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CHAPTER 2: Environmental impacts

The energy supply is still dominated by fossil fuels, which contribute to the main environmental problems at the world level: climate change and air pollution. Renewable energies use means lower greenhouse gas emissions and reduced air pollution, representing a key solution to reach a sustainable future.

Wind is clean, free, indigenous, and inexhaustible. Wind turbines do not need any type of fuel, so there are no environmental risks or degradation from the exploration, extraction, transport, shipment, processing or disposal of fuel. Wind generation is not only produced with zero emissions of carbon dioxide (during operational phase) but it also does not release toxic pollutants (e.g. mercury) and conventional air pollutants (e.g. smog-forming nitrogen dioxide and acid rain forming sulphur dioxide). Furthermore, the adverse impacts caused by mountaintop mining and strip mining of coal, including acid mine drainage and land subsidence are avoided, and the negative effects of nuclear power, including radioactive waste disposal, security risks, and nuclear proliferation risks, are not created. Finally, wind power can have a long-term positive impact on biodiversity by reducing the threat of climate change - the greatest threat to biodiversity. At the same time, the construction and operation of both onshore and offshore wind turbines can result in potential negative local environmental impacts on birds and cetaceans, landscapes, sustainable land use (including protected areas), and the marine environment. The negative environmental impacts from wind energy installations are much lower in intensity than those produced by conventional energies. They still have to assessed and mitigated, however, when necessary.

The EU Directive 85/337 defines the Environmental Impact Assessment (EIA) as the procedure which ensures that environmental consequences of projects are identified and assessed before authorisation is given. The main objective is to avoid or minimise negative effects from the beginning of a project rather than trying to counteract them later. Thus, the best environmental policy consists of preventing pollution or nuisances at source so the environment is not damaged. The procedure requires the developer to compile an Environmental Statement (ES) describing the likely significant effects of the development on the environment and proposed mitigation measures. The ES must be circulated to statutory consultation bodies and made available to the public for comment. Its contents, together with any comments, must be taken into account by the competent authority (e.g. local planning authority) before it may grant consent.

The Strategic Environmental Assessments (SEA) is the procedure to evaluate the adverse impacts of any plans and programmes on the environment. National, regional and local governments must undertake SEAs of all wind energy plans and programmes that have the potential for significant environmental effects. Appropriate Assessments (AA) have to be carried out in accordance with Habitats Directive to evaluate the effects on a Natura 2000 site. Where potential trans-boundary effects are foreseen, international cooperation with other governments should be sought. SEAs should be used to inform strategic site selection for renewable energy generation and identify the information requirements for individual EIAs.

Worldwide, biodiversity loss is in principle caused because of human activities on the environment (such as intensive production systems, construction, and extractive industries), global climate change, invasions of alien species, pollution and over-exploitation of natural resources. In 2005 the transportation and energy (DG TREN) and environment (DG ENVI) directorates at the European Commission created an ad hoc working group on wind energy and biodiversity. The group is comprised of industry, governmental and non-governmental representatives. A draft guidance document is currently debated and aims at facilitating the development of wind energy while preserving biodiversity.


Visual impact

The landscape is a very rich and complex concept. Defining landscape is not an easy task. The proof of this is the high number of definitions that exist. The most common definitions are: Painting or drawing that represents a certain extension of land; and a portion of land that is considered in its artistic aspect. According to the European Landscape Convention, landscape means: an area, as perceived by people, whose character is the result of the action and interaction of natural and/or human factors. Landscapes are not static. The landscape is changing over time according to human and ecological development.

Landscape and visual impact are key environmental issues in determining wind farms applications related to wind energy development as landscape and visual impacts are by nature subjective and changing over time and location.

Wind turbines are artificial vertical structures with rotating blades, which have the potential of attracting people's attention. Typically wind farms, with several wind turbines spread about the property, may become dominant points on the landscape.

The characteristics of wind developments may cause landscape and visual effects. These characteristics include the turbines (size, height, number, material and colour), access and site tracks, substation buildings, compounds, grid connection, anemometer masts and transmission lines. Another characteristic of wind farms is that they are not permanent, thus the area where the wind farm has been located can return to its original condition after the decommissioning phase.

Landscape and visual assessment is carried out differently in different countries. However, within the European Union, most wind farms are required to carry out an EIA. The assessment should take account of any proposed mitigation measures, predict their magnitude and assess their significance. Some of the techniques commonly used to inform the landscape and visual impact assessment are:

  • Zone of theoretical visibility (ZTV) maps. Define the areas from which a wind plant can be totally or partially seen as determined by topography. These areas represent the limits of visibility of the plant.
  • Photographs to record the baseline visual resource.
  • Diagrams to provide a technical indication of the scale, shape and positioning of the proposed wind development.
  • Photomontages and video-montages to show the future picture with the wind farm installed.

Visual impact decreases with the distance. The ZTV zones can be defined as:

  • Zone I - Visually dominate: the turbines are perceived as large scale and movement of blades is obvious. The immediate landscape is altered. Distance up to 2 km.
  • Zone II - Visually intrusive: the turbines are important elements on the landscape and are clearly perceived. Blades movement is clearly visible and can attract the eye. Turbines not necessarily are dominant points on the view. Distance between 1 to 4.5 km at good visibility conditions.
  • Zone III - Noticeable: The turbines are clearly visible but not intrusive. The wind farm is noticeable as an element in the landscape. Movement of blades is visible in good visibility conditions but the turbines appear small in the overall view. Distance between 2 and 8 km depending on weather conditions.
  • Zone IV - Element within Distant Landscape - The apparent size of the turbines is very small. Turbines are as any other element in the landscape. Movement of blades is generally indiscernible. Distance of over 7 km.

While visual impact is very specific to the site at a particular wind farm, several characteristics in the design and siting of wind parks have been identified to minimize their potential visual impact. (Tsoutsos et al, 2006, Hecklau, 2005, Stanton, 2005).

  • Similar size and type of turbines on a wind farm or several adjacent wind farms
  • Light grey, beige and white colours on turbines.
  • Three blades.
  • Blades rotating in the same direction.
  • Low number of large turbines is preferable to many smaller wind turbines.
  • Flat landscapes fit well with turbine distribution in rows.

Mitigation measures to prevent and/or minimize visual impact from wind farms on landscape can be summarised as follows (Brusa and Lanfranconi, 2007):

  • Design of wind farm according to the peculiarities of the site and with sensitivity to the surrounding landscape.
  • Locate the wind farm at a minimum distance from dwellings.
  • Selection of wind turbine design (tower, colour) according to landscape characteristics.
  • Selection of neutral colour and anti-reflex painting for towers and blades.
  • Underground cables.
  • Lights for low altitude flight only for more exposed towers.

The effects of landscape and visual impact cannot be measured or calculated and mitigation measures are limited. However, experience gained recently suggests that opposition to wind farms is mainly verified at planning stage. After commissioning the acceptability is strong.

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