substations are used to reduce electrical los ses before export of power to shore. This is done by increasing the voltage, and in some cases converting 
from alternating current (AC) to direct current (DC) . The substation also contains equipment to manage the reactive power consumption of the electrica l system 
including the capacitive effects of the export cables.  
 
 
HS 853710
Or HS 853650
Electrical SystemHVAC System HVDC System ORAssemblyHVAC switchgear
Transformers
Passive and active reactive power compensation
Earthing systems
Auxiliary electrical, control and monitoring systems
Industrial waterproof enclosures
Cable trays, tracks, clamps and supports to protect electrical itemsHVAC switchgear
Transformers
Passive and active reactive power compensation
Earthing systems
AssemblyHV AC and DC switchgear
Transformers
Converters
Passive and active reactive power compensation
Earthing systems
Auxiliary electrical, control and monitoring systems
Industrial waterproof enclosures
Cable trays, tracks, clamps and supports to protect electrical items
StructureAssemblyHelideck and/or 
heliswitch
Steel structureHS 8504
HS 853210
HS 8536
HS 853710
HS 3923
HS 853710
Or HS 853650HS 392590
CN 39259020
HS 8504
HS 850440
HS 853210
HS 8536
HS 853710
HS 3923
HS 392590
CN 39259020
HS 730890 
  INF/TE/SSD/W/26/Add.1  
 
- 19 - I.3.4.   Onshore substation  
The onshore substation transforms power to grid voltage, for example 400kV. Where a high voltage DC export cable is used, the  substation will convert the power 
three phase AC.  
 
 
 
 
 
Onshore SubstationConstruction, Installation, and AssemblyBuildings, access, and securityConstruction, Installation, and AssemblyMonitoring 
systemsAuxiliary and low 
voltage systemWelfare 
facilityHS 903180
HS 853710
HS 300650Possible Codes:
HS 853720
HS 850421
HS 850431
HS 850440 
  INF/TE/SSD/W/26/Add.1  
 
- 20 - I.3.5.   Operations base  
The operations base supports the operation, maintenance and service of the wind farm.  
 
 
 
  
Operations baseConstruction, Installation, and AssemblyWarehouse WorkshopVessel 
berthsHS 940620
HS 8425
Possible codes:
HS 401694
HS 890190 
  INF/TE/SSD/W/26/Add.1  
 
- 21 - I.4.  Installation and commissioning  
All installation and commissioning of balance of plant and turbines, including land - and sea -based activity. For offshore activities, the process starts by transporting 
components from the nearest port to manufacture to either the I.7 Construction port or straight to site. Activities are compl ete at the wind farm construction 
works completion date, where assets are handed over to operational teams.  
 
I.4.1.   Foundation installation  
Foundation installation consists of the transport and fixing of foundation in position.  
 
 
Foundation installation vesselAssemblyFoundation handling 
equipmentAssembly Pile guiding and positioning frame
Monopile plugCrane
Lifting tool
Upend frame
Pile gripper
Pile guiding and positioning frame
Monopile plug
Foundation installation 
equipmentAssemblyAnvil System
Noise mitigation 
equipmentHammer
Sea fasteningsAssemblyTransition piece cradle
Crane sea fasteningMonopile cradle
Crane
Auxiliary cranes
Dynamic positioning system
Propulsion systems
Jack-up system
Spud cans
Helideck
GangwayCrane
Auxiliary cranes
Dynamic positioning system
Propulsion systemsCrane
Auxiliary cranes
Dynamic positioning system
Jack-up systemPropulsion systemsCrane
Auxiliary cranes
Dynamic positioning systemHS 8426
HS 8426
HS 8426
Or HS 843041, Or HS 843143
HS 841229
HS 703890
HS 732599
HS 842611
HS 820590
HS 843139?
OR HS 8536?
HS 730820
OR CN 7308909811
CN 7308909811
CN 84269190
HS 8426
HS 8426
HS 9015?
HS 840810
HS 8425
HS 7307Other potentially relevant codes:
HS 843041
HS 843143
HS 761090 
  INF/TE/SSD/W/26/Add.1  
 
