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Energy from the Wind

Energy from the Wind. Outline. Introduction to Wind History of mankind's use of wind Mechanical conversion of Winds kinetic energy Types of wind turbines Electrical conversion of mechanical energy Conclusion. Wind. Creation of wind

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Energy from the Wind

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  1. Energy from the Wind

  2. Outline • Introduction to Wind • History of mankind's use of wind • Mechanical conversion of Winds kinetic energy • Types of wind turbines • Electrical conversion of mechanical energy • Conclusion

  3. Wind • Creation of wind • More Solar Radiation striking the Equator than the poles • Heating and cooling differences of land and water • Solar Radiation • Approx 174,000 TW strikes outer atmosphere • Approx 80,000 TW strikes surface • Approx 300 TW wind & wind driven waves • Approx 72 TW wind alone

  4. History of Wind Use • Man’s harnessing of the wind goes back thousands of years • Sail Boats • Ancient Egyptians and Phoenicians • Approx 4000 BCE sailed the Mediterranean • Wind Mills • Roman Empire as early as the 7th century • Most notable Eastern Europe in the 12th century • Netherlands some still exist • Mechanical use • Draw water • Grind Corn

  5. Beaufort scale

  6. Mechanics of Conversion from Wind to Mechanical Motion

  7. Turbine blades • Similar to airplane wings • FL= Lift force • FD = Drag force • Wind energy is converted to rotation velocity • Causing turbine to spin

  8. Types of Turbines • Vertical Axis • Horizontal Axis • 2 & 3 blade • Multi blade • Definitions • Yaw: rotor adjustment to stay in the horizontal plan of the wind. • Nacelle: compartment located behind the blades on top of the tower, used as housing of gears, motors, and generators.

  9. Vertical Axis • Driven by drag force • No part can move faster than the wind • Advantages • Accept wind from any direction w/o yaw • Low wind speed start up • Disadvantages • 1/2 as efficient as Horizontal axis • Located closer to ground, which means less wind.

  10. Horizontal Axis • Driven by lift forces • Blades can spin considerable faster than wind 2 bladed 3 bladed Multi bladed

  11. Power & Torque conversions • PT = ½ CPAρu03 • CP = power coefficient • A = cross section of wind front contacting turbine • ρ = wind density (mass of air per unit area) • Depends on air temperature and pressure • u0 = initial wind speed • Cp = λCN • CP = power coefficient • CN = torque coefficient • λ = 4π / n = tip speed ratio • n = number of rotors

  12. Turbines for Mechanical Work • Multi blade turbines used • Water pumping • Corn grinding • High torque in low wind • Example • Cp MAX occurs at λ = 4π / n • n = 3 → Cp MAX occurs at λ = 4π / 3 = 4.19 m/s • n = 6 → Cp MAX occurs at λ = 4π / 6 = 2.09 m/s • PT max occurs at CP MAX • Which is reached at lower tip speed with more blades

  13. Turbines for Electrical Energy • Electric generation requires more steady and higher wind velocities • 2 & 3 bladed machines are used instead of multi/many bladed machines • Up wind and down wind positioning • Blades are up or down wind of nacelle • Upwind means blades are on incoming wind side of nacelle, and must have yaw control • Downwind means that incoming wind hits nacelle before blades automatically yaws with wind as direction changes

  14. Placement of Wind Turbines • Location should have average wind speeds of 4-6 on beaufort scale at a distance 10m from ground level • Wind velocity is greater and more steady higher of ground level • Height measured from ground to center of turbine (where blades all meet) • Must have fail safe shut off for winds greater than 8 on beaufort scale • #12 complete destruction even to wind turbine.

  15. Mechanical to electrical conversion • The spinning shaft of turbine is attached to some form of the basic generator • Basic generator • Wound wire fixed • Magnets attached to shaft and rotated around wound wire • Induces electrical current which can be used as electrical energy

  16. Conclusion • Energy in the wind is no new idea • As our society advances we are finding more was to use the wind and other natural phenomenon. • Conversions from wind → mechanical → electrical + periodicity of wind • Efficiency = approx 25-35% (mostly due to its periodicity) • Global energy use in 2007 • Approx 17 TW • (72 / 2 = 36 TW wind energy)(.25 eff.) = 9 TW energy • That means that harnessing one half of the total energy in the wind would account for 50% of the global energy consumption from 2007. • Wind derived energy has been used more and more in recent years in many countries • Denmark 19% of energy consumed is generated from wind • Spain & Portugal 9%, and Germany & Ireland 6%

  17. Wind Derived Energy in the U.S.

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