Down through the ages, mandkind has used the natural and renewable power of wind for windmills. A windmill is a machine that use sails or blades to harness the kinetic energy of wind and convert it to mechanical energy to grind grain and coin, saw timber, and draw up water for irrigation and water supply.
The first practical windmill dates from 9th-century found in Persia and was likely a vertical shaft with six to twelves sails. Windmills of this type were used throughout much of Islamic world, and introduced to Europe through Islamic Spain. In China, a similar of vertical shaft windmill with rectangular blades was used in the 13th century.
A difference design was introduced in northern France in the 12th century that became the standard for Europe. A horizontal shaft was mounted to an upright body and buck that could be rotated to face the direction of the wind.
By the end of 13th century, windmills mostly were made of brick with a timber cap that rotated rather than the body of the mill. This made it possible to build windmills that were much taller, allowing sails to be larger, making it possible to work even in low winds.
A small auxiliary set of sails, called a fantail, at the rear of the cap helped keep the sails facing the direction of the wind. With the industrial revolution, windmills became less important sd primary industrial energy force and were largely replaced by steam and the internal combustion engines. They did experience a brief heyday during and after World War II due to the lack of fuel, electricity and other means to run machines. In Holland, about 100,000 were in operation by end of the 19th century. Today, there are bout 1000. In the US, where windmills were used on farms in the Midwest to pump water, there were about six million windmills by the end of the 19th century of which only 15,000 remain.
The modern generation of windmills, more properly called Wind Turbine, are used to generate electricity from wind power. The largest turbine can generate uo to 6MW of power.