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Introduction to Sound, Noise, Flicker and the Human Perception of Wind Farm Activity

Mr Bruce Rapley, Editor

Man has sought to harness the awesome power of the wind since the beginning of recorded history. As early as 3,500 BC boats were using sails to harness the wind, allowing man to explore the world by water and as a consequence, expand trade. Architects have been using wind-driven ventilation in buildings from about the same period. In the 17th century BC, the Babylonian emperor Hammurabi was planning to use wind power to drive irrigation. As early as 300 BC saw the ancient Sinhalese utilising the monsoon winds to power furnaces. This allowed these early artisans to generate furnace temperatures of about 1200 degrees Celsius needed for smelting metals. History records the ‘Windwheel’ of Heron of Alexandra around 200 BC, however the first practical wind mills were built in Sistan, Iran, around the 7th century. These were vertical axis windmills with long vertical drive shafts and rectangular blades. Made of 6 to 12 sails of reed matting or cloth covered material, these windmills were used for the arduous task of grinding corn and drawing up water. Horizontal axle windmills were not to appear until the beginning of the 1180s in Europe. Many Dutch horizontal-axle wind mills still exist in Holland to this day.

Man’s fascination with machines, and this apparently free source of power from wind, saw the development of wind-powered automata in the middle of the 8th century. Such wind-powered statues existed over the domes of the four gates and palace complex of the round City of Baghdad. The Green Dome had a statue of a horseman carrying a lance that was believed to point at the enemy, moving with the wind.

Widespread use of wind power, through windmills, came into prominence around 1185 AD. In medieval England, waterpower sites were often confined to nobility and clergy, so wind power was an important resource for the new middle class. In addition, windmills, unlike water mills, were not rendered inoperable by the freezing water in winter. By the 14th century, Dutch windmills were in use to drain areas of the Rhine delta. Denmark was just as innovative and by 1900 there were about 2500 windmills used for pumping water and grinding mills producing an estimated peak power of 30 Megawatts. Across the Atlantic, the American midwest had built around six million small windmills between 1850 and 1900, mainly on small farms that used them for irrigation.

The first windmill used to generate electricity was built in Scotland in 1887 by Professor James Blythe of Anderson’s College, Glasgow (the precursor of Strathclyde University). This 33 foot high structure with cloth sails was installed in the garden of his holiday cottage at Marykirk in Kincardineshire where it was used to charge accumulators to power lights. Blythe offered excess power from his "contraption" to the people of Marykirk for powering lighting in the main street. This kind offer was turned down however as they thought electricity was "the work of the devil", perhaps showing us the first public resistance to wind-generated electricity! In a strange turn of fate, Blythe later built a wind machine to supply emergency power to the local Lunatic Asylum, Infirmary and Dispensary of Montrose. The technology never really caught on however as it was not considered to be economically viable; an issue that may still haunt us. (Refer to Bryan Leyland’s chapters in the section entitled: Economic Assessment of Wind Farms.)

In the 20th century, two distinct periods can be identified: 1900 to 1973, which saw widespread use of individual wind generators competing against fossil fuels plants and centrally generated electricity, and 1973 onwards when the first oil crisis shifted the focus to electricity generation without the use of fossil fuels.

In Denmark, wind power was an important factor in the decentralisation of electrification in the first quarter of the century. At this time wind-powered electric generators were developed with an output of 5 to 25 kilowatts. The largest machines were on 79 foot (24 m) masts with four-bladed, 75 foot (23 m) diameter rotors. In 1956 Johannes Juul installed a 24 m diameter wind turbine at Gedser which ran until 1967. Denmark continued with incremental improvements until the present day when they are considered one of the world leaders of wind turbine design and construction. It is perhaps worth noting that while Denmark leads the world with the highest penetration of wind turbines for electricity generation— some 20% of their internal energy demand is claimed to be met by wind power—they have both the highest cost of electricity of 27 countries in the European Union and the worst carbon dioxide emissions in Europe.

In America in 1927, two brothers, Joe and Marcel Jacobs, operated a factory in Minneapolis to produce wind turbine generators for farms. Over 30 years the factory produced some 30,000 small wind turbines that ran for many years. They were even exported to such remote places as Africa and Antarctica. By the 1930s wind turbines were widely used to generate electricity on farms throughout the United States where distribution systems had not yet been installed. Power was stored in batteries for uses as varied as lighting through to electrifying bridges to prevent corrosion. Such small generators had limited power and were generally of a few hundred Watts to a few hundred kilowatts. The cheap price of high tensile steel favoured the construction of open-lattice towers on which to mount the blade assemblies and generators. In the 1930s the most widespread wind turbinewas the Wincharger, a two-blade, horizontal axis, 200 Watt machine. These machines continued to be manufactured into the 1980s, proving the effectiveness of the design. It was fitted with hub breaks so that the turbine speed could be regulated in the case of severe winds. The widespread rural electrification project in the United States killed the market for these turbines. In Australia, the Dunlite Corporation built hundreds of small wind turbine generators for use in isolated postal stations and farms. Manufacture of these units stopped in 1970.


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