renewable energy

1. Energy systems and architecture
Dr.Arch. Nagham Ali Hasan
Wind Power
Second semester 2014-2015

2. History of Wind usage:
 one of the earliest energy resources.
Recordedin history, first to power boats
andgrind grain, laterto pump water, press
oil,saw lumber and make paper.
Windmillswere mentioned at the
beginningof Islamic civilization (7th
century).
Windmillswere developedin Persia and
used paddles made of bundled reeds.
Egyptiansmay have been the first to go
up the Nile river around 4th century B.C,
poweredby wind.
AncientChinese used vertical axis
windmillsto grind grain and pump water.
Windmillswere introducedto Europe by
the crusaders around 1300 A.D
*windmillsused for pumping water.
Wind Today!!!
Windmillsare used for pumping
water from deep underground.
Modernwind turbine is the result
of design and materialadvances
made during the 1980s and 1990s,
which enabledwind turbines to
become increasinglyefficient.
Today,wind turbines are size same
as the traditionalEuropean
windmill.It can generate 250 to 300
kilowattsof power- a nearly tenfold
increase in efficiency.

3. Catalyst for progress: OPEC
Crisis (1970s)
• Economics
• Energy independence
• Environmental benefits Turbine
Key attributes of this period:
• Scale increase
• Commercialization
• Competitiveness
• Grid integration

5. Wind turbinesconvert the
kineticenergy in the wind into
mechanical power.
This mechanicalpower can be
used for specifictasks (such as
grindinggrain or pumping
water) or a generatorcan
convert this mechanical power
into electricity.
Windin action:
When wind strikes an object, it exerts a force in an attempt to move it out of the way. Some of
the winds’ energy is transferred to the object,in this case the windmill, causing it to move.
The energy in the wind turns two or three propeller-
like blades around a rotor. The rotor is connected to
the main shaft, which spins a generator to create
electricity.
Wind turbines are mounted on a tower to capture the
most energy. At 100 feet (30 meters) or more above
ground, they can take advantage of faster and less
turbulent wind.

6. Two types of turbine design: Horizontal axis and Vertical axis.
Horizontal axis turbines: Can reach higher altitude wind but requires a
substantial tower structure. Used in most modern wind turbine designs.
Vertical axis turbines: No need to turn into wind (yaw), easier
construction and maintenance (generator and gear box are on the ground)
level, lower efficiency.
Wind Turbine Design
Horizontal axis
Turbine
Vertical axis
Turbine

8. Drag or Lift Design
8
Drag Design
The wind literally
pushes the blades out
of the way.
Slower rotational
speeds and high torque
capabilities. Useful for
providing mechanical
work (water pumping
e.g.).
Wind turbines are designed based on either aerodynamic
Drag or Lift force.

9. Lift Design
• Blade is essentially an airfoil (like wings of
airplanes).
• When air flows past the blade, a wind
speed and pressure differential is created
between the upper and lower blade
surfaces. The pressure at the lower
surface is greater and thus acts to "lift" the
blade.
• The lift force is translated into rotational
motion.
• Lift design generally has higher efficiency
and is used in most modern turbines.
Lift

10. A Wind Turbine
Blades
Tower
Pitch
Generator
Rotor
Therotoris connected to the
main driveshaft, which spins a
generatorto create electricity.
Wind turbinesare mounted on a
towerto capturethe most energy.
At 30 metres or more above
ground, they can take advantage
of fasterand less turbulentwind.
Wind turbinescan be used to
produceelectricity fora single
homeor building, orthey can be
connectedto an electricitygrid
for more widespreadelectricity
distribution.

12. Fundamental Equation of Wind
Power
• –Wind Power depends on:
– amount of air (volume)
– speed of air (velocity)
– mass of air (density)
Power = ½ (ρ)(A)(V)3
(Cp)
A = swept area = (radius)2
, m2
V = Wind Velocity, m/sec.
ρ = Density of air = 1.2 kg/m3
at sea level, 20 o
C and dry air
Cp = Efficiency=0.35~0.45, typically
A

13. 0 ~ 5 m/s --- Wind speed is too low for generating power. Turbine is not
operational. Rotor is locked.
5 ~ 15 m/s ---- 5 m/s is the minimum operational speed. It is called “Cut-in
speed”. In 10 ~ 25 mph wind, generated power increases with
the wind speed.
15 ~ 25 m/s ---- Typical wind turbines reach the rated power (maximum operating
power) at wind speed of 15 m/s (called Rated wind speed).
Further increase in wind speed will not result in substantially
higher generated power by design. This is accomplished by, for
example, pitching the blade angle to reduce the turbine efficiency.
> 25 m/s ---- Turbine is shut down when wind speed is higher than 50mph
(called “Cut-out” speed) to prevent structure failure.
Typical Wind Turbine Operation

14. General advantages
• Wind energy is friendly to the surrounding
environment, as no fossil fuels are burnt to
generate electricity from wind energy
• Wind turbines requires less space than average
power stations.
• When combined with solar electricity, this
energy source is great for developed and
developing countries to provide a steady,
reliable supply of electricity

15. disadvantage
• The main disadvantage regarding wind
power is down to the winds unreliability
factor. In many areas, the winds strength
is not enough to support a wind turbine
• Wind turbines generally produce allot less
electricity than the average fossil fuelled
power station, which means that multiple
wind turbines are needed to make an
impact.