Windmill

Windmills aren’t exactly a new invention. They have been around for centuries. However, from being used as a grain grinder to now generating electricity, they have come a long way.

1.0Types of Windmills

Depending on how the windmill’s rotor axis moves, windmills can be of two types:

Vertical Axis Windmills

As the name suggests, Vertical Axis Windmills (VAWTs) are a type of windmill with rotors spinning around a vertical axis. This axis stays perpendicular to the wind’s direction. In most cases, they are used for small-scale, domestic applications. This is because VAWTs perform when the wind speed is moderate and there is not a high demand for efficiency.

Key Features:

• The mechanical setup of VAWTs includes components such as a gearbox and dynamo, which are installed at ground level. So, there is no need for a tall tower.
• Since the wind is typically slow near the ground, it reduces the energy output.
• These are easier to maintain, but they are also less efficient than the horizontal systems.

Sub-types of Vertical Axis Windmills:

• Darrieus Wind Turbines – These turbines have curved blades shaped like an eggbeater. It is difficult to start them, but they are more efficient.
• Savonius Wind Turbines – They have S-shaped blades. They have a simple ensign, but are less efficient. 

Horizontal Axis Windmills

Horizontal Axis Windmills (HAWTs) have rotors spinning around a horizontal axis. These rotors are parallel to the wind direction and the group. They are primarily used in modern energy systems.

Key Features:

• Their blades resemble aeroplane propellers, optimised to catch wind effectively.
• Typically, they feature two or three blades, though designs with more blades exist for specific applications.
• These turbines are widely used for large-scale electricity generation due to their high efficiency and ability to operate at greater heights where wind speeds are stronger.
• However, they require significant initial investment and infrastructure, including tall towers and complex control systems.

Sub-types of Horizontal Axis Windmills:

• Upwind Turbines – Face the wind head-on. These require a yaw mechanism to stay aligned with the wind direction.
• Downwind Turbines – The rotor is placed on the leeward side of the tower, allowing the wind to hit the blades after passing the tower.

2.0Components of a Windmill

The main windmill parts are:

3.0How Do Windmills Work?

A common question is: How do windmills work?

Windmills operate by capturing the kinetic energy of moving air (wind) with their blades. When wind hits the blades, it causes them to turn. This rotation is transferred via a shaft into a gearbox, which increases the rotational speed. The high-speed rotation then powers a generator, producing electricity.

Key points:

• Wind energy → blade rotation.
• Mechanical movement → gear acceleration.
• Electricity is generated through a magnet and coil system inside the generator.

4.0How Do Windmills Generate Electricity?

The design of the rotor blade has been made to catch as much wind as possible. So, when there is wind, it pushes against the blade, causing it to start spinning. When that happens, the main shaft begins to work. This shaft connects to the gearbox, which further boosts the rotational speed of the blades.

When this happens, the shaft turns the generator, which creates an electric current. Before it is transmitted, it is stabilised and made compatible with the grid. This electricity is then transmitted to the city or to the grid.

5.05 Uses of Windmill

1. Electricity Generation – Windmills help generate clean, renewable electricity to power homes and businesses, especially in rural areas.
2. Water Pumping – In rural or desert regions, windmills are used to get water from wells. This water can be used for drinking or agriculture.
3. Grain Milling – Although this process is no longer as common, older systems utilised mechanical windmills to grind wheat into flour.
4. Sustainable Architecture – Many eco-friendly buildings have begun incorporating small windmills to power their infrastructure.
5. Hydrogen Production – This process is currently in the experimental stage, but wind energy can be utilised to produce hydrogen fuel and power electrolysis systems.

6.0Advantages and Disadvantages of Windmills

1. Free and Abundant Energy Source

Wind is something that we don’t have a shortage of. It is natural, renewable, and costs nothing. The right technology can harness this energy for several applications.

2. Environmentally Friendly

When windmills generate electricity, there are no air pollutants, toxic chemicals, or greenhouse gases. Unlike fossil fuels, this is a clean and sustainable source of energy.

3. Land Utilisation Efficiency

Wind turbines are installed on a tall tower. This means that the land around the tower is available for uses such as agriculture and livestock grazing.

4. Ideal for Remote Locations

Several off-grid areas remain unconnected to the national power supply. Windmills are ideal for such areas as they can power them.

Now, let’s take a look at the disadvantages of windmill:

1. Inconsistent Energy Production

Wind energy depends on the weather. If the wind speeds are low, it can impact the energy generation, making it unreliable.

2. Noise Pollution

When the blades rotate, a lot of noise is produced. This can be a nuisance to nearby residents.

3. High Initial Investment and Maintenance

While the operating costs of windmills are low, there is a one-time capital investment that can be substantial. And if it is a large-scale project, repairs and maintenance can be costly.