WIND POWER

							Wind Power

   Technical Science in
   Electrical Trades
Essential Question

 Is wind energy a dependable source of electricity? Why
  or why not?
 How does a wind turbine produce electricity?
Wind Energy Research

As stated by the US Department of Energy:
   Our Nation's wind energy resources can
  provide an inexhaustible domestic source
     of energy. By developing these wind
    resources, we can help stimulate rural
  economic development, displace harmful
  emissions created by traditional fuels, and
 increase our options for low-cost electricity
                 generation.
What is wind?

 Air circulation and wind patterns are complex and due to the earth’s rotation on its
  axis (Coriolis Effect)
 The underlying cause of wind is the unequal hearing of the Earth’s surface
  (insolation= in coming solar radiation). In tropical regions, more solar ration is
  received than is radiated back to space. In regions near the poles, less solar radiation
  is received than lost.
 Wind is caused by topographic effects of by variations in surface composition in the
  immediate area.
     •Uneven heating of the Earth’s surface (due to surface texture, color, soil, water, etc)
     by the sun causes the wind. The warmer air in some places rises. The resulting low
     pressure area draws in cooler air.



     •Wind energy potential increases very rapidly with increasing wind speed. If fact, if
     wind speed doubles the energy content goes up by a factor of eight.
Coriolis Effect
Coriolis Effect explained

 As air moves from high to low pressure in the northern hemisphere, it
  is deflected to the right by the Coriolis force. In the southern
  hemisphere, air moving from high to low pressure is deflected to the
  left by the Coriolis force.
 The amount of deflection the air makes is directly related to both the
  speed at which the air is moving and its latitude. Therefore, slowly
  blowing winds will be deflected only a small amount, while stronger
  winds will be deflected more. Likewise, winds blowing closer to the
  poles will be deflected more than winds at the same speed closer to
  the equator. The Coriolis force is zero right at the equator.
             1. Warm air over land rises
             2. Sea Breeze moves inland
      3. Cumuli develop aloft and move seaward
          4. Upper level return land breeze
          5. Cool air aloft sinks over water
           6. Sea Breeze (meso-cold) Front

Why is is so important near Lake Ontario to understand
       a Sea Breeze Circulation for wind power?
The land-sea breezes are caused by the
  uneven warming of land and large bodies
  of water. (the uneven heating is due to
  specific heat required to warm up water
  and land) The sea breeze develops because
  cooler air over the water at higher
  pressures moves towards the warmer land.
  Wind Turbines take advantage of this daily
  occurrence.
Mountain and Valley Breezes

 In mountainous regions, the sides of the mountains are exposed to sunlight for longer
  periods of the day, than the valleys. As a result, the air near the sides of the mountains
  becomes warmer than the surrounding air and it rises throughout the day; the upward
  moving air is replaced from air within the valleys. Therefore, during the day, valley air
  moves up the sides of the mountain. This process is responsible for clouds and
  precipitation that occurs over mountainous terrain almost every day in the summer!
 At night, the sides of the mountain cool. This cool air is pulled downward by gravity.
  Therefore, in the morning, the coldest air often is found within the valley. If the air is
  moist enough, then valley fog may form.
Winds of the United States
Wind Energy Potential

                                    




    Percent U.S. Land Area with Wind Resource Class 3 or Above (Annual)
Wind Power Plant
A Working Wind Turbine






      http://www.nrel.gov/wind/animation.html - animation
Parts of a Wind Turbine
   Anemometer: Measures the wind speed and transmits wind speed data to the
    controller.
   Blades: Most turbines have either two or three blades. Wind blowing over the
    blades causes the blades to "lift" and rotate.
   Brake: A disc brake which can be applied mechanically, electrically, or
    hydraulically to stop the rotor in emergencies.
   Controller: The controller starts up the machine at wind speeds of about 8 to
    16 miles per hour (mph) and shuts off the machine at about 65 mph. Turbines
    cannot operate at wind speeds above about 65 mph because their generators
    could overheat.
   Gear box: Gears connect the low-speed shaft to the high-speed shaft and
    increase the rotational speeds from about 30 to 60 rotations per minute (rpm)
    to about 1200 to 1500 rpm, the rotational speed required by most generators
    to produce electricity. The gear box is a costly (and heavy) part of the wind
    turbine and engineers are exploring "direct-drive" generators that operate at
    lower rotational speeds and don't need gear boxes.
   Generator: Usually an off-the-shelf induction generator that produces 60-
    cycle AC electricity.
   High-speed shaft: Drives the generator.
   Low-speed shaft: The rotor turns the low-speed shaft at about 30 to 60
    rotations per minute.
Parts of a Wind Turbine,
(Continued)
   Nacelle: The rotor attaches to the nacelle, which sits atop the tower and
    includes the gear box, low- and high-speed shafts, generator, controller, and
    brake. A cover protects the components inside the nacelle. Some nacelles are
    large enough for a technician to stand inside while working.
   Pitch: Blades are turned, or pitched, out of the wind to keep the rotor from
    turning in winds that are too high or too low to produce electricity.
   Rotor: The blades and the hub together are called the rotor.
   Tower: Towers are made from tubular steel (shown here) or steel lattice.
    Because wind speed increases with height, taller towers enable turbines to
    capture more energy and generate more electricity.
   Wind direction: This is an "upwind" turbine, so-called because it operates
    facing into the wind. Other turbines are designed to run "downwind", facing
    away from the wind.
   Wind vane: Measures wind direction and communicates with the yaw drive to
    orient the turbine properly with respect to the wind.
   Yaw drive: Upwind turbines face into the wind; the yaw drive is used to keep
    the rotor facing into the wind as the wind direction changes. Downwind
    turbines don't require a yaw drive, the wind blows the rotor downwind.
   Yaw motor: Powers the yaw drive.
  Wind Energy Now World's Fastest-
    Growing Energy Generation
            Technology
 Wind energy is the fastest-growing type of energy
  generation in the United States and around the world.
  Global wind energy capacity reached 31,000 MW by the
  end of 2002.
 The United States had almost 4,700 MW of installed
  wind energy capacity, enough to power almost 3 million
  average homes. Utility-scale wind power plants are now
  located in 27 states. The average U.S. wind energy
  growth rate for the past five years is 24%. This growth
  can be attributed to a greatly reduced cost of production
  (from 80 cents [current dollars] per kilowatt-hour [kWh]
  in 1980 to 4 cents per kWh in 2002).
Question….

