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Wind Energy Essentials

This part of the Guidance offers an overview of wind energy related information primarily for heritage practitioners and decision-makers not familiar with this field. A brief overview of the main technical features and processes behind wind energy planning will allow a more effective understanding of their potential impacts on World Heritage and catalyse more efficient dialogue between stakeholders to seek solutions. In addition, this section approaches this field with a focus on World Heritage matters, highlighting sensitive conservation issues.

What is renewable energy?

Renewable energy is energy that is derived from natural processes (for example, sunlight and wind) that are replenished at a higher rate than they are consumed. Solar, wind, geothermal, hydro, tidal, and biomass (as defined in the figure below) are common sources of renewable energy. These resources are continually replenished by nature and are thus sustainable thanks to their:

  • capacity not to be substantially depleted by continued use;
  • minimal pollutant emissions and environmental problems;
  • minimal health hazards;
  • contribution to overcoming social injustice in relation to accessibility to clean sources of energy.

Types of renewable energy, their source and ‘end product’

All around the world, the production of energy from renewable sources is steadily increasing. The energy demands from renewable sources come from different types of infrastructure both in Europe and in North America.

The energy supplied by wind farms, amounts to:

  • 16% of the electricity demand of the European Union (2020 – source: WindEurope);
  • 8.4 % of the electricity demands in the United States (2020 – source: US EIA government);
  • 6% of the electricity demand in Canada (2018).

There are countries which put large emphasis on enhancing their capacities to acquire their energy need from renewable sources. (As an example, in 2020 42% of the electricity produced in the Federal Republic of Germany came from wind farms and solar parks).

Organizations, such as WindEurope, the US Energy Information Administration, the American Clean Power Association and the Canadian Renewable Energy Association regularly publish statistics and information concerning installed capacity, production and projections for the future of the wind and renewable energy sectors.

As technical and statistical information changes rapidly in the wind energy industry, for up-to-date information, please visit the above websites and that of the wind energy associations all around the world.

Key data related to renewable energy production in Europe, the USA and Canada:


In 2020, operating wind energy capacity met 16% of Europe’s electricity demand at an average. (In many EU countries this percentage is much higher). The International Energy Agency expects wind to be the number 1 power source in Europe by 2027. By 2050, wind energy capacity may rise from 220 GW today to up to 1,300 GW. This entails an increase in offshore wind energy by 25 times in the EU. Most of the power capacity increase, however, will come from onshore wind.

(The source of this statistic isWindEuropeand refers to Europe and not solely the European Union.)


Operating wind capacity (as of 2020): 111,808 MW.

Wind energy capacity projections: 20–30 GW (offshore).

For updates see: https://www.eia.gov/renewable/


Total wind capacity (as of 2020): 13,588 MW.

Wind projects under construction: 745 MW.

Wind energy capacity projections: capacity to range from 78 GW to 150 GW.

For updates see: https://cleanpower.org

The European Union

The European Green Deal (launched by the European Union in 2019 - advocates for a stronger reduction of greenhouse emissions by 2030 to reach carbon neutrality by 2050. The strategy ascribes a pivotal role to the energy sector to contribute to this target and strives to accelerate the transition to clean, sustainable and affordable energy in all EU countries.

In 2021, the European Union increased its 2030 target for the reduction of greenhouse gas emissions from 40% to 50–55%. The European Commission had presented an Impact Assessment of the proposed measures showing that among all energy sources, wind energy would have the most capacity installed by 2030 with up to 452 GW. Out of this total power providing 36% of EU’s electricity, 374 GW would be generated onshore and 78 GW offshore.

One of the goals of the European Union is to remain leading in wind energy technology and development. The EU thus plans to generate more than 1,200 GW through wind power by 2050.

In 2019, wind energy covered 15% of the electricity demand in the EU, only 1% more than in 2018. However, the total installed capacity in the EU reached 192 GW, which is 13% higher than in 2018. The great majority of the installations are located onshore (then 170 GW) and a much smaller part offshore (22 GW).

In 2019 and 2020, EU Member States submitted their National Energy and Climate Plans (NECPs) in which they outline how much renewable energy they plan to produce by 2030. Based on the assessment of WindEurope, wind energy capacity in the EU could reach a total of 339 GW by 2030, with 268 GW generated onshore and 71 GW offshore.

