COLORADO ANEMOMETER LOAN PROGRAM
 

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AKRON - 2/13/2011 to 2/9/2013

LOCATION DETAILS
Latitude:
N 40° 8.977’ or N 40° 8’ 59"
Longitude:
W 103° 8.901’or W 103° 8’ 54"
Survey Meridian:
Colorado, Sixth Principal Meridian
Township:
2 N
Range:
52 W
Section:
12
Elevation:
1,382 m (4,534 ft)
Datum:
WGS 84
Tower Type:
Earth Turbines Tilt-Up
Tower Height:
34 m (112 ft)
Vane Offset (deg):
+81° (built into raw data)
Direction Basis:
Magnetic North
Mag. Declination:
7° 59' E, changing by 8' W/yr
Symphonie S/N:
309020393
Site No.:
0340

 

CSU ALP Install Team (from left): Joel Schneekloth (CSU Water Institute and CSU Extension), Dennis Kaan (CSU Extension), Sarah Bass, Eric Rasbach, Jacqueline Hess, Kevin Gosselin, Mark Goudreault, and Mike Kostrzewa (taking picture).

DATA DETAILS

February 12, 2011 to February 9, 2013:

The anemometer tower was installed on February 12, 2011 and removed on February 9, 2013. The site was located in a field about 0.75 miles WSW of the USDA Agricultural Research Service on U.S. Highway 34 and 3.2 miles due east of Akron. The terrain was an open field with rough pasture, generally flat in all directions.

Data is collected using three (3) NRG #40C Calibrated Anemometers and one (1) NRG #200P Wind Vane, as follows:

  • Anemometers
    • Sensor A mounted at 33.8 m (111 feet) on an NRG 60" standard boom
    • Sensor B mounted at 33.8 m (111 feet) on an NRG 60" standard boom
    • Sensor C mounted at 20.0 m (65.6 feet) on an NRG 60" standard boom
  • Wind Vane
    • NRG #200P wind direction vane at 34.7 m (114 feet) heading 166° on an NRG 60" standard boom with the null point facing toward the tower
  • Temperature Sensor
    • NRG #110S Temperature Sensor with radiation shield at 1.8 m (6 feet) on an NRG 6" boom

All sensors fed into an NRG Symphonie data logger. The certifications for the anemometers are as follows:

NRG #40C Calibrated Anemometers
Anem. No.
1
2
3
Height
33.8 m
33.8 m
20 m
Model No.
1900
1900
1900
Serial No.
1795-00088151
1795-00087825
1795-00088088
Calibration Date
11/4/08 1:37:14 a.m.
10/31/08 8:34:07 a.m.
11/14/08 12:16:41 a.m.
Slope
0.759 m/s per Hz
0.758 m/s per Hz
0.759 m/s per Hz
Offset
0.35 m/s
0.35 m/s
0.36 m/s

The data logger generated wind reports for each day. Using the Symphonie Data Retriever software, each day's data was complied into one large data file. A zipped file that contains all of the NRG data files for all days are given below:

Raw Wind Data Files
NRG Data Plug Files
Akron_Raw_Wind_Data_2011_0213_to_2013_0209.zip

It is important to note that the wind direction data included in these files has already been adjusted for offset at the data logger.

From the collected data, an analysis of the wind resource report was developed for entire data collection period using Windographer 3.0.10. Since the data set contains data for two or more wind speed sensors at different heights above the ground, Windographer considered the wind shear relationship between different wind speed sensors to extrapolate the data to different heights. A best fit using the power law profile was chosen to extrapolate the data.

Using this data, an analysis of the wind resource report was developed and the data was flagged for icing in two ways:

  1. Any wind speed data (from any anemometer) where the wind speed was less than 0.5 m/s at a temperature less than 0 °C for 3 hours or more was flagged and ignored when calculating the wind resource statistics.
  2. Any wind direction data where the wind direction varied by less than 3 degrees at a temperature less than 0°C for 3 hours or more was flagged and ignored.

