Wind Energy


• What is Wind Energy
• Wind Energy is Versatile
• Wind Energy is Clean and Renewable
• Wind Energy Equation
• Wind Features
• The Unit of Wind Speed
• Wind Speed Unit Conversion
• Wind Speed Table
• Wind Directions
• Wind Turbines
• Wind Farms
• Wind Farm Site
• How Wind Turbines Work
• Advantages and Challenges of Wind Energy
• The Future Growth of Wind Energy
What is Wind Energy
You will feel that you cant stand steady, that is mean wind has its power. Wind energy is kinetic energy that is present in moving air , that is mean air horizontal movement produced its power.


We have been harnessing the wind's energy for hundreds of years. From old Holland to farms in the United States, windmills have been used for pumping water or grinding grain. Today, the windmill's modern equivalent - a wind turbine - can use the wind's energy to generate electricity.

Wind turbines, like windmills, are mounted on a tower to capture the most energy. At 100 feet (30 meters) or more aboveground, they can take advantage of the faster and less turbulent wind. Turbines catch the wind's energy with their propeller-like blades. Usually, two or three blades are mounted on a shaft to form a rotor.


A blade acts much like an airplane wing. When the wind blows, a pocket of low-pressure air forms on the downwind side of the blade. The low-pressure air pocket then pulls the blade toward it, causing the rotor to turn. This is called lift. The force of the lift is actually much stronger than the wind's force against the front side of the blade, which is called drag. The combination of lift and drag causes the rotor to spin like a propeller, and the turning shaft spins a generator to make electricity.

Wind turbines can be used as stand-alone applications, or they can be connected to a utility power grid or even combined with a photovoltaic (solar cell) system. For utility-scale sources of wind energy, a large number of wind turbines are usually built close together to form awind plant. Several electricity providers today use wind plants to supply power to their customers.

Stand-alone wind turbines are typically used for water pumping or communications. However, homeowners, farmers, and ranchers in windy areas can also use wind turbines as a way to cut their electric bills.

Small wind systems also have potential as distributed energy resources. Distributed energy resources refer to a variety of small, modular power-generating technologies that can be combined to improve the operation of the electricity delivery system.
Wind Energy is Versatile
When air moves, causing wind, it has kinetic energy—the energy created whenever mass is in motion. With the right technology, the wind’s kinetic energy can be captured and converted to other forms of energy such as electricity or mechanical power. That’s wind power.
Just as the earliest windmills in Persia, China and Europe used wind power to pump water or grind grain, today’s utility-connected wind turbines and multi-turbine wind farms use wind power to generate clean, renewable energy to power homes and businesses.
Wind Energy is Clean and Renewable
Wind energy should be considered an important component of any long-term energy strategy, because wind energy generation uses a natural and virtually inexhaustible source of power—the wind—to produce electricity. That is a stark contrast to traditional power plants that rely on fossil fuels.
And wind energy generation is clean; it doesn’t cause air, soil or water pollution. That’s an important difference between wind energy and some other renewable energy sources, such as nuclear power, which produces a vast amount of hard-to-manage waste.
Wind Energy Equation
The power available to the rotor (that is, the spinning blades) of a wind generator is defined by the equation:


P =1⁄2d · A · V3


P is the power at the rotor,


D is the density of the air,


A is the swept area of the rotor,


V is the speed of the wind.
Wind Features
Wind is nature phenomenon, has its features. Usually, we use wind speed, wind

direction, wind frequency to express wind features.


1. wind speed: Is a term about the movement of air from one place to the next. As the wind is changeable, usually, what we said wind speed is the average value of various instantaneous wind speed in a period time, that is mean average wind speed. Wind speed can be measured by anemoscope. Wind speed changes depend on the height. The wind speed is increased as the height increase.


2. Wind frequency: To be wind speed frequency and wind direction frequency


Wind speed frequency: The frequency extent of different wind speed , wind generator operate smooth and it is easily to be control when the average wind speed is high, but the wind speed is stable.

Wind direction frequency: The frequency extent of different wind direction. To be wind generator, hope always a certain wind direction frequency to be large.
The Unit of Wind Speed
Normally we use the following unit as the wind speed: M/S, MPH, KTS, FT/S, KMH,
Wind Speed Unit Conversion
From the user, we are given a wind value and the unit to convert.


