Considerations for Wind Turbine Site Selection
When selecting a site for a wind turbine, several factors are crucial to ensure the turbine operates efficiently and safely.
- Hill Effect: Wind accelerates as it climbs up a hill due to increased pressure, which can enhance the wind speed at the hill’s crest. Installing turbines on hilltops can maximize this wind speed increase, leading to higher energy output.
- Surface Roughness: The roughness of the land affects wind speed. Open oceans have low roughness, while urban areas and forests create high friction, slowing the wind.
- Tunnel Effect: Wind can accelerate when funnelled through narrow passages, such as between buildings or mountains. Placing turbines in such areas can take advantage of the increased wind speeds, although care must be taken to manage turbulence.
- Turbulence: Turbulence occurs due to rapid changes in wind speed and direction, often caused by obstacles like buildings or natural barriers. Turbulence can cause wear and tear on turbines, reducing their lifespan. Hence, turbines are mounted on tall towers to minimize turbulence.
- Variations in Wind Speed: Wind speed can vary by time of day and season due to solar heating. Understanding these patterns helps predict turbine performance.
- Wake Effect: Wind turbines affect each other’s performance through wake turbulence. To avoid this, turbines should be spaced adequately, typically three rotor diameters apart.
- Wind Obstacles: Nearby trees, buildings, or geological features can reduce wind speed and increase turbulence. The site should be free of significant obstacles to optimize turbine performance.
- Wind Shear: Differences in wind speeds at various heights can stress turbine blades. Sites should be evaluated for wind shear to ensure longevity and efficiency.
Site Selection Guidelines:
- Optimal Locations: Turbines should be placed on high, exposed sites where wind speeds are typically higher, such as coastal areas.
- Avoid Highly Populated Areas: Urban centres and densely populated areas are generally unsuitable due to turbulence, noise, and safety concerns.
- Roof-Mounted Turbines: Avoid installing turbines on rooftops, as vibrations can cause structural damage to buildings.
- Distance Considerations: The farther the distance between the turbine and the power requirement, the more power will be lost in the cable. The distance of the cabling will also impact the overall cost of the installation.
- Turbulence Mitigation: To reduce turbulence, turbines should be installed at a distance greater than twice the height of the nearest obstacle, or the turbine height should be more than twice that of the obstacle.
- Wind Speed Requirements: Small turbines typically require an average wind speed of over 4.5 m/s for efficient electricity generation.
- Remote Locations: In remote areas, connecting turbines to the national grid may be expensive. Off-grid solutions with battery storage may be more feasible