AE/ME Wind Engineering Module 1.2

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AE/ME Wind EngineeringModule 1.2

• Lakshmi Sankar
• lsankar_at_ae.gatech.edu

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OVERVIEW

• In the previous module 1.1, you leaned about the
  course objectives, topics to be covered, and the
  deliverables (assignments)
• In this module, we will first review the history
  of the wind turbines
• We will also learn some basic terminology
  associated with wind turbines
• We will also discuss what factors go into
  choosing sites where you may build/deploy your
  own wind turbines or farms.
• We will conduct this discussion through case
  studies.

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History of Wind Turbineshttp//www1.eere.energy.g
ov/windandhydro/wind_history.html

• Technology is old, in some respects!
• Wind was used to propel sail boats as early as
  5000 BC in Egypt.
• Chinese used wind energy to pump water by as
  early as 200 BC
• Persians used wind energy about the same time to
  grid grain
• By the 11th century, people in the middle east
  were using wind mills for food production
• Traders and crusaders carried the ideas to Europe.

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History of Wind Turbines (Continued..)

• Dutch were looking for ways of draining lakes and
  marshes.
• Wind turbines became very popular.
• The technology spread to US when settler brought
  these ideas to America.
• Industrialization (use of coal to generate steam)
  brought a decline in the use of wind energy.
• Steam engines replaced wind mills for pumping
  water and producing electricity.
• Rural electrification began in the 1930s.
• Wind turbines had to make their case
  economically!
• Their popularity rose and fell with the
  availability and cost of alternative forms of
  energy production.
• Oil crisis in the 1970s and energy crisis during
  the past decade has brought wind energys
  potential as a clean, renewable, sustainable,
  energy source,

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Wind Power's Beginnings (1000 B.C. - 1300 A.D.)

• Persians used the drag of the blades (i.e.
  aerodynamic force along the direction of the
  wind) to generate rotation of the blades.
• Struts connected the sails to central shaft.
• Grinding stone was attached to the central shaft.
• Only one half of the turbine was useful at any
  instance in time.

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Early Designshttp//www.telosnet.com/wind/early.h
tml
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Lift vs Drag

• The aerodynamic force along the direction of the
  wind is called drag
• Early wind turbines used drag to generate the
  torque.
• The aerodynamic force normal to the wind
  direction is called lift.
• For a properly designed blade (or airfoil) lfit
  to drag ratio may be 100 to 1!
• Dutch began using lift force rather than drag to
  turn the rotor.
• Over the past 500 years, the design has evolved
  through analysis and experimentation.

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Use of Drag to Produce Torque
Pelton Wheel uses this concept
Drag Force
Wind
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Use of Lift forces for Torque Production
Propulsive force Lsinf - Dcosf
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Wind Turbine History in the US

• During the 19th century wind mills were used to
  pump water.
• Rotor diameter reached 20 meters.
• Water was used to operate steam engines,
• Eray designs used wood as the material and had a
  paddle like shapes.
• Drag force was used.
• Later designs used steal blades which could be
  shaped to produce lift forces.
• The blades spun fast, requiring gears to reduce
  the angular velocity.
• Mechanisms were developed for folding blades in
  case of high winds.
• In 1888, electricity was produced using the wind
  turbine shown on the lower right by Charles F.
  Brush.
• By 1910s, coal and oil fired steam plants became
  popular, and the use of wind turbines became less
  common.

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Installed Wind Power Generation (in
MW)http//www.windenergyinstitute.com/installed.h
tml
Rank County 2005 2006 2007
1 Germany 18,415 20,622 22,247
2 United States 9,149 11,603 16,818
3 Spain 10,028 11,615 15,145
4 India 4,430 6,270 8,000
5 China 1,260 2,604 6,050
6 Denmark ( Faeroe Islands) 3,136 3,140 3,129
7 Italy 1,718 2,123 2,726
8 France 757 1,567 2,454
9 United Kingdom 1,332 1,963 2,389
10 Portugal 1,022 1,716 2,150
11 Canada 683 1,459 1,856
12 Netherlands 1,219 1,560 1,747
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Basic Terminology

• Vertical Axis (or Darrieus) Wind Turbines vs.
  Horizontal Axis Wind Turbines
• We will study HAWTs in this course.

