Transcript Slide 1

ENERGY FROM THE WIND
WIND
TECHNOLOGIES
EDUCATION MODULE
CACTUS MOON
EDUCATION, LLC
www.cactusmooneducation.com
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© Cactus Moon Education, LLC.
INDEX
• Slide 1
Title Slide
• Slide 2
Index
• Slide 3 – 4
Wind Basics
• Slide 5 – 6
Wind Technology
• Slide 7 – 9
Wind Turbine Development
• Slide 10 – 13
Wind Turbine Components
• Slide 14
Wind Farms
• Slide 15
The Future
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Historical Use of Wind Energy
• Wind energy has been used for
many years.
• It has been used to drive the
earliest sailing ships in Egypt,
grind flour and meal in
England, and pump water to
keep the land dry in Europe.
• More recently, wind energy has
been used to generate
electricity.
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Where Does the Wind Come From?
•
The sun heats the earth unevenly and
some parts of the earth become
warmer than others.
•
The air in contact with the warmer land
areas becomes warm and rises.
•
As the warm air rises, cooler air
moves in to take its place.
•
The wind we feel is simply the moving
air molecules and the energy in the
wind is the energy in the moving air.
•
The energy in the wind is the kinetic
energy of the moving air molecules.
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Betz’s Law
• We need to keep the wind
moving forwards after it has
gone through the turbine
blades.
• The optimum situation is to
extract 59% of the wind energy
(Betz’s Law).
• The turbine/generator converts
about 70% of the captured
energy into electricity.
• 40% of the wind’s total energy
can be converted into
electricity.
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Wind Turbine Power Curve
• A typical wind turbine will “cut in” and
begin to produce power at a wind
speed of about 12 mph.
• It will reach its rated power output at
about 28 to 30 mph.
• At this point, the blade pitch control
system will begin to limit the power
output to prevent overloading the
generator.
• At about 50 mph, the control system
pitches the blades to stop rotation to
prevent damage to the turbine’s
components.
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The power in
the wind is
proportional to
the cube of the
wind speed!
Wind Turbine Development
• Over the years advances in wind turbine
technology has increased the power of wind
machines.
• The size of the turbine
blades has increased.
• The power of the
turbines has increased.
Year
Rotor Diameter (meters)
Rating (kW)
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1981
10
45
1990
27
225
2000
71
1,650
2009
120
2,600
Wind machines - 1
• Horizontal Axis Wind Turbines (HAWT) have the main
rotor shaft and electrical generator at the top of a tower.
• HAWT machines look like conventional windmills.
• The tall tower allows access to stronger winds.
• Vertical Axis Wind Turbines (VAWT) have a vertical rotor
shaft with the electrical generator placed on the ground.
• VAWT machines look like giant eggbeaters.
• VAWTs have lower wind startup speeds than HAWTs.
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Wind Machines - 2
VAWT TECHNOLOGY
Savonius Turbines
Uses drag-type technology,
not as efficient as other
type of windmills
Darrieus Turbines
The Darrieus wind
turbine consists of a
number of aerofoils
Wind
HAWT TECHNOLOGY
Wind
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The blades rotate at about
20 RPM. The pitch of the
blades can be changed to
control the speed of the
rotor under different wind
conditions.
Wind Turbine Components
The tower contains the wires that feed the generated
electricity to the grid, and the ladder access to the upper
part of the windmill.
The Nacelle contains the gears,
shaft, and electrical generator,
The blades are driven by the wind and
spin around to run the equipment in the
Nacelle.
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The Tower
Towers are transported
1 in sections on flatbed
semi-trucks and
assembled on site.
The other sections
3 are hoisted by
cranes and bolted
together.
2 The bottom section is bolted
to the concrete foundation.
5
The height of the tower is selected to
4 optimize energy capture.
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250 to
300 feet
The Nacelle
The gearbox converts the
1 slow speed of the blades
into a high speed to drive
the generator.
2 The high speed shaft
turns the generator to
make electricity.
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The Blades
• The turbine blade length is based on the
desired output power of the wind turbine.
–
L=(P/(Cp*0.5*air density*pi*(wind velocity^3)))^0.5
(Cp is typically 0.45)
• The turbine blades are made from molded
fiberglass composite or epoxy-based
composite.
• The turbine blades are transported on flatbed
semi-trucks to the wind farm and attached to
the nacelle on site.
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Wind Farms
•
Wind farms are groups of wind turbines
located in areas where there is a good wind
resource.
•
Areas with good wind resources are seldom
found close to load centers and so dedicated
transmission lines are often required.
•
Wind farms are very land
intensive, and typically
require 60 Acres/MW.
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A Look into the Future
• “Monster” 4 to 8 MW turbines are on the horizon,
especially for off-shore installations.
• New foundation designs will be required as turbines
find deeper water - maybe floating foundations will
be used in water deeper than 200 feet.
• Turbines are being developed with no gearbox to
increase reliability.
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