Windmills have a long history of being used to run millstones for grinding grains and drawing up water for irrigation. Over the years, the windmill has undergone a sea change with the introduction of mechanical engineering in its methods and procedure of harnessing wind energy to generate electricity. Windmills for electricity have now become the need of the hour, and a step towards a cleaner environment.
Earlier, windmills were constructed in the same location where electricity was required because there were no proper means of electricity transmission. However, with the advent of long distance electricity transmission, it has become possible to transmit electricity from wind farms located in far away windy locations to places where it is required.
Use of Windmills to Generate Electricity
The basic structure of a windmill hasn't changed, it still has three large sails (blades) connected by a long vertical shaft. The sails are turned by the force of the wind. Presently wind turbines are used to harness wind energy or power to turn large metal blades, which in turn spin the generator that produces electricity. Throughout the 1970s, the United States government worked with NASA and the private engineering sector to build windmills for electricity, by enabling the production and installation of large commercial turbines. This promoted the use of windmills to generate electricity on a large-scale for both, domestic as well as commercial use. Denmark and Germany are known for harnessing wind power to produce electricity on a large scale.
Generation of electricity through a windmill follows a very simple mechanism. A windmill has large blades which are connected to the shaft, which in turn is connected to the generator. It is based on the basic principle of conversion of mechanical energy to electrical energy. Wind energy moves the large blades, swirling or rotating them. The speed the blades move with is determined by different air pressures created on their surface. Low and high pressures on the blade force the blades to move.
As the blades rotate, operated by the wind turbine tilted at an angle, they produce mechanical energy, which is converted into electrical energy by the electrical generator. The wind turbines are fitted with brakes that can be applied to stop the blades, if the wind blowing is too hard. The turbine creates quite a bit of noise, probably the reason why windmills are built nearly eight stories and above. For a windmill to generate electricity, it has to be located at a place where wind blows at a speed of 12 to 14 miles per hour. A ten storied windmill with three 50 feet blades can produce approximately 50 to 300 kilowatts of electricity. A larger turbine has the capacity to generate up to 6MW of power.
Windmills for Domestic Use
As an efficient, inexpensive, renewable and alternative energy source, windmills for electricity is being advocated and promoted for a wide scale domestic use. Small wind turbines that have the capacity of producing about ten kilowatts of windmill electricity are usually enough for providing sufficient electric power for a house. Electricity generated through wind power can be used when the wind blows, and when it stops, the local electric connection can be used.
Domestic windmills are basically of two types; horizontal axis wind turbines and vertical axis wind turbines. Out of the two, horizontal axis turbines are much popular than vertical axis turbines. Small-scale wind turbines are either pole mounted or building mounted. Pole mounted ones do not require any kind of support and are installed in an exposed position, whereas, building mounted turbines are set up on roof tops which have adequate source of wind.
Small-scale wind turbines reduce electricity bills to a large extent and can store electricity for a day when there is no wind in the surroundings. These are easy to install and affordable (with one time installation cost and low intermittent maintenance costs). Besides these advantages, the greatest benefit of using a windmill for electricity is that it helps in reducing carbon footprint by avoiding the release of harmful gases in the atmosphere. However, before installing a windmill, one must investigate and satisfy legal requirements of the local ordinances, zoning and building codes.
Using a windmill for electricity generation is a wise choice as it is a powerful source of electricity which can be used without affecting the environment in a negative way. It is a deed for saving the Earth by using its pollution-free and renewable source of energy.