wind 101-half-5 fundamentals - wind-works: welcome€¦ · · 2013-08-06wind turbines @ wulf...

Fundamentals of Wind Energy

Paul Gipe, wind-works.org

Power in the Wind

321 AVP

Where is air density (kg/m3),A is area (m2), andV is velocity (m/s).


Air Density

TRp*


Where p is air pressure (mb),R is the gas constant, andT is temperature (K)


Vegetative Indicators--Wind

Throw

Aude, France

Increase in Wind Speed Over Ridges


Seasonal Wind Distribution


Jan Feb March April May June July Aug Sept Oct Nov Dec

Month

0

2

4

6

8

10

12

14

16

18Avg. Monthly Wind Speed (mph)

Amarillo, TexasErie, Penn.San Francisco, Calif.

Rayleigh Wind Speed Distribution

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20Wind Speed Bin

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16Frequency of Occurrence %

5 m/s6 m/s7 m/s


Weibull Wind Speed DistributionFor Same Average Speed


0 2 4 6 8 10 12 14 16 18 20 22 24

Wind Speed (m/s)

0

0.05

0.1

0.15

0.2

0.25Frequency (%)

0

10

20

30

40

50

60

70

Power Density (W/m2)

Tera Kora %Tera Kora W/m2Helgoland %Helgoland W/m2

Speed, Power, & Height


V/Vo = (H/Ho) α

P/Po = (H/Ho) 3α

Where α is the surface friction coefficient.• 1/7 (0.14), Low Grass Prairies• 1/4 (0.25), Suburbs• 0.40, Urban

Increase in Wind Speed with Height

1 1.5 2 2.5 3 3.5 4 4.5 51

1.1

1.2

1.3

1.4

1.5

1.6

Wind Shear Exponent0.1 0.14 (1/7) 0.2 0.25

V=Vo (H/Ho)"

H/Ho


Increase in Power with Height

1 1.5 2 2.5 3 3.5 4 4.5 51

1.5

2

2.5

3

3.5Wind Shear Exponent

0.1 0.14 (1/7) 0.2 0.25

P=Po (H/Ho)

H/Ho

"3


Change in Wind Speed & Power with Height

2 X Height 25 to 50 m

5 X Height 10 to 50 m

Wind Speed 1.1 1.25

Wind Power 1.35 1.99


1/7 (0.14), Low Grass Prairies

Wind Resources of Ontario


Wind Resources of the Dakotas


Energy in the WindAnnual Energy Output (AEO)

Annual Energy Production (AEP)

AEO = 1/2 ρ A V ή (8,760 hrs/year)3


AEO Estimating Methods


• Back-of-the-Envelope (Swept Area)Simple Approximation

• Power Curve & Speed DistributionMethod Used by the ProsAccuracy Dependent Upon Data

• Manufacturers’ TablesDependent Upon Honesty of Manufacturer

• SoftwareMust Know Assumptions Used (RETScreen)


Rotor Dimensions

Medium-Size & Large Wind Turbines

01020304050607080

Rotor Diameter (m)

250

1500

1000

500

50

15 25 40 60 70 80Diameter (meters)

0

1000

2000

3000

4000

5000

Swept Area (m²)

2000


Measured Efficiency of Small Wind Turbines @ Wulf Field

0 5 10 15 20 25 30 35Wind Speed (mph)

0

0.05

0.1

0.15

0.2

0.25

0.3Efficiency (%)

MarlecLVMAir 303Air 403BWC 850Ampair


AEO Small Wind Turbines


Conversion Efficiency


0

0.1

0.2

0.3

0.4

0.5

Effi

cien

cy

0 2 4 6 8 10 12 14 16 18 20 Wind Speed (m/s)

L 18/80 S31 E40 V47

Medium Size Wind TurbinesMeasured Efficiency

bk1/medturbeffic.wb3

California Annual Specific Yield


86 87 88 89 90 91 92 93 94 95 96 97 98 99 '00 '01 '02 '03

Year

0

200

400

600

800

1,000

1,200

1,400Annual Specific Yield (kWh/m2/yr)

Cal. Avg.San Gorgonio Farms

Tararua New Zealand Yields

Tararua Wind Plant New Zealand Specific YieldsVestas V47

Specific YieldSwept AreaDiameterApproximatekWh/m2/yrm2mkWh/yr

8008401,735471,457,901Low1,5001,4401,735472,500,000Median1,8001,7601,735473,050,622High

WindStats, Spring 2005, Vol. 18, No. 2, pg 13.


AEO Medium & Large Turbines


Estimating AEOSwept Area Method for 7 m/s*

Paul Gipe, wind-works.org *At Hub Height

Turbine Swept Area (m2)

Yield (kWh/m2/yr)

AEO (kWh/yr)

36 m; .5 MW 1,000 1,000 1,000,000

50 m; .75 MW 2,000 1,000 2,000,000

62 m; 1 MW 3,000 1,000 3,000,000

80 m; 2 MW 5,000 1,000 5,000,000

Sample Power Curve CalculationPower Curve


8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40

Wind Speed (mph)

00.10.20.30.40.50.60.70.80.9

11.11.2

Kilowatts

Sample Power Curve CalculationSpeed Distribution


8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40

Wind Speed (mph)

0

100

200

300

400

500

600Hours per Year

Sample Power Curve CalculationAnnual Energy Production


8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40Wind Speed (mph)

0

20

40

60

80

100kWh/year

Net Generation from Wind Plants


Net

Availability 98%

Electrical 97%

Array Interference 90%-95%

Total 86%-90%


Measures of Productivity

• Capacity (Plant) FactorMisleading IndicatorUsed for Fossil-Fired PlantsNot Suited for Wind Energy Use

• kWh/kW/yr (for Planning Purposes)When Sufficient Data is Unavailable

• Annual Specific Yield (kWh/m2/yr)The Only Measure Specific to Wind Energy

Measures of Cost• $/kW of Installed Capacity

Often a Misleading Indicator

• $/m2 of Installed Swept AreaMost Useful When Resource is Unknown

• $/kWh/yr of Annual GenerationMost Important Criteria in the End


Wind Energy Software• Spreadsheets

Integrated (Tom Wind)Fully Integrated (RETScreen)

• Wind Farm Design ToolsWAsP (Risø)WindFarm (ReSoft)WindFarmer (Garrad Hassan)WindPro (EMD)WindMap (Brower)



Wind Turbine StandardsSmall Turbines

Caveat Emptor (Buyer Beware)You Get What You Pay For

Big TurbinesMinimum Design Stds. (GL)Power Curve Field TestsWarranteed Power CurvesPerformance GuaranteesField Experience Best Guide

Trade Magazines


• Windpower Monthly• WindStats• WinDirections• RE World• New Energy• Neue Energie• North American Windpower• Systèmes Solaires

• Power Curves• Noise• Power Factor• Flicker


Measured Performance Data

Pricing

• Model• Tower• Transformer• €/kWh/annum• €/m2


New Wind Books


2002 20012002

2005

WWW Sites


• www.windpower.dkDanish Manufacturers

• www.eole.org/ en français

• www.wind-energie.deBWE, German Wind Turbine Owners

• wind-works.orgArchive of Articles by Paul Gipe

Don’t Be Afraid of Foreign Language Web Sites

wind 101-half-5 fundamentals - wind-works: welcome€¦ · · 2013-08-06wind turbines @ wulf...

Documents