PROGRAM INFORMATION

WALSENBURG AIRPORT NORTH (POTTS)

3/6/2006 through 12/7/2011

DATA DETAILS

March 6, 2006 through March 6, 2007:

This anemometer tower was owned by the San Isabel Electric Association. It was installed in a pasture by SIEA on March 6, 2006. Also known by the name Potts, the site is 1.5 miles northeast of the airport (Johnson Field) and approximately 6 miles north-northwest of the town of Walsenburg. Interstate Highway 25 is located about 1,500 feet west of the tower.

All data was collected using an NRG #40 Anemometer and NRG #200P Wind Vane mounted on a tilt-up tower located on the landowner's property at a height of 30m. This equipment fed into an NRG Wind Explorer data logger. Seven data plugs were sent into the Governor's Energy Office and then to the University of North Dakota 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.

It is also important to note that there is a data plug file missing and unavailable for the period from 2/24/2006 through 4/5/2006.

For this data, UND applied no offset to the wind vane data. The data from February 1, 2006 through March 6, 2007 using no offset and the wind resource summary report for the same period are available here:

• Walsenburg_Airport_North_Potts_Wind_Resource_Summary_Report_2006_0201_to_2007_0306.pdf
• UND_Walsenburg_Airport_North_Potts_2006_0201_2007_0306.txt

March 6, 2007 through December 7, 2011:

CSU was chosen as the contractor for the program on September 14, 2007. The last data for the site was received from SIEA covering the period through December 7, 2011. The data collected September 2007 is given below:

Again, it is important to note that these are the raw files without any compensation for offset or temperature.

It is also important to note that there is a data plug file missing and unavailable for the period from 11/20/2008 at 12:50 through 6/2/2009 at 7:50.

Wind Vane Offset

Based on measurements taken by SIEA personnel during the tower installation, the wind vane boom was pointing at 10° 27' W from true north. Other measurements showed that when the wind vane was pointing 135° 20' the datalogger was showing 208°, indicating that an offset of 287° should be applied to the wind vane data. However, applying this offset yields a wind rose with the predominate wind direction from due north, which is counter to anecdotal experience and to the wind data collected at the Walsenburg Airport - South site.

Onsite readings taken on September 3, 2008 showed that when the wind vane was pointing to 226° magnetic north the datalogger was reading 120°. Allowing the a magnetic declination of 9°E, the offset to true north is (226° + 9°) - 120° = 115°. When this offset is applied, the wind rose shows that the wind direction is predominately from the south.

Onsite readings taken on March 25, 2010 showed that when the wind vane was pointing to 277° magnetic north the datalogger was reading 52°. Allowing the a magnetic declination of 9°E, the offset to true north is (277° + 9°) - 52° = 234°. When this offset is applied, the wind rose shows that the wind direction is predominately from the west-northwest.

Using the raw data from all data plugs for this site, an analysis of the wind resource report was developed using Windographer 1.49. For this data, an offset of 234° was applied to the wind vane data for the period from March 6, 2007 through May 19, 2010. A data validation analysis was then performed on the wind speed and wind vane data. This data was filtered as follows:

1. Any wind speed data where the wind speed was less than 1 mph for 3 hours or more was deleted.
2. Any wind direction data where the direction changed less than 3° over 8 hours was deleted.

Windographer was then used to add in synthetic data to these intervals with suspect data. A summary report, the combined data files (with and without data validation and offset), and the Windographer files (with and without data validation and offset) are given below:

• Walsenburg_Airport_North_Potts_2006_0201_to_2011_1207_Summary_Report.pdf
• Walsenburg_Airport_North_Potts_2006_0201_to_2011_1207_without_data_validation.windog
• Walsenburg_Airport_North_Potts_2006_0201_to_2011_1207_without_data_validation.txt
• Walsenburg_Airport_North_Potts_2006_0201_to_2011_1207_with_data_validation_offset_234.windog
• Walsenburg_Airport_North_Potts_2006_0201_to_2011_1207_with_data_validation_offset_234.txt

Final Wind Resource Summary

As of November 7, 2012, no more data is expected from this site and the anemometer tower will be removed from the site shortly. Highlights of the entire wind resource at this site through December 7, 2011 are shown below:

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.

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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