Wind Poster

Highlights

• How do Wind turbines work? Very similarly as airplane wings. When the wind passes over the blade it creates a localized low pressure area behind the blade. The blade is then pulled into this area, causing the rotor to turn. This is called lift. The push of the wind on the blade is drag. The force of lift is significantly stronger than the drag. The combination of lift and drag cause the rotor to turn and spins the generator creating electricity. In turbines, the blades are connected to a drive shaft that turns a generator that creates electricity.
• HAWT vs. VAWT
  • Hawt - Horizontal Axis Wind Turbine – make up 95% of all wind machines in the world. The blades look like airplane propellers. There can be 1, 2, or 3 blades on a tower. Most commonplace are 2 or 3 blades because the blades correct torque
  • VAWT – Vertical Axis Wind Turbines. Have a much higher strain on rotors. Also can't be placed on higher towers.
    • VAWT picture -- http://www.memagazine.org/backissues/jun04/features/apptowind/30topc.jpg

Power

• Power available works as a CUBE of the amount of wind present. In general a site needs to have average wind speeds of over 5m/s (11mph) for cost effective generation. Stronger less turbulant wind is 30 m above the ground and higher. A single 750-kilowatt (kW) wind turbine, typical of those now being installed in power plants around the world, produces roughly 2 million kilowatt-hours (kWh) of electricity annually

Environmental Impact

• Polution
  • Based on the U.S. average fuel mix, approximately 1.5 pounds of CO2 is emitted for every kWh generated. A 750 W Wind turbine can prevent the production of CO2 that 500 acres of forest can absorb. On average, 300 American homes can be powered by a 1kW turbine.
• Noise
  • At a distance of 700-1000 ft, an operating wind farm is no louder than the hum of a refridgerator or a moderately quiet room.
    • Rural night-time background - 20-40 dB
    • Wind farm at 350m - 35-45 dB
    • Car at 40 mph at 100m - 55 dB
    • Busy general office - 60 dB
    • Jet aircraft at 250m - 105 dB
  • Small turbines generally create more noise than the larger ones, because:
    • they have a higher rotational speed of the tip
    • more research money has been devoted to decreasing the noise in larger turbines.
• Bird and Bats
  • The national Audubon Society has recently isssued a statement that wind turbines are not more harmful to bird populations than cars, planes, and other man-made contributions. The National Audubon Society has supported the development of Wind Energy. According to research in the U.S. And Denmark, the leading country in wind energy production, powerlines poses a higher threat to birds than wind turbines.

Comparison of Power Plants

Project Life (years)	30	30
Construction Period (years)	0.5	1
Plant Size (MW)	100	500
Average O&M ($/Mwh)	15	24
Variable O&M ($/Mwh)	0	2.4	}