Fitting into the landscape
Whether a person’s initial reaction is to like the appearance of wind turbines or not is a matter of personal preference, but many people find them an interesting and graceful feature in the landscape and soon become accustomed to seeing them.
As you can see from the photograph on the right, even on a clear day the turbines at Skelmonae Windfarm can be quite hard to spot on the skyline.
At Skelmonae Windfarm the visual impact of the turbines is also lessened because there are 160 acres of trees to the north, while at Hill of Skilmafilly there are 500 acres of trees to the north and west.
From the Methlick direction, the wind turbines at Hill of Skilmafilly are on the other side of the hill and appear to be behind those at Skelmonae, which has the effect of reducing any apparent height difference. From the south and east it is only possible to see part or all of both sets of turbines at the same time from a very few positions.
While the larger blades on the three turbines at Hill of Skilmafilly take slightly longer to complete each rotation than the smaller blades on the four turbines at Skelmonae, the tips of the blades travel at almost the same speed – helping to unify their appearance in operation.
In order to warn any low-flying aircraft of the presence of the wind turbines, especially at night or during periods of low visibility, we have installed infra-red lights on the towers at Hill of Skilmafilly. These lights, being infra-red, are not visible to the naked eye from the ground.
Photo-montages
When applying for planning permission for a windfarm, a range of photo-montages must first be produced to give an accurate illustration of what the wind turbines would look like on their proposed site from various vantage points. If you click to open the first document below, you will see a map of the Hill of Skilmafilly site and 12 photographs onto which the wind turbines were super-imposed at the correct heights and locations, to demonstrate exactly how they would appear. Text boxes at the bottom of each page describe the specific location, direction and distance from which each photograph was taken (the arrow in the map box at bottom right also gives a visual indication of this).
A further three wide-view photo-montages taken from the surrounding area are contained in the second document below.
As you can see from these photo-montages of the Skelmonae and Hill of Skilmafilly turbines, they are not intrusive and do blend very well into the surrounding landscape.
pdf File HillOfSkilmafillyLayoutPhoto-montages1-12
pdf File HillOfSkilmafillyWide-viewPhoto-montages
Strict rules about noise
Wind turbines are not noisy. The evolution of windfarm technology over the past decade has rendered mechanical noise from turbines almost undetectable, with the main sound being the aerodynamic “swoosh” of the blades passing the tower. It is possible to stand underneath a turbine and hold a conversation without having to raise your voice. As wind speed rises, the noise of the wind itself masks the noise made by wind turbine blades.
By law, the exterior audible sound levels downwind from a wind turbine, at any property not associated with it, must not exceed 35 decibels. Once inside the walls of such a property, even with all windows open, the audible noise level would drop by at least an additional 10 decibels to just 25 decibels. As a useful comparison, 30 decibels is equal to the sound of a whisper, or a quiet library.
Research has repeatedly shown that the levels of very low frequency inaudible noise, known as “infrasound”, and vibration radiated from modern, upwind configuration wind turbines are so low that they lie below the threshold of perception. There are no known health effects arising from noise at the low levels produced by wind turbines.
How we prevent shadow flicker
Shadow flicker can occur occasionally, when the sun is very low in the sky behind a wind turbine that is angled into the wind from the same direction, so that the blade casts a moving shadow long enough to reach a nearby property. The occurrence of shadow flicker is uncommon, because turbine towers are usually sited too far away from houses for the latter to be affected. Nevertheless, if it might possibly be a concern, measurements are taken at any potentially affected place and the turbines are then programmed to halt blade rotation for a short time until the angle of the sun’s rays or the wind direction has altered and the flicker effect has ceased to impact on any houses.
Avoiding radar interference
Both the National Air Traffic Control Service and the Ministry of Defence have confirmed that the wind turbines at Skelmonae Windfarm and at Hill of Skilmafilly do not present any problems for aviation radar.
The Meteorological Office had some initial concerns that the turbines at Hill of Skilmafilly might cause interference with their weather radar, so it was agreed that the three turbines would be placed in line with the angle of the radar beam, to solve this potential problem.
Studying and safeguarding wildlife
As part of the planning application process for a windfarm in the UK, it is a requirement that a comprehensive Environmental Impact Assessment is produced. For Skelmonae and Hill of Skilmafilly this has included detailed studies carried out by independent experts, over a period of many months, or even a full year, before each planning application could be submitted, looking into the possible effects on all types of wildlife that live in or migrate through the area around the windfarms.
Specialised studies have also been carried out into some particular species of animals and birds that can be found in the local area, such as badgers, raptors (birds of prey), and migratory geese. If concerns had been raised about any potentially negative effects on these or other forms of wildlife near the site, appropriate steps would have been taken to prevent them from occurring, before an application could be approved. In practice, no such concerns were found.
How we got them here
Our wind turbine components were delivered from Germany by ship to Peterhead Harbour, then had to be transported to Skelmonae and Hill of Skilmafilly by road.
The installation of wind turbine towers and blades often requires the use of heavy and slow-moving lorries and cranes to transport them to the site and manoeuvre them into position. To reduce the possibility of road congestion during the process of erecting the turbines, road surveys were carried out and a suitable route agreed with the council and the traffic police.
Timing of the transportation of turbine components was designed to minimise the risk of traffic congestion and we also paid for the vehicles to be accompanied by a police escort.
Construction – complying with regulations and obligations
Strict rules were observed concerning working practices and hours, protective equipment and clothing used, the type and placement of signage provided, and all aspects of site management during the various phases of windfarm construction. Adherence to health and safety laws was rigorously implemented and supervised.
In constructing the Skelmonae and Hill of Skilmafilly windfarms, we fulfilled our promise to utilise skills and materials available from the local area, whenever and wherever this was possible.
Decommissioning – planning far ahead
The working lifespan of a modern wind turbine is initially expected to be in the region of 25 years, although developments in technology could possibly extend this in the future. Planning permission is usually only granted for this period, after which a new application must be made or the turbines would have to be decommissioned and taken down. Therefore, money solely for this purpose has to be set aside at outset in a Decommissioning Bond, long before any electricity has been produced, to provide for the removal of the wind turbines when power generation finally ceases.
This will cover the costs of dismantling the turbines, the concrete bases, the electricity sub-station, the cable for grid connection, and the access roads on site – so that the ground is returned to its former appearance. Onshore wind turbines are therefore a reversible technology, with no permanent environmental impact, unlike most other forms of power generation.