P Development and project management
Function

Development and project management covers the activities up to the point of financial close or placing firm orders to proceed with wind farm construction. This includes activities required to secure planning consents such as the environmental impact assessment, and activities required to define the design and engineering aspects.

What it costs

About £120 million for a 1GW wind farm. This includes development and consenting services, environmental surveys, resource and metocean assessment, geological and geotechnical surveys, engineering and consultancy. It also includes development expenditure incurred by lost projects (not itemised in sections below).

Who supplies them

The development and consenting stage is managed by the wind farm developer. The main UK developers are: EDF Renewables, EDP Renewables, Equinor, Ørsted, Red Rock Power, RWE Renewables, ScottishPower Renewables, SSE and Vattenfall.

Key facts

Sea bed leasing for existing offshore wind farms has been managed by The Crown Estate through several leasing rounds that began in 2000.
In 2017, a new body, Crown Estate Scotland, was formed to own and manage the sea bed in Scottish Territorial Waters and adjacent areas of the United Kingdom Exclusive Economic Zone. The Crown Estate retains responsibility for the sea bed in England, Northern Ireland and Wales.
Before the consenting process can begin, the developer must secure a sea bed lease from The Crown Estate or Crown Estate Scotland. These are granted through periodic leasing rounds.
Offshore wind projects of more than 100MW installed capacity in England and Wales are defined as nationally significant infrastructure projects (NSIP) and are examined by the Planning Inspectorate.
The Secretary of State for the Department for Business, Energy and Industrial Strategy (BEIS) grants or refuses consent based on a recommendation made by the Planning Inspectorate.
In England, a Development Consent Order is granted under the Planning Act 2008 (as amended) which incorporates a number of consents, including a marine licence and onshore consents. In Wales the marine licence is determined by Natural Resources Wales.
In Scotland, Marine Scotland examines applications for the offshore works and Scottish Ministers grant or refuse consent under the Marine (Scotland) Act of 2010 (up to 12nm from shore) and the Marine and Coastal Access Act 2009 for projects 12-200 nm from shore. A streamlined process incorporates consent under Section 36 of the Electricity Act 1989 in parallel.
In Northern Ireland, the Marine Strategy and Licensing team within the Department of Agriculture, Environment and Rural Affairs (DAERA) manages the consent application and decision making process for offshore wind projects.
Onshore consent including where the transmission cable landfall is awarded by the relevant local planning authority (LPA), except where a project is handled under an NSIP in England and Wales, in which case the onshore consents are considered within the NSIP process.
Developers typically build internal teams of about up to 50 staff during the development phase, which contract specialist packages of work to environmental and engineering consultancies and data acquisition and analysis companies.

P.1 Development and consenting services
Function

Development and consenting covers the work needed to secure consent and manage the development process through to financial close.

What it costs

About £50 million for a 1GW wind farm. This includes environmental impact assessments plus staff costs and other subcontractor work (neither of these itemised in sections below).

Who supplies them

Development services are led by the developer’s special purpose vehicle (SPV), which manages the development process and subcontracts work to a range of specialist consultancies. The SPV is a legal entity, which invests in and owns the wind farm project.

