How Do Windmills Work?

Windmills have been around for a very long time. Somewhere early on in mankind’s history, someone figured out that you could use the wind to perform certain jobs that would otherwise have been much more difficult. In ancient Persia, a version of a windmill was used for grinding corn. In 13th century China, a windmill was used to pump water for irrigation. Later in Europe, windmills that resemble today’s more modern versions were used for a variety of tasks. Many old windmills can still be seen dotting the countrysides, even as more modern windmills are being installed and used to provide an alternative means of energy. Yet how do windmills work? What happens if there is no wind? As the world today goes “green”, here is some useful information that could help out the environment as well as save you some money.

What Is a Windmill? What Does It Do?


A windmill is an engine that uses the wind as a source of power. Windmills are designed to take the energy of the wind and convert it into something useful or to complete a task. Windmills have large, sail-like blades that can catch the wind. As the wind blows it creates a lift and the blades of a windmill turn. The stronger the wind, the faster the blades will turn.

The word ‘windmill’ also refers to the original purpose of the structure. In much of Europe and eastern Asia, windmills were used to grind grain, thus a ‘mill’. As the wind turned the blades, a large shaft would turn a heavy stone grinding wheel that crushed grain and made flour.  It wasn’t until some time later that windmills were used to pump water. Most windmills commonly seen across the American landscape were used for that purpose. These windmills were smaller than their European counterparts and had a small engine at the top that pumped the water. Recent innovations in windmill technology have led to what are now referred to as wind turbines. These modern day windmills use the power of the wind to create electricity.

There are two types of windmills; horizontal axis turbines and vertical axis turbines. Vertical axis turbines are uncommon. They closely resemble a giant eggbeater. The name is derived from the direction that the blades turn. Despite the difference, vertical axis windmills work using the same principle. Horizontal axis turbines are the ones most people are familiar with. The blades look like airplane propellers and have a similar rotating spin.

How Does a Windmill Work

There are two main uses for a windmill: pumping water and generating electricity. The basic principles for both are very much the same but it’s the details that are different.

A windmill that pumps water, or a windpump, is used in many arid regions to provide water for crops and livestock. They are still used extensively today in some areas of Australia, Africa, and dry regions of the U.S. The main mechanics of the windpump is the pump rod and the piston. How it works is this: as the wind turns the blades, the pump rod raises and lowers the piston. The water from the well is brought to the surface when the pump rod raises the piston. Then the piston check valve closes and the water is held above the piston. As this happens, water is also drawn into the lower part of the pump cylinder through the lower check valve. When the pump rod begins to lower, the lower check valve closes and the piston check valve opens up. This allows the water in the cylinder to again pass through the piston check valve and so on. It is a constant pumping cycle that is repeated as the wind turns the blades.

The other use for a windmill is to produce electricity. A modern wind turbine is designed to convert the energy of the wind into electricity. The largest of these wind turbines can generate up to 6MW (that’s mega watts) of power. That’s really not a lot. A energy plant whose generators run on fossil fuels can put out anywhere from 500 to 1,000 MW of power so there is a significant difference.

Wind turbines work by their spinning blades catching the wind and turning a drive shaft that runs down to a generator which is at the windmill’s base. When the blades spin, the drive shaft turns which causes the generator to spin. This creates electricity. It is the same as a traditional power plant except instead of the generator being run by gas or diesel, it is powered by the wind. Once the generator produces electricity, it is dispersed through wires to the appropriate homes or buildings where it is needed. This electricity is then run through wires that lead directly into the buildings where the electricity is needed. Windmills come in many sizes and all produce varying amounts of power. A single windmill might only produce about 100 kilowatts of electricity. Other larger windmills can produce enough to run a cluster of homes. In parts of the world such as Spain or the American Midwest, there are entire fields of giant wind turbines that produce enough electricity to power an entire town.

Why Windmills are Good for the Environment

Windmills that produce electricity are very eco-friendly. For one thing, they produce no harmful waste products. Also, they do not require consumption of a limited amount of natural resources nor do they endanger the environment through mining or drilling. The natural resource, wind, is already available and cannot be used up. As the concern about fossil fuels and the impact it has had on our environment grows, there are more efforts being diverted to finding renewable energy sources. However, here is the one catch about windmills. You have to have a wind supply in order for them to work. If there is no wind, the blades will not spin and nothing will be produced. Windmills are not very practical in areas of the world where there is little to no wind. However, as long as you live in a region that experiences plenty of wind, you will find that windmills are a cheap source of energy and can create electricity without the harmful effects.

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