HomeMy WebLinkAboutChevak Wind Energy Recovery Wind Resource Report - Feb 2007 - REF Grant 7050875Chevak, Alaska Wind Resource Report
Report prepared by: Douglas Vaught, V3 Energy LLC, Eagle River, AK
Date of report: February 21, 2007
Photo: Doug Vaught
Summary Information
Chevak has an outstanding wind resource for wind power development. Not only does the site
rate as Class 6 (of seven designated classes of wind), the winds are relatively directional and low
turbulence. Besides logistics and construction issues, the one significant challenge to installing
wind turbines in Chevak is the permafrost soils at the designated wind farm site.
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Meteorological Tower Data Synopsis
Wind power class Class 6 – Outstanding
Average wind speed (30 meters) 7.64 m/s
Maximum wind speed (10 min. avg) 28.6 m/s
Mean wind power density (50 meters) 675 W/m2
Mean wind power density (30 meters) 553 W/m2
Roughness Class 1.02 (fallow field)
Power law exponent 0.15 (moderate wind shear)
Data start date December 10, 2004
Most recent data date October 31, 2006
Community Profile
Current Population:916 (2005 State Demographer est.)
Pronunciation/Other Names:(CHEE-vack); a.k.a. Kashunamiut
Incorporation Type:2nd Class City
Borough Located In:Unorganized
School District:Kashunamiut School District
Regional Native Corporation:Calista Corporation
Location:
Chevak is located on the north bank of the Niglikfak River, 17 miles east of Hooper Bay in the Yukon-
Kuskokwim Delta. It lies at approximately 61.527780° North Latitude and -165.586390° West Longitude.
(Sec. 34, T017N, R090W, Seward Meridian.) Chevak is located in the Bethel Recording District. The
area encompasses 1.1 sq. miles of land and 0.1 sq. miles of water.
History:
Eskimos have inhabited the region for thousands of years. Chevak is also known as New Chevak
because residents inhabited another village called Chevak before 1950. "Old" Chevak, on the north bank
of the Keoklevik River, 9 miles east of Hooper Bay, was abandoned because of flooding from high storm
tides. The name Chevak refers to "a connecting slough," on which "Old" Chevak was situated. The new
site was first reported by the U.S. Coast and Geodetic Survey in 1948. A post office was established in
1951. The City government was incorporated in 1967.
Culture:
Chevak is a Cup'ik Eskimo village. Commercial fishing and subsistence activities are an important part of
the local culture. The sale or importation of alcohol is banned in the village.
Economy:
Employment in Chevak is at its peak in the summer months and declines to a few full-time positions
during winter. Construction projects and BLM fire fighting provide summer employment. Eighteen
residents hold commercial fishing permits. Incomes are supplemented by subsistence activities and
handicrafts. Salmon, seal, walrus, clams and waterfowl are harvested.
Facilities:
Construction began in 1995 to provide piped water and sewer to all 170 homes and the school.
Completed projects include a new landfill, a washeteria renovation, a new watering point, water treatment
plant, a 150,000-gallon water storage tank, sewage lagoon, and a vacuum sewer plant. Water and sewer
mains and household connections are completed. 193 homes have been connected to the new system.
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Transportation:
A State-owned 2,610' long by 40' wide gravel airstrip is available, although heavy winds and rain can
preclude air access. A relocation of the airport is currently underway. Float planes can land on Chevak
Lake/Ninglikfak River. There are no docking facilities; however, a barge landing is available for cargo off-
loading. Skiffs are used for local travel on the river in the summer, and snowmachines are used in the
winter. Winter trails exist to Scammon Bay (25 mi.), Hooper Bay (20 mi.) and Newtok (50 mi.)
Climate:
Chevak has a maritime climate. Its location near the Bering Sea renders the area subject to heavy winds
and rain. Temperatures range from -25 to 79 degrees Fahrenheit. Snowfall averages 60 inches per year.