Most of the newly installed farms are onshore making up nearly 90% of the total wind energy capacity within the EU. However, investments in the development of offshore farms have allowed for the record installation of 3.6 GW of new capacity in 2019. Based on the European Commission’s long-term decarbonization strategy, offshore wind would still need to grow to up to 450 GW by 2050. This goal requires an accelerated development.

United States of America

The USA has committed to meet the goals of 100% clean electricity by 2035 and net-zero emission by 2050. It has also committed to curb emissions by 50% to 2005 levels by 2030.

In 2020, renewable energy accounted for about 20% of energy generation and 12% of energy consumption. The US Energy Information Administration (EIA) projects that the share of renewables in the US energy generation will be 42% in 2050.

Wind power generation has more than tripled in the last decade and capacity continues to grow at a strong pace. Wind has become the largest source of renewable power in the USA. By the third quarter of 2020, the USA had an operating wind capacity of 111,808 MW with over 60,000 wind turbines operating across 41 of the 50 states. At the end of September 2020, there were 24,355 MW of wind capacity under construction and 19,220 MW in advanced development.

In 2021, the Government announced a goal of 20–30 GW of offshore wind capacity by 2030. The USA has one offshore wind farm with 5 turbines providing 30 MW. It is anticipated that up to 30,000 MW of offshore wind capacity will be operational by 2030.

Land-based wind capacity in the USA has grown from 2,500 MW to 105,500 MV in 2019.

Total wind capacity in the USA had increased from 40.1 GW in 2011 to 118.3 GW in 2020, adding a total amount of 14.2 GW wind capacity in 2020 alone.

The Department of Energy’s Wind Vision of 2015 sets the target to supply 10% of the nation’s electrical demand through wind energy by 2020, 20% by 2030, and 35% by 2050.


Globally, in 2019 Canada was in the 9th position for installed wind energy capacity and in the 20th position for installed solar energy capacity. Wind energy has been the largest renewable source in Canada over the last decade. In 2018, about 6.8% of Canada’s electricity needs were met by wind and solar generation.

Wind, solar and energy storage companies united in July 2020 to form the Canadian Renewable Energy Association. Within Canada, the province of Alberta introduced a successful means to boost the sector and regulate CO2 emissions with the Technology Innovation and Emissions Reduction (TIER) Regulation. It sets limits to carbon emission by industrial facilities and provides incentives to reduce emissions and share carbon credits. Alberta currently leads the investment market for renewable energy in Canada.

The Canadian Government introduced a new plan in 2020 titled ‘A Healthy Environment and a Healthy Economy’ to address climate change, reduce greenhouse gas (GHG) emissions and invest in a low-carbon economy. The plan includes 64 new measures and US$15 billion in investments in addition to the Canada Infrastructure Bank’s US$6 billion over seven-years in energy efficiency retrofits. In October 2020, the Canadian Infrastructure Bank further committed to allocate US$2.5 billion to invest in clean power projects.

The Government of Alberta announced the Energy Savings for Business programme in 2020 to provide grants to small- and medium-scale businesses to implement energy-efficient technologies. In the same year, the Federal Government introduced Bill C-12, an Act respecting transparency and accountability in Canada’s efforts to achieve net-zero GHG emissions by 2050.

By the end of 2020, Canada had a total wind capacity of 13,588 MW, with 166 MW of wind-power generation installed in the same year. It has 745 MW of wind projects under construction. Canada has 307 wind farms producing power across the country. Wind energy costs have declined 71% since 2009.

According to the North American Renewable Integration Study (NARIS, 2016), wind energy capacity in Canada is projected to range from 78 GW to 150 GW by 2050.

In 2021, Canada committed to reduce its GHG emission by 40 to 45% below 2005 levels by 2030 under the Paris Agreement. It also pledged to reach net-zero GHG emissions by 2050. In May 2021, the Government launched the Canada Greener Homes Grant programme to support energy-efficiency retrofits and deployment of wind and solar energy in homes.

Canada has also committed to ban the sale of gasoline cars in Quebec by 2035, and in British Columbia by 2040.

What is wind energy?

How is energy generated by the wind?

