Wind Resource Evaluation: North Ashland
OREGON ANEMOMETER LOAN PROGRAM
Wind Resource Evaluation: North Ashland
Prepared By:
Energy Resources Research laboratory Oregon State University
August 31, 2006
NOTICE This publication was prepared as an account of work sponsored by the Energy Trust of Oregon, Inc. Neither the Energy Trust of Oregon, Inc. nor any of their contractors, subcontractors, or their employees make any warranty, express or implied, or assume any legal liability or responsibility for the accuracy, completeness, usefulness, or reliability of the research data, and conclusions reported herein, or of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. For these reasons and for the reason that the views, opinions, and conclusions contained in this material are those of the contractor.
Wind Resource Evaluation: North Ashland
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OREGON ANEMOMETER LOAN PROGRAM
Wind Resource Evaluation: North Ashland
Prepared by: Philip L. Barbour Stel N. Walker, Ph.D. Energy Resources Research Laboratory Department of Mechanical Engineering Oregon State University Corvallis, OR 97331
Sponsor: Energy Trust of Oregon, Inc. 733 SW Oak Street, Suite 200 Portland Oregon,97205
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1.0
INTRODUCTION
The Oregon anemometer loan program was established in the fall of 2002 in order to assist landowners in the state evaluate the wind energy potential of their property. The program is funded by a grant from the Energy Trust of Oregon and is administered by the Energy Resources Research Laboratory at Oregon State University. The program involves several steps, beginning with a preliminary evaluation of the site. If estimates of the site show promise then a monitoring system is installed for a fixed duration (typically on year). The site is monitored regularly and the data processed and checked at regular intervals. Upon completion of the first year, the collected wind data is summarized and a report is prepared evaluating the wind data and the wind resource of the location. This report represents the final portion of the project and is designed to give the landowner the information necessary to make an informed choice about the role wind energy might play in their property. The report is separated in to sections with section 2.0 devoted to a description of the site, its location and the type of terrain found there. Section 3.0 includes a summary of the wind data collected during the study period including data quality checks and a characterization of the measured winds. In section 4.0 the wind data is analyzed to determine the amount of power production that might be expected from the site and to examine characteristics that might influence these estimates. This is followed in section 5.0 in which wind data from a nearby site is summarized and used to place the current study period in climatological context. A discussion and summary is then presented in section 6.0
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2.0
SITE DESCRIPTION Site Name: Latitude: Longitude: Elevation: County: Sensor Height: Types of Sensors: Types of Data: Installation Date: Removal Date:
North Ashland 42-13-49 122-44-18 1760 ft. Jackson 67 ft. NRG Maximum #40 wind speed NRG 200 series2 wind vane 10 min. average wind speed (mph) 10 min. std. dev. wind speed (mph) 10 min. wind direction (16 categories) May 24, 2005 @ 1550 PST June 19, 2006 @ 1400 PST
Site Location: Ashland is located in southwestern Oregon along the I-5 corridor. The city sites at the base of a broad valley boarderd by the foothills of the Cascades on the east and the Siskiyou Mountains to the west. The valley extends from Medford southeast towards Ashland. The current site is located just north of the city of Ashland on a small rise. Access to the site is found by turning east off of I-5 at exit 19 and turning southeast on East Ashland Lane. The site was located near the top of the small hill located just to the east. The area is primarily grass land with a few small trees. The tower location is marked on the map included in Appendix A. Pictures of the tower and the local terrain have been included in Appendix B. Project Description: The owner of the site is interested in evaluating the site for possible installation of a small wind turbine for home use. There has been a lot of interest in home wind systems from this area and this site was selected over other sites because it was the site of previous monitoring from 1979 through 1980. That monitoring indicated the site had an annual mean of 8.3 mph at 35 meters. Properties in the area consists of several acres and have room to be equipped with small turbines.
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3.0
WIND CHARACTERISTICS
In the following sections, several characteristics of the winds at the North Ashland site are examined and discussed. The goals are to evaluate the characteristics that can help explain the physical processes at work at the site and to highlight the properties that are important to assessing the wind energy potential. These evaluations are done using hourly averaged means that have been constructed using the 10 minute means recorded at the site. This is done so that existing analysis programs can be used and is not expected to have any appreciable influence on the interpretation of data. Data Recovery: The amount of data recovered during an observation period is important to characterize and should be examined to determine the confidence of other characteristics. During the initial annual period at this site, there were no problems detected that might influence the collected wind data. A table of site visits and the actions taken has been included in Appendix A. Data were plotted and scanned manually to identify any problems with the site. For the most part, data collection from the site was complete and there were no periods of missing data. Data for several periods were removed from the records because the effects of icing were detected. This was only done for periods with a clear presence of icing and it is possible that other periods with a more limited influence occurred. Icing is identified as prolonged periods with a wind speed of 0.0 mph and a constant direction. For the North Ashland site icing was confined to the month of December.
Data Recovery
Recovery Rate (%)
100 80 60 40 20 0 Jun
Jul
Aug
Sep
Oct
Nov Dec
Jan
Feb
Mar
Apr
May Ann.
Figure 3.1: Data recovery by month for the North Ashland site.
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Month
Jun
Rec. (%)
Jul
100
Aug
100
Sep
100
Oct
96.77
Nov
100
Dec
100
Jan
95.8
Feb
100
Mar
100
Apr
100
May
100
100
Ann
99.7
Monthly Means: Monthly means are often constructed and used to determine the overall strength of the winds during different periods of the year. Monthly means show that the North Ashland site has slightly higher winds during the winter months but no period of sustained strong winds. All of the months over which the sensor was in place had winds below 12.0 mph. December, February and March were the only months with winds above 10.0 mph. This suggests that even during high wind periods this site has a fairly low wind resource.
