WIND ENERGY

It Blows You Away

By:
Dr. Hirra Anjum
 Introduction
■ Wind is created by the unequal heating of the Earth’s
surface by the sun. As a renewable resource, wind is
classified according to the wind power classes, which are
based on typical wind speeds.
■ Wind turbines convert the kinetic energy into mechanical
power that runs a generator to produce clean electricity.
■ There are several reasons why wind energy is growing so
rapidly. One of them is low cost (post installation) and
second is that construction of wind energy takes months
instead of years.
■ Wind turbines do not produce atmospheric emission that
causes acid rain or greenhouse gasses.
■ In other words, wind energy is both environmentally and
economically sustainable.
 History of Wind Power
■ Wind power evolved from the use of simple, light
devices driven by aerodynamic forces to heavier
drag devices and finally to light, more efficient
lifts.
■ The sailboat is the earliest known use of wind
power.
■ The first windmills were made to automate the
tasks of grain grinding and water pumping in
Persia 500-900AD
 Wind as Electricity
• The first use of a windmill to
generate electricity was in
Cleveland, Ohio in 1888 by
Charles F. Brush.
• In 1891, Dane Poul la Cour
made the first aerodynamically
(low solidity, four bladed)
designed system.
• By 1920, the la Cour system
replaced all previous sail and
fan systems.
Sizes and Applications

Small (10 kW)

• Homes Intermediate
• Farms (10-250 kW)
• Remote Application • Village Power
• Hybrid Systems
• Distributed Power

Large (660 kW - 2+MW)

• Central Station Wind Farms
• Distributed Power
• Community Wind
Large and Small Wind Turbines are
Different
■ Large Turbines (500-1500 kW)
Installed in “Windfarm” Arrays
Totaling 1 - 100 MW; $1,000/kW;
Designed for Low Cost of Energy
Requires 6m/s (13mph)
Average Sites.
■ Small Turbines (0.3-100kW)
Installed in “Rural Residential” On-
Grid and Off-Grid Applications
$2,500-5,000/kW; Designed for
Reliability/Low Maintenance.
Requires 4m/s (9mph) Average Sites
 Wind Power
■ Wind power is a measure of the energy available
in the wind. It is a function of the cube (third
power) of the wind speed.
■ If the wind speed is doubled, power in the wind
increases by a factor of six.
■ This relationship means that small differences in
wind speed lead to large differences in power.
 Equation Of Wind Power
■ The amount of power available in the wind is determined by
the equation:
w = 1/2 r A v3
w is power,
r is air density,
A is the rotor area, and
v is the wind speed.

■ This equation states that the power is equal to one-half, times

the air density, times the rotor area, times the cube of the
wind speed. Air density varies according to elevation,
temperature and weather fronts.
 Types of Wind Mills

■ Vertical Axis
■ Horizontal Axis
 Vertical Axis Turbines

■ Although vertical axis

wind turbines have
existed for centuries, they
are not as common as
their horizontal
counterparts.
■ The main reason for this
is that they do not take
advantage of the higher
wind speeds at higher
elevations above the
ground as well as
horizontal axis turbines.
 Horizontal Axis Turbine

■ This is the most common wind

turbine design. In addition to
being parallel to the ground, the
axis of blade rotation is parallel
to the wind flow.
■ Some machines are designed to
operate in an upwind mode,
with the blades upwind of the
tower.
■ In this case, a tail vane is
usually used to keep the blades
facing into the wind.
■ Other designs operate in a
downwind mode so that the
wind passes the tower before
striking the blades.
 Main Parts of Wind Mill
■ Rotor- The hub and the blades
together are referred to as the rotor.
Wind turns the blades which turn
the drive shaft.
■ Shaft- Two different shafts turn the
generator. One is used for low
speeds while another is used in high
speeds.
■ Gear Box- Gears connect the high
and low speed shafts and increase
the rotational speeds from about 10-
60 rotations per minute to about
1200-1800 rpm, the rotational speed
required by most generators to
produce power.
Generator-
■ The generator is what converts the turning motion of a wind
turbine's blades into electricity. Inside this component, coils of wire
are rotated in a magnetic field to produce electricity.
■ Different generator designs produce either alternating current (AC)
or direct current (DC), and they are available in a large range of
output power ratings.
■ The generator's rating, or size, is dependent on the length of the
wind turbine's blades because more energy is captured by longer
blades.
Controller-
■ Turns the blades on at 8-16 mph and shuts them down around 65 to
prevent any high wind damage.
Tower-
■ Tall tubular metal shaft. The taller the tower, the more power
produced.
PROS OF WIND POWER
■ Wind power Units are quickly constructed.
■ Wind generators are much smaller in size compared
other types electrical generators.
■ Small size allows wind power to be very versatile.
■ Wind power is a great compliment to a house
with a pre-existing photovoltaic system.
■ Serves as a great backup system.
■ Wind power gives off no harmful emissions
into the environment.
■ It is a renewable
resource.
■ The more time spent
researching makes
each new wind turbine
more efficient.
■ Mass production of
wind turbines drives
down costs.
• The wind blows day and night, which allows windmills to
produce electricity throughout the day. (Faster during the day)
• Energy output from a wind turbine will vary as the wind varies,
although the most rapid variations will to some extent be
compensated for by the inertia of the wind turbine rotor.
• Wind energy is a domestic, renewable source of energy that
generates no pollution and has little environmental impact. Up to
95 percent of land used for wind farms can also be used for other
profitable activities including ranching, farming and forestry.
• The decreasing cost of wind power and the growing interest in
renewable energy sources should ensure that wind power will
become a viable energy source in the United States and
worldwide.
Downfalls To Wind Energy

■ Aesthetics – “Not in my back

yard.”
■ Inefficient and unreliable
■ Hazard to bird migration
 Aesthetics

■ Turbines are around 50ft high and can be

seen for miles
■ Wind Farms use up more space than any
other form of power plant
■ Access roads will follow the construction of
a wind farm
■ Houses too close to turbines will be
disturbed by their noise
“Not In My Back Yard”
 Inefficient & Unreliable

■ It is not uncommon for turbines to be hit by

lightning strikes. This can cause damage to
the turbine, and also provoke forest fires.
■ Propellers often fall off and are not repaired
■ Inefficient: 9,369 turbines only produce 1.7
% of Germany’s power
■ No Wind = No Power
Hazard To Bird Migration
■ Turbines and power lines - English nature stated that
and a danger to migrating habitat loss, significant
birds death to birds, and
■ Proof: changes in migratory
patterns are a result of
- Wind Power Monthly stated wind farms
that large numbers of
several bird species
protected by European Law
have been killed by
turbines (1994)
- 200-300 Red Tail Hawks,
40-60 Golden Eagles are
killed each year by turbines
Growth of Wind Energy
Capacity Worldwide
Wind Energy In Pakistan
■ Pakistan has a 1,046 km coastline in the South
■ Average wind speed more than 7 m/s in Gharo Wind Corridor
■ Estimated wind potential more than 50,000 MW
■ Other sites in Balochistan, Punjab and Northern Areas being
identified
 Not everything that
counts can be counted, and
not everything that can be
counted, counts

Albert Einstein