The idea of building windmill can easily be traced back to the ancient trend of mankind to use the force of nature for our benefit. The basic principle of a windmill is to rotate large turbines when the wind blows and use that energy to produce electricity. The mechanical energy that is created from the rotation of the turbines is converted to electrical energy and stored for later use. There is some initial cost of setting up the windmills and after that it’s like free energy from nature.
A windmill is a machine that is powered by the energy of the wind. It is designed to convert the energy of the wind into more useful forms using rotating blades or sails. The term also refers to the structure it is commonly built on. In much of Europe, windmills served originally to grind grain (hence the "mill" derivation), though later applications included pumping water and, more recently, generation of electricity. Contemporary electricity-generating versions are referred to as wind turbines.
In the context of our country, where we continually suffer from load shedding, windmill sounds like a creative solution. Although the idea of setting up windmills here is a new idea, the concept is lot older. We have the “Kaptai Dam” in “Karnafuli” where we use the force of water to produce electricity which is based on the same principle.
According to definition, a windmill is - "a machine that is powered by the energy of the wind." There are two basic kinds of windmills. One kind, the horizontal mill has sails that revolve in a horizontal plane around a vertical axis. Such mills are known from the 7th century AD in the region around modern Iran and Afganistan. [Gimpel 1976 p. 24]
It is relatively easy to attach a grindstone directly to the rotating vertical axis (made of wood). On the other hand typical rotational speeds of such mills (dictated by the wind) are unsuitable for efficient grinding of grain. The other kind of windmill is the vertical or post mill. seen to the right in a picture reproduced from Gimpel. [Gimpel 1976 p 25] Here the sails are vertical, revolving around a horizontal axle. The other end of this axle is attached to a wooden gear which in turn is attached to gear on a separate vertical axle to which the millstone is attached. The gear ratio is set to provide a reasonable grinding speed in a typical wind. The illustration shows such a mill with its vertical sails and a ladder up to the mill itself. If one looks closely he can see the vertical post supporting the mill. The mill can be turned on this post by means of the arm seen to the left near the foot of the peasant bringing grain to the mill. The arm looks here like a small bit of a fence. The post mill seems to be a purely European invention developed independently of the horizontal mill. While the first surviving mention of one comes from Yorkshire in England in 1185, by 1195 they were sufficiently common that the Pope levied a tithe on them. The post mill was introduced to the Middle East by members of the Third Crusade. [Mokyr 1990 p 44] The post mill suffers a large disadvantage if it cannot face the wind. To overcome this, the entire mill housing was raised from the ground and made mobile, rotating on a vertical axis. It was light enough to be easily turned by one man. In this way it could be kept turned into the wind at all times. The post mill could generate roughly 2 to 8 horsepower (1 1/2 to 6 kilowatts). [Usher 1954 p 335] A later development saw larger, permanent mills with rotatable tops. A second sail (a large fin) projected out the back of such mills, automatically keeping them pointed into the wind.
Reasons for Choosing This Topic
My reason for choosing this topic is largely influenced by the recent and ongoing circumstances which are mostly about the power crisis of Bangladesh. Bangladesh is going to face a massive power crisis in the recent future....
Please join StudyMode to read the full document