Freeze-up occurs at the end of October. Break-up occurs in June.
(Above information from State of Alaska Department of Commerce, Community, and Economic
Development website, http://www.dced.state.ak.us/)
Site Information and Location
Site number 0014
Site Description On hill about coastal flats; west side of village
Latitude/longitude N 061° 31.492’; W 165° 36.389’
Site elevation 22 meters
Datalogger type NRG Symphonie
Tower type NRG 30-meter tall tower, 152 mm (6-in) diameter
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Met Tower Sensor Information
Channel Sensor type Height Multiplier Offset Orientation
1 NRG #40 anemometer 30 m (A) 0.765 0.35 North
3 NRG #40 anemometer 20 m 0.765 0.35 East
4 NRG #40 anemometer 30 m (B) 0.765 0.35 Northeast
7 NRG #200P wind vane 30 m 0.351 004 South
8 NRG #200P wind vane 20 m 0.351 330 Southeast
9 NRG #110S Temp C 2 m 0.136 -86.383 N/A
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Data Quality Control Summary
Data was filtered to remove presumed icing events that yield false zero wind speed data. Data
that met the following criteria were filtered: wind speed < 1 m/s, wind speed standard deviation
= 0, and temperature < 3 °C. Other obvious icing data was removed even if it did not meet the
above criteria. The Chevak met tower has experienced more than typical sensor problems.
Upon installation in December 2004, the 20 m anemometer and the temperature sensor failed to
work properly. Changes were made to the datalogger in June 2005 and these two sensors began
recording. A second anemometer at the 30 meter level and an anemometer at the 20 meter level
were installed in July 2005. For this report, data was synthesized to replace data missing due to
inoperative sensors and icing events. All further information in this report is from the
synthesized data file unless otherwise noted.
Speed 30 m A Speed 20 m Speed 30 m B
Year Month Records Recovery Records Recovery Records Recovery
Rate (%) Rate (%) Rate (%)
2004 Dec 2,877 86.9 0 0 0 0
2005 Jan 4,216 94.4 0 0 0 0
2005 Feb 4,032 100 0 0 0 0
2005 Mar 4,166 93.3 0 0 0 0
2005 Apr 4,320 100 0 0 0 0
2005 May 4,378 98.1 0 0 0 0
2005 Jun 4,320 100 3,357 77.7 0 0
2005 Jul 4,464 100 4,464 100 2,324 52.1
2005 Aug 4,464 100 4,464 100 4,464 100
2005 Sep 4,320 100 4,320 100 4,320 100
2005 Oct 4,464 100 4,464 100 4,464 100
2005 Nov 4,320 100 4,320 100 4,320 100
2005 Dec 4,464 100 3,366 75.4 3,281 73.5
2006 Jan 3,730 83.6 3,730 83.6 3,730 83.6
2006 Feb 4,032 100 4,032 100 4,032 100
2006 Mar 4,264 95.5 4,464 100 4,464 100
2006 Apr 4,320 100 4,320 100 4,320 100
2006 May 4,464 100 4,464 100 4,464 100
2006 Jun 4,320 100 4,320 100 4,320 100
2006 Jul 4,464 100 4,464 100 4,464 100
2006 Aug 4,464 100 4,464 100 4,464 100
2006 Sep 4,320 100 4,320 100 4,320 100
2006 Oct 4,392 100 4,392 100 4,392 100
All data 97,575 98.0 71,725 72.0 66,143 66.4
Direction 30 m Direction 20 m Temperature
Year Month Records Recovery Records Recovery Records Recovery
Rate (%) Rate (%) Rate (%)
2004 Dec 3,025 91.3 0 0 0 0
2005 Jan 4,025 90.2 0 0 0 0
2005 Feb 3,751 93 0 0 0 0
2005 Mar 4,093 91.7 0 0 0 0
2005 Apr 4,320 100 0 0 0 0
2005 May 4,464 100 0 0 0 0
