What is Windmill?
A windmill is a big structure also called a mechanical device that transforms wind energy into electrical energy. It is a big structure that contains sails mounted on a rotating shaft.; these rotating sails help transform wind’s kinetic energy into electricity.
These sails make an angle so that when they rotate, the force of the wind against them is divided into the two following components:
One in the plane of sails, and
Another imparts rotation
Windmills are prime movers that have replaced humans as a source of power and in this article, you will learn to make this device.
How to make a Windmill?
Building a model of a windmill is a great craft project for students. Vedantu has provided here a stepwise method to create a Windmill. Once students have got your windmill assembled, they must observe how the spinning blades of the windmill convert wind into energy.
Materials used to Build Working Windmill
Materials used in this method are shown below to build a windmill working model at home by taking the help of your parents.
8*8 inch square piece of paper
Scissor
Pins
Thermocol ball
Soft pencil
Scale
Blade
Fevicol or glue
The Steps to Build a Paper Windmill are as follows
Take an 8 inch by 8-inch square piece of paper.
Wrap it corner-to-corner, do the same thing for the other two corners.
(Image will be uploaded soon)
Now, after folding a square paper, take a midpoint on it and cut from both ends, and do the same thing on the other side.
Since there are two corners after cutting around each corner of a square, now pierce along each alternative corner with the help of a pin. Do the same in the centre of the square also.
Now, fold these pierced corners and leave the unpierced ones as such. We get tilted and folded blades, as shown in the image below:
(Image will be uploaded soon)
Put a thermocol ball on the pointed end of the pin at the backside of this folded arrangement.
Now, attach a straw through this thermocol ball or we can pin a soft pencil to this ball.
Bring these windmills in the open air, as the wind blows, these blades will start rotating.
What is a Windmill and How does it Work?
Windmills have been a useful source of power for the last many years. Even during World War-I, windmills manufacturers produced 10,000 farm windmills each year for water pumping.
At present, windmills are used for electricity generation, and this electricity generation is possible because of the blades that are constructed by the concept of aerodynamic analysis and other performance-enhancing equipment.
Working Principle of a Windmill
A windmill is a big structure containing sails that are attached by a fixed rotating shaft, as you can see in the image below. The rotating shaft rotates these blades that help convert the kinetic energy of wind into electricity.
Now, let’s understand its basic working:
When a blowing wind forces the blades, these rotating blades generate electricity because of the generator attached to the windmill. Do you know how blowing wind turns a wing?
If we closely look at the cross-section of the blade, it has a lot of airfoils on the surface. The concept of an airfoil is simple. Whenever there is a pressure difference between the two surfaces, an upward force acts on the blade, which is a dynamic lift. Since all the blades have airfoils, in this way, a lift generates in all the three blades, which makes these wind turbine blades turn, as we encounter with the windmills in the farm.
Types of Wind Turbines
Horizontal axis
Vertical axis
Ducted Wind Turbines
How much Electricity can a Wind Turbine Produce?
Wind strength largely influences Electricity production. According to a study, a typical wind turbine has a 2-3 MW (megawatts) capacity and can produce over 6 million kWh (kilowatt-hours) electricity per year, which is enough to power around 1500 average households. The wind turbine has on average 30% to 45% efficiency reaching 50% in the best possible scenarios. That may seem low but at 100% efficiency, it can be assumed that all wind would be absorbed by the wind turbines.
The faster the wind, the more power the wind turbine generates. 8 times more electricity is generated when the speed of the wind doubles. However, there is a cap and wind turbines need to be stopped if the wind is too strong or they risk being damaged.
Relative Velocity of Wind Turbines
Just like moving trains, wind turbines also experience the wind relatively. So the relative velocity of the wind is given by the following formula:
V RELATIVE = VWIND - VBLADE
So, the relative velocity is the difference between the velocity of the wind and that of a blade. So that’s why blades are tilted in such a way that they align to the relative wind speed.
Now, as the blade velocity increases to the tip, the relative velocity becomes more inclined towards the tip, which means a continuous twist is given to the blade from the root to tip.
Since due to low mechanical strength and wind noise, the blades don’t rotate and give high rpm with a generator. So, how to gain maximum speed?
How to gain Maximum Speed in a Windmill?
Now, what we do is, we connect a gearbox before the generator, which helps achieve a high-speed ratio of 1: 90 (cut-off speed of 80 kmph). A brake is also fitted in a nacelle that helps tackle the wind arrest during windy conditions.
Consecutively, the electricity generated is transferred to the transformer filled at the base of the windmill.
This is how a windmill works. Now, we will learn about the types of windmills.
History of Windmills
Using windmill power for rotation of objects has been used since the 1st century in Greece. Windmills have been used to lift things up and down, mainly water from the ground, to power machines that crush grain and process food, and recently to power motors to generate electricity. windmills are the best example of wheel-and-axle machines.
