GRANBY - 1/5/2010 to 5/20/2011
LOCATION DETAILS |
Latitude: |
N 40° 6.993’ or N 40° 6’ 59.6" |
Longitude: |
W 105° 55.450’ or W 105° 55’ 27.0" |
Survey Meridian: |
Colorado, Sixth Principal Meridian |
Township: |
2 N |
Range: |
76 W |
Section: |
20 |
Elevation (ft.): |
8,018 |
Datum: |
WGS 84 |
Tower Type: |
NRG Tilt-Up |
Tower Height: |
20 m (65.6 feet) |
Vane Offset (deg): |
+165° |
Direction Basis: |
Magnetic North |
Mag. Declination: |
8° 56' E, changing by 7' W/yr |
Wind Explorer S/N: |
0750 |
Site No.: |
1112 |
![](images/Granby_20m_Install_2010_0105_11_Install_Crew_13.50.08_600.jpg)
CSU ALP Install Team (from left): Kevin Gosselin, Todd MacDonald, Aron Seader, Eric Rasbach, Daniel Fink, Mike Kostrzewa, and Nathan Davis
DATA DETAILS
January 5, 2010 to May 20, 2011:
The anemometer tower was installed on January 5, 2010 and removed on May 20, 2011. The site was located in Grand County in an open field about 2 miles NNE of Granby and about 0.4 mile off of Hwy 34. The location was flat with clear viewsheds all around. The wind was expected to predominate from the NE and SW along the Colorado River valley between Lake Granby and the Windy Gap.
All data was collected using an NRG #40 Calibrated Anemometer and NRG #200 Wind Vane mounted on a tilt-up tower located at a height of 30m. The certification for the anemometer is as follows:
NRG #40C Calibrated Anemometer |
Model No. |
1900 |
Serial No. |
179500087805 |
Calibration Date |
10/31/2008 4:27:49 a.m. |
Slope |
0.761 m/s per Hz |
Offset |
0.35 m/s |
This equipment fed into an NRG Wind Explorer data logger. All data plugs were sent to the Colorado ALP at Colorado State University for analysis. The data plug files and text versions of these files are given below.
It is important to note that these are the raw files without any compensation for offset. It is also important to note that the temperature was not recorded during this period.
Also, note that although the last data plug was installed on January 1, 2011, the battery level was too low (6.5V) to keep the logger powered and recording. The lessee replaced the battery on January 30, 2011, which was sufficient to start recording again. So there is a gap of about 29 days when no data was collected.
Using this data, an analysis of the wind resource report was developed using Windographer 1.45. For this data an offset of +165° was applied to the wind vane data. For this report, a validation analysis was performed on the data. This data was filtered two ways:
- Any wind speed data where the wind speed was less than 1 mph for 6 hours or more was deleted.
- Any wind direction data where the wind direction varied by less than 3 degrees over 6 hours was deleted
Windographer was then used to add in synthetic data to these intervals with suspect data. The combined data files (with and without the validation analysis), and the Windographer files (with and without the validation analysis) are given below:
Final Wind Resource Summary
Highlights of the final wind resource assessment at this site are shown below:
Data Properties |
Variable |
Data Set Starts: |
1/5/2010 13:40 MST |
Height above ground (m) |
20 |
Data Set Ends: |
5/20/2011 13:20 |
Mean 10 min avg. wind speed (mph) |
6.470 |
Data Set Duration: |
16 months |