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2005 Jun 4,320 100 0 0 3,317 76.8
2005 Jul 4,464 100 2,352 52.7 4,464 100
2005 Aug 4,464 100 4,464 100 4,464 100
2005 Sep 4,320 100 4,320 100 4,320 100
2005 Oct 4,364 97.8 4,364 97.8 4,464 100
2005 Nov 4,320 100 4,320 100 4,320 100
2005 Dec 1,920 43 1,920 43 4,464 100
2006 Jan 3,642 81.6 2,897 64.9 4,464 100
2006 Feb 4,032 100 4,032 100 4,032 100
2006 Mar 4,464 100 4,464 100 4,464 100
2006 Apr 4,320 100 4,320 100 4,320 100
2006 May 4,464 100 4,464 100 4,464 100
2006 Jun 4,320 100 4,320 100 4,320 100
2006 Jul 4,464 100 4,464 100 4,464 100
2006 Aug 4,464 100 4,464 100 4,464 100
2006 Sep 4,320 100 4,320 100 4,320 100
2006 Oct 4,392 100 4,392 100 4,392 100
All data 94,732 95.1 63,877 64.1 73,517 73.8
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Measured Wind Speeds
The Channel 4 (30-meter [B]) anemometer wind speed average for the reporting period is 7.64
m/s. The Channel 1 (30-meter [A]) anemometer wind speed average is 7.61 m/s and the Channel
3 (20-meter) anemometer wind speed average for the reporting period is 7.18 m/s. The daily
wind speed profile indicates that the lowest winds of the day occur in the morning at about 3 a.m.
to 9 a.m. and the highest winds of the day occur in the afternoon and early evening hours of
about 2 p.m. to 8 p.m.
Speed 30 m A Speed 30 m B Speed 20 m
Month Mean Max
Std.
Dev.
Weibull
k Weibull c Mean Max Mean Max
(m/s) (m/s) (m/s) (m/s) (m/s) (m/s) (m/s) (m/s)
Jan 9.14 27.2 4.10 2.34 10.28 9.10 27.2 8.61 26.2
Feb 9.80 27.7 4.56 2.28 11.07 9.78 28.6 9.22 27.9
Mar 8.95 21.2 4.17 2.25 10.07 8.86 21.2 8.39 20.7
Apr 8.87 20.5 3.97 2.34 9.97 8.87 21.0 8.38 19.7
May 6.68 20.9 3.24 2.15 7.53 6.83 20.8 6.39 20.3
Jun 6.19 16.1 2.57 2.56 6.94 6.14 16.7 5.85 15.7
Jul 5.85 20.2 2.78 2.20 6.59 5.67 20.4 5.43 19.0
Aug 6.05 15.5 2.93 2.15 6.81 6.16 15.9 5.83 14.9
Sep 6.98 26.9 3.88 1.89 7.88 7.29 27.2 6.75 25.4
Oct 6.48 24.6 3.75 1.78 7.27 6.60 23.8 6.02 23.3
Nov 7.97 19.6 4.19 1.99 8.99 8.01 20.2 7.35 18.8
Dec 8.94 23.3 4.28 2.18 10.07 8.86 23.3 8.30 22.2
All
data 7.61 27.7 3.97 2.00 8.59 7.64 28.6 7.18 27.9
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Time Series of Wind Speed Monthly Averages
The average wind speed at 30 meters for the measurement period is 7.64 m/s. Typically, the
highest wind speeds occur during the winter months of October through March with the lowest
winds during the summer months of May through September. The unusually low winds
measured in January 2006 were due to a persistent high pressure system over Alaska that month
that yielded calm winds and extremely cold weather Statewide. January 2006 was then followed
by an extremely windy February.
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Wind Shear Profile
The average annual power law exponent was calculated at 0.15, indicating moderate wind shear
at the Chevak met tower test site, although as one would expect, shear is higher in the winter
than the summer because of the higher winter wind speeds. The practical application of this data
is that there may be an advantage of increased power production with increased turbine tower
height. A tower height/energy production cost tradeoff study is recommended.
