HomeMy WebLinkAboutBuckland, Deering, Noorvik Wind Farm Project Deering Wind Resource Report - Aug 2010 - REF Grant 2195377Deering Wind Resource Report
Report by: Douglas Vaught, V3 Energy LLC, Eagle River, Alaska
Date: August 31, 2010
Village of Deering; D. Vaught photo
Contents
Summary.......................................................................................................................................................2
Test Site Location......................................................................................................................................2
Photographs..................................................................................................................................................4
Data Recovery...............................................................................................................................................4
Wind Speed...................................................................................................................................................6
Time Series................................................................................................................................................7
Daily Wind Profile .....................................................................................................................................8
Probability Distribution Function..............................................................................................................9
Wind Shear and Roughness....................................................................................................................10
Extreme Winds............................................................................................................................................11
Temperature and Density...........................................................................................................................11
Wind Direction............................................................................................................................................12
Turbulence..................................................................................................................................................13
Airport ASOS Data.......................................................................................................................................15
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Summary
The wind resource measured in Deering is good at high wind power Class 3. The met tower site
experiences low turbulence conditions but is subject to storm winds that raise the probability of
extreme wind events higher than might otherwise be expected for a Class 3 site. Met tower placement
was based on observations of wind patterns in Deering, the relatively high elevation of the site, and
proximity to existing roads. The site is thought to have the best developable wind regime near Deering.
Other locations near Deering, such as the summit plateau of the high, broad hill east of the village, are
likely windier but development costs there would be very high.
Met tower data synopsis
Data dates August 9, 2008 to August 6, 2010 (24 months)
Wind Power Class High 3 (fair)
Power density mean, 30 m 322 W/m2
Wind speed mean, 30 m 6.06 m/s
Max. 10-min wind speed average 25.9 m/s
Maximum wind gust 30.9 m/s (Jan. 2009)
Weibull distribution parameters k = 1.78, c = 6.72 m/s
Wind shear power law exponent
Roughness class 0.0 (smooth)
IEC 61400-1, 3rd ed. classification
Turbulence intensity, mean 0.075 (at 15 m/s)
Community profile
Current Population: 118 (2009 DCCED Certified Population)
Incorporation Type: 2nd Class City
Borough Located In: Northwest Arctic Borough
Taxes: Sales: None, Property: None, Special: None
National Flood Insurance Program Participant:Yes
Coastal Management District: Northwest Arctic Borough
Test Site Location
The met tower is located 1.5 km (0.9 miles ft) from the western edge of the village. The site is south of
Cape Deceit on a broad sloping hill overlooking Kotzebue Sound with good exposure to winds from all
directions.
Site information
Site number 7312
Latitude/longitude N 66° 5.1’,W 162° 45.8’ (WGS 84)
Site elevation 15 meters
Datalogger type NRG Symphonie, 10 minute time step
Tower type NRG 30-meter tall tower, 152 mm diameter
Anchor type Buried plate (configured with plywood and screw-in anchor)
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Topographic map image
Google Earth image
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Tower sensor information
Channel Sensor type Height Multiplier Offset Orientation
1 NRG #40 anemometer 29 m (A) 0.765 0.35 WNW
2 NRG #40 anemometer 29 m (B)0.765 0.35 ENE
3 NRG #40 anemometer 20 m 0.765 0.35 NNW
7 NRG #200P wind vane 29 m 0.351 000 359° T
9 NRG #110S Temp C 3 m 0.136 -86.383 N
Photographs
Deering crew; D. Vaught photo Installing plate anchors; D. Vaught photo
Deering met tower; D. Vaught photo Deering crew; D. Vaught photo
Data Recovery
The quality of data from the Deering met tower was acceptable to describe the essentials of the wind
resource, but unfortunately there were a number of problems including inoperability of the
temperature sensor for the first three months after tower installation (after which the sensor was
replaced but data has been suspect) and complete failure of the wind vane that resulted in no recorded
wind data. Fortunately, the nearby Deering airport has been equipped with an Automated Surface
Deering Wind Resource Report Page | 5
Observing System (ASOS) weather station since 1984 and hence wind direction from it is a suitable
substitute for the met tower site. Other data problems with the met tower include two long episodes of
missing data: 6/30/09 to 8/31/09 and 11/14/09 to 2/3/10. Reportedly, one episode was due to a lost or
misplaced data card and the other to failure of the datalogger.
