Horizontal Wind Turbine: All You Wanted to Know
Wind turbines have become one of the most well-established green energy sources after the solar system. Although there are two types of them, horizontal axis wind turbines are the most efficient ones when it comes to producing energy in large scale.
Previously windmill was an effective machine to harness wind energy. Today, wind turbines use this power of nature in a more efficient way. If you are interested to know more about this modern machine, you are in the right place.
A Basic Demonstration of Horizontal Wind Turbine
Horizontal wind turbines are by far the most common and widely used wind turbine across the globe. These turbines are primarily made of two or three blades; often time you will see such turbines having one and four blades as well. The more a turbine has, the more power it can produce.
Because of blades, they look like a giant airplane propeller. The airplane-shaped blades use lift to generate driving torque and make them rotate.
So, How Does a Wind Turbine Work?
The curve shaped rotor blades spin using lift force when the wind blows. When the wind comes in contact with the blades, it loses its kinetic energy to some extent and the turbine gets that energy. This kinetic energy then gets converted into electricity to power household, commercial, and business devices.
If the blades are larger, they can get even more energy. And when the wind blows much faster than usual, the turbine will get the chance of harvesting even more power as well. How much electricity a wind turbine will produce, depends on the wind.
When multiple turbines within a farm are linked, and multiple farms are linked to a power grid, then the power supply gets into a stable condition.
How does a Horizontal Axis Wind Turbine Produce Electricity?
The main rotor shaft of a wind turbine is pointed towards the wind direction so that it can extract wind energy. When the wind flows, the rotors get energy and start producing torque and trigger a low-speed shaft that rotates at 10-20 rpm.
The shaft then sends the energy to the gearbox. Then the energy is further transferred to the high-speed shaft as well as the generator. When the gearbox gets the energy, it turns the overall output speed of the shaft into around 1,800 rpm where the output frequency is about 60 Hz.
However, direct drive wind turbines don’t come with a gearbox and they have DC generator instead of AC.
The high-speed shaft converts rotational motion to AC after connecting the generator. When the generator gets the kinetic energy from the shaft, it converts the wind power into electrical energy. If a 2MW wind turbine can run at its maximum capacity, the generator will create 2 million watts of electricity at around 700 volts.
Wind vanes and anemometers monitor the speed and direction of the wind. When the situation is extremely windy and turbulent, the brakes stop the rotors from spinning as safety.
The electricity from the generator then flows inside the tower through a cable. When that electricity gets to the transformer, it converts them 50x higher voltage to transmit the power efficiently to the power grid or nearby households or communities.
Reaching to the grid, the electricity then gets converted to 130,000 volts or even more by a substation and finally communities, businesses enjoy clean and green energy.
Types of Horizontal Wind Turbine
Depending on the numbers of blades, there are 4 types of horizontal wind turbines. Although all of them function pretty much in the same way, they differ from each other when it comes to the efficiency of power production.
1. Single Blade Wind Turbines
These turbines are the latest model from the horizontal wind turbine family, but they are not used to power a wide variety of applications like two and three blade turbines. Although the turbine has one blade, it comes with one or two counterbalances to be able to rotate smoothly.
As it has only one blade, the cost is comparatively low. To produce the same amount of electricity, a single blade wind turbine has to rotate at a higher speed than a two or three-blade wind turbine. Due to the high-speed factor, these turbines require higher maintenance cost since the parts have high tendency to wear and fatigue failure.
The setup procedures of single-blade turbines are quite extensive. You need to ensure the blade is perfectly mounted and well balanced to reduce vibration and oscillation.
2. Two Blade Wind Turbines
Two-blade turbines are easier to set up and cost lower than three-blade turbines. But the turbine needs to rotate at a much higher speed to convert kinetic energy to electricity. This cause wearing of crucial bearings, gearboxes, and shafts which increase the overall maintenance cost.
More thick and wide blades can improve efficiency. When the blades are stronger, there will be less fatigue failure as well. But that doesn't increase the weight and cost if new composite materials are used to produce such blades. Lifting an entire unit of such a turbine is much easier too.
3. Three Blade Wind Turbines
Most of the horizontal axis wind turbines have three rotor blades to maximize energy production while limiting vibration as the noise at the same time. Due to the number of blades, these turbines have more ground to convert wind energy to electricity than others.
The fact that three-blade turbines are huge in size, the parts require to transport individually. You also need larger cranes to set up one of these. To support the turbine's weight and get the most out of wind energy, the tower needs to build much higher. So here, the set up cost is much higher than the previous two turbines.
These turbines produce electricity with much efficiency and are highly recommended to use for producing energy on a large scale.
4. Five Blade Wind Turbine
Five blade turbines are ideal for places where the wind speed is low. These turbines have thinner and narrower blades that efficiently produce electricity. But if the wind flows at a higher speed, the turbine becomes inefficient and creates more noise.
Both the tower and base of such turbines need to be built on a concrete roof of a building so that it can hold the turbine strongly. A cowling is also required to direct the wind straight into the blades.
Despite having some limitations, horizontal axis turbines are providing us green energy without causing the greenhouse effect. Engineers are still figuring out ways to reduce their limitations and improve efficiency. Compared to other power plants, wind turbine farms have great potentiality which makes more people find interest in using such machines.