1. KidWind Learning to build a Wind TurbineBy
Willem Scholten
The Learning Access Institute

3. KidWind
Learning about harnessing the power of the wind and generate energy (electrical) from it in the most efficient way.

4. Windmills and Wind Turbines What are they?
Session #1
Windmills and Wind Turbines
What are they?

5. “Windmills have fascinated us for centuries and will continue to do so
“Windmills have fascinated us for centuries and will continue to do so. Like campfires or falling water, they’re mesmerizing; indeed, entrancing.”
Paul Gipe, Wind Power for Home, Farm, & Business

6. What things are called Wind Machine Wind System Windmill Wind Turbine
Kinetic device used to capture the wind and put it to work
Wind System
Wind machine, tower, and all ancillary equipment
Windmill
Wind machine that generates mechanical motion (ie. water pumping, grain grinding, saw mill, etc)
Wind Turbine
A device that produces electricity from kinetic energy of wind

7. Wind Energy has been popular for a long time
The pilgrims arrived under the power of wind. Cape Cod was home to America’s first wind mill. Wind helped fuel our country’s early economy.

8. A long history.... Don Quixote fighting “giants”
Fighting Windmills
A long history.... Don Quixote fighting “giants”

9. Early “WINDMILL” in Afghanistan (900AD)

10. Dutch style windmills used for 100’s of years!

11. Kinderdijk, the Netherlands
Serial Wind Power......
Kinderdijk, the Netherlands

12. Water pumping windmill helped settle the American West

13. Early Electric Wind Turbines helped Electrify Remote Farms

14. Birth of the Modern Wind Turbine
Smith-Putnam 1.25MW Turbine, Vermont, 1940
California Wind Turbines, 1980

15. Wind Farms

16. Wind Farms

17. Session #2
Wind what is it?

18. How Wind Works
Wind energy is created by uneven heating of the earth’s surface.

19. Wind Energy Wind is moving Air
Anything that moves has energy in the form of Kinetic Energy
Wind contains a lot of Kinetic energy
The more the Wind blows the more Kinetic Energy it contains

20. Sea Breeze

21. Valley Breeze

22. Mountain Breeze

23. Mountain-Valley Breezes
Typically strongest in summer
Nighttime mountain breezes are stronger than daytime valley breezes
Mountain-Valley winds can be enhanced by prevailing winds - wind flows between the interior and the coast

24. Where is the Wind?

27. Power in the Wind Wind Energy Calculations Advanced Topic
Session #3
Power in the Wind
Wind Energy Calculations
Advanced Topic

28. Kinetic Energy in the Wind
Kinetic Energy = Work = 1/2 mV2
Where:
M = mass of moving object
V = Velocity of moving object
What is the mass of moving air?
= density (ρ) x volume (Area x distance)
= (ρ) x A x d
= (kg/m3)(m2)(m) A V d

29. Calculation of Wind Power
Power in the wind
= 1/2 ρ A V3
= Effect of air density, ρ
= Effect of swept area, A
= Effect of wind speed, V
Swept Area: A =
∏ R2
Area of the circle swept by the rotor (m2)

30. Importance of Rotor Diameter
Swept area is proportional to square of the rotor.
20% increase in rotor diameter increases area by 44%
Doubling diameter increases area 4 times

31. Importance of Wind Speed
No other factor is more important then the amount of power available in the wind than the speed of the wind
Power is a cubic function of wind speed: VxVxV
20% increase in wind speed means 73% more power
Doubling wind speed means 8 times more power

32. Wind Speed and Height

33. “Micro-Siting”

34. Turbulence
Top View
Side View

35. Introduction to Energy Concepts
Session #4
Introduction to Energy Concepts

36. Four basic forms of Energy
Kinetic = 0.5 x mass x speed2
Thermal - energy of vibrating molecules within a material
Electrical - force between electrical charges
Chemical - electrical energy that holds molecules together
Gravitational - also known as “potential energy”
- force x distance = weight x height = m x g x h
Nuclear - force that holds atoms together

37. Units of Energy
Energy requires a force. Each form of energy has it’s own force: gravity, strong & weak nuclear forces, electrical, and kinetic forces.
Kinetic Force = Mass x Acceleration
Unit of Force = 1 Newton = 1 Kilogram x 1m/s
Energy is a measurement of work accomplished by a force
Energy = Force x Distance
1 Joule = 1 Newton x 1 Meter

38. Energy and Power Energy is a quantity, like distance.
1 kilowatt-hour = 1000 Watts x 1 hour
1 kilowatt-hour = 3.6 x 106 Joules
Power is a rate, like speed, it is the rate that energy is converted from one form to another.
1 Watt = 1 Joule / second

39. Laws of Thermodynamics
First Law: In any transformation of energy from one to another, the total quantity of energy remains unchanged. “Energy is neither created nor destroyed, it only changes forms.”
Second Law: In all energy changes, the potential energy of the final state will be less than that of the initial state - (useful energy is always lost.)
“Lost” energy is usually energy that has been converted to heat, could be noise (kinetic energy of air), or other forms of wasted energy.

40. Efficiency
The ratio of the amount of useable energy obtained to the amount of energy input is the efficiency of a process.
This is usually expressed as a percent and is always less then 100%.

