Transcript Slide 1
ENERGY FROM THE WIND WIND TECHNOLOGIES EDUCATION MODULE
__________________________ © Cactus Moon Education, LLC.
CACTUS MOON EDUCATION, LLC www.cactusmooneducation.com
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Slide 7 – 9
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Slide 10 – 13
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Slide 15
INDEX
Title Slide Index Wind Basics Wind Technology Wind Turbine Development Wind Turbine Components Wind Farms 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.
The power in the wind is proportional to the cube of the wind speed!
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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) 1981 10 45 1990 27 225 2000 71 1,650 2009 120 2,600 __________________________ © Cactus Moon Education, LLC.
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
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 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
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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
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Towers are transported in sections on flatbed semi-trucks and assembled on site.
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The other sections are hoisted by cranes and bolted together.
The bottom section is bolted to the concrete foundation.
5 4
The height of the tower is selected to optimize energy capture.
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250 to 300 feet
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The gearbox converts the slow speed of the blades into a high speed to drive the generator.
The Nacelle
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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. __________________________ © Cactus Moon Education, LLC.