- 22 -  
 
 
 
 
 
  
Installed MonopileGroutingDrivingPile positioningLiftingPreparationsPositioningTransportMonopileFoundation 
Installation 
Vessel
DumpingRocks or 
stonesFallpipe
vesselHS 7308
HS 890190
HS 890190
HS 681599
OR HS 680299 
  INF/TE/SSD/W/26/Add.1  
 
- 23 - I.4.2.   Offshore substation installation  
The installation of the offshore substation consists of the transfer of the substation from its quayside fabrication site and  the installation on the foundation.  
 
 
 
 
  
Offshore substation installationSubstation Installation VesselVessel selection
Semisubmersible vesselHeavy lift vesselBargeSheerleg crane vesselFactored into vessel type selection GangwayHelideckCrane
Auxiliary cranes
Dynamic 
positioning system
Propulsion 
systems
OR OR ORHS 8426
HS 8426
HS 9015?
HS 840810
HS 761090HS 890520
OR HS 890590
HS 890190
HS 890520
OR HS 890590
HS 890520 
  INF/TE/SSD/W/26/Add.1  
 
- 24 - I.4.3.   Onshore substation construction  
The construction of the onshore substation consists of the construction of the infrastructure and the installation of electrical equipment.  
 
 
 
 
  
Onshore Substation ConstructionMain civil construction contractingAddressing constraining featuresSubcontracted supporting workFencing Curbing Tree cutting DemolitionSite levelling
Civil worksEngineering 
designSubcontracted supporting workSealing roadsSteelwork
Flooring
Fencing
Hard -standingCar parking areas
Access tracks
Gravel pathsSteelwork
Flooring
Sealing roadsFencingSteelwork
Flooring
Car parking areasSealing roadsFencingSteelwork
Flooring
Electrical WorksSubcontracted 
high voltage 
electrical serviceMain Electrical 
Supplier Services 
  INF/TE/SSD/W/26/Add.1  
 
- 25 - I.4.4.   Onshore export cable installation  
The installation of the onshore export cable completes the connection between the offshore export cable and the onshore substation.  
 
 
 
Onshore export cable installationInstallation planningPre-Construction ActivitiesSite 
investigationEnvironmental 
work
Local services
Temporary 
bridgesSignageTraffic 
managementWheel washing
Road cleaning
Onsite compoundConstruction Welfare 
facilities for 
staffEquipment 
storage
Car parking
Cable corridor
Access roadCable trench
Storage for spoolsCable installation
Open trenching Ducting
Trench laying
MDPE 
ductsCable laying
CableDirectional drilling
Drilling equipment
Laying 
equipmentTrenching 
equipment
HS 854449 HS 847910 HS 391721 HS 842959HS 845929HS 761090 HS 8310 CN 96039091HS 847989
OR HS 842489 HS 481960 
  INF/TE/SSD/W/26/Add.1  
 
- 26 - I.4.5.   Offshore cable installation  
The installation of array cables enables the connection of the wind turbines to the offshore substation whilst the installati on of the export c able enables the 
connection between the offshore and onshore substations.  
 
 
 
Cable -laying vesselRemote Operated 
Vehicle (ROV)Assembly
Manipulator armPower supplyLighting systemPropulsion system
Control system
Remote camera
Cable -handling 
equipmentAssemblyCable 
storageCable lay 
equipmentAssembly AssemblyReelTankCarousel
QuadrantChuteCable highway (rollers)tensioners
Personal transfer 
gangwayChuteHS 840810
HS 8537
HS 852589
HS 940541
HS 850440
HS 847950
OR HS 847989HS 890690
https://rulings.cbp.gov/ruling/N159975
HS 842890
HS 392510
HS 392340
HS 848350
HS 732690
HS 847990
HS 761090HS 847490
HS 847910
HS 842790 
  INF/TE/SSD/W/26/Add.1  
 
- 27 - I.4.6.   Turbine installation  
Turbine installation involves transportation of the turbine components from the Construction port and installation of the tur bine components onto the foundation.  
 