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Probability Distribution Function
The graphed probability distribution function provides a visual indication of measured wind
speeds in one meter per second “bins.” Note that most wind turbines do not begin to generate
power until the wind speed at hub height reached 4 m/s; using this criteria, 19% of Chevak’s
winds are calm (less than 4 m/s). The black line in the graph is a best fit Weibull approximation
of the wind speed distribution. At the 30 meter level, the Weibull parameters are k = 2.00
(indicates a relatively narrow distribution of wind speeds) and c = 8.59 m/s (scale factor for the
Weibull distribution). The PDF information is shown visually in another manner in the second
graph, the Cumulative Distribution Function.
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Wind Roses
Chevak winds are strongly directional north-northeast with lesser south and east-southeast
components. This observation is confirmed with consideration of the power density roses which
indicate that Chevak’s power producing winds are also strongly oriented NNE. The practical use
of this information is that wind turbines should be located with clear zones to the NNE
(especially), SSE and south to minimize wind shear and turbulence. Also, several turbines could
be located relatively close together (two to two and a half rotor diameters hub-to-hub) along an
alignment perpendicular to the NNE power wind direction.
Wind frequency roses (top – 30 meters vane, bottom – 20 meters vane)
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Wind power density rose (30 meters vane)
Monthly wind power density roses (30 m vane); scale is common
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Turbulence Intensity
The turbulence intensity is quite acceptable for the north-northeast, south and east-southeast
wind directions. The mean turbulence intensity (TI) is 0.0866 for the 30 meter [A] anemometer
and 0.0666 for the 30 meter [B] anemometer, indicating relatively smooth air. At 20 meter, the
TI is 0.0729. This TI is calculated with a threshold wind speed of 4 m/s (only wind speeds
exceeding 4 m/s are considered). As indicated below, turbulence at the Chevak project test site
is well within International Energy Agency (IEA) Category A and B acceptability standards (30
meter A anemometer shown).
Turbulence Intensity (calculated with 30 m [A] speed and 30 m vane)
Turbulence Intensity (calculated with 30 m B speed and 30 m vane)
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IEA Turbulence Intensity Standards
The turbulence intensities at 30 meters at the Chevak project test site meet the International
Energy Agency (IEA) standards as indicated below.
Turbulence Table
Bin Bin Endpoints Records
Standard
Deviation Mean
Standard
Deviation Characteristic
Midpoint Lower Upper In of Wind Speed Turbulence of Turbulence Turbulence
(m/s) (m/s) (m/s) Bin (m/s) Intensity Intensity Intensity
1 0.5 1.5 2013 0.376 0.398 0.191 0.589
2 1.5 2.5 4110 0.392 0.200 0.112 0.312
3 2.5 3.5 6346 0.412 0.139 0.076 0.215
4 3.5 4.5 8575 0.451 0.114 0.058 0.172
5 4.5 5.5 10331 0.506 0.102 0.048 0.150
6 5.5 6.5 11354 0.564 0.095 0.042 0.137
7 6.5 7.5 10462 0.625 0.090 0.037 0.127
8 7.5 8.5 9365 0.680 0.086 0.034 0.120
9 8.5 9.5 8213 0.714 0.080 0.032 0.111
10 9.5 10.5 6557 0.784 0.079 0.030 0.109
11 10.5 11.5 5254 0.853 0.078 0.029 0.107
12 11.5 12.5 4289 0.901 0.076 0.026 0.102
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13 12.5 13.5 3303 0.937 0.072 0.023 0.096
14 13.5 14.5 2467 0.980 0.070 0.022 0.092
15 14.5 15.5 1889 1.052 0.070 0.021 0.092
16 15.5 16.5 1323 1.103 0.069 0.021 0.090
17 16.5 17.5 916 1.166 0.069 0.021 0.090
18 17.5 18.5 727 1.252 0.070 0.023 0.092
19 18.5 19.5 534 1.360 0.072 0.022 0.093
20 19.5 20.5 322 1.402 0.070 0.023 0.094
21 20.5 21.5 150 1.521 0.073 0.024 0.097
22 21.5 22.5 106 1.558 0.071 0.025 0.096
23 22.5 23.5 79 1.624 0.071 0.027 0.098
24 23.5 24.5 42 1.840 0.077 0.020 0.097
25 24.5 25.5 26 2.008 0.081 0.020 0.101
26 25.5 26.5 20 1.930 0.074 0.019 0.094
27 26.5 27.5 18 1.733 0.064 0.008 0.072
28 27.5 28.5 2 1.750 0.063 0.002 0.066
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Air Temperature and Density
Over the reporting period, Chevak had an average temperature of 0.7 degrees C. The minimum
recorded temperature during the test period was -30.0° C and the maximum temperature 24.3° C.
