Wind Power

1. Wind Power Technical Science in Electrical Trades

2. Essential Question • Is wind energy a dependable source of electricity? Why or why not? • How does a wind turbine produce electricity?

3. 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.

4. 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. 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.

5. Coriolis Effect

6. 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.

7. Warm air over land rises • Sea Breeze moves inland • Cumuli develop aloft and move seaward • Upper level return land breeze • Cool air aloft sinks over water • Sea Breeze (meso-cold) Front Why is is so important near Lake Ontario to understand a Sea Breeze Circulation for wind power?

8. 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.

9. 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.

10. Winds of the United States

11. Wind Energy Potential Percent U.S. Land Area with Wind Resource Class 3 or Above (Annual)

12. Wind Power Plant

13. A Working Wind Turbine http://www.nrel.gov/wind/animation.html - animation

14. 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.

15. 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.

16. 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).

17. 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.

18. 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

19. 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?

20. 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.

21. 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.

22. How a generator works • Http://www.wvic.com/how-gen-works.htm

23. 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.

24. 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.

25. 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?

26. 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_research.html • http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/fw/crls.rxml • Tarbuck and Lutgens, Earth Science by Prentice Hall, 2006