Ain Shams University Wind Energy, ERGY 530
Faculty of Engineering Spring-2017
New Programs, CHEP
Where Does the Wind Come From?
• Uneven heating of the Earth
– What if the Earth did not rotate?
Where Does the Wind Come From?
• Add rotation (and thus the Coriolis effect) and
what happens?
Where Does the Wind Come From?
• Secondary and tertiary
circulations also occur
around the earth
– Secondary
• Hurricanes (tropical cyclones)
• Extratropical cyclones
– Tertiary
• Uneven heating due to terrain
or surface properties
– Land/sea breezes
– Mountain/valley breezes
– Thunderstorms
– Tornadoes
Power in the Wind Foundations
•
mass m kg
Density [ 3]
volume V m
• Volume area * length AL [m 3 ]
• Velocity
length L m
time
[ ]
t s
• Power
energy J
time
[ W]
s
• Energy 1
2
1
K . E . mass * ( velocity ) 2 mv 2 [ J ]
2
Come up with an equation for power as a function only of Area, Velocity and Density:
1 2 1 1
K .E. 2 mv ( V ) v 2
( AL ) v 2
1
Power 2 2 Av 3
t t t t 2
What Happens to the Wind as you Go
Up in Elevation?
A sample graph of wind speeds from 0 to 140 m
L
( )
= TI
𝑁
𝑣 3
𝑖𝑥= h
WPD = ½ ρ 𝑁
ρ
𝑣m
𝑣ℎ
𝑁
𝑣 3
ℎ=1 h
EPF = 𝑁𝑣m 3
Power in the Wind
kg m
• Let’s check our units: N 2
s
1 J Nm
PW Av 3
2
3
2
kg m kg m
m 2
3 3
m s s
kg m 2 N m J
s 3
s
s
Watt
Capacity Factor
24 hr 365 days
# hr / yr 8760 hr / yr
day yr
The amount of energy generated divided by the
amount which could be produced if the turbine were
running at its full capacity all of the time.
Typically considered over a year, but could be
measured over any timeframe.
