Windmill

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Image:Pitstone-windmill.600px.jpg

This article is about the structure. A windmill is also a breakdancing move. For the famous London Theatre, see Windmill Theatre.

A windmill is an engine powered by the wind to produce energy, often contained in a large building as in traditional post mills, smock mills and tower mills. The energy windmills produce can be used in many ways, traditionally for grinding grain, pumping water, sawing wood or hammering seeds. Modern wind power machines are used for generating electricity and are more properly called wind turbines.

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History

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Early history

Windmills have been around for a long time. The first windmill had vertical shafts and were reportedly built in Persia around the 7th century AD for the second caliph, Umar Ibn Al-Khttab 12 3. Made of six to twelve sails covered in fabric or palm leaves, they were used to grind corn and draw up water. A similar type of vertical shaft windmill can also be found in 13th century China.

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In Europe

Image:Prokudin-Gorskii-06.jpg Image:KinderdijkMolens klein.jpg

In Europe, windmills were developed in the Middle Ages. The earliest mills were probably grinding mills. They were mounted on city walls and could not be turned into the wind. The earliest known examples date from early 12th century Paris. Because fixed mills did not suffice for regions with changing wind directions, mill types that could be turned into the wind were developed. With some subsequent development mills became versatile in windy regions for all kind of industry, most notably grain grinding mills, sawmills (late 16th century), threshing, and, by applying Archimedes' screws, pumping mills.

They soon became the major energy source in the low lands, where the older watermills could hardly operate due to the lack of height difference in the water ways. The pumping mills allowed the drainage of the Dutch wetlands to claim new land, polders. By continuously pumping water out to the rivers, land below sea level could be created. The earliest Dutch polders date from the middle ages, the first lake was emptied by Jan Leeghwater from 1607. To claim ever more land it became necessary to build series of mills (molengang, mill pace), because an Archimedes screw can only efficiently pump water for a limited height. Each mill pumps water into a higher reservoir, with the last pumping it out to the river. In the 18th century several molendriegangen (3 mills), and molenviergangen (4 mills), were built. The largest preserved mill pace in Kinderdijk was awarded world heritage status in 1997.

Image:Campo de Criptana Molinos de Viento 1.jpg


Another region well-known for its windmills is La Mancha, Spain. The windmills of La Mancha were made particularly famous by a scene in Cervantes' Don Quixote de La Mancha where the title character mistakes them for giants sent by an evil enchanter, giving rise to the phrase "tilting at windmills".

With the industrial revolution, the importance of windmills as primary industrial energy source was replaced by steam and internal combustion engines. Polder mills were replaced by steam, or diesel engines. More recently historic windmills are being preserved for their historic value, which requires regular use because the wooden machinery is likely to be destroyed by maggots when the mill remains stationery for too long. Image:Hessenpark Windmuehle.jpg With increasing environmental concern, and approaching limits to fossil fuel consumption, wind power has regained interest as a renewable energy source. This new generation of wind mills produce electric power and are more generally referred to as wind turbines.

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Mill language in the Netherlands

Windmills were among the tallest structures in a time when communication was much slower than now. In the Netherlands the position of the blades (when not milling) acquired meaning. Most well known and still practised are signals for 'joy' (e.g. birth) and 'mourning'. In wartime the stationary position of the mill was used to send warnings, visible over long distance[1]

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In the United States

Image:Windmill Sheridan Co KS 1939.jpg

The development of the water-pumping windmill in the USA was the major factor in allowing the farming and ranching of vast areas of North America, which were otherwise devoid of readily accessible water. They contributed to the expansion of rail transport systems throughout the world, by pumping water from wells to supply the needs of the steam locomotives of those early times. They are still used today for the same purpose in some areas of the world where a connection to electric power lines is not a realistic option.

The multi-bladed wind turbine atop a lattice tower made of wood or steel was, for many years, a fixture of the landscape throughout rural America. These mills, made by a variety of manufacturers, featured a large number of blades so that they would turn slowly but with considerable torque in low winds and be self regulating in high winds. A tower-top gearbox and crankshaft converted the rotary motion into reciprocating strokes carried downward through a pole or rod to the pump cylinder below.

In areas not prone to freezing weather, a pump jack (or standard) was frequently mounted at the top of the well in the center of the base off the tower. This was the connection between the windmill and the pump rod, which generally went through the drop pipe to the cylinder below. The pump jack provided a means for manual operation of the pump when the wind was not blowing. Some pump jacks provided a sealed connection, allowing water to be forced out under pressure allowing a tank at a higher elevation to provide water for a home and other uses, but many had a simple spout allowing water to flow away in a trough by gravity.


The drop pipe and pump rod continued down deep into the well, terminating at the pump cylinder below the lowest likely groundwater level. A suction tube usually continued a short distance more. This arrangement allowed wells as deep as 1200 feet (370 m) to be constructed, though most were much more shallow.

Windmills and related equipment are still manufactured and installed today on farms and ranches, usually in remote parts of the western United States where electric power is not readily available. The arrival of electricity in rural areas, brought by the Rural Electrification Administration (REA) in the 1930s through 1950s, contributed to the decline in the use of windmills in the US. Today, with increases in energy prices and the expense of replacing electric pumps, has led to an increase in the repair, restoration and installation of new windmills.

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Wind Turbines

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With increasing energy demands, wind has come to the fore once more as a source of renewable energy. All over the world wind farms are being constructed to create electricity from the wind.

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See also

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External links

Indices

Collections

Mixed

History

Theory Template:Commons

Test and construction

Small windmills for urban rooftop use

da:Vindmølle pdc:Windbump de:Windmühle el:Ανεμόμυλος eo:Ventmuelejo fr:Moulin à vent hr:Vjetrenjača he:טחנת רוח id:Kincir angin li:Windmeule nl:Windmolen no:Vindmølle pl:Wiatrak pt:Moinho de vento fi:Tuulimylly sv:Väderkvarn tr:Yel değirmeni uk:Вітряк zh:风车 (机械)

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