Wind Energy and Solar PV : Site Selection and Wind Turbine Types

Wind Energy and Solar PV : Site Selection and Wind Turbine Types

Site Selection for Wind Farms

1. Power Density (W/m2) and Wind Speed (m/s): Power Density: Measure the power available in the wind per unit area, calculated using the formula: P=12ρv3P = \frac{1}{2} \rho v^3P=21ρv3 where ρ\rhoρ is the air density (typically 1.225 kg/m3 at sea level), and vvv is the wind speed. Wind Speed: Preferably, the average wind speed should be above 6-7 m/s for economically viable wind power projects. Wind speeds are measured at various heights using anemometers on wind masts over a period of at least one year.
2. Wind Direction and Elevation (Hub Height): Wind Direction: Analyzing wind direction is crucial to optimize turbine placement and minimize wake effects. Use wind vanes and wind roses to map prevailing wind directions. Elevation (Hub Height): Higher elevations generally experience stronger and more consistent winds. Turbines are placed on towers (hub height) to capture these winds, typically 80-120 meters above ground.
3. Monitoring Wind Mast: Install wind masts with anemometers and wind vanes at various heights (e.g., 10m, 30m, 50m, 80m) to measure wind speed and direction over time. Data should be collected for at least one year to account for seasonal variations.
4. Energy Intensity (Wh/m2): Calculate the energy intensity by integrating the power density over time. This gives the total energy available from the wind per unit area over a specific period.

Types of Wind Turbines

1. Horizontal Axis Wind Turbines (HAWT): Design: Most common type, with blades rotating on a horizontal axis. Advantages: Higher efficiency, better performance at higher wind speeds. Tracking: Typically equipped with yaw mechanisms to track wind direction.
2. Vertical Axis Wind Turbines (VAWT): Design: Blades rotate around a vertical axis. Advantages: Omni-directional, can capture wind from any direction without needing a yaw mechanism. Disadvantages: Generally less efficient than HAWTs, and more suitable for urban or low-wind environments.

Wind Direction Tracking

• Yaw System: Mechanism in HAWTs that rotates the nacelle to align with the wind direction.
• Wind Vanes and Anemometers: Mounted on top of the turbine to provide real-time data for the yaw system.

Solar Energy: Site Selection and PV Materials

Site Selection for Solar Farms

1. Solar Radiation (W/m2): Measure the solar radiation using pyranometers to determine the Global Horizontal Irradiance (GHI). Preferably, select sites with high average annual GHI, often above 1,500 kWh/m2/year.
2. Angle from Compass Heading and Horizon: Azimuth Angle: The compass direction that the solar panels face. Typically, panels are oriented to the south in the northern hemisphere and to the north in the southern hemisphere to maximize exposure. Tilt Angle: The angle between the solar panel and the horizontal plane. Optimize based on latitude to maximize energy capture throughout the year.
3. Daytime Monitoring: Collect data over several months to a year to account for seasonal variations in solar radiation. Use data loggers to record solar radiation, temperature, and other relevant parameters.

Types of Solar PV Materials and Sun-Tracking Ability

1. Types of Solar PV Materials: Monocrystalline Silicon: High efficiency (15-20%), more expensive, best for space-constrained installations. Polycrystalline Silicon: Moderate efficiency (13-16%), more affordable, slightly lower performance. Thin-Film (e.g., CdTe, CIGS): Lower efficiency (10-12%), flexible, lightweight, and better performance in low light and high temperatures. Bifacial Panels: Capture sunlight on both sides, increasing overall efficiency.
2. Sun-Tracking Systems: Fixed-Tilt Systems: Panels are fixed at an optimal angle, simple and low cost, but less efficient. Single-Axis Trackers: Panels rotate along one axis (typically east-west) to follow the sun's path, increasing energy capture by 15-25%. Dual-Axis Trackers: Panels move along two axes (north-south and east-west), tracking the sun more precisely, increasing energy capture by 25-35%, but more complex and costly.

Summary

• Wind Energy: Select sites based on power density (W/m2), wind speed (m/s), and wind direction. Monitor using wind masts and choose turbine types (HAWT or VAWT) based on site conditions.
• Solar Energy: Select sites based on solar radiation (W/m2) and optimize panel orientation (azimuth and tilt angles). Choose PV materials and tracking systems (fixed, single-axis, or dual-axis) to maximize energy capture.