ALP No. 13 - Boulder

LOCATION DETAILS
Latitude:	N 39.9136° or N 39° 54' 38.34"
Longitude:	W 105.2469° or W 105° 14' 5.28"
Township:	2 S
Range:	70 W
Section:	4
Elevation (ft.):	6,085

DATA DETAILS

September 23, 1996 through December 31, 2005:

The tower is located at the western edge of the National Wind Technology Center's compound. The data are derived from instruments mounted on or near a 82 meter (270 foot) meteorological tower located at the western edge of the NWTC Site and about 11 km (7 miles) west of Broomfield, and approximately 8 km (5 miles) south of Boulder. The tower is located at 39° 54' 38.34" N and 105° 14' 5.28" W (datum WGS84) with its base at an elevation of 1855 meters (6,085 feet) above mean sea level.

For more information and real time measurement, please visit the NWTC M2 Tower website

The collected data includes the following data fields:

Wind speed, standard deviation of the wind speed, and data quality flag for an anemometer at 10m height
Wind speed, standard deviation of the wind speed, and data quality flag for an anemometer at 20m height
Wind speed, standard deviation of the wind speed, and data quality flag for an anemometer at 50m height
Wind speed, standard deviation of the wind speed, and data quality flag for an anemometer at 80m height
Wind direction, standard deviation of the wind direction, and data quality flag for a wind vane at 10m height
Wind direction, standard deviation of the wind direction, and data quality flag for a wind vane at 20m height
Wind direction, standard deviation of the wind direction, and data quality flag for a wind vane at 50m height
Wind direction, standard deviation of the wind direction, and data quality flag for a wind vane at 80m height
Temperature from a sensor mounted at a height of 50m

Only a text data file is available from this site, though more data is available from the NWTC M2 tower website. You can find this file here.

The file includes suspect data and when that data occurs, the value is generally a negative number. There is also a flag filed that indicates these suspect data values. For a version of this wind data with blanks rather than negative numbers, you can download here.

CSU was chosen as the contractor for the program on September 14, 2007. Using the raw data from all data plugs for this site, an analysis of the wind resource report was developed using Windographer 1.21. No data quality analysis was performed for this data other than what was available from the flag data fields included in the data. The suspect data was first removed from the collected data. Windographer was then used to add in synthetic data to these intervals with suspect data. The Windographer files (with blanks for the suspect data and with the blanks filled with synthetic data) are given below:

Highlights of the wind resource analysis at this site are shown below:

Data Properties
Data Set Starts:	9/23/1996 00:00
Data Set Ends:	1/1/2006 00:00
Data Set Duration:	9.3 years
Length of Time Step:	60 minutes
Calm threshold (mph):	0
Wind Power Coefficients
Power Density at 50m:	167 W/m²
Wind Power Class:	1 (Poor)
Wind Shear Coefficients
Power Law Exponent:	0.126
Surface Roughness:	0.0102 m
Roughness Class:	0.78
Roughness Description:	Rough pasture

Variable	WS80	WS50	WS20	WS10
Height above ground	80 m (262. ft)	50 m (164.0 ft)	20 m (65.5 ft)	10 m (32.8 ft)
Mean wind speed (mph)	10.67	10.15	8.93	8.25
Median wind speed (mph)	8.29	7.91	6.83	6.32
Min wind speed (mph)	0.02	0.02	0.02	0.02
Max wind speed (mph)	74.17	70.92	64.15	58.64
Mean power density (W/m²)	198	169	117	92
Mean energy content (kWh/m²/yr)	1,735	1,481	1,026	803
Energy pattern factor	3.64	3.6	3.66	3.64
Weibull k	1.42	1.45	1.46	1.48
Weibull c (mph)	11.8	11.27	9.94	9.20
1-hr autocorrelation coefficient	0.86	0.86	0.86	0.86
Diurnal pattern strength	0.08	0.07	0.09	0.10
Hour of peak wind speed	19	19	17	16
Mean turbulence intensity	0.18	0.19	0.19	0.2
Standard deviation (mph)	8.21	7.71	6.78	6.24
Coefficient of variation (%)	77	76	75.9	75.6
Frequency of calms (%)	0	0	0	0
Possible records	81,288	81,288	81,288	81,288
Valid records	7,7453	77,445	77,465	77,458
Suspect records	3,835	3,843	3,823	3,830
Data completeness (%)	95.3	95.3	95.3	95.3

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, allowing for losses of about 13%. 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	40	9.76	47.49	2.69	0.83	7,200	11
Bergey Excel-S	6.7	10	40	9.76	24.14	1.76	0.97	8,500	9.7
Bergey XL.1	2.5	1	40	9.76	5.84	4.1	0.13	1,200	13.2
Southwest Skystream 3.7	3.7	1.8	40	9.76	42.87	0	0.23	2,000	12.8
Southwest Whisper 500	4.5	3	40	9.76	47.27	3.34	0.42	3,700	13.9
Northern Power NW 100/20	20	100	40	9.76	60.31	0	7.59	66,500	7.6
Vestas V47 - 660 kW	47	660	65	10.39	42.73	0.86	69.2	606,600	10.5
GE 1.5s	70.5	1,500	80.5	10.69	51.01	3.19	143	1,252,400	9.5
Vestas V80 - 2.0 MW	80	2,000	100	11.00	49.28	2.00	237	2,073,800	11.8
GE 2.5xl	100	2,500	110	11.14	39.87	3.58	331	2,902,700	13.3

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Last updated: June 2009
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