   How can a group of wind turbines can make electricity
  for the utility grid? The electricity is sent through
  transmission and distribution lines to homes, businesses,
  schools, and so on.

 Three-bladed wind turbines are operated "upwind," with
  the blades facing into the wind. The other common wind
  turbine type is the two-bladed, downwind turbine.
So how do wind turbines make
electricity?
 Simply stated, a wind turbine works
 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.
 Utility-scale turbines range in size from
 50 to 750 kilowatts. Single small
 turbines, below 50
Question…

Ok so the wind turns the blades and then
  spins a shaft that is connected to a
  generator to make electricity. How does
  the generator change mechanical energy to
  electrical energy?
Converting mechanical energy
to electrical energy
 The generator is based on the principle of
  "electromagnetic induction" discovered in 1831
  by Michael Faraday, a British scientist. Faraday
  discovered that if an electric conductor, like a
  copper wire, is moved through a magnetic field,
  electric current will flow (be induced) in the
  conductor. So the mechanical energy of the
  moving wire is converted into the electric energy
  of the current that flows in the wire.
Converting mechanical energy
to electrical energy
 Mechanical energy needed to turn the generator comes
  from the hand crank at the front of the generator. In a
  power plant, the mechanical energy to turn the generator
  comes from the wind turbine, which is turned by the force
  of wind. The hand crank causes the wire to spin inside a
  magnetic field. As Faraday learned, moving the wire
  through the magnetic field causes electric current to flow
  in the wire. The turning red wire is connected to a volt
  meter, which shows the amount of electric current that is
  produced. In a hydroelectric or wind plant, the generator
  is connected to transmission lines that deliver the
  electricity to your home or business.
How a generator works

Http://www.wvic.com/how-gen-works.htm
Potential

 The considerable wind electric potential has not
  been tapped before because wind turbine
  technology was not able to utilize this resource.
  However, during the past decade, increased
  knowledge of wind turbine behavior has led to
  more cost-effective wind turbines that are more
  efficient in producing electricity. The price of the
  electricity produced from wind by these
  advanced turbines is estimated to be competitive
  with conventional sources of power, including
  fossil fuels.
In conclusion

 A demand for clean, diverse sources of electricity, and state and
  federal incentives to stimulate the market also contributed to wind
  energy's growth.
 Wind energy is valued as a dependable source of electricity
  worldwide. As a renewable, domestic resource, wind energy is poised
  to become our least expensive form of bulk electricity generation.
  Although the promise of wind energy is immense, continued industry
  growth rests heavily on sustaining aggressive research, development,
  and support programs.
 In order to expand wind energy's contribution to the nation, the US
  Department of Energy’s Wind and Hydropower Technology
  Program's wind energy research focuses on the two elements of its
  mission:
        Increasing the technical viability of wind systems, and
        Increasing the use of wind power in the marketplace.
Now, lets answer your
Essential Questions…..

 Is wind energy a dependable source of electricity? Why
  or why not?
 How does a wind turbine produce electricity?
Sources

 http://www.nrel.gov/wind/
 http://www.nrel.gov/wind/wind_potential.html
 http://www.wvic.com/how-gen-works.htm
 http://eereweb.ee.doe.gov/windandhydro/wind_re
  search.html
 http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/f
  w/crls.rxml
 Tarbuck and Lutgens, Earth Science by Prentice
  Hall, 2006