41. Energy definitions
Primary Energy - amount of energy contained in the initial source of energy
Delivered Energy - amount of useable energy delivered to the “customer”
Useful Energy - amount of energy attributed to the amount of work accomplished

42. Wind Energy to ...... Conversion Pumping Water, Wind Energy
Sawing Wood,
Grinding Grain
Wind Energy
Efficiency ??

43. Wind Energy to ....
Conversion
Wind Energy
Electricity
Efficiency ??

45. Converting Wind Energy into Electrical Energy The Rotor Blades
Session #5
Converting Wind Energy into Electrical Energy
The Rotor Blades

46. Wind Energy to Electricity
Conversion
Wind Energy
Electricity
Efficiency

47. The Turbine.....

48. Many different rotors

49. Parts of a Wind Turbine

50. Wind Turbine
Workers
Blade
112’ long
Nacelle
56 tons
Tower
3 sections

51. Large Wind Turbines 450’ base to blade Each blade 112’
Span greater than 747
163+ tons total
Foundation 20+ feet deep
Rated at 1.5 – 5 megawatt
Supply at least 350 homes

52. Number of blades - One
Rotor must move more rapidly to capture same amount of wind
Gearbox ratio reduced
Added weight of counterbalance negates some benefits of lighter design
Higher speed means more noise, visual, and wildlife impacts
Blades easier to install because entire rotor can be assembled on ground
Captures 10% less energy than two blade design
Ultimately provide no cost savings

53. Number of blades - Two Advantages & disadvantages similar to one blade
Need teetering hub and or shock absorbers because of gyroscopic imbalances
Capture 5% less energy than three blade designs

54. Number of blades - Three
Balance of gyroscopic forces
Slower rotation
increases gearbox & transmission costs
More aesthetic, less noise, fewer bird strikes

55. Blade Composition - Wood
Strong, light weight, cheap, abundant, flexible
Popular on do-it yourself turbines
Solid plank
Laminates
Veneers
Composites

56. Blade Composition - Metal
Steel
Heavy & expensive
Aluminum
Lighter-weight and easy to work with
Expensive
Subject to metal fatigue

57. Blade Construction - Fiberglass
Lightweight, strong, inexpensive, good fatigue characteristics
Variety of manufacturing processes
Cloth over frame
Pultrusion
Filament winding to produce spars
Most modern large turbines use fiberglass

59. Converting Wind Energy into Electrical Energy Optimum Blade Design
Session #6
Converting Wind Energy into Electrical Energy
Optimum Blade Design

60. Lift & Drag Forces
The Lift Force is perpendicular to the direction of motion. We want to make this force BIG.
The Drag Force is parallel to the direction of motion. We want to make this force SMALL.
α = low
α = medium
<10 degrees
α = High
Stall!!

61. Airfoil Shape
Just like the wings of an airplane, wind turbine blades use the airfoil shape to create lift and maximize efficiency.

62. Blade Engineering

63. Lift/Drag Forces Experienced by Turbine Blades
Lift and Drag Forces
Lift/Drag Forces Experienced by Turbine Blades

64. Twist and Taper
Speed through the air of a point on the blade changes with distance from hub
Therefore, tip speed ratio varies as well
To optimize angle of attack all along blade, it must twist from root to tip
Fast
Faster
Fastest

65. Betz Limit
All wind power cannot be captured by rotor or air would be completely still behind rotor and not allow more wind to pass through.
Theoretical limit of rotor efficiency is 59%
Most modern wind turbines are in the 35 – 45% range

66. Experimental Classroom Blades
Cardboard Tube for twisted blades
Airfoil Blades

67. KidWind Challenge
Students perform experiments and design different wind turbine blades
Use simple wind turbine models
Test one variable while holding others constant
Record performance with a multimeter or other load device

68. KidWind Challenge
Goals: Produce the most voltage, pump the most water, lift the most weight
Minimize Drag
Maximize LIFT
Harness the POWER of the wind!

72. Generating the Electricity
Session #7
Generating the Electricity

73. What is Electricity?
Electricity is energy transported by the motion of electrons.
We do not make electricity, we convert other energy sources into electrical energy.
Conversion is the name of the game!

74. Faraday Effect Voltage – V – Potential to Move Charge (volts)
 Basic Concepts
Voltage – V – Potential to Move Charge (volts)
Current – I – Charge Movement (amperes or amps)
Resistance – R – V = IxR (R in =ohms)
Power – P = IxV = I2xR (watts)

75. How does a generator work?

76. Electrical Generator
Mechanical
Energy
Electrical
Energy G

77. KidWind Turbine Test We will measure:
Voltage
Current
We will measure:
Voltage - using Vernier Computer Sensor (V)
Current - using Vernier Computer Sensor (A)
Windspeed - using Vernier Computer Sensor (m/s)
We will calculate:
Power - P = V2/ R - calculated in (W)
R = 10 Ohm in our setup

78. Experiment Templates

80. Making theWindmill Cut out the square
Cut on each of the dotted lines from the corners towards the little hash marks (no further!)
Fold a corner of each cut part toward the middle making sure it stays ‘rounded’ not folded flat, and glue down with a little bit of glue
Do this 4 times
Take a pencil with an eraser top, and stick a thumbnail through the Windmill in the center (black little square) and into the eraser
Now experiment -- does it move better if the wind comes from the site or from the front? What happens if there is to much wind....

81. A B

82. Making the Airfoil
Fold side ‘A’ over side ‘B’, side “B” is shorter so side ‘A’ should create a curved surface. (The line in the middle is the fold line)
Tape the two sides together, so that the ‘B’ side is flat
Use a pencil to make a hole where the black dot is, so that it can slide from one side to the other
Stick a straw through the hole, and attach it to the top and the bottom of the wing with a small piece of tape
Cut the straw so that is little as possible is above and below the wing
Feed some string through the wind, and tie a paper clip to the end of the string which is coming through the flat part of the wing (the ‘B” side)
Now hold the top and and the bottom of the string tight in front of a box fan, and notice what happens
You can also do this as you run down the hallway or playground