Apparent icing events, characterized by relatively long periods of zero sensor output, non-variant sensor
standard deviation, and temperatures near or below freezing, were removed from the data set for
quality control purposes. It is apparent from the data that icing events (likely freezing rain/sleet but also
possibly hoarfrost conditions) certainly occur frequently during the winter months, but the site is not of
sufficient elevation for the highly problematic rime icing conditions.
Data recovery summary table
Label Units Height
Possible
Records
Valid
Records
Recovery
Rate (%)
Speed 29 m A m/s 29 m 104,717 79,341 75.8
Speed 29 m B m/s 29 m 104,717 79,229 75.7
Speed 20 m m/s 20 m 104,717 76,768 73.3
Direction 24 m ° 24 m 104,717 0 0.0
Temperature °C 104,717 67,853 64.8
Anemometer data recovery
29 m A 29 m B 20 m
Possible Valid Recovery Valid Recovery Valid Recovery
Year Month Records Records Rate (%) Records Rate (%) Records Rate (%)
2008 Aug 3,227 3,227 100.0 3,227 100.0 3,227 100.0
2008 Sep 4,320 4,320 100.0 4,320 100.0 4,320 100.0
2008 Oct 4,464 4,443 99.5 4,439 99.4 4,455 99.8
2008 Nov 4,320 2,365 54.8 2,348 54.4 2,368 54.8
2008 Dec 4,464 4,290 96.1 4,276 95.8 4,331 97.0
2009 Jan 4,464 3,539 79.3 3,511 78.7 3,192 71.5
2009 Feb 4,032 3,615 89.7 3,614 89.6 2,325 57.7
2009 Mar 4,464 4,464 100.0 4,464 100.0 4,464 100.0
2009 Apr 4,320 4,320 100.0 4,320 100.0 4,320 100.0
2009 May 4,464 4,464 100.0 4,464 100.0 4,464 100.0
2009 Jun 4,320 3,906 90.4 3,906 90.4 3,906 90.4
2009 Jul 4,464 0 0.0 0 0.0 0 0.0
2009 Aug 4,464 54 1.2 54 1.2 54 1.2
2009 Sep 4,320 4,320 100.0 4,320 100.0 4,320 100.0
2009 Oct 4,464 4,464 100.0 4,464 100.0 4,464 100.0
2009 Nov 4,320 1,578 36.5 1,578 36.5 1,578 36.5
2009 Dec 4,464 0 0.0 0 0.0 0 0.0
2010 Jan 4,464 0 0.0 0 0.0 0 0.0
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2010 Feb 4,032 3,106 77.0 3,245 80.5 2,114 52.4
2010 Mar 4,464 4,464 100.0 4,464 100.0 4,464 100.0
2010 Apr 4,320 4,320 100.0 4,320 100.0 4,320 100.0
2010 May 4,464 4,464 100.0 4,277 95.8 4,464 100.0
2010 Jun 4,320 4,320 100.0 4,320 100.0 4,320 100.0
2010 Jul 4,464 4,464 100.0 4,464 100.0 4,464 100.0
2010 Aug 834 834 100.0 834 100.0 834 100.0
All data 104,717 79,341 75.8 79,229 75.7 76,768 73.3
Wind Speed
Wind data collected from the met tower, from the perspective of mean wind speed and mean wind
power density, indicates a good wind resource for wind power development. The cold arctic
temperatures of Deering contributed to the high power density. It is problematic, however, analyzing
wind data with significant concentrated data loss, such as occurred in Deering during the two data loss
episodes. Fortunately, however, with met tower data collection encompassing a two year time period,
missing months of data in 2009 and 2010 were duplicated by data collected in 2008 and 2009.
