wind turbines
TRANSCRIPT
Wind Turbineshttps://pursuitengineering.blogspot.com/2017/02/wind-
turbines.html
• A wind turbine works the opposite of 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.
• 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.
• If the mechanical energy is then converted to electricity, the machine is
called a wind generator.
Types of Wind Turbines
Wind turbines are classified into two general types
• Horizontal axis• Vertical axis
A horizontal axis machine has its blades rotating on an axis parallel to the ground
A vertical axis machine has its blades rotating on an axis perpendicular to the ground
Horizontal-axis wind turbines (HAWT)
Theses wind turbines typically either have two or three
blades. These three-bladed wind turbines are operated
"upwind," with the blades facing into the wind.
Horizontal-axis wind turbines (HAWT)
Up-Wind Turbines
Some wind turbines are designed to
operate in an upwind mode (with the
blades upwind of the tower). Large
wind turbines use a motor-driven
mechanism that turns the machine in
response to a wind direc tion. Smaller
wind turbines use a tail vane to keep
the blades facing into the wind
Horizontal-axis wind turbines (HAWT)
Down-Wind Turbines
Other wind turbines operate in
a downwind mode so that the
wind passes the tower before
striking the blades. Without a
tail vane, the machine rotor
naturally tracks the wind in a
downwind mode.
Horizontal-axis wind turbines (HAWT)
Shrouded Wind Turbines
Some turbines have an added structural design feature called an augmentor. The augmentor is intended to increase the amount of wind passing through the blades.
Vertical-axis wind turbines (VAWT)
Vertical-axis wind turbines (VAWT)
Savonius Wind Turbine
The Savonius turbine is S-shaped if
viewed from above. This drag-type
VAWT turns relatively slowly, but yields
a high torque. It is useful for grinding
grain, pumping water, and many other
tasks, but its slow rotational speeds
make it unsuitable for generating
electricity on a large-scale
Vertical-axis wind turbines (VAWT)
Flapping Panel Wind Turbine
This illustration shows the wind coming from one direction, but the wind can actually come from any direction and the wind turbine will work the same way
Vertical-axis wind turbines (VAWT)
Darrieus Wind Turbine
The Darrieus turbine is the most famous vertical axis wind turbone. It is characterized by its C-shaped rotor blades which give it its eggbeater appear ance. It is normally built with two or three blades.
Vertical-axis wind turbines (VAWT)
Giromill Wind Turbine
The giromill is typically powered by two or three vertical aerofoil’s attached to the central mast by horizontal supports. Giromill turbines work well in turbulent wind conditions and are an affordable option where a standard horizontal axis windmill type turbine is unsuitable
Parts of a Wind Turbine
• The nacelle contains the key components of the wind turbine, including the gearbox, and the electrical generator.
• The tower of the wind turbine carries the nacelle and the rotor. Generally, it is an advantage to have a high tower, since wind speeds increase farther away from the ground.
• The rotor blades capture wind energy and transfer its power to the rotor hub.
• The generator converts the mechanical energy of the rotating shaft to electrical energy
• The gearbox increases the rotational speed of the shaft for the generator
Installing a Wind Turbine
• The basic steps for installing a small wind turbine on your property are:
• Determine whether the wind resource in your area makes a small wind system economical.
• Determine your household electricity needs by checking your monthly or yearly electricity usage.
• Find out whether local zoning ordinances allow wind turbine installations.
• Purchase and install a wind turbine sized to the needs of your household.
Siting a Wind Farm
• Winds Minimum class 4 desired for utility-scale wind farm (>7 m/s at hub height)
• Transmission Distance, voltage excess capacity
• Permit approval Land-use compatibility Public acceptance Visual, noise, and bird impacts are biggest concern
• Land area Economies of scale in construction Number of landowners
Advantages of Wind Power
• Environmental• Economic Development• Fuel Diversity & Conservation• Cost Stability• small project size• Short/flexible development time • Dispatch ability
Disadvantages
• Generally remote location • Grid connectivity -- lack of transmission capability • Intermittent output only when the wind blows • Low capacity factor• Birds of Prey (hawks, owls, golden eagles) in jeopardy • Shutting down all the turbines for at least two months
each winter• Replace all before permits expire in 13 years
Wind Energy and Power
Atmospheric pressure differences accelerate and impart kinetic energy into the air
Wind energy conversion machines (WEC) convert wind energy into electrical or mechanical forms
How much power can we extract?
Wind Energy Natural Characteristics
• Wind Speed
Wind energy increases with the cube of the wind speed 10% increase in wind speed translates into 30% more electricity
2X the wind speed translates into 8X the electricity
Wind energy increases with height to the 1/7 power2X the height translates into 10.4% more electricity
• Air density
Wind energy increases proportionally with air density
Humid climates have greater air density than dry climates
Lower elevations have greater air density than higher elevations
Wind energy in Denver about 6% less than at sea level Blade swept area
Wind energy increases proportionally with swept area of the blades
• Blades are shaped like airplane wings10% increase in swept diameter translates into 21% greater swept area
Longest blades up to 413 feet in diameter, resulting in 600 foot total height
• Height
Wind energy increases with height to the 1/7 power
2X the height translates into 10.4% more electricity