Types of Windmills
There are various types of windmills, so let’s understand their types one-by-one:
Post mill
Smock mill
Fan mill
Tower mill
Uses of Windmill
Windmills have a mounted wind turbine that captures most energy and performs various tasks that have replaced human beings as a source of power. They are used in the following places:
They are used for pumping water,
For grinding grains, and
Generating electricity.
Components of Windmill
Following are the components of windmill:
Rotor: Rotor is also known as a propeller.
Blades: Blades are one of the essential components of the windmill as they control the functioning of rotor speed.
Anemometer: This component is used for measuring the wind speed.
Tower: This is the support system holding the blades and propeller together.
FAQs on How to Make a Windmill?
1. What is a windmill and what is its basic working principle?
A windmill is a structure or machine that converts the kinetic energy of the wind into usable mechanical energy. The working principle is based on its large blades, or sails, which are mounted on a rotating shaft. These blades are set at an angle, so when the wind blows against them, it creates a force that causes the entire assembly to rotate. This rotation can then be used directly for tasks like grinding grain or pumping water, or it can be used to turn a generator to produce electricity.
2. What materials are needed to make a simple paper windmill for a school project?
To make a simple windmill that spins, you will need the following common materials:
- An 8x8 inch square piece of paper
- Scissors
- A pin with a head
- A straw or a soft pencil with an eraser at the end
- A ruler
- A small thermocol ball or a bead (optional)
- Glue
3. Can you explain the step-by-step process of making a paper windmill that spins?
You can easily make a windmill at home by following these steps:
- Fold the Paper: Take your square piece of paper and fold it diagonally from corner to corner to create an 'X' crease.
- Cut the Creases: Use scissors to cut along each crease line, stopping about halfway to the centre. Do not cut all the way through.
- Fold the Corners: Take every other corner point and fold it towards the centre of the paper. Do not crease these folds.
- Pin the Blades: Carefully push a pin through the centre of each folded corner and then through the centre of the square paper itself.
- Attach the Handle: Push the sharp end of the pin into the eraser of a soft pencil or through a straw. You can add a small bead or thermocol ball between the paper and the handle to reduce friction and help it spin more freely.
Your windmill is now ready to spin in the wind.
4. What are the main advantages of using windmills as an energy source?
Windmills offer several important advantages as a source of energy, making them a key part of renewable energy strategies. The main benefits include:
- Clean Fuel Source: Wind energy does not produce air pollutants or greenhouse gases.
- Renewable: Wind is a natural and inexhaustible resource.
- Cost-Effective: While the initial investment is high, the operational costs are low as the fuel (wind) is free.
- Domestic Energy: It allows countries to generate their own electricity, reducing reliance on foreign energy sources.
- Land Use Efficiency: Wind farms can share land with agriculture and other activities.
5. What are the major disadvantages and challenges associated with windmills?
Despite their benefits, windmills and wind turbines face several challenges and disadvantages:
- Intermittent Power: Wind is not consistent. If the wind isn't blowing, no power is generated, requiring backup power sources or expensive energy storage systems.
- Impact on Wildlife: The rotating blades can pose a threat to birds and bats, although modern siting and technology aim to minimise this.
- Noise and Visual Pollution: Some people find the noise from the blades and the visual impact on the landscape to be undesirable.
- High Initial Cost: The construction and installation of large-scale wind turbines require a significant upfront investment.
- Land Requirement: Commercial wind farms require a large area of land to generate a substantial amount of power.
6. How is a modern wind turbine different from a traditional windmill?
The main difference lies in their primary purpose and technology. A traditional windmill is primarily a mechanical device designed to do specific work, such as grinding grain (a gristmill) or pumping water. A modern wind turbine is a highly engineered machine specifically designed to convert wind's kinetic energy into electricity. Wind turbines are more aerodynamically efficient, use advanced materials, and are connected to a generator and the electrical grid.
7. How can a simple school-project windmill be modified to generate a small amount of electricity?
A simple paper windmill only demonstrates rotation. To generate electricity, you need to add a component that converts mechanical energy into electrical energy. You can achieve this by connecting the windmill's rotating shaft to a small DC motor or a dynamo. As the wind spins the windmill blades, the shaft turns the motor's spindle, causing the motor to act as a generator. To prove it works, you can connect the motor's output terminals to a small LED (Light Emitting Diode), which will light up when the windmill spins fast enough.
8. What is the difference between a windmill and a wind vane?
A windmill and a wind vane serve two completely different functions. A windmill is designed to harness the power of the wind to perform work or generate electricity. In contrast, a wind vane is a simple meteorological instrument used only to indicate the direction from which the wind is blowing. It does not capture energy but simply aligns itself with the airflow.
