Ali Hassan Hafeez
Junaid Ahmad Joya
Zia Ur Rehman
What is Energy ?
Physicists, who are scientists who study force, motion and energy, say that energy is the
ability to do work, and work is moving something against a force, like gravity. There are a
lot of different kinds of energy in the universe, and that energy can do different things.
Energy can be found in many things, and takes many forms. There is a kind of energy
called kinetic energy in objects that are moving. There is something that scientists call
potential energy in objects at rest that will make them move if resistance is removed.
Sources Of Energy
All renewable energy (except tidal and geothermal power), ultimately comes from the
The earth receives 1.74 x 1017 watts of power (per hour) from the sun
About one or 2 percent of this energy is converted to wind energy (which is about 50-100
times more than the energy converted to biomass by all plants on earth
Differential heating of the earth’s surface
and atmosphere induces vertical and horizontal
air currents that are affected by the earth’s
rotation and contours of the land WIND.
e.g.: Land Sea Breeze Cycle
A typical 600 kW wind turbine has a rotor diameter of 43-44 meters, i.e. a rotor area of
some 1,500 square meters.
The rotor area determines how much energy a wind turbine is able to harvest from the
Since the rotor area increases with the square of the rotor diameter, a turbine which is
twice as large will receive
22 = 2 x 2 = 4times as much energy.
To be considered a good location for wind
energy, an area needs to have average
annual wind speeds of at least 12 miles per
Hero of Alexandria uses a wind machine to power an organ
~ 400 A.D.
Wind driven Buddhist prayer wheels
1200 to 1850
Golden era of windmills in western Europe – 50,000
9,000 in Holland; 10,000 in England; 18,000 in Germany
Multi-blade turbines for water pumping made and marketed in U.S.
Thomas Edison commissions first commercial electric generating stations in NYC and London
Competition from alternative energy sources reduces windmill population to fewer than 10,000
1850 – 1930
Heyday of the small multi-blade turbines in the US midwast
As many as 6,000,000 units installed
US Rural Electrification Administration extends the grid to most formerly isolated rural sites
Grid electricity rapidly displaces multi-blade turbine uses
Increasingly Significant Power Source
Wind currently produces less than
1% of the nation’s power.
Source: Energy Information Agency
Types of Wind Power
The major types of wind power are:
Utility-scale wind: wind turbines larger than 100 kilowatts are developed with
electricity delivered to the power grid and distributed to the end user by electric
utilities or power system operators;
Distributed or "small" wind: which uses turbines of 100 kilowatts or smaller to
directly power a home, farm or small business as it primary use;
Offshore wind: which are wind turbines erected in bodies of water around the
world, but not yet in the United States.
When wind blows past a turbine, the blades capture the energy and rotate.
This rotation triggers an internal shaft to spin, which is connected to a gearbox increasing
the speed of rotation.
The gearbox is connect to a generator that ultimately produces electricity.
Construction & Equipment
Parts of a wind turbine:
Transformer (this is not a part of the Wind Turbine)
Tower and foundation
In order to guarantee the stability of a wind turbine a pile or flat foundation is
used, depending on the consistency of the underlying ground.
The tower construction doesn’t just carry the weight of the nacelle and the rotor
blades, but must also absorb the huge static loads caused by the varying power of the
Rotor and rotor blades
The rotor is the component which, with the help of the rotor blades, converts the energy in
the wind into rotary mechanical movement.
Currently, the three-blade, horizontal axis rotor dominates.
The rotor blades are mainly made of glass-fiber or carbon-fiber reinforced plastics
The blade profile is similar to that of an airplane wing.
They use the same principle of lift. (on the lower side of the wing the passing air generates
higher pressure, while the upper side generates a pull. These forces cause the rotor to move
forwards, i.e. to rotate.)
The nacelle holds all the turbine machinery.
Turbine machinery consists of gearbox, generator, coupling and brakes to the rotor.
It rotates to follow the wind direction.
It is connected to the tower via bearings.
The gearbox converts the rotor motion of 18-50 rpm into the approx. 1,500 rpm which the
The gearbox thus takes on the task of matching the rotation speeds of the slow-moving
rotor and the fast-moving generator, and generally has several steps to cover for various
For high power wind turbines, doubly-fed asynchronous generators are most frequently
The operating rotation speed can be varied somewhat, unlike when using conventional
Another concept uses synchronous generators. A grid connection of synchronous
generators is only possible via transformers, due to the fixed rotation behavior.
The disadvantage of requiring complicated control systems is countered by the overall
efficiency and better grid compatibility.
Coupling and brake
Because of the enormous torque, the coupling between the main shaft and the
transmission is a rigid one.
The type of brake depends on the control mechanism for the blades.
These are composed of the generator, the system for the grid in feed of the
electricity, and various sensors.
Wind Direction Sensor
Wind Speed Sensor
Fault Sensor in nacelle
Control and Monitoring
The wind turbine contains components for following the wind direction, for
cooling, heating and lightning protection, as well as lifting gear (e.g. winches for spare
parts) and fire extinguishing equipment.
Working of Turbines
3 Phase High
Typical Wind Turbine Operation
Wind Speed is too low for generation power. Turbine is not operational. Rotor
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.
typical wind turbines reach the rated power at wind speed of 15 m/s.
Turbine is shut down when speed is higher than 50 mph (called “Cut-Out”
speed) to prevent structure failure
Wind Power Advantages
Fuel Diversity & Conservation
No air pollution
No greenhouse gasses
Does not pollute water with mercury
No water needed for operations
Pollution from Electric Power
Toxic Heavy Metals
Electric power is a primary source of industrial air pollution
Economic Development Benefits
Expanding Wind Power development brings jobs to rural communities
Increased tax revenue
Purchase of goods & services
Cost Stability Benefits
hedge against fuel price volatility risk
Wind electricity is inflation-proof
Power in the Wind (W/m2)
= 1/2 x air density x swept rotor area x (wind speed)3
Density = P/(RxT)
P - pressure (Pa)
R - specific gas constant (287 J/kgK)
T - air temperature (K)
Area = r2
(not mean speed)
Siting a Wind Farm
Minimum class 4 desired for utility-scale wind farm (>7 m/s at hub height)
Distance, voltage excess capacity
Visual, noise, and bird impacts are biggest concern
Economies of scale in construction
Number of landowners
Intermittent source of power
Operational characteristics different from conventional fuel sources
Wind Energy and the Grid
Small project size
Short/flexible development time
Generally remote location
Grid connectivity -- lack of transmission capability
Only When the wind blows (night? Day?)
Low capacity factor
Predicting the wind -- we’re getting better
Birds - A Serious Obstacle
Birds of Prey (hawks, owls, golden eagles) in jeopardy
Altamont Pass – News Update – from Sept 22
shut down all the turbines for at least two months each winter
eliminate the 100 most lethal turbines
Replace all before permits expire in 13 years
Wind Energy- The need of Pakistan
Now-a-days Pakistan is suffering from a great downfall of energy that is causing a great
loss in all walks of life.
Now Pakistan need a permanent and reliable source of energy, i.e. THE WIND ENERGY
There are many sites in Pakistan that are compatible for installing the Wind Turbines.
In future, if Pakistan work on this permanent source of energy, In Sha ALLAH, we will
overcome this shortfall of energy.