Wind Power Introduction

What is Wind?

To understand how wind turbines work we need to first understand how wind works and the energy that is contained within it. Wind is quite simply air that is moving over the planets surface. It can be moving slowly in a gentle breeze or moving very fast in a hurricane or cyclone.

The air moves around the planet due to the Sun heating the planets surface and the air unevenly. For example the sun is directly overhead at the equator so the warming effect is greater there than at the poles. This in turn leads to differences in air pressure. When combined with the effects of the rotation of the earth we get wind!

The wind around the planet contains a lot of energy, in fact if we could capture all of the energy it would be enough to easily meet the worlds entire energy needs. The big advantage of wind power is that the wind is freely available any where on the planet and will never run out.

First Uses of Wind Power

As early as 200 B.C it was discovered that you could capture the energy in the wind and use to do something useful. Grinding grain and pumping water are both hard work so using the energy of the wind to do this had great benefits. Early designs used the movement of the vanes or blades to directly drive a mill or water pump. As many early wind powered devices were used to grind grain in a mill we find that the term 'wind mill' is popular and often used (inncorrectly) to describe any device that spins in the wind. A wind mill grinds grain, a wind pump draws water from a well and a wind turbine generates electricity.

Types of Wind Turbine

Wind turbines can be split into two main types depending on the axis in which the turbine rotates:

  • Horizontal axis wind turbine (HAWT)
  • Vertical axis wind turbine (VAWT)

Horizontal axis wind turbines are much more efficient than Vertical axis turbines and as they can be mounted on tall towers they can be placed high up where the wind speed is higher and less turbulent. For those reasons, the horizontal axis wind turbine (HAWT) is the most commonly seen type, just about every commericial wind farm in the world uses HAWT turbines.

Vertical axis turbines are less efficient than Horizontal axis turbines but they do have some other advantages. They do not have to be pointed into the wind, they can be mounted nearer to the ground, they start at low wind speeds and can be simply contructed. In fact they are so easy to build we have even built one ourselves, find more on our DIY Savonius turbine page.