Wind energy is electricity created from the naturally flowing air in by wind turbines. As the wind moves the turbine’s rotor, it captures the movement through its blades and transforms the kinetic energy of the wind through rotation into mechanical energy. This initiates the spin of internal shafts. These are, in most cases, connected through a gearbox that spins a generator to produce electricity, which is then transformed into higher voltage electricity and transported through connected storage as well as distribution facilities and cable systems.

Wind energy technology is evolving rapidly. Whereas wind turbines originally required a placement on mountains and hilltops, today, thanks to technological developments, they can be installed in more diverse settings. Wind farms can both be constructed onshore (on the terrestrial areas) and offshore (constructed on water, dominantly in seas and oceans). Higher towers and longer blades make them increasingly cost-efficient (especially offshore) and allow a broader extension.

Components of wind energy infrastructure

Wind Turbines

Wind turbines have towers made of steel and/or concrete and are crowned by a hub connecting to blades of composite materials, a nacelle with the rotors, cables, a generator and a central computer system. At the bottom of the tower is a transformer, which connects the turbine to the power connection and distribution grid.

A wide range of possible designs exist for wind turbines to adapt to different areas and conditions regarding transportation requirements or technical and commercial necessities of the developer. Turbines with larger rotor diameters increase the captured energy, and higher hub heights have access to higher wind speeds. They can reach a total height of 246.5 m (Source (Nicole): Gaildorf, Germany (Max Bögl Wind AG), although the weighted average of onshore wind turbines in Europe in 2020 is just below 120 m including some 16 m high turbines. The average height of onshore turbines has steadily increased since 2010 (in 2020, the total height of offshore wind turbines could reach up to 260 m).

(See wind basics and offshore Wind Europe key trends and statistics 2020 by WindEurope)

Main elements of onshore and offshore wind turbines (source: Wind Europe)

The foundation of wind turbines bears the load transmitted from the wind turbine tower and the turbine on the top, especially the huge overturning moments. Careful planning therefore is needed to choose the right basis for these constructions. Foundations of wind turbines can be of different types and depths depending on their location (onshore or offshore) additionally, there are multiple criteria related to their construction needs (these include the structure and height of a turbine, the wind intensity, the characteristics of the soil/seabed at the construction area and the likelihood of disasters in the development area, like earthquakes).

For onshore wind turbines, 5 common types of foundation are used today:

  • the shallow mat extension
  • the ribbed beam basement
  • the underneath piled foundation
  • the uplift anchors and
  • the ‘new type’

Each of these types could be round shape or octagonal shape. The average diameter of the foundation ranges from 15 m to 22 m.

For offshore wind turbines, there are several types of foundations depending on the depth of water at the site of the wind farm:

  • Fixed foundations
    • gravity-based foundation
    • monopole foundation
    • triple foundation
    • tripod foundation
    • jacket foundation
    • pile cap
    • suction bucket
  • Floating foundations
    • spar buoy foundation
    • tension-leg platform (TLP) foundation
    • semi-submersible foundation
    • barge
    • multi-platform.
The technology related to the construction of wind turbines is rapidly evolving. Therefore, the most up-to-date information about the characteristic and dimension of onshore and offshore wind turbines and the types of their foundation would need to be checked in the relevant literature, of which many is available with a free access on the world wide web.

Ancillary infrastructures

Wind energy facilities in a schematic landscape/seascape (sources: WindEurope and Canadian Wind Energy Association)


Sub-stations are essential annexes of wind farms and function as interface between the power generated by the wind turbines and the transmission of the energy into the electricity grid. Sub-station compounds normally include:

  1. control, protection, and metering system that allows the correct operation of the wind farm according to local regulations and grid requirements;
  2. communication system made of optical fibre or wired cable – it guarantees the correct communication with the nearby substations and with the grid control centre;
  3. protection systems against fire and intruders – it includes detectors, sirens and fire extinguishing tools.

Offshore substations are placed on the sea in the proximity of their wind farms or parks. These are generally large structures, weighing between 400 and 22,000 tonnes. They are built on fixed foundations – either steel mono pile foundations, larger jacket foundations or concrete gravity base structures.

Access roads and tracks

The transportation, construction, maintenance and decommissioning of wind farms require access tracks. Wide and sturdy roads or tracks are needed to provide access to substations and to the base of the wind turbines. They are usually created either by improving the capacity and width of existing road infrastructures or by building new access roads.