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Terminology (Continued)http//www.energybible.com
/wind_energy/glossary.html

• Availability Factor
• The percentage of time that a wind turbine is
  able to operate and is not out commission due to
  maintenance or repairs.
• Capacity Factor
• A measure of the productivity of a wind turbine,
  calculated by the amount of power that a wind
  turbine produces over a set period of time,
  divided by the amount of power that would have
  been produced if the turbine had been running at
  full capacity during that same time interval.

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Terminology (Continued)

• Rotor
• Comprises the spinning parts of a wind turbine,
  including the turbine blades and the hub.
• Hub
• The central part of the wind turbine, which
  supports the turbine blades on the outside and
  connects to the low-speed rotor shaft inside the
  nacelle.
• Root Cutout
• The percentage of the rotor blade radius that is
  cut out in the middle of the rotor disk to make
  room for the hub and the arms that attach the
  blades to the shaft.
• Nacelle
• The structure at the top of the wind turbine
  tower just behind (or in some cases, in front of)
  the wind turbine blades that houses the key
  components of the wind turbine, including the
  rotor shaft, gearbox, and generator.

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Parts of a Wind Turbine

• Turbine controller is connected to the rotor.
• Converter controller, connected to converters and
  main circuit breaker, is needed to control the
  output voltage and power

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Wind Power Classificationhttp//www.awea.org/faq/
basicwr.html
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(No Transcript)
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The following slides are from a Presentation in
2002 byAmerican Wind Energy Association
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Wind Power is Ready
Clean Energy Technology for Our Economy and
Environment
American Wind Energy Association, 2002
Image courtesy of NEG Micon
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Wind Power Market Overview
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Ancient Resource Meets 21st Century Technology
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Wind TurbinesPower for a House or City
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Ready to Become a Significant Power Source
Wind could generate 6 of nations electricity by
2020.
Wind currently produces less than 1 of the
nations power. Source Energy Information Agency
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Wind is Growing Worldwide
1. Germany 8754 MW 2. U.S. 4260 MW 3. Spain
3195 MW 4. Denmark 2492 MW 5. India 1507 MW
Source AWEAs Global Market Report
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Wind Taking Off in the U.S.

• U.S. installed nearly 1,700 MW in 2001
• Wind power capacity grew by 66
• Over 4,265 MW now installed
• Expecting over 2,500 of new capacity in 2002-2003
  combined

Source AWEAs U.S. Projects Database
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United States Wind Power Capacity (MW)
New Hampshire 0.1
Maine 0.1
Washington 180.2
Vermont 6.0
Wisconsin 53.0
Montana 0.1
North Dakota 1.3
Minnesota 322.7
Michigan 2.4
Oregon 156.9
South Dakota 2.9
Massachusetts 1.0
Wyoming 140.6
New York 48.2
Iowa 324.3
Nebraska 3.5
Utah 0.2
Pennsylvania 34.5
Colorado 61.2
Kansas 113.7
California 1,715.9
Tennessee 2.0
New Mexico 1.3
Source AWEAs U.S. Projects Database
Texas 1,095.5
Alaska 0.9
4,270 MW as of 07/31/02
Hawaii 1.6
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Washington 180
Wisconsin 30
New York 30
Minnesota 218
Oregon 132
Iowa 82
Main Areas of Growth in 2001
Pennsylvania 24
Kansas 112

1,697 MW added in 2001
Texas 915
Source AWEAs U.S. Projects Database
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U.S. Wind Power Capacity Growth
Source AWEAs U.S. Projects Database
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Wind Power Economics
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Cost Nosedive Driving Winds Success
38 cents/kWh
2.5-3.5 cents/kWh
Levelized cost at excellent wind sites in nominal
dollars, not including tax credit
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Wind Power Cost of Energy Components

• Cost (/kWh) (Capital Recovery Cost OM) /
  kWh/year
• Capital Recovery Debt and Equity Cost
• OM Cost Turbine design, operating environment
• kWh/year Wind Resource

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Capital Costs

• Revenue Streams
• Commodity Power Sale 30-45/MWh
• Production Tax Credit 18/MWh
• Green Credit New Market, Values Vary
• Debt/equity ratios close to 50/50
• Increased debt/equity ratios can significantly
  increase return

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Long-Term Debt

• Better loan terms with longer-term power purchase
  agreement (PPA)
• Loan terms up to 22 years, determined largely by
  PPA

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Equity Considerations

• Return requirements vary with risk
• Perceived risk of wind projects may be larger
  than real risk
• Returns evaluated after tax credit
• Wind energy projects can expect return in low
  teens (10 to 15)