Key facts

Developers typically set up a SPV for a wind farm. Should the project advance to construction, the SPV will continue to operate for the duration of the wind farm’s life.
If the SPV is a joint venture between two or more developers, it is likely that the development team will be based in stand-alone offices to manage confidentiality.
The SPV provides a structure to enable external investment, although this investment is most likely to take place at final investment decision (FID) or post construction.
In the UK, the SPV manages the design of the wind farm and secures consent for the wind farm and transmission assets.
An early formal step in the consenting process is the production of a scoping report, the purpose of which is to scope the level of impact on various receptors in order to properly define the required assessment process and methodologies, and to ensure the environmental impact assessment (EIA) focuses on those impacts that may lead to substantial effects, It also provides an early opinion from the planning authorities to help shape and focus the development activity.
Developers will aim to secure planning consent while retaining as much design flexibility as they can. A particular risk for developers is specifying a specific foundation solution or a maximum turbine size, which may prove to be restrictive at the point of procurement and require the developer to request variations to the consent order.
With too much design flexibility, the environmental impacts become less certain and more complex to analyse, which may be deemed undesirable by the consenting authorities. The range of options included in the proposed design is known as the design envelope, which includes a clear upper and lower bound on the scale of the project for example in terms of tip height.
Developers need to undertake an EIA, which describes the potential impacts with regards to a wide range of environmental factors.
The environmental statement is based on a number of detailed analyses. Most offshore wind developers have a predominantly in-house development management capability, with specialist work being outsourced. Specialist suppliers will often second employees into the developer’s team for the duration of the development phase.
Throughout the development process, developers are obliged to seek the views of a number of statutory consultees. These include a wide range of government appointed consultees and authorities, affected local authorities and those that have an interest in the land affected. Non-statutory consultees with specific interests in the development are also likely to be consulted (such as RSPB).
Developers will also seek the views of local communities as part of this process and hold a series of public information and consultation events.
Supporting the work will be a range of specialist consultants, covering engineering design, legal issues, land use, environmental and stakeholder relations.

P.1.1 Environmental impact assessments
Function

An EIA assesses the potential impact of the proposed development on the physical, biological and human environment during the construction, operation and decommissioning of the wind farm.

What it costs

About £8 million for a 1GW wind farm.

Who supplies them

EIA suppliers include AECOM, Arcus, GoBe, Intertek, Natural Power (Fred. Olsen), Royal Haskoning, RPS and SLR.

Key facts

Based on European Legislation, certain projects, such as large offshore wind farms, are required to carry out an EIA.
The most recent EIA regulations specify that the assessment must consider impacts on human health, climate change and biodiversity. To determine the impacts, a full suite of environmental surveys is undertaken.
After assessing the potential impacts, mitigation measures are defined and applied in order to determine the residual effects associated with the development. A core part of the EIA is the Cumulative Impact Assessment (CIA) where the development’s impacts combined with those impacts from other foreseeable projects are assessed. The EIA is used to inform the Environmental Statement (ES) (or EIA Report), which forms the core documentary evidence that is submitted to support a consent application.
Consultation with statutory consultees, special interest groups and the local community is performed throughout the EIA process and allows the consenting authority as well as other stakeholders and the public to voice their opinion and concerns.
The EIA process can take up to three years to complete, with the main driver being the length of time it takes to complete the required environmental survey work.
Under the Habitats Directive and the Conservation of Habitats and Species Regulations 2010 (as amended), developers should consider the potential effects on protected habitats. If the development is likely to affect a designated European site, the developer must provide a report with the application showing the designated European site that may be affected together with sufficient information to enable the decision maker to make an appropriate assessment, if required. A Habitat Regulations Appraisal (HRA) is performed as an integral part of an EIA to ensure that a project conforms to The Conservation of Habitats and Species Regulations (2010).

What's in it

Scoping
Assessment
Site-specific impacts
Mitigation
Residual impacts
Environmental Statement
Habitat regulations assessment

P.2 Environmental surveys
Function

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.

What it costs

About £4 million for a 1GW wind farm.

Who supplies them

Several companies offer a range of environmental surveys: ERM, Fugro, Gardline, Natural Power (Fred. Olsen), RPS, RSK Environment and SLR.

Key facts

Environmental surveys are one of the first tasks to be undertaken at a potential wind farm site and it can take two years or more before sufficient data is collected in order to apply for consent.
The surveys include bird, fish, marine mammal and habitat surveys as well as marine navigation studies, socio-economic surveys, commercial fishing, archaeology, noise analysis, landscape and visual assessment and aviation impact assessments.
Companies and developers recognise more detailed surveying can reduce costly consenting delays and post construction environmental monitoring requirements.
Some surveys need to establish regional behaviours of wildlife, for example bird feeding and breeding patterns and in these cases data may need to be collected for several years. For highly mobile wildlife populations such as birds or sea mammals, it may be difficult to establish whether the predicted impacts during construction will be enduring.
Surveys require vessels and aircraft are used to collect the data. Surveys look at the distribution, density, diversity and number of different species.
A challenge in the assessments is trying to understand the cumulative impacts of several wind farms, particularly when these are the subject of separate EIA and consenting processes.
Some environmental surveys are undertaken by companies that also offer geological or hydrological surveys, in which case the work can be done from the same vessels in parallel.
Environmental surveys are typically undertaken by companies from the home market, partly because there is sufficient local resource and partly because some of the wildlife impacts are site specific and require detailed local knowledge and expertise.

