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micrositing
Turbine Micro-siting
Siting turbines within a wind project, or micro-siting, involves careful consideration of an array of factors relating to wind flow, terrain, equipment access, environmental and land-use issues, and visual impact. Maximizing production is the most important factor, but without attention to aesthetics, the project may not make it past the permitting phase. To maximize production, careful attention must be paid to the prevailing wind direction(s), wind obstructions from man-made structures or vegetation, and terrain effects. The impact of the wind disturbance caused by one turbine on another turbine is another important factor. Below is a list of general rules for siting turbines.
- On a site with multiple wind turbines, the turbines should be placed at least two rotor diameters apart in the plane perpendicular to the prevailing wind direction, and at least ten rotor diameters apart in the plane parallel to the prevailing wind direction. This will prevent the turbines from experiencing reduced wind speeds and increased turbulence due to the other turbines.
- To avoid turbulence, turbines should be placed at a distance twenty or more times the height of any man-made structure or vegetation upwind of the project. The turbulent wind flow created by a structure generally extends vertically to twice the height of the structure, so small structures may not have any impact on the tall turbines used today.
- Avoid areas of steep slope. The wind on steep slopes tends to be turbulent and has a vertical component that can affect the turbine. Also, the construction costs for a steep slope are greatly increased.
- On ridgelines and hilltops, set the turbines back from the edge to avoid the impacts of the vertical component of the wind.
Along with the rules stated above, it is important to take into consideration the visual impact of the site. Grids of turbines tend to be much less visually appealing than turbines placed along the curves created by natural features. It is also sometimes possible, on a large site, to place turbines where they will not be as visible to residents in the proximity.
Software programs now available are capable of taking into consideration most of these factors. When wind resource and topographical data are entered into these programs, the software can optimize turbine siting for maximum production and minimal visual impact. The turbine sites can be adjusted, and models within the program can show a simulated view of the project from different locations. This software can be quite complicated to use, so it is recommended that a consultant undertake the analysis. The consultant can also use site visits and local knowledge when creating a project plan.