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Turbine Technology Constantly Improving

• Larger turbines
• Specialized blade design
• Power electronics
• Computer modeling produces more efficient design
• Manufacturing improvements

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How big is a 2.0 MW wind turbine?
This picture shows a Vestas V-80 2.0-MW wind
turbine superimposed on a Boeing 747 JUMBO JET
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Construction Cost Elements
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Technology Improvements Leads to Better
Reliability

• Drastic improvements since mid-80s
• Manufacturers report availability data of over 95

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Improved Capacity Factor

• Capacity Factors Above 35 at Good Wind Sites
• Performance Improvements due to
• Better siting
• Larger turbines/energy capture
• Technology Advances
• Higher reliability

• Examples Project Performance (Year 2000)
• Big Spring, Texas
• 37 CF in first 9 months
• Springview, Nebraska
• 36 CF in first 9 months

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Bottom Line 20 Years of Wind Technology
Development
1981 1985 1990 1996 1999 2000
Rotor (Meter) 10 17 27 40 50 71
KW 25 100 225 550 750 1650
Total Cost 65 165 300 580 730 1300
Cost/kw 2,600 1,650 1,333 1,050 950 790
Capacity Factor 21 25 28 31 33 39
MWh produced over 15 years 675 3300 8250 22,200 33,000 84,000
Amortized cost of turbine per unit of energy 9.6 5 3.6 2.6 2.2 1.5
Economy of scale reduces price per kw of capacity
Technology improvements yield more energy bang
for the buck
Combined, they dramatically reduce turbine price
per unit of energy produced
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Benefits of Wind Power
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Advantages of Wind Power

• Environmental
• Resource Diversity Conservation
• Cost Stability
• Economic Development

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Benefits of Wind PowerEnvironmental

• No air pollution
• No greenhouse gasses
• Does not pollute water with mercury
• No water needed for operations

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Electricity Production is Primary Source of
Industrial Air Pollution
Source Northwest Foundation, 12/97
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Benefits of Wind PowerEconomic Development

• Expanding Wind Power development brings jobs to
  rural communities
• Increased tax revenue
• Purchase of goods services

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Benefits of Wind PowerEconomic Development
Case Study Lake Benton, MN 2,000 per 750-kW
turbine in revenue to farmers Up to 150
construction, 28 ongoing OM jobs Added 700,000
to local tax base
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Benefits of Wind PowerFuel Diversity

• Domestic energy source
• Inexhaustible supply
• Small, dispersed design reduces supply risk

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Benefits of Wind PowerCost Stability

• Flat-rate pricing can offer hedge against fuel
  price volatility risk
• Electricity is inflation-proof

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Wind Project Siting
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Siting a Wind Farm

• Winds
• Minimum class 4 desired for utility-scale wind
  farm (gt7 m/s at hub height)
• Transmission
• Distance, voltage excess capacity
• Permit approval
• Land-use compatibility
• Public acceptance
• Visual, noise, and bird impacts are biggest
  concern
• Land area
• Economies of scale in construction
• Number of landowners

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Power in the Wind (W/m2)
Density P/(RxT) P - pressure (Pa) R -
specific gas constant (287 J/kgK) T - air
temperature (K)
Area ? r2
Instantaneous Speed (not mean speed)
kg/m3
m2
m/s
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Perceived Market Barriers

• Siting
• Avian
• Noise
• Aesthetics
• Intermittent Fuel Source

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Actual Market Barriers

• Transmission constraints
• Financing
• Operational characteristics different from
  conventional fuel sources

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Wind Characteristics Relevant to Transmission
System

• Intermittent output
• Generally remote location
• Small project size
• Short/flexible development time
• Low capacity factor

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Wind Development IssuesTransmission Grid
Operating Rules

• What wind wants
• Liquid, transparent spot market for imbalance
  settlements
• Near real time, flexible scheduling protocols
• Robust secondary markets in transmission rights
  (flexible firm)
• Postage stamp pricing allocated to load (or
  volumetric pricing)
• Statistical determination of conformance to load
  shape to set value
• What wind gets
• System designed exclusively to transport firm,
  fixed blocks/commodity strips
• Rigid advance scheduling protocols/onerous
  imbalance charges
• License plate pricing allocated to incremental
  generation
• Grid balkanization/rate pancaking

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Wind Development IssuesTransmission Expansion

• What wind wants
• Pro-active regional planning with political
  buy-in.
• Programmatic expansion focused on shared goals.
• Public infrastructure financing repaid through
  user fees.
• What wind gets
• Reactive, piecemeal gridlock decoupled from
  political process.
• Project specific expansion focused on immediate
  needs of existing players.
• Uncertain capacity rights as sole rate recovery
  mechanism.