P.2.1 Benthic environmental surveys
Function

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.

What it costs

About £450,000 for a 1GW wind farm.

Who supplies them

Suppliers include ABPmer, APEM, Fugro, Gardline and Natural Power (Fred. Olsen).

Key facts

Sampling sites are chosen so as to produce the most effective broad-scale categorisation of the overall region, as well as attempting to investigate smaller scale features such as reefs.
Specific attention is given to the presence of particular ecosystems, such as certain reef species, where their presence is of crucial significance to the EIA.
Methods include grab and sampling, epibenthic beam trawling and drop down video (DDV). Generally, surveys are designed to ground proof on geophysical data (bathymetry and sidescan), acquired for site characterisation of ground conditions, which has been interpreted to provide predictive habitat mapping.

What's in it

Species identification and counting

Laboratory analyses

Impact models and reports

P.2.2 Fish and shellfish surveys
Function

Fish and shellfish surveys establish what species are 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.

What it costs

About £400,000 for a 1GW wind farm.

Who supplies them

Suppliers include ABPmer, APEM, Fugro, Gardline, Natural Power (Fred. Olsen) and Precision Marine.

Key facts

Beam trawls or otter trawls (dragging a net along the sea bed) are used to sample the species present in the area. In addition other fishing methods such as lobster pots or gill nets can also be used on area where trawling cannot take place. Plankton nets can also be used for fish egg/larval studies (these are required).
Surveys are generally undertaken in order to characterise the species present in the area of the wind farm, but also to address specific questions such as whether fish are spawning in the area, should this be an issue for EIA.
Surveys can often be done using locally based fishing vessels, providing it can reach minimum safety standards. This approach offers the potential for good engagement with the local fishing community.

What's in it

Species identification and counting
Laboratory analyses
Impact models and reports

P.2.3 Ornithological environmental surveys
Function

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.

What it costs

About £1 million for a 1GW wind farm.

Who supplies them

Suppliers include APEM, ECON, ESS Ecology, HiDef Aerial Surveying, Natural Power (Fred. Olsen) and RPS.

Key facts

Offshore ornithological surveying is normally one of the first tasks to be undertaken at a potential wind farm site because at least two years of data are needed to establish baseline conditions given the high level of spatial and temporal variation in bird abundance and distribution throughout the annual cycle. Furthermore, offshore ornithological constraints can have an important influence on wind farm design.
Seabirds, inshore wintering waterfowl, and terrestrial birds on migration are all surveyed to determine how they make use of the proposed area and therefore the different effects that a wind farm may have, including potential collision with turbines, disturbance and displacement, and both direct and indirect habitat loss (for example through effects on prey species).
A variety of methods are available for these purposes, each with their own advantages and disadvantages. Boat-based and digital aerial surveys are typically used to establish site-based population estimates and to gather behavioural data including species’ flight heights (a key variable used to assess potential collision). Other methods such as GPS tracking, radar and coastal vantage point (VP) surveys can also be used to answer site-specific questions for example to establish connectivity between a specific breeding colony of seabirds and the proposed wind farm.

What's in it

Species identification and counting
Impact models and reports

P.2.4 Marine mammal environmental surveys
Function

Marine mammal surveys establish the diversity, abundance, distribution and behaviour of cetaceans (including porpoises, dolphins and whales) and seals within the wind farm boundary and surrounding areas. Surveys are typically undertaken monthly for at least two years to establish how these variables change across seasons and between years. The data from these surveys is used to establish the potential impacts to marine mammals that a wind farm may pose.

