WIND ENERGY TYPES ,CAUSES, ETC

1. Wind Energy
By Group 2 – Seminar for E.V.S.By Group 2 – Seminar for E.V.S.

2. Cause for Wind Energy
• Wind is a form of solar energy. Wind is caused by huge
convection currents in the Earth's atmosphere, driven by
heat energy from the Sun. This means as long as the
sun shines, there will be wind.
• Winds are caused by the uneven heating of the
atmosphere by the sun, the irregularities of the earth's
surface, and rotation of the earth. Wind flow patterns are
modified by the earth's terrain, bodies of water, and
vegetative cover. This wind flow, or motion energy, when
"harvested" by modern wind turbines, can be used to
generate electricity.

3. How do winds form?
• Typically, this begins with the sun’s radiation, which is absorbed
differently on the earth’s surface. The earth's surface is heated
differently because of scenarios like cloud cover, mountains,
valleys, water bodies, vegetation and desert lands.
• As a result of this uneven heating, there are bound to be earth
surfaces that vary a lot in temperature. Air on surfaces with higher
temperatures will then begin to rise because it is lighter (less
dense). As the air rises, it creates low atmospheric pressure. Air on
surfaces with cooler temperatures sink (do not rise). The sinking
creates higher atmospheric pressure. This behaviour or warm gases
or liquids moving upward and being replaced by cooler particles is
called Convection. The energy moving during convection is
called convectional current.

4. Title
In the diagram above, notice how cool air falls, resulting in high
pressure, and moving towards regions of low pressure.

5. Classification of winds
Beaufort scale is an empirical measure that relates
wind speed to observed conditions at sea or on land.

6. Types of winds

7. Land and Sea Breezes
• In the night, the reverse happens. The
land quickly loses its’ heat whiles the
water retains its’ warmth. This means
the air over the water is warmer, less
dense and begins to rise. Low
pressure is created over the water.
Cold and dense air over the land
begins to move to the water surface to
replace the warmer rising air. The cool
breeze from the land is called a
land breeze.or offshore breeze
• In the day, when the sun is up, the
land heats up very quickly and the air
above it warms up a lot more than the
air over the water. The warm air over
the land is less dense and begins to
rise. Low pressure is created.
The air pressure over the water is
higher with cold dense air, which
moves to occupy the space created
over the land. The cool air that comes
along is called a sea breeze or
onshore breeze

8. Global wind

9. How Wind Power Is Generated
• The terms "wind energy" or "wind
power" describe the process by which the
wind is used to generate mechanical
power or electricity. Wind turbines
convert the kinetic energy in the wind into
mechanical power. This mechanical power
can be used for specific tasks (such as
grinding grain or pumping water) or a
generator can convert this mechanical
power into electricity to power homes,
businesses, schools, and the like.

10. Wind Power
• Wind power has been used as long as humans have put sails into
the wind. For more than two millennia wind-powered machines have
ground grain and pumped water.
• The first windmill used for the production of electricity was built in
Scotland in July 1887 by Prof James Blyth of Anderson's College,
Glasgow (the precursor of Strathclyde University). Blyth's 10 m high,
cloth-sailed wind turbine was installed in the garden of his holiday
cottage at Marykirk in Kincardineshire and was used to charge
accumulators developed by the Frenchman Camille Alphonse Faure
, to power the lighting in the cottage, thus making it the first house in
the world to have its electricity supplied by wind power. Blyth offered
the surplus electricity to the people of Marykirk for lighting the main
street, however, they turned down the offer as they thought
electricity was "the work of the devil."

11. Charles Brush's windmill of 1888, used for
generating electricity.

12. OFFSHORE AND
ONSHORE WIND POWER
TURBINES

13. Onshore wind power
• Wind farms consist of many individual wind turbines
which are connected to the electric power transmission
network. Onshore wind is an inexpensive source of
electricity, competitive with or in many places cheaper
than coal or gas plants.

14. Onshore Horizontal Axis Wind Turbines in
Zhangjiakou, China

15. Offshore wind power
• Offshore wind is steadier and stronger than on land, and
offshore farms have less visual impact, but construction and
maintenance costs are considerably higher. Small onshore wind
farms can feed some energy into the grid or provide electricity to
isolated off-grid locations.
• Offshore wind power refers to the construction of wind farms in large
bodies of water to generate electricity. These installations can utilize
the more frequent and powerful winds that are available in these
locations and have less aesthetic impact on the landscape than land
based projects. However, the construction and the maintenance
costs are considerably higher.
• World's largest offshore wind farms
London Array with a capacity of 630megawatts in United Kingdom
commisioned in 2012.

16. Offshore Horizontal Axis Wind Turbines (HAWTs) at
Scroby Sands Wind Farm, UK

17. wind turbine
• A wind turbine is a device that converts kinetic energy from the
wind into electrical power.
• Wind turbines, like aircraft propeller blades, turn in the moving air
and power anelectric generator that supplies an electric current.
Simply stated, a wind turbine is the opposite of a fan. Instead of
using electricity to make wind, like a fan, wind turbines use wind to
make electricity. The wind turns the blades, which spin a shaft,
which connects to a generator and makes electricity.

18. Wind Turbine Types
• Modern wind turbines fall into two basic groups; the horizontal-
axis variety, like the traditional farm windmills used for pumping
water, and the vertical-axisdesign, like the eggbeater-style
Darrieus model, named after its French inventor. Most large modern
wind turbines are horizontal-axis turbines.

