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Wind Energy in the Classroom

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1 Wind Energy in the Classroom
This slide show is a basic outline. We often make changes to this template depending on the time and location of the event. The Kidwind Project and WindWise

2 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 | KidWind Project |

3 Yesterday & Today Holland & Colonial America
First documented windmill: Afghanistan (900AD) Wind Pumper Greece First windmills were found in Persia. They were vertical axis and were used to grind grains and seeds. Reeds form blades. They were kind of like a waterwheel turned on its side. Most of the paddles were covered by a wall and wind would run through a narrow opening to push the blades. Many have seen the Dutch windmills. Used to grind grains, seeds, pump water, saw lumber…these were fairly sophisticated devices. Used to cover much of New England coastline.

4 Very Low Maintenance Requirements Proven: ~ 5,000 On-Grid
Wind Energy Technology in the World Today: Modern Small Wind Turbines: Horizontal Axis Downwind Rotor 10 kW Technically Advanced Minimal Moving Parts Very Low Maintenance Requirements Proven: ~ 5,000 On-Grid American Companies are the Market and Technology Leaders 50 kW Upwind Rotors 400 W 900 W When teachers build their Basic PVC Turbines they are more like a small wind turbine, simple direct drive systems. Emphasize high RPM…these things spin fast RPM. Many of these are sent to villages offshore as they can provide power for an entire village…here in the US is hard to justify the cost for one household. $$ on small wind turbines 10K-100K (Not to scale)

5 Vertical Axis Wind Turbines?
Advantages Omnidirectional 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 Disadvantages Rotors generally near ground where wind poorer Centrifugal force stresses blades & components Poor self-starting capabilities 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) Windspire See testing on early Mariah Windspire at NREL – test was discontinued due to failures. Spire seen swaying in the wind. Beware “Hope & hype” hucksters Savonious

6 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

7 Wind Energy is a Growing Industry
US total installed wind energy capacity now over 43,635 MW as of Sept 2011 per Enough electricity to power the equivalent of over 7 million households! KidWind Project |

8 US Capacity is Growing in fits and starts

9 Costs are Decreasing 1979: 40 cents/kWh 2000: 4 - 6 cents/kWh
NSP 107 MW Lake Benton wind farm 4 cents/kWh (unsubsidized) Increased Turbine Size R&D Advances Manufacturing Improvements The rapid growth in wind power can be attributed to two things….reduction in cost of the electricity produced and more interested in Green Power. I usually ask people here what they pay for their electricity by kwh….typical # are 7-20 cents. Wind has come way down in terms of cost over the last 40 years. The cheapest power out there is coal and wind cannot compete with that…Natural Gas and coal are comparable. The costs for wind listed above are the wholesale rate…do not include transmission etc. On this slide I often ask the crowd how we generate most of our electrical power in the US. Coal 50% Nuclear 20% Natural Gas 17% Hydro 7% Oil 3% Renewables 3% Wind less than 1% 2004: 3 – 4.5 cents/kWh

10 Issues Today: Costs & Benefits
We also need to change students perceptions about what the future may look like and the limits of this technology. Wind will never be “base load” for the grid. The wind farm above is capable of generating 15-20Mw of electricity at full capacity. The oil fired facility below is at 300Mw. Most Nuclear plants are at Mw… Must keep the scale in mind….a very aggressive wind program can generate 10-20% of our power needs. To move towards a green future we are going to need mix of sources and also a great deal of energy efficiency….Wind cannot do it all.

11 Where do we get our electricity?
KidWind Project | 11

12 Fighting windmills has a long history!
Don Quixote fighting “Giants”

13 KidWind Project |
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 |

14 Impacts of Wind Power: Noise
Modern turbines are relatively quiet Rule of thumb – stay about 3x hub-height away from houses Many people think wind turbines are noisy. While this may have been true in the past (it is still somewhat true on older smaller devices)…newer larger devices are much quieter.

15 Impacts of Wind Power: Wildlife
It is a common complaint that wind turbines kill birds. While it is true that turbines kill birds, this graph puts that in perspective with other human technologies.

