Where relevant, for each element in the wind farm this interactive guide covers:
- Function. What the component or service does.
- What it costs. We provide typical prices for a project with parameters described above. We recognise that there can be quite a range in prices of any element, due to specific timing or local issues, exchange rates, competition and contracting conditions. Prices for large components include delivery to nearest port to supplier and warranty costs. Developer costs (including internal project- and construction management, insurance, typically spent contingency and overheads) are included in the highest-level boxes but are not itemised. The sum of costs in lower-level boxes therefore is often lower than in the highest-level box. Costs, when combined with project life of 25-30 years, capacity factor of just over 50% and weighted average cost of capital equate to the bid prices seen in recent UK Government Contract for Difference auctions.
- Who supplies them (examples only). The list of suppliers is indicative rather than exhaustive. We have focused on suppliers with proven capability and generally have not listed suppliers with likely future capability or located distant from the UK (for example in US or China). Nevertheless any omission does not reflect any judgement of a company’s capabilities.
- Key facts. Description including dimensions / materials where relevant or what is involved in delivering the service / how it relates to other elements and other relevant information.
- What’s in it. We list the sub-components / services described elsewhere in the guide, or standard components / materials / processes used across a range of industries.
Glossary:
| Term | Definition |
| Annual energy production (AEP) | The amount of energy generated in a year.
Gross AEP is the predicted annual energy production based on the turbine power curve, excluding losses. Net AEP is the metered annual energy production at the offshore substation, so includes wind farm downtime, wake, electrical and other losses. |
| Array cable | Electrical cable that connects the turbines to each other and the offshore substation. |
| Availability | The percentage of time the assets are available to produce / transfer power if the wind speed is within the operational range of the turbine. |
| Balance of plant (BoP) | Includes all the components of the wind farm except the turbines, including transmission assets built as a direct result of the wind farm. |
| Department for Business, Energy and Industrial Strategy (BEIS) | Government department that is responsible for business, industrial strategy, science and innovation and energy and climate change policy. |
| Consent | Planning permission. |
| Cable protection system (CPS) | Cable protection systems protect the subsea cable against various external aggressions. Systems include bend restrictors and bend stiffeners where the cable may be subject to increased loading. |
| Capacity factor | Ratio of annual energy production to maximum energy production if the turbine / wind farm ran at rated power all year. |
| Capital expenditure (CAPEX) | Spend on all activities up until works completion date. |
| Contract for difference (CfD) | Contract where government agrees to pay the wind farm owner the difference between an agreed strike price and the average market price of electricity (reference price). If the difference is negative the wind farm owner pays the difference to the government. |
| Crew transfer vessel (CTV) | A vessel used to transport wind farm technicians and other personnel to the offshore wind farm turbines either from port or from a fixed or floating base. Vessels operating today are typically specially designed catamarans that accommodate around 12 passengers. |
| Cross-linked polyethylene (XLPE) | A thermoset material widely used as electrical insulation in power cables. |
| Doubly-fed induction generator (DFIG) | An electrical arrangement where part of the wind turbine generator power passes via slip rings and convertors to enable a limited variable speed operating range whilst minimising the cost of power electronics. |
| Decommissioning expenditure (DECEX) | Spend on removal or making safe of offshore infrastructure at the end of its useful life, plus disposal of equipment. |
| Environmental impact assessment (EIA) | Assessment of the potential impact of the proposed development on the physical, biological and human environment during construction, operation and decommissioning. |
| Engineer, procure, construct and install (EPCI) | A common form of contracting for offshore construction. The contractor takes responsibility for a wide scope and delivers via own and subcontract resources. |
| Export cable | Electrical cable that connects the onshore and offshore substations, or between an AC offshore substation and a DC converter substation. |
| Front end engineering and design (FEED) | 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. |
| Final investment decision (FID) | The point at which a developer has in place all the consents, agreements and major contracts required to commence project construction (or these are near execution form) and there is a firm commitment from equity holders and debt funders to provide funding to cover the majority of construction costs. |
| Floating foundation | A buoyant foundation structure anchored to the sea bed via mooring lines. The term includes several foundation types including spar buoys, tension leg platforms and semi-submersibles. |
| Gas insulated switchgear (GIS) | Gas-insulated switchgear is often chosen for its compactness and increased reliability over than air insulated switchgear, but has higher cost. |
| Gigawatt (GW) and Gigawatt hour (GWh) | Unit of power and unit of energy. |
| Gravity base foundation | A type of foundation designed to be transported offshore as a (normally concrete) hollow structure that is later fixed to the sea bed with the addition of ballast. |
| High voltage alternating current (HVAC) | An electric power transmission system that uses alternating current for the bulk transmission of electrical power. Alternating current is the form in which electric power is generated by wind turbines and delivered to an end user. |
| High voltage direct current (HVDC) | An electric power transmission system that uses direct current for the bulk transmission of electrical power. For long-distance transmission, HVDC systems may offer lifetime cost advantages over HVAC systems over long transmission distances. They are currently only used for point-to-point connections. |
| Highest astronomical tide (HAT) | The highest tidal height predicted to occur under average meteorological conditions and any combination of astronomical conditions. |
| Horizontal directional drilling (HDD) | Horizontal directional drilling is a low impact (trenchless) method of installing underground cables using a surface-launched drilling rig. |
| Jacket foundation | See Non-monopile steel foundation. |
| Levelised cost of energy (LCOE) | Levelised cost of energy is a commonly used measure of the cost of electricity production. It is defined as the revenue required (from whatever source) to earn a rate of return on investment equal to the WACC over the life of the wind farm. Tax and inflation are not modelled. |
| Mean high water springs (MHWS) | The average tidal height throughout the year of two successive high waters during those periods of 24 hours when the range of the tide is at its greatest. |
| Mean sea level (MSL) | The average tidal height over a long period of time. |
| Megawatt (MW) and Megawatt hour (MWh) | Unit of power and unit of energy. |
| Monopile foundation | A type of foundation with a cylindrical tube (normally steel) that is normally driven tens of metres into the sea bed, although it can also be inserted into pre-drilled holes. |
| Non-monopile steel foundation | Collective term used to describe all steel foundations other than monopiles. Includes braced, welded, space-frame structures (collectively called ‘jackets’), tripods and tripiles. |
| Offshore substation (OSS) | The structure used to transform and transfer the energy collected by the wind turbines to land in the most efficient manner. It may involve increasing the voltage, providing reactive compensation and converting the current from AC to DC. Some wind farms may have more than one offshore substation and equipment may be located on a number of smaller structures and potentially on one or more turbine transition pieces. |
| Offshore Transmission Owner (OFTO) | An OFTO, appointed in UK by Ofgem (Office of Gas and Electricity Markets), has ownership and responsibility for the transmission assets of an offshore wind farm. |
| Operational expenditure (OPEX) | Spend on all activities from works completion date until decommissioning. |
| Operations, maintenance and service (OMS) | OMS comprises wind farm OMS and onshore transmission OMS.