Median 10 min avg. wind speed (mph) |
4.130 |
Length of Time Step: |
10 minutes |
Min 10 min avg. wind speed (mph) |
0.126 |
Elevation (ft.): |
8,018 |
Max 10 min avg. wind speed (mph) |
51.05 |
Mean air density (kg/m³): |
0.962 |
Mean power density (W/m²) |
56 |
Wind Power Coefficients |
Mean energy content (kWh/m²/yr) |
490 |
Power Density at 50m: |
75 W/m² |
Energy pattern factor |
4.808 |
Wind Power Class: |
1 (Poor) |
Weibull k |
1.107 |
Wind Shear Coefficients |
Weibull c (mph) |
6.737 |
Power Law Exponent: |
0.126 |
1-hr autocorrelation coefficient |
0.770 |
Surface Roughness: |
0.01 m |
Diurnal pattern strength |
0.545 |
Roughness Class: |
0.78 |
Hour of peak wind speed |
15 |
Roughness Description: |
Rough Pasture |
Mean turbulence intensity |
0.3176 |
Note: The wind power density and wind power class at 50m are projections of the data from 20m. A surface roughness of 0.01 meters was assumed for this projection. This is equal to that of a rough pasture. This value was then used this to calculate the roughness class and the power law exponent shown above. |
Standard deviation (mph) |
6.06 |
Total data elements |
215,994 |
Suspect/missing elements |
16,236 |
Data completeness (%) |
92.5 |
![](ALP_Sites/Granby_(77)/Data_Plug_2011_0520/Granby_PDF_600.png)
Probability Distribution Function at 20m: Frequency (%) vs. Wind Speed
|
![](ALP_Sites/Granby_(77)/Data_Plug_2011_0520/Granby_Wind Shear_600.png)
Vertical Wind Shear, Height (m) vs Mean Wind Speed (mph)
|
![](ALP_Sites/Granby_(77)/Data_Plug_2011_0520/Granby_Wind Energy Rose_600.png)
Wind Energy Rose at 20 meters
|
![](ALP_Sites/Granby_(77)/Data_Plug_2011_0520/Granby_Wind Frequency Rose_600.png)
Wind Frequency Rose at 20 meters
|
![](ALP_Sites/Granby_(77)/Data_Plug_2011_0520/Granby_Daily Wind Speed Profile_600.png)
Daily Wind Speed Profile, Hourly Mean Wind Speed (mph) vs. Hour of the Day
|
![](ALP_Sites/Granby_(77)/Data_Plug_2011_0520/Granby_Seasonal Wind Speed Profile_600.png)
Seasonal Wind Speed Profile, Monthly Mean Wind Speed (mph) vs. Month
|
![](ALP_Sites/Granby_(77)/Data_Plug_2011_0520/Granby_Boxplot_600.png)
Boxplot: Seasonal Wind Speed Profile, Monthly Mean Wind Speed (mph) vs. Month
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.
Turbine |
Rotor
Diameter
meters |
Rotor
Power
kW |
Hub
Height
meters |
Hub
Height
Wind
Speed
mph |
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
% |
Bergey Excel-R |
6.7 |
7.5 |
20 |
6.47 |
68.5 |
0.7 |
0.6 |
4,800 |
7.4 |
Bergey Excel-S |
6.7 |
10 |
20 |
6.47 |
56.1 |
0.2 |
0.6 |
5,200 |
5.9 |
Bergey XL.1 |
2.5 |
1 |
20 |
6.47 |
32.5 |
0.9 |
0.1 |
700 |
8.4 |
Southwest Skystream 3.7 |
3.7 |
1.8 |
20 |
6.47 |
66.4 |
0.0 |
0.2 |
1,400 |
8.8 |
Southwest Whisper 500 |
4.5 |
3 |
20 |
6.47 |
68.5 |
0.8 |
0.3 |
2,500 |
9.4 |
Northern Power NW 100/21 |
21 |
100 |
37 |
6.99 |
64.4 |
0.0 |
7.3 |
64,200 |
7.3 |
Vestas V47 - 660 kW |
47 |
660 |
65 |
7.51 |
64.2 |
0.1 |
53.9 |
471,800 |
8.2 |
GE 1.5s |
70.5 |
1,500 |
80.5 |
7.71 |
68.0 |
0.8 |
105.1 |
920,300 |
7.0 |
Vestas V80 - 2.0 MW |
80 |
2,000 |
100 |
7.92 |
67.3 |
0.3 |
182.0 |
1,593,900 |
9.1 |
GE 2.5xl |
100 |
2,500 |
110 |
8.02 |
62.6 |
1.0 |
259.7 |
2,274,900 |
10.4 |
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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