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2 Micro-Wind
10. Micro-wind turbines have been used for many years in domestic, light industrial and farming applications for both water pumping and electricity generation. Micro-wind turbines have the potential to provide electricity in both domestic and commercial locations. The power generated and associated carbon emission reductions per turbine are relatively small, but cumulative benefits could be significant. The cost of micro-wind is falling and will be amongst the most financially viable technologies as more devices are installed, particularly since Scotland has the best wind resource in Europe.
11. There are currently an estimated 650-700 micro-wind installations in the UK. It is likely that we will see an increased use of micro-wind on homes and both commercial and public buildings. At present the typical financial payback period on micro-wind is 7-12 years. However, the cost of micro-wind turbines is predicted to fall as the technology develops. Additionally, there is a range of funding schemes in place which help fund the installation of micro-wind turbines. A domestic micro-wind turbine could save an average household (with an average wind regime) approximately a third of its typical energy requirement. The larger micro-wind systems can provide nearly all the energy required in a home.
12. After the initial outlay of the micro-wind turbine and associated equipment, running costs are comparatively low as they require little in the way of maintenance. Micro-wind turbines typically have a working life of 20-25 years, although excessive turbulence will cause fatigue damage, reduce the amount of power generated and shorten a turbine's working life. However, as the testing and development of micro-wind turbines continues and more knowledge and experience is gained and shared among manufacturers it is likely that the lifespan of turbines will increase.
Existing Planning Controls
13. Most micro-wind turbines are likely to require planning permission. However, it is for planning authorities to consider whether planning permission is required for micro-wind turbines in the particular circumstances of each case and taking into account the size, location, and surroundings of the proposed siting of the device. There are no specific permitted development rights for micro-wind systems. However, the Executive will be examining the option for new permitted development rights for micro-renewable systems in the context of the review of the GPDO, see paragraph 9.
How Do They Work?
14. Turbines catch the wind's energy using blades which are mounted on a shaft. The shaft is connected, normally via a gearbox, to a generator which produces electricity. The blades and shaft are connected to the nacelle, which contains the gearbox and other power/ mechanical components. The micro-wind turbine may have a tail or motor to align the blades with the direction of the wind to maximise energy generation. Wind speed increases with height and the greater the wind speed, the more power is produced. Most wind turbines undergo test certification procedures, which must conform to the guidelines laid down by the International Electro-technical Commission ( IEC), the main standard for small wind turbines is BS EN 61400-2 1996.
Stand-alone
15. Micro-wind systems are often used as a source of power in remote locations where conventional methods of supply are expensive or impractical, for example where new power lines would be required. The wind turbines are generally connected to batteries, which are charged when spare energy is produced and provide power when needed, for instance during periods of low wind speeds. It is common to combine this with a diesel generator for use when additional power is required. There will likely be a need for associated equipment housing for any batteries and generator and thus these systems generally require more thorough safety precautions/measures to be undertaken, with regard to fuel storage and battery banks. This may involve separate storage areas/compartments.
Grid-connected
16. Micro-wind installations can be connected to the grid. In periods of high wind, turbines may produce more power than is needed which allows excess electricity to be exported back to the grid and sold to an electricity supply company. When additional power is required, for instance during periods of lower wind speed, electricity can be imported from the grid.
Types of Turbines
17. Wind turbines can be either horizontal axis or vertical axis style.
Horizontal Axis Wind Turbines
18. Most wind turbines are horizontal axis machines, which can generate electricity in low wind speeds. Horizontal axis micro-wind turbines generally range in size from 1.75 metres to 4 metres in diameter. To work effectively most horizontal axis wind turbines need to face into the wind. This can either be done by a tail, or a control system and motor to rotate the turbine - this usually depends on the size of the turbine. Other types of horizontal axis machines work 'down wind' and face away from the wind.