Note that the temperature sensor at this site did not work on installation in December 2004 and
was replaced in June 2005. Missing data in the air density D Map below is shown at standard
density.
Consequent to the cool average temperature in Chevak, air density is rather high, boosting the
nominal performance of wind turbines. The average air density in Chevak is 1.270 kg/m3,
approximately four percent higher than standard atmospheric air density of 1.225 kg/m3. This
density variance from standard is accounted for in turbine performance predictions in this report.
Temperature Air Density
Month Mean Min Max
Std.
Dev. Mean Min Max
(°C) (°C) (°C) (°C) (kg/m³) (kg/m³) (kg/m³)
Jan -18.75 -28.7 -8.8 5.53 1.303 1.222 1.440
Feb -8.28 -30.0 1.6 8.34 1.276 1.222 1.447
Mar -11.56 -26.3 0.5 5.86 1.284 1.222 1.426
Apr -9.68 -21.4 0.7 4.66 1.279 1.222 1.398
May 2.08 -8.6 15.4 4.38 1.251 1.220 1.330
Jun 9.21 -1.9 22.5 4.62 1.244 1.190 1.298
Jul 11.11 4.3 24.3 3.54 1.238 1.183 1.269
Aug 10.47 1.0 21.9 2.86 1.241 1.193 1.284
Sep 7.95 -0.8 19.9 2.71 1.252 1.201 1.292
Oct 1.27 -9.9 11.3 3.46 1.283 1.237 1.337
Nov -10.37 -20.3 1.2 4.55 1.340 1.283 1.392
Dec -10.43 -26.7 1.0 5.25 1.290 1.222 1.428
All data 0.68 -30.0 24.3 10.78 1.270 1.183 1.447
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Air Density DMap
The DMap below is a visual indication of the daily and seasonal variations or air density. Air
densities higher than standard will yield higher turbine power than predicted by the turbine
power curves while densities lower than standard will yield lower turbine power than predicted.
Density variance from standard is accounted for in the turbine performance predictions. Note in
the D Map that a standard air density is assumed for those time periods (December 2004 to June
2005) where the temperature sensor was not functional.
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Wind Turbine Performance
The turbine performance predictions noted below are based both on 100% turbine availability
and on 90% turbine availability with an assumed 10% downtime for maintenance, repairs and/or
other outages. Note that these performance estimates were predicted with use of
Windographer® wind analysis software; power curves provided by manufacturers are not
independently verified and are assumed to be accurate. The power curves are presented for a
standard air density of 1.225 kg/m3 at 15° C; however the predictions of power production are
density compensated by multiplying the standard density power output by the ratio of the
measured air density to standard air density. For the months of missing temperature data, there is
no density compensation. This will bias low the predicated energy recovery for cool weather
months with missing temperature data.
Entegrity eW-15:65 kW rated power output, 15 meter rotor, stall-controlled (power curve
provided by Entegrity Energy Systems). Additional information is available at
www.entegritywind.com.