What it costs

About £1 million for a 1GW wind farm.

Who supplies them

Suppliers include ABPmer, APEM, Cork Ecology, ECON, ESS Ecology, Fugro, Gardline, HiDef Aerial Surveying, Natural Power (Fred. Olsen) and RPS.

Key facts

Marine mammals are surveyed to determine how they make use of the proposed area and therefore the different effects that a wind farm may have, including potential disturbance and displacement, physical and auditory injury during pile driving, and both direct and indirect habitat loss (for example through effects on prey species).

A variety of methods are available for these purposes, each with their own advantages and disadvantages. The method/s used will be dependent on the species and site in question. Traditional visual surveys using boat and aerial platforms are being supplemented or replaced by new, more accurate technologies such as static and towed acoustic monitoring, tagging of individuals with satellite transmitters and remotely controlled video monitoring.

What's in it

P.2.4.1 Offshore ornithological and mammal surveying vessels and craft
Species identification and counting
Impact models and reports

P.2.4.1 Offshore ornithological and mammal surveying vessels and craft
Function

Bird and marine mammal survey vessels and aircraft provide a platform for surveying to take place.

Who supplies them

Vessels: Bay Marine, Enviro-serve, Fugro, Gardline and Ocean Marine Services.
Aircraft (including, but not limited to): APEM, HiDef Surveying.

Key facts

Traditional visual methods for surveying marine mammals are often undertaken concurrently with offshore ornithology surveys, offering a cost saving. Unfavourable weather and sea conditions have to be considered in the planning of surveys to ensure that the data collected is robust.
Multiple crews are used, including experienced and qualified surveyors, who rotate in shifts in order to avoid fatigue and maintain visual acuity.
Traditional visual boat-based surveys can be supplemented with a towed hydrophone in order to undertake passive acoustic monitoring for marine mammals.
The Collaborative Offshore Wind Research Into the Environment (COWRIE) provides guidance relating to standardised survey methods and vessel specifications. Vessels should provide a stable viewing platform so vessel length and height are important considerations.
Whilst traditional visual aerial surveys can be used to record marine mammals, these are not suitable to record marine birds as they fly at relatively low altitudes and can cause disturbance (and therefore the data collected are not representative of baseline conditions). Instead, digital aerial survey aircraft can be used which fly at much higher altitudes, recording both birds and marine mammals.
These survey aircraft have a range of remote sensing instruments on board such as high-resolution digital cameras, lidar, video imaging and imaging spectrometers. Twin-engine planes, with long-range fuel tanks and autopilot capabilities allow for extensive surveying offshore without the need for on-board surveyors.

What's in it

Vessels and aircraft
Provision of suitably experienced and qualified crew

P.2.5 Onshore environmental surveys
Function

Onshore environmental surveys consider the potential ecological impact that cable-laying and onshore substations may have on the onshore environment.

What it costs

About £550,000 for a typical 1GW wind farm.

Who supplies them

Suppliers include Andrew McCarthy Associates, APEM, BCM Environs, ESS Ecology, Natural Power (Fred. Olsen), RSK Environment and Thomson Ecology.

Key facts

Wildlife surveys are often undertaken by ecological companies who have specialised capabilities for particular species. Skilled ecologists are often deployed.
Studies tend to look at the distribution, density and number of different species.
Wildlife ranging from badgers to small reptiles are considered, depending on the nature of the proposed site.
Fragile coastal ecosystems are a prime area of focus.

What's in it

Surveying
Data analysis
Reporting

P.2.6 Human impact studies
Function

Human impact studies assess the impact that a proposed wind farm may have on the community living in and around the coastal area near the wind farm.

What it costs

About £350,000 for a 1GW offshore wind farm.

Who supplies them

Suppliers include Arcus, Hayes Mackenzie, Hoare Lea, LUC, Royal Haskoning, RPS and SLR.