| Vertical Axis Wind Turbines |
| 19. Vertical axis wind turbines are not sensitive to wind direction and so do not require a means of orientating themselves. They are well suited to the turbulent wind found in urban areas as they are not affected by rapid changes in wind direction and able to cope well with upward and downward gusts. There are various designs of vertical axis turbines available, however their installation to date has not been common in Scotland. The main advantages of vertical axis wind turbines are that they are quieter and often thought to be more aesthetically pleasing. However, they are generally less efficient at harnessing the wind energy and require a fairly high wind speed to start rotation. |  |
Roof Mounted Turbines
20. A number of companies have developed micro-wind turbines that can be mounted on buildings and other structures, including domestic properties. Roof mounted turbines can be either horizontal or vertical axis. Rooftop mounted turbines are likely to increase the overall height of a building to take advantage of higher wind speeds and will be comparable in height to a large television ariel or chimney stack. These will be attached to sturdy structural elements, such as external walls, but chimney stacks will generally not be suitable. The building must be able to take the extra weight and the extra wind load caused by the turbine and installations should meet the satisfaction of the council's Building Standards officer. (See para 28)
Turbines on Towers
21. Micro-wind turbines can be fitted on towers. These turbines tend to be horizontal axis and can be mounted on either lattice or solid towers, set in secure foundations. Taller towers can be supported by guide wires to ensure their stability. Higher towers will reach greater wind speeds and therefore have increased power generation capacity, but will have an increased visual impact.
Building Integrated Turbines
22. There is growing interest in integrating wind turbines into buildings and other structures. In this setting wind turbines can be used as a design feature as well as a method for generating renewable energy. They can be integrated at the design stage into homes and both commercial and public buildings, particularly tall buildings. Micro-wind turbines can also be integrated into buildings so that they are concealed from view. They can be incorporated into both the design of side elevations and with roofscapes. Ducted turbines sit at the edge of the roof of a building and utilise the updraft of the airflow along a building side.
Siting and Design
23. The perceived visual impact of micro-wind turbines depends on how they are seen both in terms of the image they convey and their siting and composition. Micro-wind turbines can be seen as symbols of positive action to address climate change and promote sustainability.
24. The erection of micro-wind turbines must be undertaken in a manner that keeps the environmental impact to a minimum whilst still ensuring they provide sufficient power. Sensitive siting and design in both urban and rural areas can reduce visual intrusion and play a part in making these installations an accepted feature. Individual circumstances will dictate the optimum position for micro-wind turbines. This will be influenced by the size of the installation and its surrounding environment. The potential impacts of micro-wind turbines are considerably less than wind farms. However, the potential siting of micro-wind turbines close to, on, or integrated with buildings means that special attention must be given to the need to protect amenity.
25. The ideal location for a micro-wind turbine is up high, taking advantage of prevailing south-westerly winds. It should preferably have a clear exposure, free from excessive turbulence and obstructions such as large trees or buildings. Planning authorities and developers will both need to be flexible in considering locations so as to ensure an adequate balance is struck between maximising energy production and minimising unwelcome visual impacts. It is possible to locate micro-wind turbines in more enclosed locations and still generate an appropriate amount of power for a home, however, the financial payback periods are likely to be consequently longer. Planning authorities can ask applicants to provide justification for siting a micro-wind turbine in a given location or encourage alternatives to be considered at the pre-application stage.
Colour and Form
26. The colour and finish of the wind turbine should be appropriate to the setting and designed to minimise visual impact and reflection of light. It is best practice to colour the various elements of the turbine as part of the manufacturing, which can be done either through painting or by coating with a coloured gel base. Where the main background is the sky then an off-white colour may be appropriate. If the main background is vegetation then a green/brown colour may be suitable. Where the main background includes building elements the best colour will vary, although in many cases green/brown is likely to be the most appropriate. There will usually be cost implications in colouring the turbines and in some instances for practical reasons it may not be possible to colour the blades. However, it may be possible to colour the associated equipment such as the mast or the cabling. Conditions can be attached to limit corporate branding on the turbine.