Vestas V15: 75 kW rated power output, 15 meter rotor, stall-controlled (power curve provided
by Powercorp Alaska LLC). Additional information is available at www.pcorpalaska.com.
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Fuhrländer FL100: 125 kW rated power output, 21 meter rotor diameter, stall-controlled
(power curve provided by Lorax Energy). Additional information is available at www.lorax-
energy.com).
Northwind 100/19 and 100/20: 100 kW rated power output, 19 meter rotor and 20 meter rotor
(19 meter rotor blades with 0.6 meter blade root extensions added), stall-controlled (power curve
provided by Northern Power Systems). Additional information is available at
www.northernpower.com.
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Vestas V27: 225 kW rated power output, 27 meter rotor, pitch-controlled (power curve provided
by Alaska Energy Authority)
Fuhrländer FL250: 300 kW rated power output, 29.5 meter rotor diameter, stall-controlled
(power curve provided by Lorax Energy). Additional information is available at www.lorax-
energy.com).
Chevak, Alaska Wind Resource Report Turbine Power Output Comparison (100% turbine availability) Hub Hub Height Time At Time At AverageNet Annual Net AverageNetHeightWindSpeedZeroOutputRatedOutputPowerOutputEnergyOutputCapacityFactorTurbine (m) (m/s) (%) (%) (kW) (kWh/yr) (%)Entegrity eW-15 60 Hz 25 7.42 19.1 6.2 22.4 196,53134.5Entegrity eW-15 60 Hz 31 7.61 17.9 6.8 23.5 205,66536.1Vestas V15 25 7.42 24.8 3.9 21.8 191,25929.1Vestas V15 34 7.72 22.5 4.6 23.6 206,92831.5Northern Power NW 100/20 25 7.42 19.1 5.8 33.0 289,30333.0Northern Power NW 100/20 32 7.65 17.7 6.6 34.9 305,58234.9Fuhrländer FL100 35 7.75 5.0 5.3 47.2 413,64537.8Vestas V27 32 7.65 7.4 5.8 85.6 750,20538.1Vestas V27 42 7.97 6.7 6.9 91.5 801,21640.7Fuhrländer FL250 42 7.97 4.8 1.3 103.0 900,31634.3Fuhrländer FL250 50 8.18 4.5 1.6 107.0 939,29035.7Capacity Factor <20% Capacity Factor >20%, <30% Capacity Factor >30%, <40% Capacity Factor >40%, <50% Capacity Factor >50% V3 Energy LLC 24 of 29
Chevak, Alaska Wind Resource Report Turbine Power Output Comparison (90% turbine availability) Hub Hub Height Time At Time At AverageNet Annual Net AverageNetHeightWindSpeedZeroOutputRatedOutputPowerOutputEnergyOutputCapacityFactorTurbine (m) (m/s) (%) (%) (kW) (kWh/yr) (%)Entegrity eW-15 60 Hz 25 7.42 19.1 6.2 20.3 177,59331.2Entegrity eW-15 60 Hz 31 7.61 17.9 6.8 21.2 185,84732.6Vestas V15 25 7.42 24.8 3.9 19.7 172,82926.3Vestas V15 34 7.72 22.5 4.6 21.3 186,98828.5Northern Power NW 100/20 25 7.42 19.1 5.8 29.8 261,42629.8Northern Power NW 100/20 32 7.65 17.7 6.6 31.5 276,13631.5Fuhrländer FL100 35 7.75 5.0 5.3 42.7 373,78634.1Vestas V27 32 7.65 7.4 5.8 77.4 677,91634.4Vestas V27 42 7.97 6.7 6.9 82.6 724,01136.7Fuhrländer FL250 42 7.97 4.8 1.3 92.9 813,56231.0Fuhrländer FL250 50 8.18 4.5 1.6 96.9 848,78132.3Capacity Factor <20% Capacity Factor >20%, <30% Capacity Factor >30%, <40% Capacity Factor >40%, <50% Capacity Factor >50% V3 Energy LLC 25 of 29