Nevertheless, to correct the anemometer data loss problem, synthetic data was inserted in the data
gaps to create a more complete wind speed profile. To be sure, long segments of synthetic data
introduce uncertainty to the data set, but missing data does as well. With synthetic data inserted to fill
in the data gaps, the mean wind annual wind speed and power density decrease slightly from the
original data.
Anemometer data summary
Original Data Synthesized data
Variable
Speed
29 m A
Speed
29 m B
Speed
20 m
Speed
29 m A
Speed
29 m B
Speed
20 m
Measurement height (m) 29 29 20 29 29 20
Mean wind speed (m/s) 6.00 6.06 5.96 5.94 6.00 5.82
Max 10-min avg wind speed (m/s) 25.9 25.2 24.4
Max gust wind speed (m/s) 30.9 29.8 29.8
Weibull k 1.71 1.74 1.77 1.67 1.69 1.72
Weibull c (m/s) 6.62 6.72 6.55 6.64 6.72 6.52
Mean power density (W/m²) 312 322 301 309 316 285
Mean energy content (kWh/m²/yr) 2,737 2,820 2,635 2,703 2,768 2,493
Energy pattern factor 2.244 2.236 2.183 2.311 2.299 2.268
1-hr autocorrelation coefficient 0.913 0.914 0.915 0.908 0.909 0.91
Diurnal pattern strength 0.013 0.018 0.014 0.025 0.028 0.028
Hour of peak wind speed 15 15 13 13 13 12
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Time Series
Time series calculations indicate moderately wind speed averages during the autumn, winter and spring
months, but winds die down during summer. Fortunately, however, seasonal wind speeds correlate to a
typical village electric load profile of high winter loads and light summer loads.
29m B anemometer data summary
Original 29m B Data Synth Data Added
Mean
Max
10-min
avg Max gust Weibull k Weibull c Mean
Ratio: synth
to original
mean speed
Year Month (m/s) (m/s) (m/s) (-) (m/s) (m/s) (-)
2008 Aug 5.52 15.3 17.6 2.198 6.24 5.52 100.0%
2008 Sep 5.94 13.3 15.3 2.15 6.693 5.94 100.0%
2008 Oct 5.59 15.4 18.7 1.958 6.305 5.57 99.6%
2008 Nov 6.38 13.4 16.1 2.484 7.174 6.01 94.2%
2008 Dec 7.05 20.5 24 1.945 7.913 6.92 98.1%
2009 Jan 7.14 25.1 29.8 1.536 7.963 6.69 93.8%
2009 Feb 7.55 22 25.6 1.586 8.375 6.98 92.3%
2009 Mar 6.76 24.7 27.9 1.609 7.538 6.76 100.0%
2009 Apr 5.50 25.2 29.8 1.593 6.128 5.50 100.0%
2009 May 6.30 19.6 24.8 2.175 7.118 6.30 100.0%
2009 Jun 4.91 15.9 19.5 2.042 5.543 4.91 100.1%
2009 Jul 4.96
2009 Aug 12.07 16.2 19.9 6.252 12.969 5.68 47.1%
2009 Sep 5.42 14.1 17.2 1.947 6.116 5.42 100.0%
2009 Oct 6.21 16.5 19.5 1.72 6.943 6.21 100.0%
2009 Nov 7.38 20.5 23.7 1.533 8.166 7.10 96.3%
2009 Dec 6.67
2010 Jan 7.14
2010 Feb 4.37 12.9 14.1 1.942 4.892 4.89 112.1%
2010 Mar 6.52 15.6 19.5 1.695 7.236 6.52 100.0%
2010 Apr 7.05 20.2 22.6 1.66 7.828 7.05 100.0%
2010 May 5.32 15.6 18.7 1.753 5.936 5.47 102.8%
2010 Jun 4.72 17.8 20.6 1.994 5.329 4.72 100.0%
2010 Jul 5.29 16.4 19.1 1.809 5.95 5.29 100.0%
2010 Aug 4.12 10.1 13.3 2.095 4.648 4.12 100.0%
MMM Annual 6.06 25.2 29.8 1.738 6.716 6.00 98.9%
Deering Wind Resource Report Page | 8
Time series graph (synth. data)
Daily Wind Profile
The average annual daily wind profile in Deering indicates a minor variation of wind speeds throughout
the day, with lowest wind speeds during the late night and early morning hours and highest winds
during mid to late afternoon. This perspective changes somewhat when considering monthly views of
daily profiles as much more variation is observed.
