Wind Energy 101

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Wind Energy 101
Joe Rand The Kidwind Project St. Paul,
MN joe_at_kidwind.org
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Where do we get our electricity?
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Wind Energy is the Fastest Growing Energy Source
in the World!!
US installed capacity grew a WHOPPING 45 in
2007!!!
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Why such growthcosts!
1979 40 cents/kWh
2000 4 - 6 cents/kWh

• Increased Turbine Size
• RD Advances
• Manufacturing Improvements

NSP 107 MW Lake Benton wind farm 4 cents/kWh
(unsubsidized)
2004 3 4.5 cents/kWh
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Wind Energy The Technology
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Early WINDMILL in Afghanistan (900AD)
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Jacobs Turbine 1920 - 1960
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Smith-Putnam Turbine Vermont, 1940's
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Modern Windmills
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Orientation

• Turbines can be categorized into two overarching
  classes based on the orientation of the rotor
• Vertical Axis Horizontal Axis

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Vertical Axis 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
• 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
• Have never been commercially successful

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Lift vs Drag VAWTs

• Lift Device Darrieus
• Low solidity, aerofoil blades
• More efficient than drag device
• Drag Device Savonius
• High solidity, cup shapes are pushed by the wind
• At best can capture only 15 of wind energy

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Horizontal Axis Wind Turbines

• Rotors are usually Up-wind of tower
• Some machines have down-wind rotors, but only
  commercially available ones are small turbines

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Types of Electricity Generating Windmills

• Small (?10 kW)
• Homes
• Farms
• Remote Applications
• (e.g. water pumping, telecom sites, icemaking)

• Intermediate
• (10-250 kW)
• Village Power
• Hybrid Systems
• Distributed Power

• Large (250 kW - 2MW)
• Central Station Wind Farms
• Distributed Power

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Modern Small Wind TurbinesHigh Tech, High
Reliability, Low Maintenance

• Technically Advanced
• Only 2-3 Moving Parts
• Very Low Maintenance Requirements
• Proven 5,000 On-Grid
• American Companies are the Market and Technology
  Leaders

(Not to scale)
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Overspeed Protection Furling
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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

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US Large Wind Manufactures

• General Electric
• Clipper

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Wind Turbine Technology
North Wind 100 rating 100 kW rotor 19.1 m hub
height 25 m
Lagerwey LW58 rating 750 kW rotor 58 m hub
height 65 m
Enercon E-66 rating 1800 kW rotor 70 m hub
height 85 m
Boeing 747 wing span 69.8m length 73.5 m
North Wind HR3 rating 3 kW rotor 5 m hub
height 15 m
Enercon E-112 rating 4000 kW rotor 112 m hub
height 100 m
Comparative Scale for a Range of Wind Turbines
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Inside a Wind Turbine
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Airfoil Shape
Just like the wings of an airplane, wind turbine
blades use the airfoil shape to create lift and
maximize efficiency.
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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

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Wind Farms
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Windfarm 2
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Off-Shore Windfarms
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Middelgrunden
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Wind Turbine Perspective
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Twist 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

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The importance of the WIND RESOURCE
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Why do windmills need to be high in the sky??
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Calculation of Wind Power

• Power in the wind
• Effect of air density, ?
• Effect of swept area, A
• Effect of wind speed, V

Power in the Wind ½?AV3
R
Swept Area A pR2 Area of the circle swept by
the rotor (m2).
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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

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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

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Wind Energy Potential
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Wind Farms in Southwest Minnesota
Buffalo Ridge
Buffalo Ridge
Worthington, MN
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• Wind Farms in SW Minnesota
• North Shaokatan 11.9 MW
• Shaokatan Hills 11.9 MW
• Lake Benton II 103.5 MW
• Viking 12 .0 MW
• Chanarambie 85.5 MW
• Moraine 51.0 MW
• Woodstock 10.2 MW
• Buffalo Ridge 25.0 MW
• Ruthton 15.8 MW
• Lake Benton I 107.2 MW
• Lakota Ridge 11.2 MW

Southwest Ridge Total 433.2 MW
Minnesota Total 895 MW
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Wind Potential
Source U.S. DOE
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Key Issues facing Wind Power
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FACT
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1980s California Wind Farm Older Technology
Higher RPMs Lower Elevations Poorly
Sited Bad News!
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• 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.

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Impacts of Wind PowerNoise

• Modern turbines are relatively quiet
• Rule of thumb stay about 3x hub-height away
  from houses

Go to Hull or Searsburg listen! Note
Searsburg turbines are older a bit louder than
many modern turbines
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Tax Credits

• No Federal Incentives for Small Wind Since 1985
• Large Wind Supported with Production Tax Credit
  3 Yr. Renewal in the 2005 Energy Bill EXPIRES
  END OF THIS YEAR!!!
• States have varying levels of support
• NY 50-75 Support
• ME 0
• MA 20-50

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Residential Small Wind Incentives
May 1, 2002
Tax Incentives Buydown
Local Option Tax Incentives
Contact your utility to see if you qualify for
the Renewable Energy Resources Program.
Contact your city or county to see if they offer
tax incentives for small wind systems.
Net Metering Only
Tax Incentives, Net Metering Buydown
Net Metering Buydown
Net Metering Local Option Tax Incentives
Tax Incentives Net Metering
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Net Metering
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Transmission Problems

• 6.5 million customers
• 330 generating units
• Over 8,000 miles of transmission lines
• 11 Interconnections
• 28,100 MW of capacity
• Peak demand 22,544MW

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Predicting Power Output
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Siting and NIMBY
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What do you want in your backyard?
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Questions???
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Joe Rand The Kidwind Project joe_at_kidwind.org