The technical requirements may vary for these tracks during the different lifecycles of wind farms. For example, the transportation of wind turbine components such as blades requires wide, straight roads without swellings or collapses on the track, and there are specifications on the type of materials needed for construction. Offshore wind energy projects will require the establishment of marine routes for the vessels involved in the operation including the maintenance of turbines and ancillary facilities.


Wind energy infrastructure may lead to a significant increase of traffic during construction and maintenance phases. It is important to pay attention to the possible impacts of traffic (including indirect impacts) not just on local communities, but also on ecosystems, wildlife and cultural attributes as these may be directly or indirectly linked with the OUV and other values as well.

For the above reason, the planning of tracks for a project concerning a World Heritage property needs to consider the OUV and the location of attributes of the concerned site.

Potential solutions may include favouring the use and upgrading of existing tracks and marine routes. Nevertheless, an assessment is needed to ensure that their use for the construction and/or maintenance of wind energy facilities will not result in damaging built or environmental heritage values.

The design of new tracks needs to reflect the local context. Project proponents should also ensure that the new tracks do not cut across areas, which express or support the OUV of World Heritage properties. In the case of onshore wind installations, supporting infrastructures may require slope stabilization or cut and fill on sloping sites. Such interventions, of course, would need to be minimized if they were to negatively impact important attributes. In such case, longer roads and trails may be a good way to better integrate the new features in the wider setting of a World Heritage property and avoid negative impacts on the attributes which convey its OUV.

For offshore wind turbines, factors like the voyage routes of marine mammals and migratory routes of seabirds need to be considered as well as reproduction or foraging sites in the wider setting of a World Heritage property.


The transformer is a station that transforms the energy produced by wind turbines into higher voltage electricity and feeds it into the power grid via cables. The transformer is connected via cables to one or more sub-stations. The size and type of a transformer depends on the type of the sub-station and of the energy capacity of the wind energy project.

There are different types of transformers, among others: GEAFOL cast-resin transformers, liquid-immersed distribution transformers and power transformers. In the case of offshore wind energy projects, the transformer (also called the converter station) can be a medium to large offshore or onshore infrastructure, usually connected to one or more sub-stations.


Cables are a key element in the electrical system of wind turbines. The installation and use of a multitude of cables is required: some are used to transmit the electricity produced to sub-stations and the power grid (transmission cables), others connect turbines (inter-turbine array). They can be installed underground or overhead, depending on the topography of the area and legal requirements (including heritage related regulations).

Depending on the characteristic of a World Heritage property, both underground and overhead cables can pose challenges and have multiple potential negative impacts in relation to values and attributes of a World Heritage property.

Among others, these could be:

  • visual impacts,
  • noise pollution,
  • damage to archaeological remains (and their setting),
  • habitat damage or loss, especially through
    • chemical pollution,
    • risk of entanglement for animals,
    • reserve effects by excluding fishing,
    • excess heat generation that affects habitat and species,
    • electromagnetic field generation (EMFs) – this risk applies particularly to offshore installations, where EMFs have the potential to harm mussels, worms, electrosensitive cartilaginous fish such as sharks and rays, and bony fish such as eels.

➔ See Impacts of wind energy projects and their assessment, Note 5 and Note 6

Power grids

A power grid is the distribution system that transmits the electricity from a wind farm to the users. It involves a series of electricity pylons or transmission towers, connected by multiple cables that can extend to long distances (super grid).

To minimize the potential negative impact of the wind energy related ancillary infrastructures on World Heritage properties, especially when it concerns cultural landscapes or landscape level properties, the siting of these features should be planned in close cooperation with the heritage protection authorities/organizations.

Solutions for avoiding or mitigating negative impacts related to power grids, need therefore to be based on a full understanding of the Outstanding Universal Value of a concerned World Heritage property. A vulnerability assessment and the creation of sensitivity maps (➔ See Note 2) may support the design process for the layout of these facilities, especially when planning the routing of a pylon or tower chain with appropriate locations for each pylon or tower and the distancing between them.

  • Planning designers may benefit of local topographical variation using screening features in the landscape to conceal ancillary features where possible.
  • Fencing or walling, where required (for example, for safety or agricultural reasons) should respond to the local context and try to blend in well in terms of type and style. (As an example, in a rural area where drystone dykes are characteristic of the landscape, the desirable design option might follow the choice of local material and stone walling practice instead of choosing a more industrial, steel palisade fencing.)

