Energy from the Wind

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

• Mans 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
Speed Descript Turbine Land effects Sea effects
0 0-0.4 Calm None Vert. smoke Mirror
1 0.4-1.8 Light None Drift. smoke Ripples
2 1.8-3.6 Poor Felt on skin Small waves
3 3.6-5.8 Low Flag lifts Occ. Break
4 5.8-8.5 Useful Pages lift Large waves
5 8.5-11 Mode. Good Noticeable White crests
6 11-14 Fresh Rated Lrg branch Crests foam
7 14-17 Strong Capacity Whole trees Crests break
8 17-21 Shut off Breakage Dense streaks
9 21-25 Gale Full shut Struct. Dam. Ext. blown
10 25-29 D. Limit Uprooted Long streaks
11 29-34 Str Gale Damage Wide Dam. Severe seas
12 gt34 Hurri. Destruct. Disaster cond Ships lost
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 CPA?u03
• CP power coefficient
• A cross section of wind front contacting
  turbine
• ? wind density (mass of air per unit area)
• Depends on air temperature and pressure
• u0 initial wind speed
• Cp ?CN
• CP power coefficient
• CN torque coefficient
• ? 4p / 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 ? 4p / n
• n 3 ? Cp MAX occurs at ? 4p / 3 4.19 m/s
• n 6 ? Cp MAX occurs at ? 4p / 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.

small Medium large
Power (kW) 10 50 100 500 1000 - 4000
Diameter (m) 6.5 - 15 20 - 50 65 130
Height (m) 20 - 30 30 - 50 60 - 80
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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

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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

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Wind Derived Energy in the U.S.