An Introduction to wind power
By Jack Bradley,
University of Bradford
Introduction to Wind Power
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History of wind power
Wind resource
How wind turbines work
Some basic characteristics
Relative efficiencies
Environmental Impacts
Where we use our energy
In the home
Where Our Energy Comes
From?
World Primary Energy Consumption 2001
Excluding Biomass (Approx 445EJ).
Oil
33%
Natural Gas
21%
Biomass
12%
Hydro electric
6%
Nuclear
Energy
6%
Coal
22%
Future Energy Sources
UK Wind Resource
• 990 TWh Onshore
of which 60+ will be
recoverable.
• 2869 TWh Offshore
of which 100+ will
be recoverable.
World Wind Resource
• 1200 TW World Resource
•10TW Theoretically recoverable
•Worlds Energy Consumption 1.3TW
Source Twidell And Weir
Persian (2000 b.c)
Direction of Prevailing
Wind
Windmills
1970’s and 80’s
2000+
Wind Pumps
Early Electricity
Source www.windpower.dk
World Wind Markets
Power Law
1 2
KE  mv
2
A
v
l
KE 1 m v2
Power( P) 
 .
t
2 t
m
 m ass. flowrate
t
A.l.

 A.v.
t
1
3
 P ( watts )  A .v
2
Turbine Size
Source Renewable Energy World Mar 02
Simple Wind Loggers
Wind Speed Distribution Curves
Normalised W ind Speed Distibution
k=2 Annual Mean =1
700
H our s/Year
600
500
400
300
200
100
0
0.0002
0.9
Mean
1.8
2.7
3.6
4.5
Energy Distribution
Normalised Speed and Energy Frequency
k=2 v,mean=5
F re q u e n c y
0.08
0.06
0.04
0.02
0
0
5
10
15
Wind speed (m/s)
20
25
European
Wind
Atlas
NOABL
Basic Principles Drag Machines
Basic Components of HAWT
Direction of Blade
Rotation
Low Speed Shaft
Nacelle
Swept Area
Yaw Bearing
Hub
Direction Free wind
Rotor
made up
hub and
blades
Tower
Lift Machines Horizontal Axis
Lift
True Wind
Direction
Drag
Lift Machines Horizontal Axis
Driving Force
Apparent wind
direction
True Wind
Direction
Direction of
Blade
Movement
Lift
Drag
Lift Machines Horizontal Axis
Driving Force
Apparent
wind
direction
vR
True Wind
Direction v
Lift
Direction of
Blade
Movement
Vb
Drag
Tip Speed Ratio (TSR)
BladeTip Speed
Tip Speed Ratio( ) 
Windspeed
Cp
TSR
Solidity
Total BladeArea
Solidity
Swept Area
 High Solidity machines have low TSR and High
Torque
Low Solidity machines have high TSR and low
torques
Different
Types of
WEC
Source Boyle
Anemometers
• Spot measurements
of little use.
• Average wind speeds
required
• Simple Anemometer
gives Run of Wind
measurement
UK
Wind
Speeds
Impacts
(Noise)
Source Boyle
Impacts (Visual)
Impacts (Birds)
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It is estimated for 1000MW in Holland
21,000 bird deaths
1,000,000 due to power lines
1,500,000 due to wild fowlers
9,000,000 due to road traffic
Source Winkleman 1995
Conclusions
• Huge world resource
• Power in the wind is proportional to the
cube of the speed
• Assessment of site wind speed is critical
• Like all generation wind power has
environmental impacts
• Careful siting can minimise these
problems