The efficiency of energy generated by wind turbines depends on several factors, among them are:
1. Wind speed and length of wind season
Wind speed determines how much power can be produced by the wind turbine. The wind power density is proportional to the cube of wind speed. Assuming all other parameters are fixed, a 10% increase in wind speed results in a 33% increase in wind power.
2. Diameter of the rotating blades
The power captured by the blades is a function of the area they sweep. The area is circular with a radius equal to the length of one blade. The power is then proportional to the square of the radius. Hence, a 10% increase in the blade length will result in a 21% increase in the captured power.
3. The efficiency of wind turbine components
The low efficiency of the various components of the wind turbine reduces the output power of the system. Improvements in the design of the blades, gearbox, and generator should increase the efficiency of the system.
4. Pitch control
With pitch control, wind turbines can produce power at a wide range of wind speeds. However, controlling the pitch angle adds to the complexity of the system and increases the maintenance cost, so it is more suitable for large turbines.
5. Yaw control
Most wind turbines are equipped with a yaw mechanism to keep the blades facing into the wind when the wind direction changes. Some turbines are designed to operate downwind; these turbines do not need yaw mechanisms as the wind aligns these turbines.
6. Arrangement of the turbines in the farm
The layout of individual wind turbines in a wind farm is very crucial. If a wind turbine is placed in the wind shadow of other turbines, the amount of generated power can be substantially reduced. This is because the blades of the front turbines create wakes of turbulent wind, which can reach the rare turbines. When this happens, the rare turbines capture less energy from the wind because blade efficiency is reduced when the wind is turbulent.
7. Reliability and maintenance
The cost of electricity generated by the wind farm is a function of the capital cost, land use, maintenance, and any other contractual arrangement. The early designs of wind turbines were high-maintenance machines as well as cost-ineffective systems. Newer designs, however, are much better with a reliability rate of around 98%.