Chevak, Alaska WV3 Energy LLC ind Resource Report 26 of 29 Annual Fuel Cost Avoided for Energy Generated by Wind Turbine vs. Diesel Generator Fuel Price (USD/gallon) Turbine Turbine HubHeight (m)AnnualEnergyOutput(kW-hr/yr) FuelQuantityAvoided(liters)FuelQuantityAvoided(gallons)$1.75 $2.00 $2.25 $2.50 $2.75 $3.00 $3.25Entegrity eW-15 25 177,59349,797 13,155 $23,021 $26,310 $29,599 $32,888 $36,176 $39,465 $42,754Entegrity eW-15 31 185,84752,111 13,766 $24,091 $27,533 $30,975 $34,416 $37,858 $41,299 $44,741Vestas V15 25 172,82948,461 12,802 $22,404 $25,604 $28,805 $32,005 $35,206 $38,406 $41,607Vestas V15 34 186,98852,431 13,851 $24,239 $27,702 $31,165 $34,627 $38,090 $41,553 $45,016Northern Power NW 100/20 25 261,42673,304 19,365 $33,889 $38,730 $43,571 $48,412 $53,253 $58,095 $62,936Northern Power NW 100/20 32 276,13677,429 20,455 $35,795 $40,909 $46,023 $51,136 $56,250 $61,364 $66,477Fuhrländer FL100 35 373,786104,810 27,688 $48,454 $55,376 $62,298 $69,220 $76,142 $83,064 $89,986Vestas V27 32 677,916190,088 50,216 $87,878 $100,432 $112,986 $125,540 $138,094 $150,648 $163,202Vestas V27 42 724,011203,013 53,630 $93,853 $107,261 $120,669 $134,076 $147,484 $160,891 $174,299Fuhrländer FL250 42 813,562228,123 60,264 $105,462 $120,528 $135,594 $150,660 $165,726 $180,792 $195,858Fuhrländer FL250 50 848,781237,998 62,873 $110,027 $125,745 $141,464 $157,182 $172,900 $188,618 $204,336N otes:1. Chevak electrical energy production efficiency is 13.5 kW-hr/gal (source: AVEC) 2. Assumes 90% turbine availability with no diversion of power to a thermal or other dump load 3. Assumes linear diesel generator fuel efficiency (i.e., 1:1 tradeoff of wind turbine kW-hr to diesel genset kW-hr)
Temperature Conversion Chart °C to °F
°C °F °C °F °C °F
-40 -40.0 -10 14.0 20 68.0
-39 -38.2 -9 15.8 21 69.8
-38 -36.4 -8 17.6 22 71.6
-37 -34.6 -7 19.4 23 73.4
-36 -32.8 -6 21.2 24 75.2
-35 -31.0 -5 23.0 25 77.0
-34 29.2 -4 24.8 26 78.8
-33 -27.4 -3 26.6 27 80.6
-32 -25.6 -2 28.4 28 82.4
-31 -23.8 -1 30.2 29 84.2
-30 -22.0 0 32.0 30 86.0
-29 -20.2 1 33.8 31 87.8
-28 -18.4 2 35.6 32 89.6
-27 -16.6 3 37.4 33 91.4
-26 -14.8 4 39.2 34 93.2
-25 -13.0 5 41.0 35 95.0
-24 -11.2 6 42.8 36 96.8
-23 -9.4 7 44.6 37 98.6
-22 -7.6 8 46.4 38 100.4
-21 -5.8 9 48.2 39 102.2
-20 -4.0 10 50.0 40 104.0
-19 -2.2 11 51.8 41 105.8
-18 -0.4 12 53.6 42 107.6
-17 1.4 13 55.4 43 109.4
-16 3.2 14 57.2 44 111.2
-15 5.0 15 59.0 45 113.0
-14 6.8 16 60.8 46 114.8
-13 8.6 17 62.6 47 116.6
-12 10.4 18 64.4 48 118.4
-11 12.2 19 66.2 49 120.2
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Wind Speed Conversion Chart, m/s to mph
m/s mph m/s mph m/s mph m/s mph m/s mph
0.5 1.1 10.5 23.5 20.5 45.9 30.5 68.2 40.5 90.6
1.0 2.2 11.0 24.6 21.0 47.0 31.0 69.3 41.0 91.7
