What is a wind farm?
What is a wind farm? A wind farm in a simple definition is an area which contains many large wind turbines grouped together to collect the power of the wind, and a large wind farm may have hundreds of wind turbines over hundreds of miles. Hundreds of mils don’t mean that the turbines exploit all this area, but we can use the space between turbines in regular agriculture farming.
And when the winds turn the wind turbine blades it converts the energy of this wind into mechanical energy then the generator converts this mechanical energy into electric power to power homes, offices and every other place.
History of wind energy:
What is a wind farm means when we think in wind turbines and the different steps for developing this turbine, and we can start from:
- The 1st century AD when Hero of Alexandria created the wind-driven wheel which was used to power a machine.
- By 7th to the 9th century, the windmills were used in the Sistan region of Iran to grind corn, grind flour, and pump water.
- And by 1000 AD the windmills were used for pumping seawater to make salt in China and Sicily.
- The vertical windmills were used in 1180 in Northwestern Europe for grinding flour.
- But the first known wind turbine used for producing electricity was built in 1887 in Scotland by Prof James Blyth, and it was used to charge accumulators to power the lighting in the cottage at Marykirk in Kincardineshire.
- In 1888 Charles Brush built the first US wind turbine for electricity and he used it to provide electricity for his mansion in Ohio.
- Also, Paul La Cour developed an electricity generating turbine in 1891, then he figured out how to use a regulator to supply a steady stream of power from the wind turbine.
- And he also converts his windmill in 1895 into a prototype electric power plant which later used to provide electricity for lighting for the village of Askov.
- Approximately 2500 windmills with a combined peak power capacity of 30 MW were used in 1900 for mechanical purposes as grinding grain and pumping water.
- Georges Jean Marie Darrieus designed the vertical axis wind turbine in 1931, and it’s still used today for niche applications as on boats, and also the horizontal axis wind turbine was built in Yalta and it has a 100 KW of capacity, a 32-meter high tower, and a 32% load factor.
The first megawatt-size wind turbine was connected to a local electrical distribution grid in 1941 and it had blades 75 feet in length.
- 1975 the NASA wind turbine developed utility-scale wind turbine starts which included steel tube towers, variable speed generators, composite blade materials, partial-span pitch control, aerodynamic, structural, and acoustic engineering design capabilities.
- And the world’s first multi-megawatt wind turbine was produced in 1978 by Tvind school teachers and students, and it’s still running today.
- In New England, in 1980 the first modern wind farm was constructed and it included 20 wind turbines.
- The first onshore wind farm was constructed in 1991 in Cornwall and it included 10 wind farms which collected together to produce electricity enough for approximately 2700 homes.
- In 2000 about 97 wind farms were used to provide enough power for up to 592000 homes.
- Now over 7000 wind turbines are used to produce 6.5 GW and there are searches to have 20 GW of power capacity installed by 2020.
How does a wind turbine generate electricity?
It’s very simple to generate electricity using a wind turbine as the energy of the wind turns two or three propellers around a rotor which connected to the main shaft, and the wind turbine connected to the shaft converts the wind power into a mechanical power which then converted by the generator to electricity.
You should know that the wind energy is a form of the solar energy; as it’s a result of the uneven heating of the atmosphere by the sun and the irrigation of the earth’s surface beside the rotation of the earth.
Types of wind turbines:
What is a wind farm? It’s important to know the different types of the wind turbine to answer this question, and the types are:
Horizontal axis wind turbine (HAWT):
It’s similar to propeller airplane engines and it consists of two or three blades which operated upwind.
a shaft that is horizontal to the ground; a generator connected to the shaft and turned by a gear on the end of the shaft; anemometer; wind fan and controller that helps the blades to meet the wind all the time.
This plant is as tall as 20-story buildings and each blade is about 100 feet long, and it’s the usually used type nowadays, and it has some advantages as:
- Most types are self-starting.
- It can be built in the forest above tree-line.
- It’s also able to pitch the rotor blades in a storm to minimize the damages.
- Also, It has a high ability to wing warp that gives the blades the best angle of attack.
And it also has some drawbacks as:
- It’s difficult to operate in near ground winds.
- It’s also difficult to transport.
- The maintenance is difficult.
- It’s also difficult to install it.
Vertical axis wind turbine (VAWT):
It looks like egg beaters and it has blades attached to the top and the bottom of a vertical rotor, and some of these plants are 100 feet tall and 50 feet wide.
There are two types of this type which are left based and drag based, and it has some advantages as:
- The maintenance is easy.
- Transportation from one place to another is easy.
- Also, costs of construction and transportation are low.
- It’s not directional.
- Also, It’s most effective at hilltops, passes, mesas and ridge-lines.
And it’s little used compared to the horizontal one because:
- It’s less efficient.
- It operates in the more turbulent wind.
- The air flow near the ground creates a turbulent flow that produces high vibrations of the blades.
- It may require energy to start turning and the starting torque is low.
Ducted (roof mounted) wind turbine:
It’s positioned at the edge of the roof of a building and utilize the airflow along a building’s side; the air flows upwards to hug the building wall and enters the front of the duct.
The diameter of the blade is around 600 mm, and this turbine has some advantages as:
- It makes use of the unused roof space in cities.