Key facts

Visual assessments comprise of photomontages from specific viewpoints of what the proposed wind farm will look like. Noise assessments assess that potential noise impacts and determine whether the impact of the proposed wind farm is within the guidance of relevant noise standards. Other areas studies include fisheries and archaeology.
The socio-economic study assesses the impacts of a wind farm or coastal infrastructure, for example a port, such as changes in employment, transportation or recreation, or changes in the aesthetic value of a landscape. It estimates the impacts on the local society, not only of these socio-economic changes, but also of the composite of biological, geological, and physical effects caused by the proposed change on the local area.
Socio-economic studies include a mix of objective and subjective data. Objective data can include statistics on age, income distribution, ethnicity, mortality, housing type and occupancy, and education. Subjective data can be derived from surveys and observations. These are used to provide systematic estimates of the ways in which various groups perceive their socio-economic environment and thus the impact of the proposed change. Studies consider the onshore cable route and substation.

What's in it

Surveys
Consultation

P.3 Resource and metocean assessment
Function

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.

What it costs

Costs for resource and metocean assessment are about £4 million for a 1GW offshore wind farm, assuming no met mast platform is installed.

Example costs for elements of this include:

  • Floating lidar: £375,000
  • Lidar mounted on an existing platform: £200,000
  • Met masts and platform: £5 million to 10 million
  • Metocean buoy: £175,000, and
  • Wave radar: £100,000.

The above systems may be used in conjunction or isolation on any particular project, so costs will vary depending on approach adopted.

Who supplies them

Resource campaign management and design: AXYS Technologies, Deutsche Windtechnik, DNV-GL, Fugro, K2 Management, Natural Power (Fred. Olsen) and Oldbaum Services.
Masts: FLI Structures, Fugro, MT Højgaard and Sembmarine.
Lidar units: Leosphere (Vaisala), ZX Lidars (Fred. Olsen).
Floating lidars: AXYS Technologies, EOLOS, EOLFI, Fraunhofer and Fugro.
Metocean campaigns and buoys: AXYS Technologies, Fugro and Partrac.
Systems integrators: PowerPoint Technical Services.
Reference data provision: The Met Office, StormGeo and Vortex.

Key facts

Wind speed data is required to at least the proposed hub-height of the wind turbines, which will likely be 100m or more above sea level.
Measurement systems are installed at the project location to collect wind data (speed, direction) and other relevant meteorological data (temperature, pressure, humidity).
In addition, metocean buoys are installed in and around the wind farm site collect metocean data, including wave and tidal characteristics.
Long-term reference datasets are required to describe the climatology of the proposed site over a longer period typically in excess of 15 years.
These combined data sets are used in the wind farm and system design process, the turbine selection process and to predict the annual energy production (AEP) of the wind farm. Metocean data is also used to inform the vessel selection and operational strategies for the site, and is made available to vessel operators and marine planners during the construction and operational phases.
A key interface exists in determining the long term site conditions between wind resource and metocean disciplines. The output from this interface is the extreme wind and wave climate for the proposed site. Hub-height wind masts are founded on the sea bed and require a subsea structure.
Masts are usually equipped with cup-anemometers or sonic anemometers.
Lidars are remote sensing anemometry devices which use lasers to measure wind speed and direction at up to 300m above sea level.
Floating lidars are moored buoys on which a lidar is mounted.
Fixed platform masts are becoming less common as floating lidar has now reached a higher level of industry acceptance, and the cost advantages of floating lidar are substantial. A number of offshore wind developers have successfully designed, financed and constructed projects based solely on lidar data.
Wind lidar can also be positioned on existing infrastructure (such as nearby gas platforms and lighthouses) or in some cases onshore or on nearby islands.
When using lidar as the primary measurement instrument, supplementary modelling is used to inform site conditions such as turbulence and horizontal wind gradients.
Wind and metocean measurement systems require power supply to run sensors, data storage and telemetry. For low power systems this is often achieved with solar PV panels, small wind turbines and battery storage. Larger systems will use diesel generators or hydrogen fuel cells.
Current state of the art campaigns integrate measurement and modelling techniques across both oceanographic and wind resource disciplines. The study can be further broadened to look at further issues such as turbulence, atmospheric stability conditions and the influence of neighbouring wind farms on the proposed site wind conditions.

