Wind Energy
in the Classroom
The Kidwind Project and WindWise
What is KidWind?
The KidWind Project is a team of teachers,
students, engineers and practitioners
exploring the science behind wind energy
in classrooms around the US.
Our goal is to introduce as many people as
possible to the elegance of wind power
through hands-on science activities which
are challenging, engaging and teach basic
science principles.
KidWind Project
Project || www.kidwind.org
KidWind
www.kidwind.org
Yesterday & Today
First documented
windmill:
Afghanistan (900AD)
Holland & Colonial America
Wind Pumper
Greece
Wind Energy Technology in the World Today:
Modern Small Wind Turbines:
Horizontal Axis
• Technically Advanced
• Minimal Moving Parts
• Very Low Maintenance
Requirements
• Proven: ~ 5,000 On-Grid
• American Companies are the
Market and Technology
Leaders
Downwind
Rotor
10 kW
400 W
50
kW
Upwind
Rotors
900 W
(Not to scale)
Vertical Axis Wind Turbines?
Advantages
Disadvantages
• Omnidirectional
• Rotors generally near ground
where wind poorer
• Centrifugal force stresses
blades & components
• Poor self-starting capabilities
Windspire
• Requires support at top of
turbine rotor
• Requires entire rotor to be
removed to replace bearings
• Overall poor performance
and reliability/less efficient
• Have never been
commercially successful
(large scale)
– Accepts wind from
any angle
• Components can be
mounted at ground
level
– Ease of service
– Lighter weight
towers
• Can theoretically use
less materials to
capture the same
amount of wind
Savonious
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
Upwind rotors
Wind Energy is a
Growing Industry
•US total installed wind energy
capacity now over 43,635 MW
as of Sept 2011 per
WindPoweringAmerica.com
• Enough electricity to power
the equivalent of over 7 million
households!
KidWind Project | www.kidwind.org
US Capacity is Growing in fits and starts
Costs are Decreasing
1979: 40 cents/kWh
2000:
4-6
cents/kWh
• Increased
Turbine Size
• R&D Advances
• Manufacturing
Improvements
NSP 107 MW Lake Benton wind farm
4 cents/kWh (unsubsidized)
2004:
3 – 4.5 cents/kWh
Issues Today: Costs & Benefits
Where do we get our electricity?
KidWind Project | www.kidwind.org
Fighting windmills has a long history!
Don Quixote fighting “Giants”
Accidents & Troubles
“So far no evacuation zone has been declared. There are no threats to sea life, and the
fallout from the disaster was not detectable thousands of miles away. Cleanup efforts
are in progress, and will not include covering the area in a giant concrete dome. No
workers have been asked to give their lives in order to save their countrymen from the
menace of this fallen wind turbine.”
– Christopher Mims
KidWind Project | www.kidwind.org
Impacts of Wind Power: Noise
• Modern turbines are
relatively quiet
• Rule of thumb – stay
about 3x hub-height
away from houses
Impacts of Wind Power: Wildlife
• In the November-December Audubon Magazine, John
Flicker, President of National Audubon Society, wrote a
column stating that Audubon "strongly supports wind
power as a clean alternative energy source," pointing to
the link between global warming and the birds and
other wildlife that scientist say it will kill.
Prospecting the Right Site:
Lessons Learned
1980’s California Wind Farm
Older Technology
+ Higher RPMs
+ Lower Elevations
+ Lattice Towers
+ Poorly Sited
= Bad News!
Prospecting the
Right Site:
Off-Shore
On the Farm
On a Mountain
The Transmission Challenge
•Where is the wind?
•Where are the
population centers?
•Where are the wind
farms?
•How do we get wind
energy from the wind
farms to the population
centers?
Where is the Wind?
KidWind Project | www.kidwind.org
Get more local details at
http://nyswe.awstruepower.com/
Importance of Wind Speed
• No other factor is more
important to 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
Calculation of Wind Power
•Power
the=wind
Power
in theinWind
½ρAV3
– Effect of swept area, A
– Effect of wind speed, V
– Effect of air density, 
Swept Area: A = πR2 Area
of the circle swept by the
rotor (m2).
