Fig. 2. Advanced geographical information system methodology which combines database information with mapping and modelling.
“Each drawing contains detailed elements, such as adjacent windfarms and national grid links.”
Wind farms are generally connected to the 33–66kV electricity distribution grid. Te cost of this connection can have a significant bearing on economic viability, and the distance from the wind farm to the grid can have significant impact on the connection cost. Sites within 10 kilometres of the grid are therefore preferable to keep cabling costs low. Electromagnetic interference generated by wind turbines can affect wireless communication – for example shadow or digital interference to TV reception. Using a database of all microwave links and television re-broadcast links registered with OfCom, potential problem areas are identified. After mappping the constraints we have a set of
provisional wind farm areas. But not all will make good potential wind farm sites. Normally around 100 sites are selected, with flexibility to enable the developer to make decisions as the project progresses. At this point it’s not only about software and data
sets. Experience, expertise and human judgment are essentia. Sites which are accepted are now manually populated within GIS with wind turbines – anything between two and 50 in each of the 100 farms.
Assuming a prevailing wind direction of west south west, turbines are placed where the topography allows in NNE–SSE arrays, perpendicular to the prevailing wind – optimising the energy and the revenue that can be generated. At this point therefore we know how much each of the 100 farms is capable of generating. Tis allows them to be compared and ranked again in order of generating capability. Tis critical information is presented in a number of formats, including a map for each of the proposed sites with wide-ranging information including NOABL average annual wind speed, number of turbines, generating capacity, indicative annual energy output and issues identified. Te same information is also indexed within a table for easy reference. Each drawing also contains detailed elements such as adjacent potential wind farms, regional boundaries, turbine layout and elliptical buffers, wind speed environment, distribution and national electric grid, microwave links, TV broadcast and rebroadcast links, NATS and weather radars, airfields, planning and regional boundaries, and environmental, landscape and historic designations. ●
Samuel Clarke is a geographical information system and renewable energy consultant with independent engineering and environmental consultancy Wardell Armstrong, headquarted in Stoke-on-Trent, Staffs, UK.
www.wardell-armstrong.com
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