P.3.1 Structure
Function

The structure provides the mounting for the meteorological and metocean, sensors and auxiliary systems plus safe access for personnel.

What it costs

About £3 million for a 1GW offshore wind farm, excluding installation.

Who supplies them

Foundation and Platform: Bladt Industries, Sif and Smulders.
Masts: Carl C, Dulas and Francis & Lewis.
Floating lidar systems: AXYS Technologies, Babcock, EOLFI, EOLOS, Fraunhofer and Fugro.
Metocean buoys: AXYS Technologies, Fugro and Gardline.

Key facts

Met mast foundations are generally monopiles with transition pieces similar to turbine foundations but of much lighter construction. Jacket structures may be used for deeper water.
Platforms consist of a three-beam structure with walkways. Far offshore these structures can also require a helideck for access and a crew refuge. Mountings for wave and current sensors extend outward from the platform. Masts are typically of galvanised steel lattice construction with a personnel climbing facility (including fall-arrest system.) Personnel access to the platform is addressed in the same way as for turbines.
Floating lidars are typically small buoys, anchored to the sea bed, with on-board power, data storage and processing and communications.
Structures should be equipped with all relevant navigational aids including hazard lighting, fog horn, automatic identification system (AIS) and illuminated identification number panel for shipping.

What's in it

Foundation
Platform
Mast
Buoys

P.3.2 Sensors
Function

Sensors provide data on meteorological and oceanographic conditions at the site of interest. Data loggers provide data storage, processing and remote communications capability.

What it costs

About £650,000 for a 1GW offshore wind farm including maintenance.
Examples of specific sensor costs:
Vertical profiling wind lidars cost about £100,000.
Class 1 sonic anemometers and cup-anemometer cost about £1,000 each.
Other meteorological sensors cost under £1,000.

Who supplies them

Meteorological sensors: FT Technologies, Gill Instruments, Kipp & Zonen, NRG Systems, Orga, Thies, Vaisala and Vector Instruments.
Wind lidars: Leosphere (Vaisala), Wood and ZX Lidars (Fred. Olsen).
Metocean sensors: Datawell, Radac, SonTek.
Data loggers: Campbell Scientific.

Key facts

Meteorological sensors include wind speed (with instruments at a number of heights or via lidar measuring over a range of heights with one sensor), wind direction, temperature, pressure, humidity, solar radiation and visibility. Measuring wind speeds at different heights provides critical information about the wind speed profile at the site, aiding decisions about the turbine and foundation design.
Metocean sensors include wave, sea level and current sensors (for example acoustic Doppler current profiler), sometimes sea bed-positioned. These will record the full wave data spectrum including velocity, direction and period. Multiple sensors are used to provide spatial coverage and redundancy.
Bird radar and hydrophones detecting cetacean activity can provide additional information to vessel and air-based environmental surveys.

What's in it

Meteorological sensors
Anemometers
Metocean sensors
Wave measurement sensors
Data loggers

P.3.3 Maintenance
Function

Offshore wind and metocean systems will require maintenance, including inspection, cleaning and refuelling (where diesel generators or hydrogen fuel cells or similar are used).

What it costs

About £300,000 during development for a 1GW offshore wind farm.

Who supplies them

System maintenance is typically undertaken by the original system supplier, who will charter vessels for the purpose.
Other providers of system maintenance include Deutsche Windtechnik, Dulas and Wood.

Key facts

Maintenance visits will typically be carried out 2-4 times per year. Systems are designed to operate autonomously, with onboard power, data and communications systems.

What's in it

Access vessel
Maintenance personnel
Equipment and consumables

P.4 Geological and hydrographical surveys
Function

Sea bed surveys analyse the sub sea bed environment of the proposed wind farm site and export cable route to assess its geological condition and engineering characteristics. The data collected is utilised in a wide range of engineering and environmental studies through the design and development phase.