The summary report, the combined data files (with and without the data quality analysis), and the Windographer files (with and without the data quality analysis) are given below:

Interim Wind Resource Summary

Highlights of the wind resource for the entire measuring period at this site are shown below:

Data Properties
Data Set Starts:
2/12/2011 16:50 MST
Data Set Ends:
2/9/2013 9:00
Data Set Duration:
24 months
Length of Time Step:
10 minutes
Elevation:
1,382 m (4,534 ft)
Mean air density (kg/m³):
1.054
Wind Power Coefficients
Power Density at 50m:
308 W/m²
Wind Power Class:
3 (Fair)
Wind Shear Coefficients
Power Law Exponent:
0.200
Surface Roughness:
0.176 m
Roughness Class:
2.47
Roughness Description:
Few trees

 

Variable
Height above ground
A: 33.8m (111 ft.)
B: 33.8m (111 ft.)
20m (66 ft.)
10-min. Mean wind speed (m/s)
6.417 6.622 5.868
10-min Median wind speed (m/s)
6.250 6.480 5.590
10-min Standard deviation (m/s)
3.006 3.071 2.861
10-min Min. wind speed (m/s)
0.35 0.35 0.36
10-min Max wind speed (m/s)
28.9 28.8 26.4
Weibull k
2.229 2.249 2.137
Weibull c (m/s)
7.233 7.458 6.617
Mean power density (W/m²)
242 262 193
Mean energy content (kWh/m²/yr)
2,121 2,296 1,692
Mean turbulence intensity
0.14 0.13 0.15
Energy pattern factor
1.737 1.715 1.822
Possible records
104,785 104,785 104,785
Valid records
104,473 104,327 104,400
Missing records
312 458 385
Data recovery rate (%)
99.7 99.56 99.63

 

Vertical Wind Shear, Height (m) vs Mean Wind Speed (m/s)

 

Wind Frequency Rose at 33.8 meters

 

Wind Energy Rose at 33.8 meters

 

Daily Wind Speed Profile, Hourly Mean Wind Speed (m/s) vs. Hour of the Day

 

Seasonal Wind Speed Profile, Monthly Mean Wind Speed (m/s) vs. Month

 

Probability Distribution Function at 33.8m - Sensor A: Frequency (%) vs. Wind Speed

 

Probability Distribution Function at 33.8m - Sensor B: Frequency (%) vs. Wind Speed

 

Probability Distribution Function at 20m: Frequency (%) vs. Wind Speed

Windographer was used to match up the wind at this site with the performance curves of some common turbines of various sizes and various heights. The table below shows the results. For the larger turbines, the tower height was increased to account for the larger turbine blades - the wind resource was extrapolated to these higher heights. Keep in mind that the larger and the higher the turbine, the better the wind and the greater the output. But of course, as the tower heights and turbine sizes increase so does the cost.

Keep in mind too that listing a particular turbine doesn't imply an endorsement - not does it imply that installing a particular turbine model is feasible or recommended for a particular site. For consistency, the larger turbines are included even at sites that where they may not be practical so that one can compare the relative production of different sites.

Turbine
Rotor
Diameter
meters
Rotor
Power
kW
Hub
Height
meters
Hub
Height
Wind
Speed
m/s
Time
At
Zero
Output
percent
Time
At
Rated
Output
percent
Average
Net
Power
Output
kW
Average
Net
Energy
Output
kWh/yr
Average
Net
Capacity
Factor
%
Southwest AIR X - 45 ft tower
1.5
0.4
13.7 5.44 24.0 0.0 0.0 234 6.7
Bergey XL.1 - 100 ft tower
2.5
1.0
30.0 6.38 2.0 5.9 0.3 2,800 32.0
Southwest Skystream 3.7 - 45 foot tower
3.7
1.8
13.7 5.44 17.0 5.8 0.4 3,800 24.4
Southwest Whisper 500 - 42 ft tower
4.5
3.0
12.8 5.36 19.7 3.5 0.7 6,300 24.1
Endurance S-250 - 100 ft tower
5.5
5.0
30.0 6.38 0.0 0.0 1.1 9,800 22.3
Bergey Excel-R - 100 ft tower
6.7
7.5
30.0 6.38 13.7 4.1 2.1 18,700 28.5
Bergey Excel-S - 100 ft tower
6.7
10.0
30.0 6.38 6.1 2.3 2.3 20,100 22.9
Endurance E-3120 - 100 ft tower
19.2
55.0
30.0 6.38 12.3 0.0 18.9 165,200 34.3
Northern Power 100-21 - 121 ft tower
21.0
100
37.0 6.57 5.3 0.0 25.5 223,100 25.5
GE 1.5-77 - 213 ft tower
77
1,500
65.0 7.25 11.5 2.4 524.2 4,591,600 34.9
Vestas V100 - 262 ft tower
100
2,000
80.0 7.50 10.4 1.3 865.3 7,580,200 43.3

IMPORTANT: No turbine losses are included in the power, energy, and capacity factor values in the table. Typically, turbine losses can be 5-20% to account for maintenance downtime, icing/soiling and losses from other turbines in a wind farm. Users wanting to be conservative in the performance projections should multiply the power, energy, and capacity values by (1- % losses) to account for these losses.


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Last updated: June 2009
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