27. The siting and design of micro-wind systems should aim to minimise the contrast with the surroundings. This can be achieved by using simple shapes with clean lines, developing a balanced composition in proportion to the surrounding environment; and using regularity, order and symmetry wherever possible. The form of micro-wind turbines clearly relates to their function, which makes them legible built elements, which can easily be understood by the observer - making them a distinctive element in the landscape may be appropriate in some circumstances.
Roof Mounted Turbines
28. Turbines should be sited in a way that creates a balanced composition that does not undermine the architectural integrity of the building or structure. They are generally positioned on the highest point of the roof, however, to reduce their visual impact it may be possible to locate them at a lower position provided they have a 0.5m clearance from the base of roof. Consideration should be given to positioning the micro-wind turbine at the rear of the property, where visual impact will typically be lessened. High rise buildings may seek to install a series of turbines around the perimeter of the roof, to take advantage of updrafts around the building. Siting should consider the relationship to other existing roof structures such as chimneys, aerials, masts equipment housing, or where they can follow the form and positioning of traditional elements on roofs like chimneys. Where more than one turbine is proposed the aim should be to achieve a balanced composition, by grouping them together or installing through the use of symmetry. In some circumstances it may be better to site a turbine on a tower in the land adjacent to a building, particularly where a roof mounted turbine will damage the building's architectural integrity.
Towers
29. Towers should be sited in a way that minimises the landscape impact. Whilst tall towers and hilltop locations will be best for capturing maximum wind energy, smaller towers and low lying locations should still be able to generate sufficient energy to meet the requirements of an average home.
30. Careful consideration should be made to the desired height of the turbine. While it will be important to avoid undue turbulence and areas of low wind speed, the choice of height needs to be carefully balanced with the visual prominence of the turbine in relation to existing buildings and surrounding landscape features. Where possible the height of towers should relate to the height of existing vertical elements in the landscape such as light columns, telegraph poles, trees, buildings and other structures. A turbine sited on a prominent ridge is generally not desirable. Where possible towers should be coloured to minimise the visual impact.
Natural Heritage
31. The key natural heritage issue related to micro-wind turbines is likely to be that of landscape and visual impact particularly in rural areas and on the urban edge. Micro-wind turbines will likely be an appropriate development within natural heritage designations provided that an appropriate approach to siting and design has been undertaken and that areas of high sensitivity have been avoided.
32. Good siting should relate to existing features and patterns within the local landscape, whether this be the grouping of farm buildings, the line of hedgerow or the proximity of power lines.
33. It is unlikely that micro-wind turbines will cause a significant increase in bird strike, beyond those already arising from birds flying into existing buildings, windows and other obstacles. Further information on birds and habitats is provided in PAN 45, paragraphs 84-88.
34. The effects of installing a micro-wind tower should be considered in terms of the ground disturbance that may be arising from construction. Full restoration measures that are appropriate to the site should be provided by the applicant. Close attention should also be paid to the need for ancillary infrastructure or servicing, such as vehicles or powerlines to the proposed location. Particular care should be paid to such proposals where they are in prominent locations or cross areas of sensitive habitat or areas of species interest. Further information regarding natural heritage can be found in NPPG 14 'Natural Heritage' and PAN 60 'Planning and Natural Heritage'.
Historic Environment
35.NPPG 18 sets out the Executive's planning policies in relation to the historic environment with a view to its protection, conservation and enhancement. NPPG 5 and PAN 42 set out Executive policy on archaeology, planning and scheduled monuments. It will not normally be possible to site micro-wind turbines on scheduled ancient monuments and it will be difficult site them on listed buildings. However, there may be opportunities to site micro-wind turbines in conservation areas or within the curtilage of listed buildings. Where this is proposed care must be taken to ensure respect is paid to the site and setting of listed buildings, scheduled monuments and other important elements of the historic environment, including gardens and designed landscapes, and to important views and vistas to and from these buildings, monuments and sites, which may be identified in a conservation area appraisal. If micro-wind turbines are being integrated into listed buildings they should be concealed wherever possible, for instance through the use of ducted micro-wind systems. Further information is given in the Memorandum of Guidance on Listed Buildings and Conservation Areas within Appendix 1, in particular section 1.7 'Items Fixed To The Exterior of the Building'.