1.5 3.4 11.5 25.7 21.5 48.1 31.5 70.5 41.5 92.8
2.0 4.5 12.0 26.8 22.0 49.2 32.0 71.6 42.0 93.9
2.5 5.6 12.5 28.0 22.5 50.3 32.5 72.7 42.5 95.1
3.0 6.7 13.0 29.1 23.0 51.4 33.0 73.8 43.0 96.2
3.5 7.8 13.5 30.2 23.5 52.6 33.5 74.9 43.5 97.3
4.0 8.9 14.0 31.3 24.0 53.7 34.0 76.1 44.0 98.4
4.5 10.1 14.5 32.4 24.5 54.8 34.5 77.2 44.5 99.5
5.0 11.2 15.0 33.6 25.0 55.9 35.0 78.3 45.0 100.7
5.5 12.3 15.5 34.7 25.5 57.0 35.5 79.4 45.5 101.8
6.0 13.4 16.0 35.8 26.0 58.2 36.0 80.5 46.0 102.9
6.5 14.5 16.5 36.9 26.5 59.3 36.5 81.6 46.5 104.0
7.0 15.7 17.0 38.0 27.0 60.4 37.0 82.8 47.0 105.1
7.5 16.8 17.5 39.1 27.5 61.5 37.5 83.9 47.5 106.3
8.0 17.9 18.0 40.3 28.0 62.6 38.0 85.0 48.0 107.4
8.5 19.0 18.5 41.4 28.5 63.8 38.5 86.1 48.5 108.5
9.0 20.1 19.0 42.5 29.0 64.9 39.0 87.2 49.0 109.6
9.5 21.3 19.5 43.6 29.5 66.0 39.5 88.4 49.5 110.7
10.0 22.4 20.0 44.7 30.0 67.1 40.0 89.5 50.0 111.8
Distance Conversion m to ft
m ft m ft
5 16 35 115
10 33 40 131
15 49 45 148
20 66 50 164
25 82 55 180
30 98 60 197
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Selected definitions (courtesy of Windographer® software by Mistaya Engineering Inc.)
Wind Power Class
The wind power class is a number indicating the average energy content of the wind resource.
Wind power classes are based on the average wind power density at 50 meters above ground,
according to the following table. Source: Wind Energy Resource Atlas of the United States
(http://rredc.nrel.gov/wind/pubs/atlas/tables/A-8T.html)
Wind Power Class Description Power Density at 50m (W/m
2)
1 Poor 0-200
2 Marginal 200-300
3 Fair 300-400
4 Good 400-500
5 Excellent 500-600
6 Outstanding 600-800
7 Superb 800-2000
Windographer classifies any wind resource with an average wind power density above 2000
W/m2 as class 8.
Probability Distribution Function
The probability distribution function f(x) gives the probability that a variable will take on the
value x. It is often expressed using a frequency histogram, which gives the frequency with which
the variable falls within certain ranges or bins.
Wind Turbine Power Regulation
All wind turbines employ some method of limiting power output at high wind speeds to avoid
damage to mechanical or electrical subsystems. Most wind turbines employ either stall control or
pitch control to regulate power output.
A stall-controlled turbine typically has blades that are fixed in place, and are designed to
experience aerodynamic stall at very high wind speeds. Aerodynamic stall dramatically reduces
the torque produced by the blades, and therefore the power produced by the turbine.
On a pitch-controlled turbine, a controller adjusts the angle (pitch) of the blades to best match the
wind speed. At very high wind speeds the controller increasingly feathers the blades out of the
wind to limit the power output.
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