Windmills: Work Principles, Pros, and Cons


The harnessing of wind energy has been taking place since time immemorial. Traditionally, it was used to pump water and to grind grain. In the modern world, wind turbine is the equivalent of wind energy and used to generate electricity. Windmills are stationed on a raised point or a tower so that it can capture a lot of energy and to capitalize on the turbulence of wind at such high levels. The turbines tap the wind energy by use of their blades, which are propeller-like. There are always two to three blades, which form one rotor. When the wind blows, air pressure forms on the lower side of the blade and the pocket pulls the blade towards it hence making the rotor to turn; this state is called lift and its force it faster than that of the wind, and it acts on the front sides of the blade, and this is referred as drag. It is the combination of the lift and the drag that make the rotor to rotate and the turning shaft spins the generator to generate electricity (Renewable Energy, 2011).

Structure and Labeling and How Parts Work

It is important to understand how the various components of windmill work as a system before we comprehend on how it functions as a whole system. The various parts of a windmill are: rotor blade, shaft, break, gear box, generator and the electrical equipment.

Rotor Blades: These are the instrumental and critical parts of a windmill. They act as a barrier to capture the wind energy. The blades only move if they have captured enough power, which can be converted into electricity by the other components of the system.

Shaft: this is the section connected to the rotor blades, and it moves the rotational energy from rotor blades to the generator.

Nacelle: this is a casing of hard metal that can house and protect the inside functioning of the windmill like the shaft.

Brake: the shaft is linked to various parts inside the nacelle. The first part that the shaft is connected to is the brake. The brake provides protection to the system in the event of failure or power overloads by the rotor. The brake squeezes down the disc connected to the shaft by slowing it down or stopping it completely.

Gearbox: this is also a critical component that linked to the shaft. It serves the function of regulating and changing the speed of the shaft. Gearbox is the expensive part of the gearbox and wears out easily.

Generator: it is connected to the shaft. The generator uses the mechanical energy from the shaft which it converts to electrical energy using electromagnetism. It works just as an alternator.

Tower: this is the biggest component of the windmills. The tower is made of steel or aluminum and at times made of wood. The tower supports the entire structure and to make it high enough so that the blades can attract the highest wind power. These components are illustrated in the diagram below.


Conversion of Energy through a Windmill

The windmill is used to harness wind energy and convert into a form that can be utilized. The wind turbines can be used to generate electricity from wind power. The rotor converts kinetic energy that is available in the wind into mechanical energy. There is a distinction between windmill and wind turbine; windmill makes use of mechanical energy directly to operate machinery while the wind turbine utilizes mechanical energy to produce electricity (Keith, 2011). The windmill can rotate the wire coil that is tied on the magnet where the generator takes the kinetic energy from the wind and coverts it into electrical energy. The windmills are rotated based on the output of the wind (Layton, 2011).

Uses of Energy from Windmill

Wind power is a very important source of renewable energy and in the modern times its utility has increased. Among the various uses of wind energy are:

Powering water pumps: Wind energy can be applied in pumping water due to its low cost of production. This water can be used for domestic or agricultural use. Windmill pump water from the underground.

Generation of electricity: Wind turbines can be used to covert wind power into a form of energy. This can help generate electricity for domestic and industrial use. In the USA, wind power provides five percent of the energy that is used. It supplements other mainstream sources of energy.

Powering vehicles: This is the latest use of wind power. It was evidenced when a car in Australia, which was primarily powered by wind power completed 3100 miles. This was a demonstration of how cars can be powered using an alternative energy. The car combined kite, batteries, and wind (Tara, 2011).

Advantages and Disadvantages of Windmill

Windmill has several advantages and disadvantages just like other machines or other sources of power. Wind power is an emerging alternative to mitigate global warming dangers since it is more environmentally friendly when compared to other sources of energy because it is natural. It is evident that wind energy is increasingly becoming the widely demanded form of renewable energy (Fitzgerald & Voege, 2010).

Among the advantages and disadvantages of windmill energy include:


  • Wind mill energy is environmentally friendly, since there is no fossil that is burnt in order to generate electricity from the wind mill. Power plants make use of the combustion of fossils, which is a form of air pollution.
  • The wind turbine which is used to generate electricity occupies little space when compared to a power station. Windmill only occupies few square meters from the base, and this will permit the use of the available space for other activities like agriculture.
  • The development of new technologies makes the exploitation of wind energy more efficient and effective. Since wind is natural resources and hence free, people will cash on this free form of energy. Wind energy is the cheapest source of renewable energy around.
  • Wind turbines are best suited to generate energy in remote places like the countryside and mountainous. Furthermore, turbines can be of different sizes hence making it flexible to support different population sizes.
  • The combination of wind energy with solar energy makes it a reliable, steady and consistent supply of electricity.
  • Since wind energy is built on ranches and farms, it has a financial benefit to the farmers, since they are given rent by the owners of the power plants while maintaining ownership of their property since the turbine only occupies a small portion of the farm (Squidoo, 2011).


  • Unreliability factor of the wind. There are some areas where the strength wind is very low and cannot effectively support the running of wind power hence making solar or geothermal power viable alternatives.
  • Furthermore, wind power generates less electric power when compared with fossil driven power stations. It requires the installation of very many turbines to generate a lot of electricity, which may be expensive in terms of space and money.
  • The construction and installation of wind turbines are at times very expensive materially.
  • Wind energy can be a massive source of air pollution. It is estimated that the noise pollution emanating from the wind turbines is comparable to that of a small jet engine which can be disadvantageous to the people living in the neighboring places. Birds flying above the rotor blades have in several occasions (Clean Energy Ideas, 2011).


Windmills have been in existence for several years, and they were used for various purposes. In the contemporary world, they are basically used for the generation of power. Windmills generate power efficiently as juxtaposed with other forms of renewable energy like the solar energy. Energy from windmills is relatively clean has no negative effect on the environment. The amount of power generated depends on the size of the rotor and hence the higher the size of the rotor, the greater the amount of power output. The greatest disadvantage of a windmill is that it cannot generate power 100 percent due to the constantly changing speed and strength of wind. Windmills can also produce a lot of noise, mainly from the rotor rotation, hence making it unfavorable to be placed around living environments or within the proximity of homes. Consequently, windmill can only serve its purpose when it is backed up by a different form of renewable energy to serve as an alternative in case of absence of enough wind to power the rotor. Despite the shortcomings, windmills are considered the better direction for a world bedeviled by the menace of global warming that threatens humanity and hence its utility and adoption are gaining momentum.


Clean Energy Ideas. (2011). Advantages & Disadvantages of Wind Energy. Clean Energy Ideas. Web.

Fitzgerald, S & Voege, D. (2010). Wind Power. New York, NY: InfoBase Publishing.

Hammer, K. (2010). Windmills: components, how they operate and their future. Scribd. Web.

Keith, J. (2011). Wind Energy: The Use of Wind Power, Past and Present. Energy-Energy Information. Web.

Layton, J. (2011). How wind power works. How Stuff Works. Web.

Renewable Energy. Wind energy. Renewable Energy World. Web.

Squidoo. (2011). Advantages and Disadvantages of Wind Energy. Squidoo. Web.

Tara, A (2011). Smart Uses for Wind-Powered Energy. Bio Friendly Energy. Web.

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