5.b) Describe the main considerations in selecting a site for a wind generator.
Answer:
Main Considerations in Selecting a Site for a Wind Generator:
Selecting the right site for installing a wind turbine is crucial to ensure optimal electricity generation, cost-effectiveness, and return on investment. The following are the main considerations:
- High Annual Average Wind Speed:
- A site with high wind velocity and adequate wind supply should be selected.
- Power in the wind is given by Pw=KV3P_w = KV^3; thus, a small increase in wind speed significantly increases power.
- Anemometer data, preferably measured at the site and hub height, is required.
- Strategy includes:
- Survey of historical wind data
- Consulting terrain and wind contour maps
- Visiting potential sites
- Instrumenting best sites for ~1 year
- Choosing the optimal site
- Availability of Anemometry Data:
- Wind speed must be measured to estimate WECS output.
- Challenges include anemometer height, shadowing, icing, inertia, and temperature effects.
- Data must be available at the exact WECS site.
- Availability of Wind Vt Curve:
- Vt curve helps predict electrical output and return.
- Desirable average wind speed: 12–16 km/h.
- Vt curve indicates reliability; long calm periods reduce system reliability.
- Ideally, measured over 5 years for accuracy.
- Wind Structure at the Site:
- Ideal wind is smooth and steady, but most sites have gusty and turbulent winds.
- Variability in wind is termed “wind structure.”
- Altitude of the Site:
- Affects air density and wind velocity.
- Higher altitudes typically have higher wind speeds.
- Terrain and Its Aerodynamic Effects:
- Placement near, but not on top of a hill, can speed up wind.
- May require tilting the rotor axis to align with wind flow.
- Hills and mountains can funnel wind to increase speed.
- Local Ecology:
- Bare rock allows for lower hub heights and structure costs.
- Vegetation causes wind destructuring and requires higher hub heights.
- Distance to Roads or Railways:
- Access is needed to transport heavy equipment, materials, and blades to the site.
- Nearness to Local Users:
- Reduces transmission line length, losses, and costs.
- Preferred sites should be close to electricity users.
- Nature of Ground:
- Ground should be stable and suitable for firm WECS foundations.
- Erosion risks must be avoided.
- Favourable Land Cost:
- Land cost impacts the overall WECS system cost.
- Other Site Conditions:
- Site should be free from icing problems, salt spray, or blowing dust, which can damage equipment.
Guidelines to Follow:
- Best wind energy sites: Offshore and coastal (~2400 kWh/m²/year).
- Second-best: Mountains (~1600 kWh/m²/year).
- Least wind energy: Plains (~750 kWh/m²/year).
- No usable wind energy in humid equatorial regions.
- In cyclone-prone areas (e.g., Japan, Caribbean), wind energy may not be viable.
Characteristics of a Good Wind Power Site:
- High annual wind speed.
- No tall obstructions within 3 km radius.
- Open plains or shorelines are ideal.
- Smooth hilltops or island locations are suitable.
- Mountain gaps that funnel wind are highly beneficial.