How is electricity produced from wind ?

Kathmandu :  As part of our weekly series on ‘Urja Gyan’, published every Friday, this week’s (Asoj 18) topic we have made an effort to provide information about wind energy and its advantages and disadvantages. In the previous week, we had mentioned about solar energy and its advantages and disadvantages.

1. What is Wind Energy ?
Answer: Wind energy is the power that we get from the wind. During the motion of the wind, when it meets the turbine blades, the blades start to spin, and as a result, it generates electricity. It is clean energy and renewable because the wind is natural, and it is never consumed. Wind energy does not pollute the air; it is a good substitute for fuels.

2. What are the component of wind turbine ?
Answer: Component of wind turbine are given below.
•  Blades: When moving air go through the blades, they start rotating. The blades are attached to the hub in such a way that they can be rotated if needed. When the wind is blowing at high speeds, the blades can be rotated and mechanical brakes applied to prevent damage to the turbine.

• Gearbox: The gearbox is utilized to change gear ratios to an acceptable one for the generator for proper operation. The input shaft of the gearbox is the main shaft while the output shaft is the secondary shaft which is connected to the generator.

• Tower/Pole: This is meant to hold the turbine in place. The height of the tower will depend on the size of the blades which is determined by the size of the turbine. Moreover, a high rise tower demonstrates a steady flow of wind. However, with the increase in turbine wattage, the height of towers has increased. Among the world’s tallest wind turbine, the height of the tower is one hundred and forty 140 meters.

•  Generator: The main shaft is linked to the gearbox and the generator is connected to the gearbox’s secondary shaft. Electricity is produced during rotation of the turbine. The gearbox reduces the rotating speed of the main shaft of the turbine from 20-500 RPM to that which the generator can accommodate.

•  Anemometer: This determines the rate at which the wind is blowing.

•  Wind Vane: This senses the wind and allows the position of the rotor shaft to change to face the blades in the desired direction.

• Controller: All information on the direction and speed of wind and other parameters will be communicated to a computerized device installed in the controller for efficient functioning of the wind turbine.

•  Nacelle: From the outside, it resembles a long round rectangular object. It encloses the main shaft, gearbox and the generator amongst other parts.

•  Hub: This is the front part of the turbine where the blades are attached.

Multiple Answer Question

1. What does wind power depend on ?
    (a) wind speed
    (b) wind density
    (c) Altitude
    (d) Both (a) and (b)
Answer: Both (a) and (b)

2. What does a wind vane detect ?
    (a) Wind direction
    (b) Wind speed
    (c) Wind humidity
    (d) Wind pressure
Answer: Wind direction

3. How is the speed of a wind turbine controlled?
    (a) By rotating the blades
    (b) By using mechanical brakes
    (c) By using both (a) and (b)
    (d) None of the above
Answer: By using both (a) and (b)

 4. Where was the first wind turbine installed in Nepal?
    (a) Pokhara
    (b) Baglung
    (c) Kagbeni (Mustang)
    (d) Phaplu (Solu)
Answer: Kagbeni (Mustang)

5. What is the value of the constant for Betz's Coefficient?
    (a) 22/7
    (b) 20/26
    (c) 15/27
    (d) 16/27
Answer: 16/27

6. What percentage of the kinetic energy in the wind can a wind turbine theoretically produce?
    (a) 0.50%
    (b) 0.40%
    (c) 0.90%
    (d) 0.59%
Answer: 0.59%

7. What factors affect the power produced by a wind turbine?
    (a) Wind speed
    (b) Wind density
    (c) Wind temperature
    (d) All of the above
Answer: All of the above