- It has a less visual impact on building’s architecture than the traditional HAWT turbines.
And there are some drawbacks as:
- It’s only suitable for urban environments and isn’t suitable for households.
- It’s uni-directional, fixed position, and it’s dependant upon the wind blowing in the correct direction.
- Also, We need more research to determine energy production potential.
At the same time, those types can be classified as:
Utility-scale wind turbines:
which ranges in size from 100 kW to as large as they could reach; and these plants are cost-effective and they bulk power to the electric grid because they are grounded together into wind farms.
Distributed (small) wind turbines:
they range below 100 KW used for homes; telecommunications dishes; water pumping and sometimes connected with diesel generators, batteries and photo-voltaic systems used in remote or off-grid locations where there isn’t availability to a utility grid.
Offshore wind turbine:
they are large turbines capable to generate more power without transportation challenges of land-based wind installations as the large components of the plant can be transmitted on ships.
Wind turbine parts:
What is a wind farm … The wind turbine is massive and has complex pieces in many sizes and configurations, while the blades range in size from 34 to 55 meters, and the hub weighs 8 to 10 tons, and the towers are 80-100 meter tall and 55 to 70-ton weight. So the major components of the turbine are:
1- The anemometer:
which measures the speed of the wind and transmit the data of the wind speed to the controller.
2- The rotor:
which consists of
- Blades: which acts as barriers to the wind and when the wind forced this blades to move it transferred some energy of the wind to the rotor and some turbines contain two or three blades.
- The hub (shaft): which spins when the rotor spins and transfers the mechanical energy into a rotational energy.
- Brake: that stops the rotor in emergencies even mechanically, electrically or hydraulically.
- And the pitch drive system: which turns the blades out of the wind to control the rotor speed and stop the rotor working at too high or too low speeds.
3- The nacelle:
which is the external shell structure resting atop the tower and it contains:
- Controller: which used to start up the machine at wind speeds about 8-16 miles per hour; also shut off the machine at about 55 miles per hour which is the maximum allowed speed.
- A gearbox: that connect the low-speed shaft to the high-speed shaft and increases the rotational speeds, and it’s costly; so engineers explore generators operates at lower rotational speeds that wouldn’t need gearboxes.
- Generator: it’s directly connected to the shaft and spins to convert the mechanical energy into electricity.
- Large bearing.
- High-speed shaft: that drives the generator.
- And electronic components used to allow the turbine to monitor changes in wind speed and direction.
4- The tower:
which made of rolled steel tube sections bolted together to provide support for the blades and nacelle.
And there are also other components as a transformer; circuit breakers; fiber optic cables, and ground-mounted electrical equipment.
Cost of wind energy:
Knowing what is a wind farm especially the components of the wind turbine make us think about costs of wind energy which are:
- The zero costs needed for the fuel.
- Capital costs: containing the wind turbine cost which is more than 70% of the entire cost; the installation costs such as construction costs; cables; turbine foundation; connections to the grid, and transportation. And the average capital costs in 2016 were about $1590/KW.
- Maintenance costs: which differs depending on the type of the turbine and the technology used as the new turbines used new techniques have cost between 1.5% to 2% per annum.
- The component cost: it’s the important thing of the farm cost as the blades occupy 23.3%, the tower 18.9%, the gearbox 16.3%, the generator 3.4%, the pitch system 3.9 %, and the all other component costs are 31.4%
Uses of wind energy:
What is a wind farm means what is the importance of building a wind farm, and we can answer this question by searching in the uses of the wind energy; as beside using wind energy in producing electricity it’s used for many other purposes as:
Wind sports and activities:
There are many sports and activities that use the wind energy as the windsurfing, land sailing, kite surfing and kite-boarding.
Civilizations had used the wind energy in transportation in the sailing form; as small and large ships can sail under the wind power.
windmills used Wind energy for food production purposes which we were use for milling grain; which could be later we use windmills for producing food as bread.
- Pumping water:
We can also use wind pumps for pumping water; as we use the wind pumps for draining the land.
Advantages of wind energy:
The advantages of the wind energy answer our question what is a wind farm ? While the advantages illustrate why wind farms occupy large importance, and there are many advantages of the wind energy as:
- It’s a free renewable source that is plentiful and readily available.
- Also, It’s a clean source which doesn’t emit greenhouse gases or pollutants.
- Wind is cost effective as it’s one of the lowest priced energy sources.
- It can offer many jobs as the U.S wind sector employed more than 100000 workers in 2016.
- we can build wind turbine anywhere on existing farms or ranches.
- It’s a space efficient as we use the free space for agricultural purposes.
- Also, the wind turbines are relatively low maintenance.
Disadvantages of wind energy:
To be fair to know what is a wind farm we need to know the drawbacks of this wind energy which are:
- Initial costs are so high.
- The unreliability of the wind.
- Also, we need a storage device to hold generated power when there isn’t enough wind.
- It’s noisy and may cause aesthetic pollution.
- Also, the blades may damage the local wildlife as the birds flying into the spinning turbine blades had been killed.
And there are some opinions to use batteries to store wind power for the peak demand times and that would make the wind power more popular.
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