Annual daily wind profile (synth. data)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
0
1
2
3
4
5
6
7 Seasonal Wind Speed Profile
Speed 29 m A
Speed 29 m B
Speed 20 m
0 6 12 18 24
0
1
2
3
4
5
6
7 Mean Daily Profile
Hour of Day
Speed 29 m A
Speed 29 m B
Speed 20 m
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Monthly daily wind profiles (synth. data)
Probability Distribution Function
The probability distribution function (PDF), or histogram, of wind speed indicates wind speed “bins”
oriented somewhat toward the lower speeds compared to a normal wind power shape curve of k=2.0,
otherwise known as the Raleigh distribution. Note in the cumulate frequency table below that 33
percent of the winds are less than 4 m/s, the cut-in wind speed of most wind turbines.
PDF of 29m B anemometer (synth. data)
0 5 10 15 20 25 30
0
1
2
3
4
5
6
7 Probability Distibution Function, All Sectors
Speed 29 m B (m/s)
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Cumulative frequency table
Bin (m/s)
Occurrences
Freq.
Cum.
Freq. Bin (m/s)
Occurrences
Freq.
Cum.
Freq.
Lower Upper (%) (%) Lower Upper (%) (%)
0 1 4,952 4.73 4.7 15 16 606 0.58 98.7
1 2 6,616 6.32 11.0 16 17 402 0.38 99.1
2 3 10,382 9.91 21.0 17 18 290 0.28 99.4
3 4 12,747 12.17 33.1 18 19 219 0.21 99.6
4 5 12,827 12.25 45.4 19 20 140 0.13 99.7
5 6 11,167 10.66 56.0 20 21 97 0.09 99.8
6 7 9,635 9.20 65.2 21 22 70 0.07 99.9
7 8 8,429 8.05 73.3 22 23 58 0.06 99.9
8 9 7,030 6.71 80.0 23 24 37 0.04 100.0
9 10 5,918 5.65 85.7 24 25 19 0.02 100.0
10 11 4,773 4.56 90.2 25 26 5 0.01 100.0
11 12 3,331 3.18 93.4 26 27 4 0.00 100.0
12 13 2,317 2.21 95.6 27 28 1 0.00 100.0
13 14 1,572 1.50 97.1 28 29 0 0.00 100.0
14 15 1,073 1.03 98.1 29 30 0 0 100.0
All 104,717 100.00
Wind Shear and Roughness
A wind shear power law exponent of 0.0951 indicates very low wind shear at the site; hence wind
turbine construction at a low hub height may be a desirable option. Related to wind shear, a calculated
surface roughness of 0.00002 meters (the height above ground level where wind velocity would be zero)
indicates very smooth terrain (roughness description: smooth) surrounding the met tower.
Vertical wind shear profile, wind > 4 m/s
0 2 4 6 8 10
0
20
40
60
80
100 Vertical Wind Shear Profile, All Sectors, 4 - 100 m/s
Mean Wind Speed (m/s)
Measured data
Power law fit (alpha = 0.0951)
Log law fit (z0 = 0.000656 m)
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Extreme Winds
The duration of Deering met tower should be considered minimal for calculation of extreme wind
probability, but nevertheless, it can be calculated with a moderate level of accuracy. Analysis indicates
that Deering experiences sufficiently robust storm wind events to exceed IEC 61400-1, 3rd edition Class
III criteria and hence classify as a Class II wind site.
