Landowners: Turbine Installation
What is involved?
The installation of a wind farm depends on the size of the wind farm; a large wind farm can take between 12-24 months for building completion. The actual construction process is a series of distinct activities that can be planned in association with the landowner so as to minimise disruption to farming activities. Once the wind turbines are in place, normal farming can continue within the wind farm. There is no requirement to fence off the towers as the rotating blades are significantly clear of the ground.
The wind turbines are built on concrete slab foundations. Foundation design has improved over the past decade however it is dependent on a number of factors that dictate the loads and hence requirements of the foundation. Factors include ground conditions at the site (water retaining land such as swamp/marsh lands require larger foundations compared to that of rigid land), wind turbine specifications (hub height, rotor diameter etc.), as well as the wind conditions that will be experienced. Typically foundations are approximately 14 x 14 metres by 2 metres deep. They are buried below normal ploughing depth, at least 1 metre below ground surface. Consequently, arable farming can continue right up to the base of the wind turbine towers. The turbines are connected together by underground cables, which again are buried below ploughing depth, approximately 1 metre below ground surface. Cables can usually be routed along tracks or field boundaries to minimise disruption.
For access to the wind turbines, 6 metre wide stone roads are required. We can normally route the roads to follow existing tracks or field boundaries, similarly the underground cables can also be run parallel with the road. Once built, the roads must remain in place for access to carry out maintenance or repairs and are available for farm use.
When the wind turbines are in operation there is little need for access. Unless there is a fault that requires a technician’s visit or a possible component failure, maintenance is undertaken from a small van, and usually once every three months. The wind turbines are usually monitored both from onsite as well as remotely depending on the operating company’s policies. The control systems in the wind turbines are fail safe, so if a fault occurs the turbines stop automatically and an alarm is raised through the wind farms internal communications network. Some faults can be amended remotely whilst others may require a visit from a technician.
Recent developments in modern day wind turbines have led to a large variety in hub heights and rotor diameters in order to provide the wind farm with the most ideal and effective wind turbine that best utilises the wind resource of that site. Wind turbine tower heights commonly range between 70 metres and 110 metres. Blades can be between 45 metres and 60 metres in length, meaning that the total height to the top tip of the blade can be in excess of 150m. For safety and turbine performance, it is necessary to have a good separation distance between wind turbines. This is somewhat site specific and will usually range between 3 and 5 rotor diameters depending on the wind conditions at the site.
In Australia, an electricity substation is normally required and needs to be placed on site. The substation will usually act as the facilities building for the wind farm. It will house spare components for the site and is where the onsite monitoring of the wind farm is conducted. The size of a typical substation and facilities building varies depending on the size of the wind farm (the bigger the wind farm the larger the substation) however the maximum dimensions of a substation is 100 x 100 metres whilst the maximum dimensions of a facilities building will be 30 x 6 metres.