# 2 Types of Wind Turbines

## #1. What is a wind turbine?

A wind turbine produces wind-based electricity. Its force activates the rotor blades that set an alternator in motion.
There are many different wind turbine design categories, but they are generally grouped into three types based on the axis of rotation orientation. The most common type of Horizontal Axis Wind Turbines and Wind Turbines of the Vertical Axis and the ducted turbines.

## #2.Horizontal Axis Wind Turbines (HAWT)

These days, HWATS wind turbines are the most used, all the components are at the top of the tower as the winds blow in height. The tower varies between 10 and 180 m in height depending on the type of wind turbine. This type of turbine can generate 12 megawatts of electricity per day, with 25 to 60-meter long shaft blades making 25 turns in a minute.

## #3.Vertical Axis Wind Turbines -VAWTS

The blades of the vertical axis wind turbine rotate around a vertically positioned rod, as the name suggests. It can pick up weaker winds which allow it to be more frequently exploited. It requires less space than a horizontal axis wind turbine. It, therefore, adapts better to buildings. It can work regardless of the direction of the wind. On the other hand, it produces less electricity than the horizontal axis wind turbine
There are two main types of VWATS, the Savonius, and the Darrieus.

• Savonius Wind Wurbine
• Darrieus Wind Turbine
• Ducted wind-Turbines
The system comprising a tubular sheath housed in a building that draws air on the side of the building to transform it into energy and then reject it at the top of the building.

## #4. Wind Turbine Power

The power of a wind turbine variates according to the size, wind speed, and air density.

P = π/2 * r² * v³ * ρ * η,
ρ: the mass of air per Volume(space)
ρ: depends on air pressure and the Temperature

η: The coefficient of Bet ‘ z, equals to 16/27.
The maximum  energy that the Turbine can extract from the  total  kinetic energy  captured by the three  blades is  59 %

## #5.The first country in this technology

China is the first country in this technology .the country has impressed the world by installing more than 145362 Megawatt in the last five years.

## #6.The main components of horizontal axis wind Turbines

The rotor

Rotating part of the wind turbine placed in height to capture strong and regular winds. It is composed of blades (usually 3) of composite material that are set in motion by the kinetic energy of the wind. Connected by a hub, the latter can average each 25 to 60 m long and rotate at a speed of 5 to 25 revolutions per minute.

The nacelle

Structure supported by the mast sheltering the different mechanical elements. Direct drive wind turbines are distinguished from those equipped with a gear train  (multiplier/reducer) depending on the type of alternator used. Conventional alternators require an adaptation of the speed of rotation with respect to the initial movement of the rotor.

The tower

Composed of the mast, the electrical control system, and the transformer. Generally of conical shape, the mast supports the nacelle. It measures between 50 and 180 m high and has a diameter at its foot between 3 and 8 m. An opening at the bottom of the mast provides access to the various equipment of the wind turbine including the transformer which increases the voltage of the electricity produced in order to inject it into the network.

## #7. How Wind Turbines Produce electricity?

To start, a wind turbine requires a minimum wind speed of about 14 km / h. For safety reasons, the wind turbine automatically stops operating when the wind exceeds 80 km / h.
The rotor drives an axis in the nacelle, called a shaft, connected to an alternator.
Thanks to the energy provided by the rotation of the axis, the alternator produces an alternating electric current.