WIND+ENERGY+-+Charlotte

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 * __EXPLANATION:__**


 * Wind power is the conversion of wind energy into a useful form of energy** (e.g. wind turbines, wind mills, wind pumps) **to make electricity, generate mechanical power, pumping water or drainage and sails to propel ships.** Wind power is non-dispatchable, meaning that for economic operation, all of the available output must be taken when it is available. Wind energy, as an **alternative to fossil fuels**, is plentiful, **renewable**, widely distributed, clean, and produces no greenhouse gas emissions during operation. However, the construction of wind farms is not universally welcomed because of their visual impact and other effects on the environment.

Wind power was used in the Middle Ages, in Europe, to grind corn, which is where the term "windmill" comes from.


 * //How do wind turbines work?//**

Wind turbines use large blades to catch the wind. When the wind blows the blades are forced round, driving a turbine which generates electricity. The stronger the wind, the more electricity produced.

1) The Sun heats our atmosphere unevenly, so some patches become warmer than others. 2) These warm patches of air rise, other air blows in to replace them - and we feel a wind blowing. 3) We can use the energy in the wind by building a tall tower, with a large propellor on the top. 4) The wind blows the propellor round, which turns a generator to produce electricity. 5) We tend to build many of these towers together, to make a "wind farm" and produce more electricity.

The more towers, the more wind, and the larger the propellors, the more electricity we can make. It's only worth building wind farms in places that have strong, steady winds, although boats and caravans increasingly have small wind generators to help keep their batteries charged.



**The benefits of wind energy:** • Harness a plentiful energy source: in the UK they have 40% of Europe's total wind energy • Cut your carbon footprint: wind electricity is green, renewable energy and doesn't release any harmful carbon dioxide or other pollutants. • Wind is free, wind farms need no fuel. • The land beneath can usually still be used for farming. • Wind farms can be tourist attractions. • A good method of supplying energy to remote areas.

• The wind is not always predictable - some days have no wind. • Suitable areas for wind farms are often near the coast, where land is expensive. • Some people feel that covering the landscape with these towers is unsightly. • Can kill birds - migrating flocks tend to like strong winds. • Can affect television reception if you live nearby. • Can be noisy. Wind generators have a reputation for making a constant, low, "swooshing" noise day and night, which can drive you nuts. Having said that, as aerodynamic designs have improved modern wind farms are much quieter. A lot quieter than, say, a fossil fuel power station; and wind farms tend not to be close to residential areas anyway. The small modern wind generators used on boats and caravans make hardly any sound at all.
 * The disadvantages of wind energy:**



ABOVE: A simple diagram to represent a wind turbine.


 * __FACTS + EXAMPLES:__**

Wind turbines are the most common example of conversion of wind energy. There are 2 types of wind turbines: **horizontal axis** and **vertical axis**. Horizontal axis turbines are the more familiar ‘windmill’ type where the blades rotate in a vertical plane about a horizontal axis and the turbine is dynamically rotated on its tower to face the wind. Vertical axis turbines do not need orientation into the wind. More recent innovations have helical blade designs that have low torque and can operate without external power. Vertical axis turbines are particularly suited to **small** wind power applications because they have a **small environmental** impact and **no noise**, but have not yet scaled up to the 5MW + turbine size of horizontal axis designs. The best places for wind farms are in coastal areas, at the tops of rounded hills, open plains and gaps in mountains - places where the wind is strong and reliable. Some are offshore. To be worthwhile, you need an average wind speed of around 25 km/h. Most wind farms in the UK are in Cornwall or Wales. Isolated places such as farms may have their own wind generators. In California, several "wind farms" supply electricity to homes around Los Angeles. The propellors are large, to extract energy from the largest possible volume of air. The blades can be angled to "fine" or "coarse" pitch, to cope with varying wind speeds, and the generator and propellor can turn to face the wind wherever it comes from. Some designs use vertical turbines, which don't need to be turned to face the wind. The towers are tall, to get the propellors as high as possible, up to where the wind is stronger. This means that the land beneath can still be used for farming.
 * Wind turbines:**



