Image:  Close-up of green grass seed head blowing in wind

Land take

 

Wind farms have a relatively small footprint and in most cases over 95% of the area on which they are built can continue being used for farming or other purposes. The land take required for a typical 10 turbine wind farm is around 1.3 Ha (excluding access tracks) plus a further 1.0 Ha during the construction phase.

Wind farm requirements (10 turbine wind farm)
Permanent (Ha)
Temporary (Ha)
Notes
Access tracks
Varies with wind farm
Varies with wind farm
5m wide stone tracks to turbines and substation
Construction compound
0.00
0.25
50m x 50m fenced-off area
Wind turbines and foundations
0.23
0.72
Each turbine foundation typically has an excavated base of 15m x 15m. Additional temporary land take required for construction lay-down areas
Crane hardstandings
1.10
0.00
Two 30m x 20m areas at each turbine
Electrical substation
0.01
0.00
8m x 9m secure area (33kV)
Meteorological mast
0.00
0.00
4m x 4m secure area
Total area
1.24 + tracks
0.97
 

Image:  Aerial view of wind turbine and access track

 

 

Image:  Aerial view of wind turbines along edges of arable fields

 

Access tracks

 

Access tracks are constructed from the public highway through to the base of each wind turbine, the electrical substation and the permanent meteorological mast. These are usually 5m wide and made of crushed stone. Where possible we make use of existing infrastructure on a site, improving and upgrading this where necessary, and construct any new tracks in locations that cause the minimum of disruption such as the edge of fields. Access tracks are either removed or left in place at the end of a project’s life depending on landowner preferences and the conditions of the planning consent.

 

 

Construction compound

 

An area of around 50m x 50m is generally needed during the construction phase for accommodating portakabins, welfare facilities, plant and equipment and for storing components prior to use. This is fenced off during use and restored to its original condition once construction is complete. In addition to the main construction compound “laydown areas”, generally at the bases of the turbines, are also sometimes needed for offloading larger wind turbine components such as towers and blades and partially assembling these prior to installation.

 

 

Wind turbines and foundations

 

Image:  Wind turbine base and hardstandingThe wind turbines we use today typically have tower (or “hub”) heights of 60-100m and blade lengths of 35-50m (or “rotor diameters” of 70-100m). The closer the turbines are located together, the more energy is lost through the effect of the wake of one turbine on another, so we generally try and design a wind farm so as to have a spacing of 5-6 rotor diameters in the prevailing wind direction and 4-5 rotor diameters crosswind.

 

Foundations for the turbines consist of a steel reinforced concrete plinth of approximately 15m in diameter with a central column of around 5m in diameter onto which the turbine tower is fixed. Foundations are backfilled and restored after construction so as to leave only a small stone apron around the base of each tower visible.

 

 

Crane hardstandings

 

As well as turbine foundations, hardstandings are needed next to each tower for use by cranes in the construction phase and, on occasion, to replace any large components which may fail once a wind farm is operational. Like the access tracks, these are usually made of crushed stone and typically each measures 30m x 20m. Two hardstandings are required for each turbine though we try where possible to locate one of these on an access track to reduce overall land take.

 

 

Electrical substation

 

Image:  Sub-station compound areaElectrical connections between the turbines are made via underground cables to a small on-site electrical substation. These cables are laid in trenches approximately 1m wide and 1m deep and, so far as far possible, routed to follow site access tracks.

 

The on-site substation contains transformers, isolating switches and electricity meters and forms the interface point between the wind farm and the external grid. Depending on the size of the wind farm (and more particularly the grid connection voltage) this generally comprises a building with a floor-plan of around 8m x 9m but, on large wind farms (connected to the electricity transmission rather than distribution grid). a larger building may be needed together with a secure compound of 50m x 70m.

 

 

Meteorological mast

 

As part of the wind farm construction works, the temporary meteorological mast used in the development phase is replaced by a more substantial mast (without guy-wires) which remains in place throughout the operational life of the project. This is generally of a similar height to the turbine towers and requires an area of approximately 4m x 4m, ideally located so as to avoid readings being affected by wind turbine wakes.

 
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