Alternative Energy How Does a Windmill Operate?

Windmills are used for pumping water, grinding grain or generating power. A windmill operates by converting kinetic energy into either mechanical or electrical energy. We describe the energy of the wind as kinetic energy; the energy of the windmills blades as they rotate as mechanical energy and the energy created by an alternator as electrical energy.

A windmill that converts energy into electrical energy is referred to as a wind turbine.

Although some historians believe that the Chinese used windmills prior to the Persians, the Persians are credited with inventing a windmill that could pump water around 500- 900 A.D. Later civilizations made adaptations to grind grain and our modern society adapted them even further to generate electricity.

The windmill began as a way for man to pump water. After thousands of years it still is an effective device used to pump water from deep underground pools of water. These underground pools of water are referred to as an aquifer.

What makes windmills so effective at pumping water is their simple yet effective design. Windmills are sturdy and it isn't uncommon for a single windmill to pump water for seventy years or more.

Although design components have changed the basic principle behind a windmill is pretty much the same. This holds true whether it is used for pumping water, grinding grain or generating electricity.

Windmills used to pump water irrigate pastures, gardens, provide water for livestock and aerate ponds.

The first and most important component of a windmill is its blades. The blades begin the process of converting the wind into energy that we can then use.

A windmill will have between 3 and 40 blades depending on the application. Notice that most wind turbines have only three gigantic blades while a windmill used on a ranch to pump water has noticeably more blades The blades turn as the wind passes through them. As they turn the shaft that they are attached to rotates. This shaft is connected to gears in a gear box which drives a rod into a well. The well must be deep enough to reach the aquifer.

At the bottom of the rod is a cylinder pump that creates a one-way flow of water up through the "sucker rod." It does this by using two seals. The upper seal is open when the lower seal is closed forcing the water to flow upwards. The lower seals only opens when the upper seal is closed and opens enough to allow water from the aquifer to flow into the rod. And the process continues over and over providing a continuous flow of water upwards.

The animated video above shows how an oil well operates. Although this hub is about windmills the operation below ground is similar enough to understand how the sucker rod pulls water up from the ground.

A windmill generates electricity in a similar fashion that it pumps water or grinds grain. Generally this type of windmill is referred to as a wind turbine. The final result being electrical energy instead of mechanical energy. This type of windmill requires an alternator, battery bank and an inverter. For a wind turbine the sequence of events is: kinetic energy to mechanical energy and mechanical energy to electrical energy.

The blades of a wind turbine take the kinetic energy of the wind and turn it into mechanical energy. The blades do this similarly as a windmill used to pump water, however most windmills for water pumping have many more blades.

Modern wind turbines have three blades.

Wind turbines generate wild electricity straight from the alternator. The electricity is described as wild because the frequency will vary according to wind speed and velocity. Therefore the electricity generated by the alternator must either be stored in batteries and/or fed through an inverter.

The system described here a description of a windmill that one might see in a single household rather than one found on large wind farms used to generate electricity for cities. Although the general operation is the same a couple of key differences are: a generator is used, a gear box helps speed up the rotation of the shaft and the electricity is fed into a transformer then directly into the city system.