Extreme wind speed probability table
Extreme Wind Speed (m/s) IEC 61400-1, 3rd
Return
Period (yr) 10-min means Gusts Class Vref, m/s
20 34.8 42.0 I 50
25 35.9 43.4 II 42.5
50 39.6 47.8 III 37.5
100 43.2 52.2 S designer-
specified
Extreme winds probability graphs
Temperature and Density
In addition to the data loss noted in the Data Recovery section of this report, by examination the met
tower temperature data appears faulty. Hence, instead of reporting met tower temperature data,
temperature data from the airport ASOS are referenced below. This data represents a long time period:
1984 to the present. Density was not directly measured, but calculated using standard pressure at 15
meters elevation and the ideal gas law. Note that in general Deering is a cool maritime climate
characterized by severely cold winters.
0 20 40 60 80 100
30
35
40
45
50
55 Extreme Wind Speeds
Return Period (yrs)
10-min means
Gusts
15 20 25 30 35 40 45
0.001
0.010
0.100
1.000 Probability of Exceedence
Annual Extreme Wind Speed (U*, m/s)
Best-fit Gumbel
Data
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Temperature and density table
Temperature Air Density
Mean Min Max Mean Max Min
(°C) (°C) (°C) (kg/m
3) (kg/m
3) (kg/m
3)
Jan -20.6 -42.2 3.9 1.395 1.526 1.272
Feb -18.3 -41.7 6.1 1.383 1.523 1.262
Mar -18.3 -36.7 2.8 1.383 1.490 1.277
Apr -10.5 -31.7 7.8 1.342 1.460 1.255
May -0.6 -26.1 18.9 1.293 1.427 1.207
Jun 7.5 -6.1 25.0 1.256 1.320 1.182
Jul 11.5 -2.2 28.9 1.238 1.301 1.167
Aug 9.8 -3.9 23.9 1.246 1.309 1.186
Sep 5.6 -8.9 17.8 1.264 1.334 1.211
Oct -2.5 -25.6 13.9 1.302 1.423 1.228
Nov -10.4 -35.6 5.0 1.342 1.483 1.267
Dec -16.5 -41.7 3.9 1.374 1.523 1.272
Annual -4.4 -42.2 28.9 1.318 1.526 1.167
Temperature graph
Wind Direction
The met tower wind vane was inoperative during the entire measurement period, with no data return.
However, nearby airport ASOS data (1984 to present) is usable for wind direction analysis and presented
below.
The wind frequency rose for Deering indicates predominately southwesterly to westerly winds with a
lesser component of east-northeasterly winds and some southeasterly winds. The mean value rose
indicates that when the easterly and southeasterly winds do occur, they tend to be very powerful.
Combining the frequency and mean value rose into the total energy rose results in the observation that
-50.0
-40.0
-30.0
-20.0
-10.0
0.0
10.0
20.0
30.0
40.0
Mean
Min
Max
Deering Wind Resource Report Page | 13
the power-producing winds are chiefly westerly. Not critically important, but note that the resolution of
the ASOS wind direction data is ten degrees, not one degree as with met tower wind vane sensors.