What it costs

About £4 million for a 1GW wind farm.

Who supplies them

Suppliers include Fugro, G-tec, Gardline and Horizon.

Key facts

Sea bed surveys consist of two main parts; geophysical surveys of sea bed features and bathymetry; geotechnical surveys of the sea bed characteristics.
Sea bed surveys are an important component of the development process and aid a number of processes, such as optimising the foundation design and wind farm layout, as well as minimising risk during installation activities.
Environmental and sea bed (geotechnical and geophysical) surveys and data collection start up five years or more before the planned operation of the wind farm.
Offshore wind development typically requires more data collection over larger areas but the technical approaches are similar to other sectors, such as oil and gas.
The move to auction based systems such as Contract for Differences (CfD) in the UK has placed a greater emphasis on geological and hydrographical surveys as developers require greater design and cost certainty earlier in the development process.

P.4.1 Geophysical surveys
Function

Geophysical surveys establish sea floor bathymetry, sea bed features, water depth and soil stratigraphy, as well as identifying hazardous areas on the seafloor and manmade risks such as unexploded ordnance (UXO).

What it costs

About £700,000 for a 1GW wind farm.

Who supplies them

Suppliers include Bibby HydroMap, Fugro, Gardline, Horizon and MMT.

Key facts

Geophysical surveys are non-intrusive and include remote sensing techniques such as seismic methods, echo sounding and magnetometry.
The techniques used consist of bathymetry (water depth) mapping with conventional single or multibeam echo soundings or swathe bathymetry, sea floor mapping with side scan sonar, magnetometer for UXO, acoustic seismic profiling methods and high resolution digital surveys.
Surveys run along transects across zones within the proposed wind farm site and cable routes.
Information from geophysical surveys is used to aid the design and implementation of the benthic and geotechnical surveys, so they are often undertaken near the beginning of the development process.
Data from geophysical surveys are used to produce charts and maps for GIS systems, which are then used for site layout design.
Geophysical surveys can be used to identify unexploded ordnance on or below the seafloor. Geophysical surveys may also consider marine archaeology that may be present in the wind farm site. This is typically dealt with by specialist archaeological survey companies, and is offered as a service in conjunction with the geophysical surveys.

P.4.1.1 Geophysical survey vessels
Function

Specialist vessels are used to carry out geophysical surveys of the sea bed.

Who supplies them

Suppliers include Bibby HydroMap, Fugro, Gardline, Horizon and MMT.

Key facts

Geophysical vessels are typically about 30-70m in length. The vessels must provide a stable platform even in unfavourable sea and weather conditions.
Multiple crews, including highly specialised equipment operators, are utilised and the vessel has sleeping berths and living quarters to allow the vessel to have an operational endurance of up to a month.
Crew work 12 hour shifts with rotations month by month enable a constant flow of data observation, processing and interpreting.

What's in it

Specialist crew
Survey and analysis equipment

P.4.2 Geotechnical surveys
Function

Geotechnical site investigations are conducted following the geophysical survey to use the information obtained to target soil/rock strata boundaries and engineering properties or specific sea floor features.

What it costs

About £2.5 million for a 1GW wind farm.

Who supplies them

Suppliers include Fugro, G-tec, Gardline and Horizon.

