WHAT IS WINDMILL?
Traditionally used to grind grain (gristmills), a windmill is a structure that converts wind energy into rotational energy using vanes called sails or blades. However, in some English-speaking regions, the term has been expanded to include windpumps, wind turbines, and other applications. Such devices are sometimes referred to as "wind engines". The horizontal or panemone windmill initially arose in Persia in the ninth century, while the vertical windmill first appeared in northwest Europe in the 12th century. Windmills were utilized throughout the high medieval and early modern periods.[2][3]In the Netherlands today, there are roughly 1,000 windmills, which are regarded as an emblem of Dutch culture.
TYPES OF WINDMILL:
The two most common types of wind turbines are:
1. Transverse-axis turbines
2. Turbines with a vertical axis
Wind turbines come in a wide range of sizes. The largest determinant in deciding how much electricity a wind turbine can produce is the length of the blades. The electricity production capability of small wind turbines that can run a single dwelling may be 10 kilowatts (kW). Around 15,000 kilowatts (15 megawatts) of power can be produced by the biggest utility-scale wind turbines now in use, and even bigger turbines are being developed. In order to establish wind power facilities, often known as wind farms, that supply electricity to grids, large turbines are frequently placed together. Horizontal-axis turbines are similar to propeller airplane engines
Horizontal-axis turbines have blades like airplane propellers, and they commonly have three blades. The largest horizontal-axis turbines are as tall as 20-story buildings and have blades more than 100 feet long. Taller turbines with longer blades generate more electricity. Nearly all of the wind turbines currently in use are horizontal-axis turbines.
Vertical-axis turbines look like egg beaters
Vertical-axis turbines have blades that are attached to the top and the bottom of a vertical rotor. The most common type of vertical-axis turbine—the Darrieus wind turbine, named after the French engineer Georges Darrieus who patented the design in 1931—looks like a giant, two-bladed egg beater. Some versions of the vertical-axis turbine are 100 feet tall and 50 feet wide. Very few vertical-axis wind turbines are in use today because they do not perform as well as horizontal-axis turbines.
Wind power plants, or wind farms, produce electricity
Wind farms are clusters of wind turbines that produce large amounts of electricity. A wind farm usually has many turbines scattered over a large area. One of the United States' largest wind farms is the Horse Hollow Wind Energy Center in Texas, which at the end of 2021, had 422 wind turbines spread over about 47,000 acres. The project has a combined electricity generating capacity of about 735 megawatts (or 735,000 kilowatts).
HOW WINDMILL WORKS
Wind turbines work on a simple principle: instead of using electricity to make wind—like a fan—wind turbines use wind to make electricity. Wind turns the propeller-like blades of a turbine around a rotor, which spins a generator, which creates electricity.Wind is a form of solar energy caused by a combination of three concurrent events:
The sun unevenly heating the atmosphere
Irregularities of the earth's surface
The rotation of the earth.
Wind flow patterns and speeds vary greatly across the United States and are modified by bodies of water, vegetation, and differences in terrain. Humans use this wind flow, or motion energy, for many purposes: sailing, flying a kite, and even generating electricity.
The terms "wind energy" and "wind power" both describe the process by which the wind is used to generate mechanical power or electricity. This mechanical power can be used for specific tasks (such as grinding grain or pumping water) or a generator can convert this mechanical power into electricity.
A wind turbine turns wind energy into electricity using the aerodynamic force from the rotor blades, which work like an airplane wing or helicopter rotor blade. When wind flows across the blade, the air pressure on one side of the blade decreases. The difference in air pressure across the two sides of the blade creates both lift and drag. The force of the lift is stronger than the drag and this causes the rotor to spin. The rotor connects to the generator, either directly (if it’s a direct drive turbine) or through a shaft and a series of gears (a gearbox) that speed up the rotation and allow for a physically smaller generator. This translation of aerodynamic force to rotation of a generator creates electricity.
IS WIND POWER IS EFFICIENT
Wind energy, also known as wind power, is the means of harnessing wind and turning it into electricity. The average wind efficiency of turbines is between 35-45%.Production of Wind Power
Wind is produced in the earth's atmosphere due to difference in earth temperatures locally or on a regional and global scale. When warm becomes heated it rises leaving the place with low air pressure; air from cooler regions with higher pressures of air moves in to equalize air pressure.
Wind mills and turbines take advantage of the kinetic energy or "motion energy" that moves air or wind from one place to another and converts it to electricity. Wind turbines are erected in windy places, so the wind can move the blades of turbines. These blades rotate a motor, and gears increase the rotations enough to produce electricity. Different designs of turbines are suitable for varying conditions.Wind Efficiency and Wind Capacity Factor
Wind efficiency is not the same as wind capacity factor, which is what is discussed when people think of energy efficiency. Wind Watch explains the difference between the two phenomena. Wind Capacity Factor
The wind capacity factor is the amount of energy produced by a generator as against what it could produce if it functioned all the time at peak capacity, according to Green Tech Media. Wind capacity factor tends to vary from place to place and at different times of the year, even with the same turbines, since it depends on the speed of wind, its density and swept area that depends on the size of the generator points out Open EI. Wind capacity factor can be optimised by choosing places where ideal wind conditions prevail the whole or greater part of the year. So it is important to consider wind capacity factor and the conditions influencing it to maximise power output.
Wind speed below 30 miles per hour produces little energy according to Wind Watch. Even small increases in speed can translate into substantial increase in power generated according to Open EI. Electricity generated is the cube of the wind speed explains Wind EIS.Air density is more in cooler regions and at sea level than in mountains. So the ideal places with high wind density are seas with colder temperatures according to Open EI. This is one reason for the large scale expansion in off-shore wind generation.
Larger and taller turbines can take advantage of more wind higher above the ground and by the increased span of their blades. Economic considerations therefore become important here.
The capacity factor is constantly being increased with improved technology. Wind turbines built in 2014 reached a capacity factor of 41.2% as compared to 31.2% for turbines built between 2004-2011, according to Green Tech Media. However, the capacity factor of wind is affected not only by technology, but also wind availability itself. Thus, in 2015 capacity factor of turbines were below previous years' average due to "wind drought" explains Green Tech Media.
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