Wind Power Feasibility Studies

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January 2007

Kurt Myers, MSEE, PERenewable Energy & Power

Wind Power Feasibility StudiesWind Data Collection, Analysis and Energy Projections

INL/CON-07-12168


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#1 Quality Wind Data is Important

All of your analysis should be based on collected data

Peoples perception of windy is not good enough fora wind power project

Define the difference between wind prospecting and

development grade data


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Initial Assessment of the Possible

Area Collect initial data from multiple sources (i.e. talk to

people, look for existing data, look at wind maps, useown experience, topo maps, etc.)

Look at lay of the land, prevailing wind direction,vegetation (flagged trees, etc.)

Decide what type of wind data tower will work best for

what you are planning (prospecting or development, 10to 80 meters, number & type of instruments, cost,permits, etc.)


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Look like a windy area? (note tree flagging)


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Data Tower Sizes and Costs

NRG 60 meterSymphonieTower Kit -

$13,900 + install

NRG 50 meterSymphonieTower Kit -

$8600 + install

NRG 30 meterTower Kit -$4000

(prospecting)

Development-grade towers: 2-4 per site


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Anemometer tower installation 20 meter, prospecting


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Anemometer tower installation 50 meter


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Anemometer tower installation 50 meter


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Data Analysis

Need data spanning at least a year (all four seasons)

If only one year of data, then correlation required as well

Work hard not to lose any data!! (on-time chip swaps, becomeproficient early with data handling/processing, cell phone system

options, etc.)

Data identifies resource potential

Use other resources to help with data analysis

Know what youre looking at, and be sure to compare apples toapples


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Data Analysis - continued

There are many factors to address in data analysis Quality of data (any icing, etc.), filtering

Is correlation with other sites possible

Elevation/air density

Weather/temperature Scaling to different heights (wind shear, variations)

Turbine sizes/types/manufacturers being considered

Wake effects, turbulence

Land topography, modeling

When to get wind power meteorological consultant(s)involved


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Items to note:

Multiple levels

Multiple sensors(shear & reliability)

Boom direction isimportant

Problems here:Stub and boomscombined

Booms should notdirectly faceprevailing wind

Need at least onelevel with twoanemometers


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Tower Effects Wake, Back-Pressure

Prevailing WindDirection


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Tower Arrangement

Document your installation!!

Latitude, longitude, elevation

Site number

Equipment types Instrument heights, boom orientations, which

instrument corresponds to which channel

Start time, date

Pictures, ownership, labeling of data

Etc.


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The Data Is Being Collected Now What? Swapping data cards/chips

When, how often, is there cell coverage

Processing data

Store, analyze, do projections

NRG Symphonie Data Retriever software (see note below) will beused at this point to illustrate data collection/analysis examples

Wind speed graphs

Check data

Summary reports with wind speed averages

Wind roses

Filtering, creating text/Excel files (exporting), etc.

Note: NRG is used as an example; other manufacturers work well. INL makesno recommendations or representation of which equipment or software touse.


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Wind Shear Formulas

Wind shear is a measure of the rate of increase in wind speed as onemoves higher above the ground.

In wind energy development, wind shear is important. Higher shear,more wind speed at higher hub heights, more energy production.

Wind shear heavily influences project economics: hub height, energyproduction vs. installed cost.

To scale up wind speed:

y = x * [(b/a)^z]

x=wind speed at lower height, y=wind speed at higher height, a=lowerheight, b=higher height, z=wind shear value

To calculate wind shear:

z = log(y/x) / log(b/a)


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Wind Shear Examples

13.0 mph wind speed average @ 20 meters, and wind shear isestimated as average. What is the average wind speed @ 80meters?:

y = 13.0mph * [(80m/20m)^(1/7)]

y = 15.85 mph

Tower measures wind speed average of 13.0mph @ 20 meters,and 16.7mph @ 80 meters. What is the estimated wind shearvalue from 20 to 80 meters?:

z = log(16.7mph/13.0mph) / log(80m/20m)z = 0.181


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Using Wind Speed Averages and RayleighDistribution For Energy Production Estimates

Energy production examples with INL Weibull spreadsheet will bedemonstrated to illustrate differences and impact on cost andproduction

Average wind speed differences (13.5, 15, 16.5mph @ 30meters AGL)

Wind shear differences (0.1, 0.14, 0.18, 0.22)

Tower height differences (30m, 65m, 80m)

Site altitude differences (sea level and 1.02kg/m3)

Standard rotor vs. long blade, low wind

Small turbine(s) vs. large turbine

Subtle differences of large turbine types (i.e. fixed speed,variable speed, variable speed direct drive)

Gross vs. net production


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Large Turbine Perspective


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Small Turbine Perspective


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More Detailed Wind Data Analysis

Demonstrate with an example of energy productionanalysis using 10-minute wind data and INLspreadsheets.

Commercial-grade assessment


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Turbine suppliers, developers, and finance institutions all requiredue-diligence, requiring information such as:

Hub height annual wind speed averages Turbulence intensities at various wind speeds and directions

Filtering required

2-second and 10-minute gusts (10 or 50 yr. projections)

Correlation with other regional data sites, preferably longer-

term sites Air densities, impacts, seasonal variations

Wind shear (also needed for financing, project economics due-diligence)

Analysis for different heights

Temperature ranges Wake effects, wind farm layout

Etc.


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INL Contacts

Renewable Energy & Power Department

Robert M. Neilson, Jr.

(208)526-8274; [email protected]

Gary D. Seifert(208)526-9522; [email protected]

Kurt S. Myers

(208)526-5022; [email protected]

INL Wind Program information www.inl.gov/wind


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Other Information Sources

U.S. Department of Energy, Office of Energy Efficiency &Renewable Energy

www.eere.energy.gov/windandhydro

Idaho Department of Water Resources Energy Divisionwww.idahowind.org

American Wind Energy Association

www.awea.org

Documents

Wind Power Feasibility Studies