Potential impacts of wind energy projects on World Heritage

The potential impacts of wind energy projects on values of World Heritage properties strongly depend on the specific characteristic of the proposed project itself. In this respect, projects should be considered with all their elements and with all project phases. Any potential impact of projects needs to be measured in relation to the OUV of World Heritage properties they might affect. This includes potential impacts on the attributes that convey the OUV and the site’s conditions of integrity and authenticity, as well as its protection and management requirements, if the World Heritage status is to be respected.

For this reason, wind energy project proposals that might affect World Heritage properties should only proceed after their potential impacts have been assessed. In a World Heritage context, impact assessments (that are often categorized as Environmental and Social Impact Assessments or Heritage Impact Assessments) need to include the assessment of impacts on the OUV of the World Heritage properties concerned. As by definition the OUV of World Heritage properties is considered unique and irreplaceable, any potential irreversible negative impacts on the OUV should be avoided altogether. Potential impacts on other heritage values need to be mitigated. If mitigation or alternatives that pose no harm to the World Heritage property are not possible, the proposed project should not proceed, and project alternatives (including choosing a different location) need to be considered. The impact assessment should also consider the cumulative impact of already implemented or already known potential future projects (including other wind energy or other renewable energy projects).

➔ See the impact assessment process in Impacts of Wind Energy projects and their assessment.

Regarding potential impacts, the following aspects of wind energy projects are surely relevant in a World Heritage context:

(1) placement and design – the siting/location, layout and extension of a wind farm, the number, height and design and model of the turbines, the type of foundation, the placement and dimensions of the ancillary facilities are all factors that play a role in an assessment;

(2) foreseen actions within each phase of the facility’s lifecycle – a systematic assessment should consider all phases within the lifecycle and identify potential impacts on the OUV of World Heritage properties for each of them.

➔ See Impacts of Wind Energy projects and their assessment

To avoid any potential negative impact on World Heritage properties, project proponents will need to consider the following during the planning and design of wind farms:

  • siting plans should be based on a careful and well-informed selection process of sites, considering all relevant data, including vulnerabilities of World Heritage properties (for example prone to visual and sound impacts, vibration or air channel impacts);
  • the number of turbines is a factor with potential impact on vistas and on the wider setting of a World Heritage property (especially for cultural landscapes and landscape level properties);
  • the layout of wind parks should fit in the most appropriate way in the spatial areas (primarily the wider setting) of World Heritage properties, considering their OUV, and other natural and cultural values that support the protection of the OUV;
  • the model, design and colour of wind turbines need to be carefully chosen with regard to the characteristics of attributes of World Heritage properties (visual qualities, ecological qualities/species). This, of course, also concerns the height and scale of the wind turbines;
  • when a property has archaeological values or provides an important habitat for wildlife, the site for the installation process of the wind turbines might require careful planning, even if located away from a World Heritage property, due to potential new discoveries or the extent of the habitats.

➔ See Impacts of Wind Energy projects and their assessment, Note 5 and Note 7

Siting and design of wind energy farms

The selection of appropriate sites for wind farms from the wind industry’s point of view will depend on multiple elements including landscape features, wind characteristics, location of the distribution grid, of residential and industrial areas, of nature protection and military areas as well as of other service infrastructures.

Further to these elements, in a World Heritage context the project proponents need to also consider the compatibility of their plans with the protection and management goals and needs of World Heritage properties. There are several tools that can help distinguish between ‘suitable’ and ‘non-suitable’ locations for wind energy projects in this respect, such as:

