Alaska Wind 101: Wind for Schools Webinar August 12th, 2010 Katherine Keith Wind-Diesel Application Center Alaska Center for Energy and Power University of Alaska, Fairbanks
ACEP RESEARCH MISSION: To meet state and local need for applied energy research by working towards developing, refining, demonstrating, and ultimately helping commercialize marketable technologies that provide practical solutions to real-world problems.
Role of ACEP • Verify performance and reliability of equipment • Assess technical and economic feasibility • Test emissions • Integration with existing power systems • Resource assessment • Procurement experiments • Work with manufacturers to improve products for use in Alaska
Role of ACEP Serve as an impartial agent on behalf of Alaskan communities and agencies to ensure we are investing wisely in energy projects that make sense and that contribute to the long-term benefit of our residents Help leverage external resources to address Alaska’s energy challenges (funding, businesses, national laboratories, other universities, etc)
The purpose of the Alaska Wind-Diesel Applications Center (WiDAC) is to support the broader deployment of cost-effective wind-diesel technologies to reduce and/or stabilize the cost of energy In rural communities.
Alaska Wind-Diesel Test Center Addressing issues to improve penetration of wind-diesel systems through improvements in controls and energy storage.
87% < 4 years old 76% < 2 years old REF installed projects < 1 year of operation
Wind-Diesel Power Systems • Intended to reduce diesel consumption • Needs good resource to be economically viable • However, wind fluctuates… • Power quality must be maintained despite the variable wind.
This is strange because…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 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
Other Reason to teach… Elegant Power Source
Smith-Putnam Turbine Vermont, 1940's 1250 kW
Orientation Turbines can be categorized into two overarching classes based on the orientation of the rotor Vertical AxisHorizontal Axis
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 Vertical Axis Turbines
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
VAWT’s have not been commercially successful, yet… Every few years a new company comes along promising a revolutionary breakthrough in wind turbine design that is low cost, outperforms anything else on the market, and overcomes all of the previous problems with VAWT’s. They can also usually be installed on a roof or in a city where wind is poor. WindStor Mag-Wind WindTree Wind Wandler
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
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 - 2+MW) • Central Station Wind Farms • Distributed Power
10 kW 50 kW 900 W 400 W Modern Small Wind Turbines:High 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)
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
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 North Wind HR3 rating: 3 kW rotor: 5 m hub height: 15 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
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
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
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 = ½ρAV3 R Swept Area: A = πR2 Area of the circle swept by the rotor (m2).