19. Horizontal-axis wind turbines
• Horizontal-axis wind turbines (HAWT) have the main rotor shaft
and electrical generator at the top of a tower, and must be pointed
into the wind. Small turbines are pointed by a simple wind vane,
while large turbines generally use a wind sensor coupled with
a servo motor. Most have a gearbox, which turns the slow rotation of
the blades into a quicker rotation that is more suitable to drive an
electrical generator.[22]
• Since a tower produces turbulence behind it, the turbine is usually
positioned upwind of its supporting tower. Turbine blades are made
stiff to prevent the blades from being pushed into the tower by high
winds. Additionally, the blades are placed a considerable distance in
front of the tower and are sometimes tilted forward into the wind a
small amount.

21. Vertical-axis wind turbine
• Vertical-axis wind turbines (or VAWTs) have the main rotor shaft arranged
vertically. One advantage of this arrangement is that the turbine does not
need to be pointed into the wind to be effective, which is an advantage on a
site where the wind direction is highly variable. It is also an advantage when
the turbine is integrated into a building because it is inherently less
steerable. Also, the generator and gearbox can be placed near the ground,
using a direct drive from the rotor assembly to the ground-based gearbox,
improving accessibility for maintenance.
• The key disadvantages include the relatively low rotational speed with the
consequential higher torque and hence higher cost of the drive train, the
inherently lower power coefficient, the 360 degree rotation of the aerofoil
within the wind flow during each cycle and hence the highly dynamic loading
on the blade, the pulsating torque generated by some rotor designs on the
drive train, and the difficulty of modelling the wind flow accurately and hence
the challenges of analysing and designing the rotor prior to fabricating a
prototype.

22. Types of VAWT
• Darrieus wind turbine
Darrieus wind turbines are commonly called "Eggbeater" turbines, because
they look like a giant eggbeater. They have good efficiency, but produce
large torque ripple and cyclic stress on the tower, which contributes to poor
reliability. Also, they generally require some external power source, or an
additional Savonius rotor, to start turning, because the starting torque is
very low. The torque ripple is reduced by using three or more blades which
results in a higher solidity for the rotor. Solidity is measured by blade area
over the rotor area. Newer Darrieus type turbines are not held up by guy-
wires but have an external superstructure connected to the top bearing.
• Savonius wind turbine
A Savonius is a drag type turbine, they are commonly used in cases of high
reliability in many things such as ventilation and anemometers. Because
they are a drag type turbine they are less efficient than the common HAWT.
Savonius are excellent in areas of turbulent wind and self starting.

25. Turbine Components
• Horizontal turbine components include:
• blade or rotor, which converts the energy in the wind to rotational shaft
energy;
• a drive train, usually including a gearbox and a generator;
• a tower that supports the rotor and drive train; and
• other equipment, including controls, electrical cables, ground support
equipment, and interconnection equipment.
• Turbine Configurations
• Wind turbines are often grouped
together into a single wind power plant,
also known as a wind farm, and generate
bulk electrical power. Electricity from
these turbines is fed into a utility grid
and distributed to customers, just as
with conventional power plants.

26. Advantages and Disadvantages of Wind-
Generated Electricity
• A Renewable Non-Polluting Resource
• Wind energy is a free, renewable resource, so no matter how much is used today,
there will still be the same supply in the future. Wind energy is also a source of clean,
non-polluting, electricity. Unlike conventional power plants, wind plants emit no air
pollutants or greenhouse gases. According to the U.S. Department of Energy, in
1990, California's wind power plants offset the emission of more than 2.5 billion
pounds of carbon dioxide, and 15 million pounds of other pollutants that would have
otherwise been produced. It would take a forest of 90 million to 175 million trees to
provide the same air quality.
• Cost Issues
• Even though the cost of wind power has decreased dramatically in the past 10 years,
the technology requires a higher initial investment than fossil-fueled generators.
Roughly 80% of the cost is the machinery, with the balance being site preparation
and installation. If wind generating systems are compared with fossil-fueled systems
on a "life-cycle" cost basis (counting fuel and operating expenses for the life of the
generator), however, wind costs are much more competitive with other generating
technologies because there is no fuel to purchase and minimal operating expenses.

27. Advantages and Disadvantages of Wind-
Generated Electricity
• Environmental Concerns
• Although wind power plants have relatively little impact on the environment compared
to fossil fuel power plants, there is some concern over the noiseproduced by the
rotor blades, aesthetic (visual) impacts, and birds and bats having been killed
(avian/bat mortality) by flying into the rotors. Most of these problems have been
resolved or greatly reduced through technological development or by properly siting
wind plants.
• Supply and Transport Issues
• The major challenge to using wind as a source of power is that it is intermittentand
does not always blow when electricity is needed. Wind cannot be stored (although
wind-generated electricity can be stored, if batteries are used), and not all winds can
be harnessed to meet the timing of electricity demands. Further, good wind sites are
often located in remote locations far from areas of electric power demand (such as
cities). Finally, wind resource development may compete with other uses for the land,
and those alternative uses may be more highly valued than electricity generation.
However, wind turbines can be located on land that is also used for grazing or even
farming.

29. THANK YOU
IT’S THE END……………..