  • Consulting the results of existing vulnerability assessments and sensitivity maps (➔ See Note 2) assisting in the selection of sites for wind energy projects, with information on the OUV, including the characteristics and the location (if possible) of attributes (such as habitats and on key views, vistas and panoramas). The preparation of such studies and the provision of relevant data are proactive and efficient actions before actual wind energy developments are proposed.
  • Strategic Environmental Assessments (SEAs) can be carried out at the national or regional level to assist informed decision-making related to wind energy installations. The SEAs take into account existing policies and restrictions. They enhance a strategic approach to wind energy development and could help to identify suitable areas for development and so-called exclusion zones where no development should take place. Individual wind energy projects would, nevertheless, require a dedicated Environmental and Social Impact Assessments (ESIAs) to decide on their appropriateness in a specific location. ➔ See Impacts of Wind Energy projects and their assessment
  • Environmental and Social Impact Assessments or ESIAs (in some cases Heritage Impact Assessments – HIAs) are usually a mandatory part of the planning process for specific wind energy projects. The result of the impact assessment can propose alternative project locations or reveal early in the planning phase if the construction of a wind energy project in a certain location is not possible from a World Heritage perspective (this could concern the area of the property, its buffer zone or its wider setting). ➔ See Impacts of Wind Energy projects and their assessment

There are wind speed maps and wind atlases that are used by the wind energy project proponents to identify potentially suitable development areas. A cross check of such atlases with the boundaries and wider setting of World Heritage properties is an advised approach to estimate the feasibility of wind energy proposals in the early project planning phases.

Result of vulnerability studies and sensitivity maps may be included in planning and development databases to support the identification of suitable development areas and ensure the avoidance of sensitive areas. (➔ See Note 2)

Close cooperation between wind energy project proponents and the authorities responsible for safeguarding of the natural and cultural heritage, as well as with local communities and other stakeholders is needed to ensure that the planning and design process of wind energy projects is informed by identified vulnerable areas and areas where the installation of wind energy projects are not possible. The wind energy project proponents could themselves follow a ‘No-Go’ commitment strategy, to safeguard the World Heritage properties from proposing developments which would have an irreversible negative impact on their Outstanding Universal Value.

To ensure the protection of World Heritage properties, the siting and design process of a wind energy project should in all cases consider the following:

  • micro-siting and positioning of wind turbines to ensure their most optimal placement and arrangement within the wider landscape;
  • type and routing of access tracks, including the amount of cut and fill required;
  • location and design of ancillary facilities;
  • location, design and restoration of construction and maintenance facilities (hard standings, cranes, borrow pits, compounds);
  • location and size of wind monitoring masts;
  • residential, industrial, and recreational areas;
  • land management changes.

➔ See also Checklist 1

Depending on the characteristics of the attributes of a World Heritage property, even small-scale wind farms and wind turbines, or vertical axis wind energy installations on buildings may have a significant impact especially on the visual characteristics of historic cities, cultural landscapes and areas of exceptional natural beauty and aesthetic importance.

Utility-scale wind turbines that are typically installed in large wind farms, owing to their impressive scale and dimensions in a landscape, are likely to have a potential impact on World Heritage properties if planned within or around them.

Wind energy life cycle

Potential impacts of wind energy projects on World Heritage properties need also to be assessed with regard to the different phases of a project life cycle. Impacts may differ from phase to phase, some may occur throughout the lifecycle of a project, others only for a short period of time, or at seasonal intervals.
➔ See Impacts of Wind Energy projects and their assessment

Schematic lifecycle depiction of wind energy facilities

From planning to commissioning

This project phase includes both strategic and detailed planning for the development of a wind energy instalment (usually the construction of several wind turbines or a wind farm) and the commissioning of the project (which is a set of activities performed before an operation permit is provided to confirm that the wind turbines have been correctly installed and that they are ready for energy production). It is characterized by a significant lapse of time and there can be several years between the planning and the operational phases.

This phase includes several activities:

  • Compliance with spatial planning regulations,
  • Assessment of resources and wind potential,
  • Identification of land available (purchasing or leasing),
  • Identification of potentially suitable areas for the development,
  • Consultation with rights-holders and stakeholders,
  • Site analysis through calculations and digital modeling that allows for the identification of the most appropriate location and type of wind turbines (height, diameter of the rotor, capacity, etc.),
  • Early assessment of the technical feasibility of the project,
  • Identification of regulatory constraints,
  • Design of the wind farm (including size, model of wind turbines, technological characteristics, electrical design, infrastructure plan),
  • Impact assessment and other technical studies (e.g. risk screening, biodiversity sensitivity, sensitivity mapping, setting studies),
  • Preparation of the planning permission process,
  • Securing financial mechanisms,
  • Construction of the wind farm (including wind turbines and ancillary facilities),
  • Commissioning (which covers all activities after the installation of the wind turbines is completed).
Average timespan requirement of each step in the planning to commissioning process
(source: WindEurope)

