Horizontal axis and vertical axis windmills are the two most widely used types of windmills. They have two or three blades that convert wind energy into rotational mechanical energy, which then powers an electricity generator.
Windmills work in the opposite manner of a fan. Fans use electricity to rotate their blades and produce a current of air. Windmills use natural currents of air to rotate their blades and turn a generator in order to produce electricity.
The power-generating capacity of most windmills ranges from about 100 kilowatts to a few megawatts. Wind farms, long rows of high-capacity windmills, produce electricity on a significantly large scale and supply it directly to a power grid. They usually employ horizontal axis models that are easy to install. Smaller windmills can be used for domestic purposes, telecommunication and even to pump water in rural areas beyond the reach of regular power grids. The energy produced by small windmills can be fed into the nearest grid.
Many countries are under pressure to reduce coal consumption due to its adverse impact on the environment. Wind power makes a favorable alternative, as it is reputed to be a clean and renewable source of energy. They can be constructed on lake and seashores, mountain plateaus or on any open land.