PROGRAM INFORMATION

WALDEN - 3/29/2004 through 4/20/2005

DATA DETAILS

March 29, 2004 through April 20, 2005:

The anemometer tower was installed on July 3, 2003. The site was located on the east side of the town of Walden. The town is in a mountain valley oriented north-south with the continental divide to the west. The tower was located on the grounds of the high school. Buildings on the west and south sides of the tower impeded the wind.

All data was collected using an NRG #40 Anemometer and NRG #200 Wind Vane mounted on a tilt-up tower located on the landowner's property at a height of 20m. This equipment fed into an NRG Wind Explorer data logger. All data plugs were sent into the Governor's Energy Office and then to the University of North Dakota for analysis. All 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.

For this data, UND applied an offset of +248° to the wind vane data. The corrected data and wind resource summary report are available here:

• UND_Walden_2004_0329_to_2005_0420.txt
• Walden_Wind_Resource_Summary_Report_2004_0329_to_2005_0420.pdf

CSU was chosen as the contractor for the program on September 14, 2007. From the UND data, an analysis of the wind resource was developed using Windographer 1.13. For this data, an offset of +248° was already applied by UND to the wind vane data. 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:

• UND_Walden_2004_0329_to_2005_0420_with_blanks.windog
• UND_Walden_2004_0329_to_2005_0420_with_blanks.txt
• UND_Walden_2004_0329_to_2005_0420_with_filled_blanks.windog
• UND_Walden_2004_0329_to_2005_0420_with_filled_blanks.txt

Complete Wind Resource Summary

The anemometer tower was removed from the site on April 20, 2005. Highlights of the wind resource at this site for the entire data collection period using the Windographer are shown below:

Note that for the graphs below, the wind speeds are given as both the measured wind speeds at 20m and the projected wind speeds (in blue) using a surface roughness of 3 m.

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.

Note that these projections are for the estimated wind speeds using a surface roughness of 3 m.

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