Definitions of O, M and S are as follows:
|
| Remotely operated vehicle (ROV) | ROVs are remotely guided subsea mobile devices. They are usually deployed from a vessel. ROVs can be used for inspections or to carry out handling and repair. |
| Service operation vessel (SOV) | A vessel that provides accommodation, workshops and equipment for the transfer of personnel to turbine during OMS. Vessels in service today are typically up to 85m long with accommodation for about 60 people. |
| Significant wave height (Hs) | The wave height (trough to crest) of the highest third of the waves over a given period. |
| Supervisory Control and Data Acquisition (SCADA) system | Data acquisition, transmission and storage system covering all wind farm assets. The SCADA system enable individual wind turbines, the wind farm substations and associated wind farm equipment to communicate operational status including faults. This allows operators to remotely diagnose faults and issue commands to stop, start and reset turbines and other equipment. The SCADA system keeps a full operating history of the wind farm. |
| Transition piece | A part of the foundation that provides the connection between the foundation and the wind turbine tower. For monopiles, it is usually installed after piling. For non-monopile steel or gravity base foundations, the transition is connected to the main structure before installation. |
| Turbine rated power | The nominal maximum power output from a wind turbine. Sometimes this is referred to as capacity. The wind turbine is limited to this power output, which typically applies when the wind speed at the hub height exceeds about 12m/s and continues until about 25-30m/s when the wind turbine stops generating to avoid excessive loading. In more benign operating conditions characterised by ambient temperature, main component temperatures, wind speed, turbulence level and grid voltage levels, the output may be allowed to exceed the rated power by about 5%. |
| Unexploded ordnance (UXO) | Explosive weapons that did not explode when they were released and remain a risk to seabed users. |
| Weighted average cost of capital (WACC) | The weighted average rate of return a wind farm owner expects to compensate itself and its internal and external investors over the life of a project. |
| Wind shear | The degree to which wind speed changes with height. |
| Works completion date (WCD) | Date at which construction works are deemed to be complete and the wind farm is handed to the operations team. In reality, this may take place over a period of time. |
P. Development and project management
T. Wind turbine
B. Balance of plant
I. Installation and commissioning
O Operation, maintenance and service
D Decommissioning
P. Development and project management
P.1 Development and consenting services
Development and consenting covers the work needed to secure consent and manage the development process through to financial close.
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).
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.
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
P.1.1 Environmental impact assessments
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.
About £8 million for a 1GW wind farm.
EIA suppliers include AECOM, ERM (KKR), GoBe, Intertek, Natural Power (Fred. Olsen), Royal Haskoning, RPS, SLR and Xodus.
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).
Scoping
Assessment
Site-specific impacts
Mitigation
Residual impacts
Environmental Statement
Habitat regulations assessment
P.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.
About £4 million for a 1GW wind farm.
Several companies offer a range of environmental surveys: ERM, Fugro, Gardline, Natural Power (Fred. Olsen), RPS, RSK Environment and SLR.
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
P.2.2 Fish and shellfish surveys
P.2.3 Ornithological environmental surveys
P.2.4 Marine mammal environmental surveys
P.2.5 Onshore environmental surveys
P.2.6 Human impact studies
- P.2.1 Benthic environmental surveys
- P.2.2 Fish and shellfish surveys
- P.2.3 Ornithological environmental surveys
- P.2.4 Marine mammal environmental surveys
- P.2.4.1 Offshore ornithological and mammal surveying vessels and craft
- P.2.5 Onshore environmental surveys
- P.2.6 Human impact studies
- P.3 Resource and metocean assessment
- P.3.1 Structure
- P.3.2 Sensors
- P.3.3 Maintenance
- P.4 Geological and hydrographical surveys
- P.4.1 Geophysical surveys
- P.4.1.1 Geophysical survey vessels
- P.4.2 Geotechnical surveys
- P.4.2.1 Geotechnical survey vessels
- P.4.3 Hydrographic surveys
- P.5 Engineering and consultancy