R
Technology
KidWind Project | www.kidwind.org
How does a generator
generate electricity?
Airfoil Shape
Just like the wings of an airplane,
wind turbine blades use the
airfoil shape to create lift and
maximize efficiency.
The Bernoulli Effect
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!!
Pitch Control Mechanisms
KidWind Project | www.kidwind.org
Twist & Taper
• Speed through the air of a
point on the blade changes
with distance from hub
• To optimize angle of attack
all along blade, it must twist
from root to tip
Fastest
Faster
Fast
Tip-Speed Ratio
Tip-speed ratio is the ratio of the
speed of the rotating blade tip to
the speed of the free stream wind.
There is an optimum angle of attack
which creates the highest lift to
drag ratio.
Because angle of attack is
dependant on wind speed, there
is an optimum tip-speed ratio
ΩR
TSR =
V
Where,
Ω = rotational speed in radians /sec
R = Rotor Radius
V = Wind “Free Stream” Velocity
ΩR
R
Performance Over Range of Tip Speed Ratios
• Power Coefficient Varies with Tip Speed Ratio
• Characterized by Cp vs Tip Speed Ratio Curve
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
Rotor Solidity
Solidity is the ratio of total rotor
planform area to total swept area
R
Low solidity (0.10) = high speed, low torque
a
A
High solidity (>0.80) = low speed, high torque
Solidity = 3a/A
Over-Speed Protection During High Winds
Upward Furling: The rotor tilts
back during high winds
Angle Governor: The rotor turns up and to one side
Yawing – Facing the Wind
• Active Yaw (all medium &
large turbines produced
today, & some small turbines
from Europe)
• Anemometer on nacelle tells
controller which way to point
rotor into the wind
• Yaw drive turns gears to point
rotor into wind
• Passive Yaw (Most small
turbines)
• Wind forces alone direct rotor
• Tail vanes
• Downwind turbines
Maintenance
KidWind Project | www.kidwind.org
Wind Energy in the Classroom
Many Topics Addressed
Use of Simple Tools & Equipment
Applied Mathematical Relationships
Practices of Engineering & Science
Forces and Change
Energy Transformations (Forms of Energy)
Circuits/Electricity/Magnetism
Properties of Air
Weather Patterns
Impacts on ecosystems, wildlife & humans
Renewable – Non Renewable Energy
KidWind Project | www.kidwind.org
Scientific & Engineering Practices
New National Frameworks
1.
2.
3.
4.
5.
6.
7.
8.
Asking questions & defining problems
Developing & using models
Planning & carrying out investigations
Analyzing & interpreting data
Using mathematics & computational thinking
Developing explanations & designing solutions
Engaging in argument from evidence
Obtaining, evaluating & communicating information
Upper Elementary/Middle
balloon
~3m
streamers
Kite or balloon string
• Building Wind
Turbines
• Assessing Wind
Resource
• Mathematics
Secondary
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•
•
•
•
Advanced Blade Design
School Siting Projects
Data Analysis
Mathematics Download lessons
Wind Turbine Blade 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
• Goals: Produce the most
voltage, pump the most
water, lift the most weight
– Minimize Drag
– Maximize LIFT
– Harness the POWER of the
wind!
KidWind Project | www.kidwind.org
KidWind
Opportunities & Resources
KidWind and Wind Wise Web Sites
Free Downloads -- Wind Wise – Math Lessons
NEW On-Line Turbine Design Competition
KidWind store – good prices: great stuff
KidWind Competitions
For Utica area, contact Raymond Pitcher at
rpitcher1@twcny.rr.com
KidWind Project | www.kidwind.org
KidWind Project | www.kidwind.org
Presenters:
The KidWind Project
www.kidwind.org
Susan Reyes
Science & Sustainability Educator
KidWind Wind Senator
KidWind Western Mass Area Event Coordinator
sreyes7@mac.com
Raymond Pitcher
Technology Education Specialist
KidWind Senator
KidWind Challenge Utica Area Event
Coordinator
rpitcher1@twcny.rr.com