Wind Energy 101 Joe Rand The Kidwind Project St. Paul, MN

Where do we get our electricity?

Wind Energy is the Fastest Growing Energy Source in the World!! US installed capacity grew a WHOPPING 45% in 2007!!!

Why such growth…costs! 1979: 40 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 2000: cents/kWh

Wind Energy: The Technology

Early “WINDMILL” in Afghanistan (900AD)

Jacobs Turbine –

Smith-Putnam Turbine Vermont, 1940's

Modern Windmills

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

Vertical Axis Turbines Advantages Omnidirectional Omnidirectional –Accepts wind from any angle Components can be mounted at ground level 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 Can theoretically use less materials to capture the same amount of wind Disadvantages Rotors generally near ground where wind poorer Rotors generally near ground where wind poorer Centrifugal force stresses blades Centrifugal force stresses blades Poor self-starting capabilities Poor self-starting capabilities Requires support at top of turbine rotor Requires support at top of turbine rotor Requires entire rotor to be removed to replace bearings Requires entire rotor to be removed to replace bearings Overall poor performance and reliability Overall poor performance and reliability Have never been commercially successful Have never been commercially successful

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

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

Types of Electricity Generating Windmills Small (  10 kW) Homes Farms Remote Applications (e.g. water pumping, telecom sites, icemaking) Large (250 kW - 2+MW) Central Station Wind Farms Distributed Power Intermediate ( kW) Village Power Hybrid Systems Distributed Power

Modern Small Wind Turbines: High Tech, High Reliability, Low Maintenance Technically Advanced Technically Advanced Only 2-3 Moving Parts Only 2-3 Moving Parts Very Low Maintenance Requirements Very Low Maintenance Requirements Proven: ~ 5,000 On-Grid Proven: ~ 5,000 On-Grid American Companies are the Market and Technology Leaders American Companies are the Market and Technology Leaders 10 kW 50 kW 400 W 900 W (Not to scale)

Overspeed Protection: Furling

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

US Large Wind Manufactures General Electric General Electric Clipper Clipper

North Wind HR3 rating: 3 kW rotor: 5 m hub height: 15 m 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 Enercon E-112 rating: 4000 kW rotor: 112 m hub height: 100 m Comparative Scale for a Range of Wind Turbines Wind Turbine Technology

Inside a Wind Turbine

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

Yawing – Facing the Wind Active Yaw (all medium & large turbines produced today, & some small turbines from Europe) 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) Passive Yaw (Most small turbines) –Wind forces alone direct rotor Tail vanes Tail vanes Downwind turbines Downwind turbines

Wind Farms

Windfarm 2

Off-Shore Windfarms

Middelgrunden

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

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

The importance of the WIND RESOURCE

Why do windmills need to be high in the sky??

Calculation of Wind Power Power in the wind Power in the wind Effect of air density,  –Effect of swept area, A –Effect of wind speed, V R Swept Area: A = πR 2 Area of the circle swept by the rotor (m 2 ). Power in the Wind = ½ρAV 3

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 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 Power is a cubic function of wind speed –V X V X V 20% increase in wind speed means 73% more power 20% increase in wind speed means 73% more power Doubling wind speed means 8 times more power Doubling wind speed means 8 times more power

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

Wind Energy Potential

Wind Farms in Southwest Minnesota Buffalo Ridge Worthington, MN

Wind Farms in SW Minnesota 1.North Shaokatan 11.9 MW 2.Shaokatan Hills11.9 MW 3.Lake Benton II103.5 MW 4.Viking12.0 MW 5.Chanarambie85.5 MW 6.Moraine51.0 MW 7.Woodstock10.2 MW 8.Buffalo Ridge25.0 MW 9.Ruthton15.8 MW 10.Lake Benton I107.2 MW 11.Lakota Ridge11.2 MW Southwest Ridge Total = MW Minnesota Total = 895 MW

Source: U.S. DOE Wind Potential

Key Issues facing Wind Power

FACT:

1980’s California Wind Farm Older Technology + Higher RPMs + Lower Elevations + Poorly Sited = Bad News!

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. 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.

Impacts of Wind Power: Noise Modern turbines are relatively quiet Modern turbines are relatively quiet Rule of thumb – stay about 3x hub-height away from houses 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

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%

May 1, 2002 Tax Incentives & Buydown Local Option Tax Incentives** Net Metering & Local Option Tax Incentives** Tax Incentives & Net Metering Tax Incentives, Net Metering & Buydown Net Metering & Buydown *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. Tax IncentivesNet Metering Only Buydown* Residential Small Wind Incentives

Net Metering

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 Transmission Problems

Predicting Power Output

Siting and NIMBY

What do you want in your backyard?

Questions???

Joe Rand The Kidwind Project