Wind frequncy rose Mean value rose
Total energy rose
Turbulence
Turbulence intensity at the Deering test site is well within acceptable standards for wind power
development with an International Electrotechnical Commission (IEC) 61400-1, 3rd edition (2005)
classification of turbulence category C, which is the lowest defined. Mean turbulence intensity at 15
m/s is 0.075
Deering Wind Resource Report Page | 14
Turbulence intensity, all wind sectors
Turbulence table
Bin Bin Endpoints Records Standard
Midpoint Lower Upper In Mean Deviation Representative Peak
(m/s) (m/s) (m/s) Bin TI of TI TI TI
1 0.5 1.5 3,858 0.416 0.170 0.634 1.333
2 1.5 2.5 6,218 0.208 0.110 0.349 0.941
3 2.5 3.5 8,963 0.138 0.070 0.228 0.769
4 3.5 4.5 10,044 0.109 0.054 0.178 0.683
5 4.5 5.5 9,206 0.095 0.045 0.153 0.660
6 5.5 6.5 7,891 0.089 0.040 0.140 0.532
7 6.5 7.5 7,298 0.084 0.036 0.131 0.354
8 7.5 8.5 5,994 0.082 0.034 0.125 0.519
9 8.5 9.5 4,751 0.080 0.031 0.119 0.326
10 9.5 10.5 4,028 0.079 0.029 0.116 0.308
11 10.5 11.5 2,995 0.077 0.024 0.108 0.255
12 11.5 12.5 2,103 0.076 0.023 0.105 0.218
13 12.5 13.5 1,359 0.077 0.025 0.109 0.235
14 13.5 14.5 885 0.075 0.022 0.103 0.200
15 14.5 15.5 539 0.075 0.020 0.101 0.158
16 15.5 16.5 317 0.077 0.021 0.105 0.178
17 16.5 17.5 228 0.078 0.021 0.105 0.164
18 17.5 18.5 151 0.078 0.021 0.105 0.152
19 18.5 19.5 99 0.078 0.024 0.109 0.195
20 19.5 20.5 64 0.071 0.018 0.093 0.128
21 20.5 21.5 38 0.070 0.019 0.095 0.125
0 5 10 15 20 25 30
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7 Turbulence Intensity at 29 m, All Sectors
Wind Speed (m/s)
Representative TI
IEC Category A
IEC Category B
IEC Category C
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22 21.5 22.5 43 0.076 0.020 0.102 0.129
23 22.5 23.5 15 0.071 0.015 0.090 0.099
24 23.5 24.5 17 0.075 0.023 0.105 0.119
25 24.5 25.5 8 0.080 0.020 0.106 0.102
26 25.5 26.5 1 0.062 0.000 0.062 0.062
Airport ASOS Data
Analysis of airport ASOS wind speed data since 1984 confirms the met tower data results. Airport data
is collected at an elevation of 10 meters. Shown below, the data was scaled to 29 meters with a power
law algorithm using an (power law exponent) value of 0.095 (measured by the met tower) and 0.14
(typical of tundra terrain). In both cases, average wind speeds measured by the met tower exceed
airport wind speeds. This likely is due to the more exposed location of the met tower on higher terrain.
In 2005, Alaska Energy Authority analyzed the Deering airport data and predicted a Class 3 wind
resource from it. Deering met tower data confirms that classification but adjusted to the high end of the
Class 3 range.
Airport/met tower data comparison
Deering Airport Met Tower, 29 m B
AWOS, 10
m sensor
(m/s)
Data
adj. to
29 m,
(m/s)
Data
adj. to
29 m,
(m/s)
Collected
Data
(m/s)
Synth.
Data
(m/s)
Jan 5.16 5.71 5.99 7.14 6.91
Feb 5.90 6.52 6.84 6.05 5.93
Mar 5.19 5.75 6.03 6.64 6.64
Apr 5.10 5.64 5.92 6.27 6.27
May 4.34 4.80 5.03 5.82 5.88
Jun 3.95 4.37 4.59 4.81 4.82
Jul 4.18 4.63 4.86 5.29 5.12
Aug 4.46 4.93 5.18 5.32 5.47
Sep 4.54 5.02 5.27 5.68 5.68
Oct 4.44 4.91 5.15 5.90 5.89
Nov 4.55 5.03 5.28 6.78 6.56
Dec 5.20 5.76 6.04 7.05 6.80
Annual 4.71 5.21 5.47 6.06 6.00