To convert between miles per hour (mph) and knots (kts):


Wind kts=0.8689762×Windmph Wind mph=1.1507794×Windkts


To convert between miles per hour (mph) and meters per second (m/s):


Wind m/s=0.44704×Windmph Wind mph=2.23694×Windm/s


To convert between miles per hour (mph) and feet per second (ft/s):


Wind ft/s=1.46667×Windmph Windmph=0.681818×Windft/s


To convert between miles per hours (mph) and kilometers per hour (km/h):


Wind km/h=1.609344×Windmph Windmph=0.621371×Windkm/h


To convert between knots (kts) and meters per second (m/s):


Wind m/s=0.5144444×Windkts Wind kts=1.9438445×Windm/s


To convert between knots (kts) and feet per second (ft/s):


Wind ft/s=1.6878099×Windkts Wind kts=0.5924838×Windft/s


To convert between knots (kts) and kilometers per hour (km/h):


Wind km/h=1.852×Windkts Windkts=0.5399568×Windkm/h

To convert between meters per second (m/s) and feet per second (ft/s):


Windm/s=0.3048×Windft/s Windft/s=3.28084×Windm/s


To convert between meters per second (m/s) and kilometers per hour (km/h):


Wind km/h=3.6×Windm/s Windm/s=0.277778×Windkm/h


To convert between feet per second (ft/s) and kilometers per hours (km/h):

Wind km/h=1.09728×Windft/s Windft/s=0.911344×Windkm/h
Wind Speed Table
Wind speed table for Conversion of Knots, Beaufort, m/s and km/h.








































































































Knots

Bft.

m/s

km/h

Label

Effect on sea

1

0

0 - 0.2

1

Calm

Sea like a mirror

1-3

1

0.3-1.5

1-5

Light Air

Ripples with the appearance of scales are formed, but without foam crests

4-6

2

1.6-3.3

6-11

Light Breeze

Small wavelets, still short, but more pronounced. Crests have a glassy appearance and do not break

7-10

3

3.4-5.4

12-19

Gentle Breeze

Large wavelets. Crests begin to break. Foam of glassy appearance. Perhaps scattered white horses

11-15

4

5.5-7.9

20-28

Moderate Breeze

Small waves, becoming larger; fairly frequent white horses

16-21

5

8.0-10.7

29-38

Fresh Breeze

Moderate waves, taking a more pronounced long form; many white horses are formed. Chance of some spray

22-27

6

10.8-13.8

39-49

strong Breeze

Large waves begin to form; the white foam crests are more extensive everywhere. Probably some spray

28-33

7

13.9-17.1

50-61

Near Gale

Sea heaps up and white foam from breaking waves begins to be blown in streaks along the direction of the wind

34-40

8

17.2-20.7

62-74

Gale

Moderately high waves of greater length; edges of crests begin to break into spindrift. The foam is blown in well-marked streaks along the direction of the wind

41-47

9

20.8-24.4

75-88

Severe Gale

High waves. Dense streaks of foam along the direction of the wind. Crests of waves begin to topple, tumble and roll over. Spray may affect visibility

48-55

10

24.5-28.4

89-102

Storm

Very high waves with long over-hanging crests. The resulting foam, in great patches, is blown in dense white streaks along the direction of the wind. On the whole the surface of the sea takes on a white appearance. The 'tumbling' of the sea becomes heavy and shock-like. Visibility affected

56-63

11

28.5-32.6

103-117

Violent Storm

Exceptionally high waves (small and medium-size ships might disappear behind the waves). The sea is completely covered with long white patches of foam flying along the direction of the wind. Everywhere the edges of the wave crests are blown into froth. Visibility affected

64-71

12

32.7-36.9

118-133

Hurricane

The air is filled with foam and spray. Sea completely white with driving spray; visibility very seriously affected
Wind Directions








































































Abbreviation

Wind Direction

Degrees

N

North


NNE

NorthNorthEast

22.5°

NE

NorthEast

45°

ENE

EastNorthEast

67.5°

E

East

90°

ESE

EastSouthEast

112.5°

SE

SouthEast

135°

SSE

SouthSouthEast

157.5°

S

South

180°

SSW

SouthSouthwest

202.5°

SW

Southwest

225°

WSW

WestSouthwest

247.5°

W

West

270°

WNW

WestNorthwest

292.5°

NW

Northwest

315°

NNW

NorthNorthwest

337.5°

Wind Turbines
Wind turbine is a machine that converts the wind's kinetic energy into rotary mechanical energy, which is then used to do work. In more advanced models, the rotational energy is converted into electricity by using a generator.


The most familiar forms of wind turbines are the horizontal axis ones that look like conventional windmills. Vertical axis ones, some of which look like egg beaters, also are in use but they are few in number.

The principle of wind turbines is very simple. Just as wind energy is utilized to make a sailboat move over water; wind energy is used to run large fans and turbines. When any object is placed in the path of the wind, the wind pushes it and, in the process, transfers some of its own power to the object. If this object is specifically engineered to provide lift, the object will move.


The turbines are usually pointed upwind as turbine towers produce a lot of air turbulence at the rear of it. The blades of a turbine are made very stiff to avoid the blades being blown towards the tower by fast winds. They are also placed at a good distance from the tower and angled to a degree to prevent them from snapping off and damaging the tower housing.