Siting Opportunities
36. Wind turbines can be designed as a piece of art helping to increase awareness and knowledge of renewable energy technology. Areas that already have engineered forms and structures may offer the best opportunity for siting equipment. These may include:
- industrial areas;
- wastewater treatment sites;
- on or near electricity pylons, water towers, floodlighting towers and gasometers;
- civic amenity sites;
- retail parks; and
- harbour areas.
Amenity Issues
Noise
37. Advice on noise is given in SODD Circular 10/1999, PAN 56 and PAN 45 paragraphs 65-68. New designs of micro-wind systems have greatly reduced noise levels due to improved blade design and reduced mechanical noise. Modern turbines are also easier to control and can be shut down at very high wind speeds, if necessary.
38. Noise stemming from micro-wind turbines will generally be of an acceptable level. However, to protect nearby residents from any potential noise, a condition can be attached to any consent controlling the level of noise. A detailed noise assessment should not be required. Where turbines are fixed to a building, there may be a risk of noise disturbance from vibration to the building itself or neighbouring buildings and a condition might be attached that appropriate measures should be taken to mitigate any such vibration.
Electromagnetic Interference
39. Like any electrical equipment, micro-wind turbines have the potential to produce electromagnetic interference. However this is unlikely to be a significant issue; where problems do arise, it is likely to be highly localised and should be able to be technically overcome. The small diameter of micro-wind turbines will limit any potential effects on television and radio reception. It is unlikely that small rooftop wind turbines will effect either mobile phone reception or fixed radio/microwave communications links. Micro-wind turbines are also unlikely to have any detrimental effects on aviation and associated radar/navigation systems. It is also unlikely that electrical interference from such systems will interfere with the smooth operation of the micro-wind turbine.
Shadow Flicker
40. Advice on shadow flicker is provided in PAN 45, paragraph 64. The small diameter and likely location of micro-wind turbines greatly reduces the probability of shadow flicker occurring. Therefore in the majority of cases shadow flicker will not be an issue, however, information on shadow flicker can generally be provided by the companies who produce the equipment.
Visual Distraction
41. The potential for micro-wind turbines to distract road users may need to be assessed. However, potential for them to distract drivers will reduce as the number of micro-wind turbines increases and they become more of an accepted and unobtrusive feature of urban and rural areas. It is unlikely that micro-wind systems will be any more of a visual distraction than existing elements in the environment, such as advertising hoardings.
Case Studies
Fife Schools Pilot Project
As part of pilot project launched by the then Deputy Enterprise Minister rooftop micro-wind turbines have been installed on five Fife primary schools, including Collydean Primary School, Glenrothes. The initiative was jointly funded by the Scottish Executive through the Scottish Community and Household Renewables Initiative, Renewable Devices, ScottishPower and Fife Council.
Each turbine can generate up to 4000 kW hours of green electricity each year, saving up to 1720kg carbon dioxide, and cutting the school's energy bill. The turbines have also served an education role in raising awareness of renewables amongst the pupils.
Domestic Off-Grid Micro-Wind
In this example located near Milnathort, Kinross, the applicant sought to install a micro-wind turbine as part of the renovation of an off-grid house. The reasons for this were both on sustainable development grounds and due to the high costs of getting a grid connection, despite the property not being remote.
Pre-application discussions were held and initial concerns that the turbine would be bad neighbour development were eradicated when it was discovered the mast was only 10m high. The property has no near neighbours.
Planning permission for the turbine was granted in 2001 by Perth and Kinross Council. A modification was later submitted to change the position of the tower in January 2002 this was granted a month later in February 2002. The turbine has blades 1.3m in length. The 1.5kw turbine provides most of the energy required for the property. A power house was also built to house the control panel, and back-up battery packs and diesel generator.
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