# Types of Wind Turbines – Horizontal Axis and Vertical Axis Wind Turbines

In this article we will learn about different types of wind turbines with their advantages and disadvantages and difference between them. Basically the turbines are used to convert the wind energy into electrical energy with the help of a generator. It extracts the energy from the wind and converts it into mechanical energy and then this mechanical energy is used to derive a generator and we get electricity. So let’s begin our journey to learn about types of wind turbines.

## Types of Wind Turbines

The wind turbines are basically divided into two types. Before discussing about wind turbine types in detail, I want to tell you about what is wind turbine?

## What is Wind Turbine?

It is a mechanical machine that converts kinetic energy of the fast moving winds into electrical energy. On the basis of axis of rotation of the blades, it is divided into two parts.
1. Horizontal axis wind turbine (HAWT)
2. Vertical axis wind turbine (VAWT)

### 1. Horizontal Axis Wind Turbine (HAWT)

It is a turbine in which the axis of rotation of rotor is parallel to the ground and also parallel to wind direction.
They are further divided into two types
(i) Upwind turbine
(ii) Downwind turbine

#### (i) Upwind Turbine

The turbine in which the rotor faces the wind first are called upwind turbine.
• Today most of the HAWT is manufactured with this design.
• This turbine must be inflexible and placed at some distance from the tower.
• The basic advantage of this turbine is that, it is capable of avoiding wind shade behind the tower.
• It requires yaw mechanism, so that its rotor always faces the wind.

#### (ii) Downwind Turbine

The turbine in which the rotor is present at the downside of the tower is called downwind turbine. In these types of wind turbines, the wind first faces the tower and after that it faces the rotor blades.
• Yaw mechanism is absent in this turbine. The rotors and nacelles are designed in such a way that the nacelle allows the wind to flow in a controlled manner.
• It receives some fluctuation in wind power because here the rotor passes through the wind shade of the tower. In other words the rotor is present after nacelle of the tower and this create fluctuation in the wind power.

The various advantages and disadvantages of the horizontal axis types of wind turbines are:

• It has self-starting ability. It does not require any external power source to start.
• It has high efficiency as compared with the HAWT.
• Capable of working in high wind speed condition.
• In the case of slow wind condition, its angle of attack can be varied to get maximum possible efficiency.
• Since all blades of this turbine work simultaneously, so it is capable of extracting maximum energy form the wind.

• Its initial installation cost is high.
• It requires large ground area for its installation.
• Because of its giant size of blades and towers, it becomes difficult to transport it to the sites.
• High maintenance cost.
• Creates noise problem.
• It cannot be installed near human population.
• It is not good for the bird’s population. They are killed by its blades rotation.

### 2. Vertical Axis Wind Turbine (VAWT)

It is a turbine in which the axis of rotation of the rotor is perpendicular to the ground and also perpendicular to the wind direction.
• It can operates in low wind situation.
• It is easier to build and transport.
• These types of Wind turbines are mounted close to the ground and are capable of handling turbulence in far better way as compared with the HAWT.
• Because of its less efficiency, it is used only for the private purpose.
VAWTs are further classified as
(i) Darrieus turbine
(ii). Giromill turbine
(iii) Savonius turbine

#### (i) Darrieus Turbine

Darrieus turbine is type of HAWT. It was first discovered and patented in 1931 by French aeronautical engineer, Georges Jean Marie Darrieus. It is also known as egg beater turbine because of its egg beater shaped rotor blades.
• It consists of vertically oriented blades which are mounted on a vertical rotor. It is not a self-starting turbine and hence a small powered motor is required to start its rotation.
• First the Darrieus turbine is rotated by using a small powered motor. Once it attains sufficient speed, the wind flowing across its blades generates lift forces and this lift forces provides the necessary torque for the rotation. As the rotor rotates, it also rotates the generator and electricity is produced.

#### (ii) Giromill Turbine:

It is similar to the Darrieus turbine but the difference is that, it has H-shaped rotor. It works on the same principle of Darrieus turbine.
• This turbine has H- shaped rotor. Here Darrieus design which has egg beater shaped rotor blades are replaced by straight vertical blades attached with central tower with horizontal supports. It may consists of 2-3 rotor blades.
• Giromill turbine is cheap and easy to build as compared with Darrieus turbine. It is less efficient turbine and requires strong wind to start. Same as darrieus types of wind turbines, it is also not self- starting and requires small powered motor to start. It is capable of working in turbulent wind conditions.

#### (iii) Savonius Turbine

Savonius turbine is HAWT.It was first discovered in 1922 by a Finnish Engineer Sigurd Johannes Savonius. It is one of the simplest turbine among all known turbines.
• It is a drag-type device and consists of two or three scoops. If we look it from above than it looks ‘S’ shape in cross section. The scoops of these turbines have curvature shape and because of that, it experiences less drag when it moves against the wind instead of moving with the wind.
• Since it is a drag-type machine, it is capable of extracting very less amount of wind power as compared with other similar sized lift-type turbines.

• It is simple in design and easy to construct and transport.
• It can be easily installed to desired location.
• It requires less ground area for its installation.
• Initial installation cost is very less as compared with the HAWT.
• It can work in turbulent wind condition.
• It is omni-directional and hence do not need to track winds.
• They are smaller in size and hence can be used for domestic or private purpose easily.
• They have low maintenance cost as compared with the HAWT.

• It is less efficient. The efficiency of this turbine is about 30-35%.
• They are not self-starting. A small powered motor is needed to start it.
• Guy wires may required to support this turbine.

### Difference between Horizontal Axis Wind Turbine and Vertical Axis Wind Turbine

The various difference between horizontal axis and vertical axis types of wind turbines in tabular form are given below:
 S.no Horizontal Axis Wind Turbine Vertical Axis Wind Turbine 1. In HAWTs, the axis of rotation of the rotor is Horizontal to the ground. In VAWTs the axis of rotation of the rotor is perpendicular to the ground. 2. Yaw mechanism is present. Absence of Yaw mechanism. 3. It has high initial installation cost. It has low initial installation cost. 4. They are big in size. They are small in size. 5. Its efficiency is high. It has low efficiency. 6. It requires large ground area for installation. It requires less ground area for installation. 7. High maintenance cost. Low maintenance cost as compared with HAWT. 8. They are self-starting. They are not self-starting. 9. They are unable to work in low wind speed condition. They are capable of working in low wind speed condition. 10. Difficult in transportation. Easy in transportation. 11. They are mostly used commercially. They are mostly used for private purpose only. 12. It cannot be installed near human population. It can be installed near human population. 13. It is not good for the bird’s population. It is good for the bird’s population.
This is all about the types of wind turbines. If you observe anything missing or incorrect than comment us. And if you find this article useful than don’t forget share and like it on Facebook and Google+.

### 1 thought on “Types of Wind Turbines – Horizontal Axis and Vertical Axis Wind Turbines”

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