Key facts

Geotechnical studies are predominantly intrusive and include such methods as boreholes with soil/rock sampling, and cone penetration testing (CPT).
Geotechnical investigation is generally the most expensive part of wind farm survey work, making it a substantial at-risk investment for developers. Typically the geotechnical surveys are performed in phases to add value to the project risk mitigation process.
Geotechnical surveys require specialised equipment and skilled personnel. The scope of the investigation depends on the type of foundation being considered and the variability in the sea bed characteristics.
Boreholes and CPTs to depths in the order of 50-70m are carried out to investigate the physical characteristics of the sea bed. Surface push CPTs are also used as a rapid method to gather sea bed soil stratigraphy. Cable routes are typically investigated using vibrocores and CPTs to a depth of 5m.
Offshore laboratories are used to obtain basic soil parameters and the samples taken are then returned to an offshore laboratory for detailed testing. Often soil dynamics tests are performed to monitor the soil behaviour under the constant dynamic loading on the foundation by the wind, waves and current.
Resultant data from the geotechnical surveys are combined with results of the geophysical survey, to improve the geological model prior to the design and installation of foundations. Geotechnical data is also used at a later date in combination with heavy lift jack-up vessel information to determine the risks and feasibility of conducting heavy lift construction activities.

P.4.2.1 Geotechnical survey vessels
Function

Specialist vessels carry out geotechnical surveys of the sea bed.

Who supplies them

Suppliers include Fugro, G-tec, Gardline and Horizon.

Key facts

The vessels are typically 60 -100m length and typically operate their drilling systems through a central moon pool. Some sea bed systems are deployed over the side or stern via A-frames or heavy lift cranes. The vessels are able to operate independently in remote locations.
Jack-up vessels can also be used (albeit smaller than those used for foundation and turbine installation) where water depth and sea bed conditions are suitable. The vessels must be able to position themselves at specific locations for borehole sampling using dynamic positioning or anchors and must be able to withstand unfavourable sea and weather conditions.
The vessels provide a stable platform for the acquisition of samples and in-situ testing. Due to the expense of hiring these vessels, multiple crews, including highly specialised equipment operators, are utilised and the vessels have sleeping berths and living quarters to allow the vessel to have an operational endurance of over a month.
Offshore laboratories also allow for data acquisition and processing onboard. Crew rotations month by month enable a constant flow of data collection, processing and interpreting.

What's in it

Specialist crew
Survey and analysis equipment

P.4.3 Hydrographic surveys
Function

Hydrographic surveys examine the impact of the wind farm development on local sedimentation and coastal processes such as erosion. This is often part of the geophysical survey. These surveys are also part of the post construction monitoring during the operations phase.

What it costs

About £800,000 for a 1GW wind farm.

Who supplies them

Specialist hydrographic survey companies such as Bibby HydroMap, Fugro, Gardline and MMT perform the surveys and consultants such as ABPmer and HR Wallingford undertake the impact modelling.

Key facts

Understanding the sedimentation environment of the proposed site is of particular importance as it will inform the scour characteristics of the site and subsequent protection measures required.

What's in it

Vessels
Crews
Survey equipment

P.5 Engineering and consultancy
Function

Front-end engineering and design (FEED) studies address areas of wind farm system design and develop the concept of the wind farm in advance of procurement, contracting and construction.
Earlier on in the process, pre-FEED studies are used to develop an outline 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 process and is ultimately used to frame and process substantial engineering and procurement decisions.

What it costs

About £4 million for a 1GW offshore wind farm.

Who supplies them

Suppliers include Arup, Atkins, DNV-GL, Mott McDonald, ODE, Ramboll and Wood.

Key facts

Key parameters such as turbine size, foundation type, wind farm layout, substation design, electrical system and grid connection method are considered in order to minimise the project’s levelised cost of energy (LCOE).
Also included is planning of onshore and offshore operations, port and vessel strategies, determining contracting methodologies and the development of key risk management and health and safety procedures.
The FEED study seeks to understand the total wind farm system in an integrated way and to consider the impact of engineering decisions on the LCOE, and to ensure that engineering decisions take full cognisance of environmental and consenting risks and impacts.
The FEED study is a multi-disciplinary process that requires extensive communication and coordination, often across multiple teams and organisations.
The output of FEED studies is used by construction management teams in order to procure and construct the wind farm.
The move to auction based systems such as CfD in the UK has placed a greater emphasis on FEED studies as developers require greater cost certainty earlier in the development process.

What's in it

Layout design and optimisation
Turbine selection
Foundation type selection
Electrical design strategy
Interface management
Health and safety planning
Installation methods
Operational strategy

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