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Consequences of Wind Characteristics

• Remote location and low capacity factor higher
  transmission investment per unit output
• Small project size and quick development time
  planning mismatch with transmission investment
• Intermittent output can higher system operating
  costs if systems/protocols not designed properly

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Federal and State Policies to Promote Wind Power
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Production Tax Credit

• Lowers price of electricity to make it more
  accessible to customers
• Currently provides credit of 1.8 per kWh
• Industry needs long-term extension to encourage
  investment

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Renewable Portfolio Standard

• Requirement that U.S. suppliers get 10 of supply
  from renewable sources by 2020
• Texas example shows how RPS can enable green
  power markets to flourish by creating a supply of
  reasonably-priced renewable energy
• Can create incentives to solve transmission
  issues

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Standard Market Design Interconnection

• Wind is square peg in a round hole
• Intermittent
• Site-specific, often rural
• Small, with short construction lead time
• SMD Interconnection NOPRs designed to make
  markets more efficient, which could make a big
  difference in cost and availability of wind power

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Clean Air Act

• Expect to see amendment to the Clean Air Act
  before 2004 elections
• Without set-asides or direct allocation for
  renewables, would strip wind projects of ability
  to claim emissions reductions
• Output based compliance that includes NOx, SO2
  and CO2 could add revenue stream of 0.4 - 0.5
  cents per kWh

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Small Turbine Incentives

• 30 Investment Tax Credit
• Net metering

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State Incentives

• State renewable portfolio standards
• Public Benefits Funds
• Electricity source disclosure
• Government procurement

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Green Power Market
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Green Power Market

• Places a monetary value on environmental benefits
• Raises visibility of renewable power promotes
  customer awareness
• Usually small scale, short-term contracts

Premium prices
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Different Ways to Buy

• Green Pricing
• Regulated utility offers customers choice to
  support wind power construction
• Green Marketing
• In competitive market, customers empowered to
  choose service providers that contract to
  purchase renewables
• Green Tags
• environmental attributes divorced from energy

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Competitive Green Market

• Has encouraged about 25 MW in CA PA to date
• Will encourage more than 75 MW in PA in next two
  years

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Green Pricing

• Has encouraged over 15 new wind projects to serve
  green pricing market
• Smaller projects
• Spread throughout the U.S. raises visibility of
  wind power

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Small Wind Turbine Market Development
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Programs for small wind development

• Buy-down programs
• Exemptions from sales, property tax
• Standardized zoning requirements

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Buy-down programs

• CA renewables fund refunds 50 of the cost of a
  renewable system
• CA sales account for over half of the small wind
  turbine market
• MA buy-down program refunds 10 capped at 100
• does not appreciably affect the market

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Property / Sales Tax

• Property or sales tax exemption offered in
  several states
• Programs to affect initial purchase price work
  best
• Net metering programs (equalizing kWh costs paid
  and received by residential generators) do not
  seem to drive purchasing decisions

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Future Trends in Wind Power
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Expectiations for Future Growth

• 2,500 MW new added by end of 2003
• 20,000 total installed by 2010
• 6 of electricity supply by 2020

100,000 MW of wind power installed by 2020
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Wind EnergyU.S. Proven Probable
ReservesNameplate MW
Region On-Line In Development Developable in Reserve
_at_2 natural gas _at_4 natural gas
West 2,254 2,750 35,000 200,000
Midwest 900 500 400 350,000
East 90 330 500 7,000
Texas 1,016 300 --- 40,000
South 2 20 100 600
Total 4,262 4,000 36,000 600,000
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Future Cost Reductions

• Financing Strategies
• Manufacturing Economy of Scale
• Better Sites and Tuning Turbines for Site
  Conditions
• Technology Improvements

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Future Technology Developments

• Application Specific Turbines
• Offshore
• Limited land/resource areas
• Transportation or construction limitations
• Low wind resource
• Cold climates

Middelgruden.dk
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• www.AWEA.org
• Windmail_at_awea.org
• American Wind Energy Association
• 122 C St, NW, Suite 380
• Washington, DC 20001