In the case of turbines, each blade in the rotor is designed for lift allowing the rotor to rotate. This rotation drives a low velocity shaft attached to a gear coupled to a high velocity shaft that eventually ends in the generator housing.


The magnetic rotor located on the end of the high speed shaft spins inside of a series of loops of copper wire wound around an iron cast. When the rotor starts to spin, electromagnetic induction takes place producing the electric current. This current is either then fed into the power grid (direct connection) or passed through a series of electronic components (indirect connection) and transformed into something useful.

Wind Farms
Wind farms are groups of wind turbines located in the same site for the purpose of producing electric power for a certain community. The individual turbines are connected to one another and usually a medium voltage power collection system and communication network are used. Wind farms may be composed of a few dozen to hundreds of wind turbines scattered at an extensive area of hundreds of miles. Though a wide area is needed for a wind farm, the lands between wind turbines can still be utilized for agricultural purposes. In most cases, wind farms are built offshore to have more wind speed brought about by the strong winds blowing in the water ways.
Wind Farm Site
Air density is one important factor to consider in selecting a site for wind farms. It indicates the effective force of the wind at a given site, often shown by the elevation present in that area over a given time.

The search for a wind farm site can sometimes cause an issue, most especially if the area has ecological or historical value and a significant bird habitat, or if there is a road widening required to be built through usable lands. Usually, Wind farm developers choose non-residential locations as wind turbines cause noise and shadow flicker.


Electrical grid access, a necessary factor for wind turbines to operate, is another concern. If the turbines are set up far from the grid, more transmission lines will be needed or transformers will have to be built in the premises.

How Wind Turbines Work
Wind is a form of solar energy. Winds are caused by the uneven heating of the atmosphere by the sun, the irregularities of the earth's surface, and rotation of the earth. Wind flow patterns are modified by the earth's terrain, bodies of water, and vegetation. Humans use this wind flow, or motion energy, for many purposes: sailing, flying a kite, and even generating electricity.

The terms wind energy or wind power describe the process by which the wind is used to generate mechanical power or electricity. Wind turbines convert the kinetic energy in the wind into mechanical power. 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.

So how do wind turbines make electricity? Simply stated, a wind turbine works the opposite of a fan. Instead of using electricity to make wind, like a fan, wind turbines use wind to make electricity. The wind turns the blades, which spin a shaft, which connects to a generator and makes electricity.

Many wind farms have sprung up in the Midwest in recent years, generating power for utilities. Farmers benefit by receiving land lease payments from wind energy project developers.
Advantages and Challenges of Wind Energy

Advantages


1. Storage is large

2. No pollution

3. Can be renewable

4. Extensively distributing

5. Lower Natural Gas Price

6. Conserve Water

7. Reduce Greenhouse Gas Emissions

8. Applicability is strong, and developing is potential


Wind energy is fueled by the wind, so it's a clean fuel source. Wind energy doesn't pollute the air like power plants that rely on combustion of fossil fuels, such as coal or natural gas. Wind turbines don't produce atmospheric emissions that cause acid rain or greenhouse gasses.

Wind energy relies on the renewable power of the wind, which can't be used up. Wind is actually a form of solar energy; winds are caused by the heating of the atmosphere by the sun, the rotation of the earth, and the earth's surface irregularities.

Wind energy is one of the lowest-priced renewable energy technologies available today, costing between 4 and 6 cents per kilowatt-hour, depending upon the wind resource and project financing of the particular project.

Wind turbines can be built on farms or ranches, thus benefiting the economy in rural areas, where most of the best wind sites are found. Farmers and ranchers can continue to work the land because the wind turbines use only a fraction of the land. Wind power plant owners make rent payments to the farmer or rancher for the use of the land.


Challenges


Wind power must compete with conventional generation sources on a cost basis. Depending on how energetic a wind site is, the wind farm may or may not be cost competitive. Even though the cost of wind power has decreased dramatically in the past 10 years, the technology requires a higher initial investment than fossil-fueled generators.


Good wind sites are often located in remote locations, far from cities where the electricity is needed. Transmission lines must be built to bring the electricity from the wind farm to the city.


Wind resource development may compete with other uses for the land and those alternative uses may be more highly valued than electricity generation.


Although wind power plants have relatively little impact on the environment compared to other conventional power plants, there is some concern over the noise produced by the rotor blades, aesthetic (visual) impacts, and sometimes birds have been killed by flying into the rotors. Most of these problems have been resolved or greatly reduced through technological development or by properly siting wind plants.

The Future Growth of Wind Energy
As the need for clean, renewable energy increases, and the world more urgently seeks alternatives to finite supplies of oil, coal and natural gas, priorities will change.
And as the cost of wind energy continues to decline, due to technology improvements and better generation techniques, wind power will become increasingly feasible as a major source of electricity and mechanical power.
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