The assessment of potential impacts of specific wind energy projects on the attributes which convey the OUV of a World Heritage property should be carried out as soon as possible in the lifecycle of the project, and preferably already at the screening and scoping steps of the impact assessment. (➔ See Impacts of Wind Energy projects and their assessment) This allows not only for timely detection of potential impacts but also to use the results to inform the planning and design of the wind energy project. Sometimes the outcome of the screening and scoping already shows the need to consider an alternative siting or design for projects, or even not to proceed with a project if unacceptable adverse impacts on the attributes which convey the OUV of a World Heritage property become evident. Halting a project at an early stage, or recognizing the need for a major revision, could save time and costs for the project proponent.

A good example of a national-level guidance document is Siting and Designing Wind Farms in the Landscape (2017), prepared by the Scottish Natural Heritage. The document advises on the siting and design of wind farms in Scotland’s landscapes. It describes an iterative design process involving the assessment of landscapes and of the visual effects of wind farms.

See also the case studies described in World Heritage and wind energy planning (2021)

Operation and maintenance

The operation and maintenance phases of wind farms generally amount to a 20 to 25 years standard lifetime with a possible extension of up to 10 years. It starts after a testing period and upon approval of the purchase contract for the produced electricity by the relevant national, regional, or local authorities. This phase includes the routine servicing and repairs that are required to achieve a wind turbine’s designed lifetime and to ensure the compliance with financial, safety, security, and leasing agreements.

When wind farms are built and are in operation, their impact might be especially averse to World Heritage properties with

  • particular landmarks in the landscape;
  • important visual relationships between different attributes (view axes, panoramas, vistas, skylines);
  • picturesque elements and points for the appreciation of the landscape’s beauty;
  • natural features of elements and areas, including landscape features as well as geological and physiographical formations (mountains, peaks, glaciers, lakes, rivers);
  • natural phenomena or areas of exceptional natural beauty and aesthetic importance;
  • sensitive ecology and biodiversity;
  • agricultural areas or areas with important seasonal activities.

➔ See Note 1 on attributes and Note 5 on Visual Impact Assessment

A comprehensive list of potential impacts on nature and biodiversity can be found in the IUCN publication, Mitigating biodiversity impacts associated with solar and wind energy development. Guidelines for project developers(2021).

End of Life Options

Lifetime Extension

Through the partial replacement of components (for example, blades, gearbox), the lifetime of wind farms can be extended by 10 years to a total of up to 30 to 35 years. To prolong the already approved and licensed lifetime, a ‘remaining useful lifetime assessment’ (i.e., a fatigue load analysis) needs to be undertaken in combination with a site inspection and review of the maintenance framework. As a result, the developers may be required to undertake certain repair works and to reinforce or renovate certain areas.


Repowering means replacing, in the same designated area, older wind turbines with taller and more powerful ones. Usually, the increase in energy yields allows deploying fewer facilities in the same zone.

The main factors for the decision on whether to repower or simply decommission a wind energy plant depends on:

  • the performance of the wind turbines and the cost of operation and maintenance;
  • the length of the support frameworks (generally 20 years);
  • the evolution of the wholesale electricity market prices; and
  • regulatory framework and environmental restrictions.

Policies around repowering may vary considerably on the national levels. Whereas it may require a whole new permission process including impact assessments (usually as part of an Environmental and Social Impact Assessment processes) and the (re-)examination of the suitability of an area in one country, it may only take a ‘fast-tracked’ permission request in another country. In addition, not all previous wind farm areas remain necessarily eligible for repowering in which case an alternative end-of-life scenario will need to be considered (i.e., lifetime-extension or decommissioning).

Wind farms are sometimes considered as temporary facilities with largely reversible impacts. Indeed, there is a possibility at the end of their operational lifetime (20 to 35 years) for wind energy facilities (turbines and even ancillary facilities) to be dismantled, and the wind farm site to be partially or fully restored to, as much as possible, pre-existing conditions. The process is driven by the strategies set out in advance in the decommissioning plan and included in the building and dismantling permits. Nevertheless, the possibility and ability to restore a site to conditions to pre-project stage will depend both on the characteristic of the project design itself (for example, location, density, material and foundation of the wind turbines and the ancillary facilities, etc.) as well as the characteristic of the World Heritage property, its OUV and attributes, and their sensitivity to the project (for example, a World Heritage property’s OUV is linked to archaeological repositories, geomorphological and hydrological features, etc.).