 
 
 
Turbine installation vesselAssemblyTurbine handling 
equipment and sea 
fasteningsAssemblyRemotely controlled electro mechanical systems
Remote controls
Crane sea fasteningTower grillageWinches
Turbine frame
Blade rack sea fastening
Tag-line systems
Crane
Auxiliary cranes
HelideckSpud cansDynamic positioning system
Propulsion systems
Jack-up systems
GangwayHS 852692
HS 84253X
CN 7308909811
HS 730890
HS 730890
HS 730820
OR HS 730890
HS 843143
HS 842620
HS 842611
HS 9015?
HS 840810
HS 842542
HS 7307
CN 7610901000HS 890520
OR HS 890590 
  INF/TE/SSD/W/26/Add.1  
 
- 28 - I.4.6.1.   Commissioning  
After installation, commissioning is the process of safely completing mechanical and electrical assembly, putting all systems  to work and addressing punch lists 
before handover.  
 
 
 
  
Commissioning CompletionChecks on critical components and connections 
after a period of attended operation, then again 
after a longer period of unattended operationFirst rotation then first generation and checks on 
normal operation of all systemsOverspeed sensor and other safety -critical checksSlow rotation of the rotor to confirm balance and 
smooth operation of the drive trainExercising of all safety -critical and auxiliary systemsTesting of each link in safety and emergency 
system chainsEnergising of all subsystemsCheck of communication systems (SCADA, VHF 
radio)Mechanical and electrical completionCheck of installation activity and documentation 
  INF/TE/SSD/W/26/Add.1  
 
- 29 - I.4.7.   Construction port  
The construction port is the base for pre -assembly and construction of the wind farm. Separate locations may be used for feeding foundations and the wind 
turbines to a wind farm. Location is critical as it affects the time spent in shipment and sensitivity to weather windows.  
 
 
 
Construction portConstructionQuay Lay-down area Cranes WorkshopsPersonnel 
facilitiesHS 8426 
  INF/TE/SSD/W/26/Add.1  
 
- 30 - I.4.8.   Offshore logistics  
Offshore logistics involves coordination and support of offshore installation and commissioning activities.  
 
 
 
Offshore logisticsOffshore logistics service provision activitiesSea-based supportInstallation and 
Commissioning 
tasks
ROVSpecialist crews
CTV
Barge
Marine 
coordinationCommunicate with all 
vessels and helicoptersEnsure the 
authorisation and 
access of appointed 
persons on the siteEnsure no conflict from 
simultaneous 
operationsMonitor all vessel, 
personnel, and 
helicopter movement 
from, to, and inside the 
offshore wind farm 
perimeter Marine coordination 
centreMarine management 
system software
Weather 
forecasting and 
metocean data
LidarCurrent meterWeather forecast report
Wave buoy
AnemometerHS 890690
https://rulings.cbp.gov/ruling/N159975
HS 8907
HS 902830
HS 901580
HS 903180HS 890110
HS 890190 
  INF/TE/SSD/W/26/Add.1  
 
- 31 - I.5.  Operation, maintenance and service  
Operation, maintenance and service (OMS) are the combined functions which, during the lifetime of the wind farm, support the ongoing operation of the wi nd 
turbines, balance of plant and associated transmission assets. OMS activities formally start at the wind farm construction wo rks completion date.  
The focus of these activities during the operational phase is to ensure safe operations, to maintain the physical integrity o f the wind farm assets and to optimise 
electricity generation.  
I.5.1.   Operations  
Operations relate to management  of the asset such as health and safety, control and operation of the asset including wind turbines and balance of plant, remo te 
site monitoring, environmental monitoring, electricity sales, administration, marine operations supervision, operation of ves sels and quayside infrastructure, and 
back office tasks.  
I.5.1.1.   Training  
Training ensures that OMS personnel are qualified to fulfil the roles needed by the wind farm while ensuring their own safety  and those of colleagues.  
 