16 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. National Audubon Society endorses wind power…

17 Prospecting the Right Site: Lessons Learned
1980’s California Wind Farm Older Technology + Higher RPMs + Lower Elevations + Lattice Towers + Poorly Sited = Bad News! Altamont Pass Wind Farm in California… This wind farm was built in the 1980’s. Without doing an Environmental Impact Assessment, they built the wind farm in a raptor migration path. This wind farm had a major problem with avian mortality, and scarred the industry. Today this farm is being repowered. This means they are taking down the old turbines and replacing them with new. With one new turbine, they can replace 10 old turbines. Still poorly sited, but this is an improvement.

18 Prospecting the Right Site: Off-Shore On the Farm On a Mountain
Many developers would like to move windfarms offshore because the wind are faster, smoother and they can be close to major population centers on the coast. This is very controversial in the US….we have a few planned offshore farms…CapeWind and Long Island…but nothing installed. Major complaints about offshore are related visual impact, navigation impact and lack of history. Check

19 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? Probably the largest issue facing Commercial Wind Energy is transmission. It is typically windy where people don’t want to live so how will you get the power from where it is generated to where the people live? Most people oppose new power line construction vehemently….so this will be a touchy issue for a very long time. Quick Fact: 1 mile of High Voltage transmission line can cost upwards of $1 million!

20 KidWind Project |
Where is the Wind? Note the Wind Belt KidWind Project |

21 Get more local details at

22 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 V X V X V 20% increase in wind speed means 73% more power Doubling wind speed means 8 times more power

23 Calculation of Wind Power
Power in the wind Effect of swept area, A Effect of wind speed, V Effect of air density,  Power in the Wind = ½ρAV3 R This is the equation for the power in the wind. (Don’t fear – there are only 2 equations in this presentation.) Each of the terms in this equation can tell us a lot about wind turbines and how they work. Lets look at wind speed (V), swept area (A), and density (Greek letter “rho,” ) one at a time. First, let’s look at wind speed, V. Because V is cubed in the equation, a small increase in V makes for a increase in power. (illustrated on next slide) (Click on the links at the bottom to get the values of both k and .) Swept Area: A = πR2 Area of the circle swept by the rotor (m2).

24 Technology Part of a turbine…all turbines from our little models to the biggest in the world have these parts.

25 KidWind Project |
The “guts” of a wind turbine KidWind Project |

26 How does a generator generate electricity?

27 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

28 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!!

29 Pitch Control Mechanisms
KidWind Project |

30 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 Fast Faster Fastest

31 Tip-Speed Ratio ΩR TSR = V R Ω = rotational speed in radians /sec
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 R ΩR V TSR = Where, Ω = rotational speed in radians /sec R = Rotor Radius V = Wind “Free Stream” Velocity

32 Performance Over Range of Tip Speed Ratios
Power Coefficient Varies with Tip Speed Ratio Characterized by Cp vs Tip Speed Ratio Curve

33 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

34 Rotor Solidity Solidity is the ratio of total rotor planform area to total swept area Low solidity (0.10) = high speed, low torque High solidity (>0.80) = low speed, high torque R a A Solidity = 3a/A

35 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

36 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

37 KidWind Project |
Maintenance Now Hiring! KidWind Project |

38 Wind Energy in the Classroom

39 KidWind Project |
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 |

40 Scientific & Engineering Practices New National Frameworks
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

41 Upper Elementary/Middle
Building Wind Turbines Assessing Wind Resource Mathematics balloon ~3m streamers Kite or balloon string 41


43 Secondary Advanced Blade Design School Siting Projects Data Analysis
Mathematics - Download lessons Math lessons – free downloads on topics such as gear ratios, tip speed ratio & tower height estimation. 43

44 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!

45 KidWind Project |

46 KidWind Project |
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 KidWind Project |

47 KidWind Project |
Download Wind Energy curriculum at Individual lessons are FREE to download KidWind Project |

48 Science & Sustainability Educator KidWind Wind Senator
The KidWind Project Presenters: Susan Reyes Science & Sustainability Educator KidWind Wind Senator KidWind Western Mass Area Event Coordinator Raymond Pitcher Technology Education Specialist KidWind Senator KidWind Challenge Utica Area Event Coordinator

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