The United Kingdom became the world leader of offshore wind power generation in October 2008 when it overtook Denmark. It also has the largest offshore wind farm in the world, the Thanet wind farm, located off the Kent coast. The UK has been estimated to have over a third of Europe's total offshore wind resource, which is equivalent to three times the electricity needs of the nation at current rates of electricity consumption. The first wind farms in the UK were built onshore and they currently generate more power than the offshore farms. The first commercial wind farm was built in 1991 at Delabole in Cornwall, it consisted of 10 turbines each with a capacity to generate a maximum of 400kW. The UK will require 7,500 offshore turbines by 2020 to meet EU targets.


 * __ENERGY TRANSFERS:__**

Wind turbines convert the kinetic energy from the wind into mechanical energy which is then used to drive a generator that converts this energy into electricity. The UK has more usable wind power than any other European country and large scale wind turbine farms on and offshore will become a major supplier of electricity to the national grid in the next twenty years. As at 28 June 2009 there are 217 UK grid-connected wind farms containing 2,537 wind turbines with the capacity to generate 3628 MW.*

In a wind farm, individual turbines are interconnected with a medium voltage (often 34.5 kV), power collection system and communications network. At a substation, this medium-voltage electric current is increased in voltage with a transformer for connection to the high voltage electric power transmission system.

Since wind speed is not constant, a wind farm's annual energy production is never as much as the sum of the generator nameplate ratings multiplied by the total hours in a year. The ratio of actual productivity in a year to this theoretical maximum is called the capacity factor. Typical capacity factors are 20–40%, with values at the upper end of the range in particularly favourable sites. For example, a 1 MW turbine with a capacity factor of 35% will not produce 8,760 MW·h in a year (1 × 24 × 365), but only 1 × 0.35 × 24 × 365 = 3,066 MW·h, averaging to 0.35 MW.


 * __FIGURES:__**

• Energy production was 340 TWh in 2009, which is about 2% of worldwide electricity usage and has doubled in the past three years • At the end of 2009, worldwide nameplate capacity of wind-powered generators was 159.2 gigawatts (GW) • As of May 2009, 80 countries around the world are using wind power on a commercial basis • Humans have been using wind power for at least 5,500 years to propel sailboats and sailing ships • Windmills have been used for irrigation pumping and for milling grain since the 7th century AD in what is now Afghanistan, Iran and Pakistan • In the United States, Charles F. Bush produced electricity using a wind powered machine, starting in the winter of 1887-1888, which powered his home and laboratory until about 1900 • In the 1890s, the Danish scientist and inventor Poul la Cour constructed wind turbines to generate electricity, which was then used to produce hydrogen • The modern wind power industry began in 1979 with the serial production of wind turbines by Danish manufacturers Kuriant, Vestas, Nordtank, and Bonus. These early turbines were small by today's standards, with capacities of 20–30 kW each • World wind generation capacity more than quadrupled between 2000 and 2006, doubling about every three years • 81% of wind power installations are in the US and Europe • The World Wind Energy Association forecast that, by 2010, over 200 GW of capacity would have been installed worldwide, up from 73.9 GW at the end of 2006, implying an anticipated net growth rate of more than 28% per year




 * __ENVIRONMENT:__**

Compared to the environmental effects of traditional energy sources, the environmental effects of wind power are relatively minor. Wind power consumes no fuel, and emits no air pollution, unlike fossil fuel power sources. The energy consumed to manufacture and transport the materials used to build a wind power plant is equal to the new energy produced by the plant within a few months of operation.

Danger to birds and bats has been a concern in some locations. American Bird Conservancy cites studies that indicate that about 10,000 - 40,000 birds die each year from collisions with wind turbines in the United States. They say that number may rise substantially as wind capacity increases in the absence of mandatory guidelines. However, studies show that the number of birds killed by wind turbines is very low compared to the number of those that die as a result of certain other ways of generating electricity.

• http://en.wikipedia.org/wiki/Wind_power • http://www.therenewableenergycentre.co.uk/wind-power/ • http://www.darvill.clara.net/altenerg/wind.htm
 * __SOURCES:__**