 
 
CertificationTraining ExaminationsTraining CoursesOffshore survival training, including marine transferEmergency first aid and advanced medical training
Helicopter winch training
Lifting and hoistingManual handlingWorking at height
Working in confined spaces
Wind turbine rescue
Electrical safety awareness 
  INF/TE/SSD/W/26/Add.1  
 
- 32 - I.5.1.2.   Onshore logistics  
Onshore logistics involves support and resources to the wind farm operations, including quayside infrastructure, warehousing,  logistics and operational planning.  
 
 
 
 
  
Facilities 
ManagementLifting equipmentAdministration facilities and operations room
Workshop facilities
Fuel bunkerWaste management facilitiesWet and dry rooms
Oil store
Gas bottle store
Parking spacesHS 8428 
  INF/TE/SSD/W/26/Add.1  
 
- 33 - I.5.1.3.   Offshore logistics  
Offshore logistics involves management and coordination of all marine based activities and operations.  
 
 
 
Offshore LogisticsCrew transfer vesselsInstallation Workshop facilitiesSpares and tooling storageAccommodation berths
Mess, welfare and leisure facilities
Walk to work system
Service operation 
vesselsInstallation Workshop facilitiesSpares and tooling storageAccommodation berths
Mess, welfare and leisure facilities
Walk to work system
Turbine access 
systemsAssemblyHydraulicsControl systems
Steel infrastructure
HelicoptersSpecialist offshore 
pilot training
Weather forecasting 
and metocean dataMarine planning 
softwareCommunications 
equipment
Asset trackingSafety planning and 
systemsHS 88021X HS 890110
HS 8537
HS 841221
OR HS 841229
HS 7308
HS 890110
HS 8517 
  INF/TE/SSD/W/26/Add.1  
 
- 34 - I.5.1.4.   Health and safety inspections  
Health and safety inspections are a crucial activity to ensure the ongoing safe operation of wind farm infrastructure and sys tems, and to fulfil statutory obligations 
to inspect safety critical systems on a regular basis.  
 
 
 
  
Health and safety inspections
Emergency communications devicesEmergency rations and waterFire extinguishers and suppressants
Survival suits, personal locator 
beacon, life -vests and floatation 
devices
Rescue equipment including 
descenders, spinal boards and 
stretchers, hub rescue equipmentEar defenders and safety eyewearGloves and safety bootsAdvanced medical kits
Eye-washing kits
Fuel and diesel spill kitsFirst aid kits for minor injuriesInventory trackingHS 300650
HS 300650
HS 300650
HS 611610 & HS 640340
HS 650610 & HS 9004
HS 392390
HS 842410
HS 300650, 
HS 8525, & 
HS 630720
HS 1904 & HS 2201
HS 8517
HS 732690 &
HS 940290 
  INF/TE/SSD/W/26/Add.1  
 
- 35 - I.5.2.   Maintenance and service  
Maintenance and service activities ensure the ongoing operational integrity of the wind turbines and associated balance of pl ant, including p lanned maintenance 
and unplanned service in response to faults, either proactive or reactive.  
 
 
 
  
Turbine maintenance and serviceTurbine maintenance 
and serviceUsed inBlade Inspection and 
RepairUnmanned Aerial 
Vehicle (UAV)
Main component refurbishment, 
replacement and repairUsed inLarge component repair vesselTurbine 
installation 
vesselMarine 
planningVessel 
Maintenance
Electrical transmission 
system maintenanceHS 890520
OR HS 890590HS 88062X 
  INF/TE/SSD/W/26/Add.1  
 
- 36 - I.5.3.   Balance of plant maintenance and service  
Balance of plant maintenance and service is focused on ensuring the operational integrity and reliability of all wind farm assets other than the wind turbines, 
including the substation(s), foundations, array cables, export cables, scour protection and corrosion protection systems.  
 
