Lecture20-AlternativeEnergyResources-WindPower

8/9/2019 Lecture20-AlternativeEnergyResources-WindPower

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Page 1of 5Lecture 20

Lecture 20: Alternative Energy

Resources The Wind PowerThe Wind Farm

A wind farmor wind parkis a group

of wind turbines in the same location used

to produce energy. A large wind farm may

consist of several hundred individual wind

turbines and cover an extended area of

hundreds of square miles, but the land

between the turbines may be used for

agricultural or other purposes. A wind farmcan also be located offshore.

Many of the largest operational onshore

wind farms are located in the United States

and China. or example, the !ansu "ind

arm in China has a capacity of over

#,$$$ M" of power with a goal of %$,$$$ M" by %$%$. &he Alta "ind 'nergy

Centre in California, United States is the largest onshore wind farm outside of China, with a

capacity of (,$%$ M". As of April %$(), the (,$$$ M" *ondon Array in the U+ is the largest

offshore wind farm in the world, followed by the #$ M" !reater !abbard wind farm in the U+.

&here are many large wind farms under construction and these include Sinus -olding "indarm /$$ M"0, *incs "ind arm %/$ M"0, *ower Sna1e 2iver "ind 3ro4ect )) M"0,

Design of Wind Farm

As a general rule, economic wind generators require wind speed of (5 1m6h ($ mph0 or greater.

An ideal location would have a near constant flow of non7turbulent wind throughout the year,

with a minimum li1elihood of sudden powerful bursts of wind. An important factor of turbine

siting is also access to local demand or transmission capacity.

Usually sites are screened on the basis of a wind atlas, and validated with wind

measurements. Meteorological wind data alone is usually not sufficient for accurate siting of a

large wind power pro4ect. Collection of site specific data for wind speed and direction is crucialto determining site potential in order to finance the pro4ect. *ocal winds are often monitored for a

year or more, and detailed wind maps constructed before wind generators are installed.

&ypically, the increase of wind speeds with increasing height follows a wind profile power law,

which predicts that wind speed rises proportionally to the seventh root of altitude. 8oubling the

altitude of a turbine, then, increases the expected wind speeds by ($9, and the expected power by

)9.

Fig. 20.1: The Wind Farm


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Page 2of 5Lecture 20

Wind Turbine

A wind turbineis a device that converts 1inetic energy from

the wind into electrical power. A wind turbine used for

charging batteries may be referred to as a wind charger.

"ind turbines can rotate about either a hori:ontal or avertical axis, the former being both older and more common.

Horizontal-axis wind turbines (HAWT) have the

main rotor shaft and electrical generator at the top of a tower,

and must be pointed into the wind. Small turbines arepointed by a simple wind vane, while large turbines

generally use a wind sensor coupled with a servo motor.

Most have a gearbox, which turns the slow rotation of the

blades into a quic1er rotation that is more suitable to drive an electrical generator.

Vertical-axis wind turbines (or VAWTs) have the

main rotor shaft arranged vertically. ;ne advantage

of this arrangement is that the turbine does not need

to be pointed into the wind to be effective, which isan advantage on a site where the wind direction is

highly variable, for example when the turbine is

integrated into a building. Also, the generator and

gearbox can be placed near the ground, using a

direct drive from the rotor assembly to the ground7

based gearbox, improving accessibility for

maintenance.

Advantages of Wind Energy

'nergy source is free


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Page of 5Lecture 20

ut by the end of year

%$$), not a single wind energy

conversion system with a generating

capacity above #$$ " had been

installed in the country. &here were

only a small number of micro7plants )$$=#$$ "0 for generating electricity and more than ($$

wind power installations in use for pumping water in the coastal regions of >alochistan and Sindhprovinces. ;n commercial grid connected electricity generation programme, the !overnment of3a1istan decided to install ($$ M" wind power form at !haro7+eti >endar through A'8>

during the year %$$# but the programme is still in its beginning of implementation. ($$ M"

+enetech wind power pro4ect in >alochistan province and (#$ M" ;mega ?ond wind farm in

Sindh province which were being planned to implement in %$$$s with co7operation of two

American investors could not be implemented. Similarly pro4ects initiated in %$$( under !'

;perational 3rogramme;35 with co7financing from U installed $ wind turbines in +arachi with

total generation capacity of less than ($ M" and also installed micro7turbines of #$$ " in

various universities of >alochistan for 28 purposes. 3resently A'8> is wor1ing on wind

mapping pro4ect. 3C2'& has installed ()# units of micro wind turbine in Sindh and >alochistan

province while electrifying ()( houses with wind power generation of more than (#( 1". !ul

Muhammad village in Sindh was the first village in 3a1istan electrified through wind energy by

3C2'& by installing %5 micro7units of #$$ " each in this village.

Wind Power

mass) (velocity) / 2 = m v

B

Fig. 20.": #a$istan Wind #ower


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Capacity vs. utput

elow cut off speed windmill doesnt

function

"ind speed more often below average than

above

Windmi!! "i#e Evo!ution

E$ponentia! %rowth

Fig. 20.%: Wind &peed 's #ower

Fig. 20.(: )n*rease in Wind &peed and #owerwith Tower height


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Lecture20-AlternativeEnergyResources-WindPower