Dismantling/deconstructing a wind energy facility completely, however, is an option rarely used, and project proponents usually opt for extending or renewing the life span of these facilities. Repowering is normally subject to a new – even if often simplified – permission process and, if needed, also a new Environmental and Social Impact Assessment.

Considering the fact that there are different policy approaches at the national level, and that in many cases designated areas for wind energy facilities will and should remain in use for a long time (in accordance with relevant national policies and legal framework), careful consideration and assessment of all potential impacts will be required to ensure that such facilities receive the first permission to be built on a suitable location.

➔ See Impacts of Wind Energy projects and their assessment

Please note that in case of potential adverse impacts of a wind energy project on the attributes which convey the OUV of a World Heritage property, the possibility of dismantling a wind farm at the end of its lifecycle will not be considered an appropriate mitigation measure (on the grounds that the installation would be considered temporal). Moreover, impact assessments should always be kept to the same level of accurateness, be it for a lifetime extension or a repowering process, to ensure that all operations are in line with the with internationally agreed obligations to protect the specific World Heritage property and its OUV.

The EU’s Revised Renewable Energy Directive (2021) declares that Member States shall facilitate the repowering of existing renewable energy plants by ensuring a simplified and swift permit-granting process. This means that although the repowering does require a new permission process, this should henceforward be ‘fast-tracked’ since the site had already been designated for wind energy generation. WindEurope recommends that the reassessment of the environmental effects of the new design should not done against the greenfield site but against the existing wind turbine site as a baseline.

Nevertheless, from a World Heritage perspective, repowering initiatives should be accompanied with an impact assessment that focuses on the foreseeable impacts of the repowered energy plant on the OUV of the World Heritage property it may affect.

Decommissioning: dismantling, removal, recycling

The decommissioning is the process of removing all wind turbines from an area. This phase consists of the dismantling and removal of the turbines and all other connecting infrastructures, including the treatment and recycling of waste and materials. Following this process, the area needs to be fully cleaned and the land restored to its original condition. The implementation of this phase depends to a great extent on the respective national policy in place and whether specific national guidelines are available for the dismantling and demolition of wind turbines and other project-specific infrastructures. If not specified otherwise, the decommissioned site must be restored to greenfield.

A detailed decommissioning plan is normally a mandatory part of the wind energy project proposal, which is examined and approved as part of the application process. This plan will later guide the removal of the wind farm, ensuring and specifying also that all related costs are to be covered by the developers. The plan usually reflects contracts regulating the land use and the grid connection points and refers to the conditions imposed by local authorities through the building or demolition permits as well as to relevant national, regional, or local legislation. Accordingly, wind energy licenses, contracts and plans need to include provisions for the complete removal and restoration of the land to the original state after the permanent decommissioning of the wind farm and, if relevant, the ancillary facilities as well.

Responsible actors of the wind industry can take proactive action to minimize the impact of wind farms on the environment. WindEurope has developed an industry guidance document, first published in November 2020, for the decommissioning of onshore wind turbines, to be used in the absence of national guidelines.

While wind farms may operate for 25 to 30 years before their decommissioning, the measures for safeguarding World Heritage properties should be developed during the planning phase of the project (ideally as a result of an impact assessment process that includes a careful consideration of the impacts of all phases of the wind farm on the OUV and attributes of World Heritage properties).

The implementation of mitigation measures should be included in management and operational documents relating to the construction phase, the long-term operation of the wind energy project, and the responsibilities for decommissioning once the lifecycle is exhausted. All these pieces of information should be an integral part of the licensing documents, the Environmental and Social Management Plan (that guides actions on the ground when the contractor implements them) and other relevant project management plans. These documents should be available to all relevant parties, throughout the operational phase of wind energy facilities.

➔ See Impacts of Wind Energy projects and their assessment, and especially the step ‘Follow-up’ in the step-by-step guidance

The decommission of a wind farm will need to follow the measures included in the above listed documents, and the operator and responsible for the decommissioning will have to ensure that the activities do not have an adverse impact on the attributes that convey the OUV of the World Heritage properties.