 
 
 
 
 
  
Balance of plant maintenance and serviceFoundation inspection and 
repairCable inspection and repairScour monitoring and 
managementSubstation maintenance and 
service
Remote 
operated 
vehicle (ROV)Autonomous 
underwater vehicle 
(AUV)
Manipulator armPower supplyLighting systemRemote cameraControl systemPropulsion system
Maintenance and service 
record managementSea bed inspection InspectionMaintenance and 
service record 
managementHS 890690
HS 890690HS 847950
OR HS 847989HS 850440HS 940541HS 852581HS 8537HS 840810 
  INF/TE/SSD/W/26/Add.1  
 
- 37 - I.6.  Decommissioning  
Removal or making safe of offshore in frastructure at the end of its useful life, plus disposal of equipment.  
I.6.1.   Turbine decommissioning  
Complete removal and shipment to shore of turbine rotor, nacelle and tower.  
 
 
 
Material recyclingReinstallation elsewhereTurbine DecommissioningDamage assessmentsHealth & Safety ManagementHealth & Safety Management
Spare partsTower removalNacelle removalHub removalIndividual blade removal Complex lifting operationsSee turbine value chain for HS 
  INF/TE/SSD/W/26/Add.1  
 
- 38 - I.6.2.   Foundation decommissioning  
Removal and shipment to shore or cut -off at sea bed level and making safe.  
 
 
 
 
Foundation decommissioningMonopile removalAbrasive waterjet cuttingHydraulic hole cuttingSawingCuttingDrillingPile cuttingStructure supports 
ecosystemRemoval of components 
below mud lineStructures left in position
OR
ROVMonopileHS 890690
HS 7308 
  INF/TE/SSD/W/26/Add.1  
 
- 39 - I.6.3.   Cable decommissioning  
Removal and shipment to shore.  
 
 
 
 
 
  
Cable decommissioningSection 
choppingDrum windingPulling from seabedCable disconnection
OR 
  INF/TE/SSD/W/26/Add.1  
 
- 40 - I.6.4.   Substation decommissioning  
Decommissioning plans typically are required as part of gaining approval to construct. These may define specific requirements for removal of components below 
the mud line which in turn may drive the choice or design of substation foundations and installation methods.  
 
 
 
  
  
Material recyclingReinstallation elsewhereSpare partsRefurbishment of parts for re -useLifting of smaller sectionsSubstation cut into sections
Left in -Situ for re -useSee substation value chain for HSOR 
  INF/TE/SSD/W/26/Add.1  
 
- 41 - I.6.5.   Decommissioning port  
Port where equipment removed is offloaded and marshalled for next stage of processing.  
 
 
 
 
 
 
  
Inverse of port installation 
processInstallation of onsite salvage 
and processing facilities 
  INF/TE/SSD/W/26/Add.1  
 
- 42 - I.6.6.   Reuse, recycling or disposal  
Once equipment is onshore, there is a motivation to extract maximum value via reuse, recycling or disposal.  
 
 
 
 
 
__________  
New CablingRemanufacturingRecyclingGrindingDryingCleaningXLPE
Waste to 
Energy for 
District 
HeatingBurning Re-use or recycling
PET
Balsa foam
Resin matricesCopper -based lightning 
protection systemBladesAluminiumCopper
Magnetic materialsSteelIronTower mass, foundations, 
and substation topsides Cable conductorFinalised assessment of disassembled componentsAge assessmentCondition 
assessmentMaterial content 
assessmentDisassemblyTurbine ComponentsHS 720410
HS 720421
HS 7404
HS 7602
HS 8505
HS 7404
HS 390761
HS 440722?
HS 390730
Or HS 390791
HS 390110