Two types of windmills are used in current scenario; one is horizontal-axis windmill and second is vertical-axis windmill and most of them are horizontal type. One windmill generally produces 1.5 to 4.0 million kilowatt hours of electricity in a year which is enough for 400-500 homes.
Horizontal-axis windmills- These machines have blade like aircraft propellers. Horizontal-axis windmill stands about as tall as twenty story building and has three sails that span 200 feet across, which stand tall and wide to capture more wind
as they capture more wind they will produce more power.The largest windmill in the world has blades longer than football ground.
Vertical-axis windmills- Vertical-axis wind machines have sails that go from top to bottom, which looks like giant egg beaters. Vertical-axis wind machines stands 100 feet tall and 50 feet which counts 4 to 5 percent wind machines that are used today.
Other types of Windmills-
- Wind Turbines- Giant three-rotor design is one of the unique features of wind turbines, which is used to produce mechanical energy and electricity, by converting wind energy into mechanical energy. Wind turbines use wind to produce electricity, which is produced by wind turbine move through distribution lines to provide electricity to homes, businesses and schools.
- Post Mills- Post mills were pioneered by the French and English and constructed throughout America, Europe, Russia and colonies all over the world. Mainly post mills are used for grinding of stones. There are two types of post mills- open post mill and closed post mill.
- Simple Drain Mill- This mill is used to pump water into irrigation canals. These mills are generally found in Netherlands, which are present in the areas where land is extremely swampy.
- American Windmill- First American windmill was developed by Daniel Halladay in 1854 in Connecticut. Halladay invented a mill, which did not require constant attention of an operator. This windmill was made up of wood and required a lot of maintenance but as the time went, metal windmills were introduced and found to be more efficient, which were also reliable for self-oiling gearboxes and pivoting wind wheels. These windmills were constantly used by railroad companies and settlers.
- Tower Mill- Tower mills are the European mills, which are built along the sea shore, facing the sea and use wind to generate energy. The blades of tower mills are like sails of boats. There are several styles of Tower Mills which are as follows-
- Grondzeilers- In this style sail rotates and can be accessed from the ground.
- Beltmolen- It is generally built on top of a hill or mountain.
- Binnenkruier- It is a mock mill with a cap turned by a trail fan.