Windmill – Definition, Types, How To Make, Uses & Components

A windmill is a machine that changes the wind’s kinetic energy into mechanical energy. The rotation of the blades of a windmill is always in a clockwise direction. Daniel Halladay, a resident of the United States, designed the first windmill in 1854. It can tap the energy from the wind with the help of sails mounted on a shaft that is rotating. The mounting of these sails is done on an angle to ensure that the wind force against them gets divided into two parts. One of these parts imparts rotation to the sails. 

Windmills were among the first movers used as a source of power to replace human beings. These were very popular in Europe in the 12th century, and their popularity went on increasing until the start of the 19th century. After steam power was invented, its popularity started to decrease. This decline was seen especially after World War I, when the internal-combustion engine was invented. 

Types of Windmills

You might be wondering what the types of windmills are. Based on their axis of rotation, there are two basic types of windmills— vertical axis windmills and horizontal axis windmills. 

1. Vertical axis windmills

These were quite popular in the early development stage and were widely used. The design is such that the blades are at right angles to the ground. These were primarily employed for pumping water or grinding grains. However, due to their incompetence, these types of windmills were later replaced by horizontal axis windmills. 

Another name for vertical axis windmills is a horizontal windmill. Therefore, you must read the name carefully; otherwise, you will end up confusing it with the horizontal axis windmill (if you miss the word axis). 

2. Horizontal axis windmills

These became even more popular than vertical axis windmills, winning the hearts of many people because of how productive and efficient they were. Horizontal axis windmills are known for their elasticity, which makes them able to harness more wind, and the operator can easily change their direction depending on the flow of the wind. These are sometimes also known as vertical windmills.

Horizontal axis windmills can further be classified into different types—smock mill, fan mill, post mill, and tower mill. Let us learn about each of these types in detail.

3. Post mill

A post mill was the oldest type of horizontal axis windmill. It has a unique characteristic: it is mounted on a single movable vertical post. Its name was set after its most significant part — the post. Initially, the post used to be concealed on base. Later, it was replaced by a wooden component known as a trestle that acted as a support. As it is wooden, the trestle requires protection and is therefore surrounded by a roundhouse. Post mills are further divided into different types like open trestle, sink, hollow, composite, and post mill with a roundhouse. Post-mills’ popularity started to decline in the 19th century as more powerful windmills like the smock mills and tower mills came into existence.

4. Smock mill

These types of horizontal axis mills have six to eight sides. Their name comes from the shape of their bodies, which looks like a smock. This part of the windmill is round in shape and is thatched. Its main characteristic is that its top is flexible. Therefore, it can be rotated according to the wind direction while the other part stays stationary. As its main body is stationary, it is much taller. It is a known fact that the amount of wind harvested depends on the height of the tower. Therefore, the taller the tower, the higher the productivity.

5. Tower mill

This type of windmill is identical to the smock mill, the main difference being that the tower mill’s body is composed of stones or bricks, making it extremely sturdy and resistant. Just like in a smock mill, the only flexible part is the cap. It is very high in duration as well as efficiency. Since the material it is made up of is bricks or stones, its body can be constructed at any height.

6. Fan mill

These are small horizontal axis windmills designed mainly for single-use purposes. Fan mills are primarily used for pumping water, and they have 4-20 blades. 

How do windmills work?

Many trial and error methods were used to determine the number of blades the windmill should have. Finally, after researching how do windmills work, it was determined that three blades work the best for windmills. That’s how they came to have three blades. The main source of energy that drives a windmill is wind. When its blades face the wind, they move in a way that the shaft starts to rotate, which produces electricity. The conversion of mechanical energy into electrical energy is done by a generator.

Components of  Windmill

Below are the components of a windmill:

Blades: These are very important components of windmill as they regulate the working rotor speed.

Rotor or a propeller 

Anemometer: Its function is to measure wind speed.

Tower: This component acts as a support system that holds the propeller and the blades together.

Uses of Windmill

Although we know what is a windmill and what are the uses of a windmill, let us know further about them. The prime function of a windmill is to change wind energy into electrical energy, when this electrical energy is produced, it is utilised in the following ways: 

• For the derivation of oil from the seeds.
• To pump groundwater.
• To mill the grains.

The objective of the experiment

Produce a model of a windmill for your garden or window sill and learn about the basics of wind energy in a practical way. Electrical energy is produced by wind turbines by employing the wind’s natural power to drive a generator. Wind energy is considered one of the most sustainable sources of energy.

Materials required 

• Pencil
• Scotch Adhesive Putty
• Straw or thin stick
• Scotch Precision Scissors
• Metal paper fastener or pushpin
• Ruler or compass
• Heavy construction paper

Procedure to Build a Windmill 

• Take one inch of adhesive putty in your hands and roll it into a ball, then keep it on one side.
• Take construction paper and cut it into the form of a square.
• Fold the square sheet of paper into half diagonally to form a triangle. Unfold it.
• Fold the paper again in the opposite direction to form another triangle. 
• Open up the paper again. We will notice that the creases have formed an X.
• Measure one inch from the centre of the X with the help of a compass or a ruler and mark the point with a pencil on all four sides.
• Cut the paper following the line marked.
• Now pull the four corners of the paper to their centre and fold the tips of the triangles facing each evenly.
• Fix the centre of the paper securely with the help of a pushpin or a metal fastener. Ensure that it covers all four corners and comes out from the back.
• Cover the top of your stick of straw with the ball of putty you made in the first step. Then fix the end of the metal fastener or the pin into the putty. 
• Your windmill is ready. Blow on it and watch it spin!

Conclusion

Many improvements have been made to windmills, and new and more efficient forms of windmills are being introduced day by day. However, the only thing that is changing is the raw materials. The basic structure of the windmill is the same as it was in the 18th century when it was first invented.

Even though the structure of windmills has not evolved much, their purpose has changed spectacularly. The ancient windmills have now developed into wind turbines that efficiently harness wind energy to produce electricity. It has a great future as it is one of the cleanest and most sustainable forms of energy. With the over-exploitation of non-renewable resources, there is a dire need to find more efficient ways to utilise renewable energy, and uses of windmill can be a solution to many of such problems.

Frequently Asked Questions

1. What is the electrical energy derived from a windmill used for?

The electrical energy derived from a windmill is used to generate electricity to be supplied for towns, industries etc.

2. How many years does a windmill last?

A good quality modern-day windmill can last for as long as twenty years. If proper maintenance procedures are followed, and the environment is favourable, the life of a windmill can even be extended up to 25 years.

3. What are the main types of wind?

Main types of Wind

• Primary Wind
• Secondary Wind
• Tertiary Wind

4. What is a windmill vs wind turbine?

Even though the terms are frequently used interchangeably, a windmill and a wind turbine have different structures and functions. It is a very old invention that uses the wind to power machinery, move water, or mill grains into flour. By turning a turbine, a wind turbine converts wind energy into electricity.