Monthly Means 14 12
(mph)
10 8 6 4 2 0 Jun
Jul
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Ann
Figure 3.2: Monthly Mean Wind Speed Values for the North Ashland site. Month Mean (mph)
Jun 8.5
Jul 7.8
Aug 8.1
Sep 7.1
Oct 6.7
Nov 7.3
Dec 11.5
Jan 9.6
Feb 10.4
Mar 11.5
Apr 8.4
May
Ann
8.0
8.7
Diurnal Means: The diurnal pattern of winds is an important characteristic for many wind sites and helps illuminate the mechanisms responsible for the winds. In general, a diurnal pattern is associated with a site at which strong thermal influences play a role. These are normally accentuated during the summer months when the daily heating cycle is at its greatest. Diurnal variations can also provide an indication of dependable and predictable winds at a site.
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As is common for many sites in Oregon, the winds at the North Ashland site show a clear diurnal pattern is present during the summer months and is strong enough to show up in the mean for the annual diurnal average (Fig. 3.3). In general, the diurnal values for summer show that the winds are very light through the night and morning hours and begin to pick up around noon. The magnitude of the winds build until around 1700-1800 and taper off slowly. On average, the winds during these days are in a usable range for about 28% of the time. The winds during these periods are predominantly from the north and are a response to large-scale heating patterns. During the winter months there is a little indication of a diurnal variation but at best it is fairly weak Diurnal Mean Winds 14 Wind Speed (mph)
12 10 AVE Jan
8 6
Jul
4 2 0 1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Hour of Day
Figure 3.3: Diurnal mean wind speed values for the North Ashland site.
Frequency Distribution: How the wind speed at a site is distributed over various wind speed categories is an important indication of the wind resource potential of a site. An ideal site would have winds that blow at a high rate for long periods. This is not normally the case, however, and wind records from a site show a skewed distribution with a higher frequency of winds at lower speeds. For the North Ashland site (Figure 3.4) we see that the distribution is fairly typical with a low frequency of winds at the lowest range, a peak centered between 5.0 to 7.0 mph and a trailing tail at the upper end. In this case the peak is relatively narrow with a single peak that drops off fairly rapidly. This peak would likely be smoother with additional data. The importance of this figure is that it illustrates the amount of time that the winds are within various energy resource ranges. For example, the winds at the North Ashland site are at or above 12.0 mph only about 18 % of the time. This suggests that it would be possible to produce appreciable amounts of energy at the site less than 20 % of the time. In addition, the winds are above 20.0 mph only about 7.0% of the time (the range at which most wind turbines produce their peak amount of power). This suggests that a typical wind turbine would produce optimal output only about 7.0 % of the time. This is Wind Resource Evaluation: North Ashland
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relatively low for a good wind site and suggests that there is a low frequency of winds at the upper end of the range. This is significant because it is at higher wind speeds where most of the potential power is produced.
Frequency (%)
Relative Frequency 10 9 8 7 6 5 4 3 2 1 0 0
5
10
15
20
25
30
35
40
45
Wind Speed Category Figure 3.4: Wind speed frequency distribution for the North Ashland site.
Wind Rose: How the wind varies with direction is also important to understanding the physical processes that contribute to the local winds at a site and eventually in designing a wind facility. A wind rose is often used to display this information and show the frequency with which the wind occurs in different direction categories. A similar plot can be used to show the strength of the wind from each of the direction categories. For this site (Figure 3.5) it is apparent that the winds come from two main directions, the Southeast and the Northwest. This is basically the orientation of the valley and is not surprising. Viewing the second figure we see that the mean wind speeds for the Southwesterly directions are much higher than for the northerly directions. This is often the case at sites in the Northwest where southerly winds associated with strong storm systems during the winter months produce much of the observed wind. The higher wind speed averages for the southerly directions suggest that this is the direction from which a majority of the energy producing winds will come from.
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Annual Directional Frequency
Annual Directional Speed 14
Mean Speed (mph)
Frequency (%)
25 20 15 10 5 0
12 10 8 6 4 2 0
N
NE
E
SE
S
SW
W
NW
N
CALM
NE
E
Direction Category
SE
S
SW
W
NW
Direction Category
Figure 3.5: Frequency (%) and average wind speed (mph) for each of 16 wind direction categories
In order to better understand the winds at the site during different times of year; similar plots have been constructed using data from the individual months of January and July. These can be seen in figures 3.6a-d and show the difference between the two periods. JANUARY
JANUARY 25
Mean Speed (mph)
Frequency (%)
30 25 20 15 10 5 0
20 15 10 5 0
N
NE
E
SE
S
SW
W
NW
N
CALM
NE
E
Direction Category
JULY
S
SW
W
NW
W
NW
JULY
35
12
30
10
Mean Speed (mph)
Frequency (%)
SE
Direction Category
25 20 15 10 5
8 6 4 2 0
0 N
NE
E
SE
S
SW
W
NW
CALM
Direction Category
N
NE
E
SE
S
SW
Direction Category
Figure 3.6: Frequency (%) and average wind speed (mph) for each of 16 wind direction categories for the months of January and July for the North Ashland site.
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4.0
SITE POWER CHARACTERISTICS
In order to evaluate the wind power potential at this site a number of quantities were computed using the collected wind data. As with the wind characteristics, hourly wind data was used to complete this work. The power density calculation requires air density. This is estimated assuming a standard atmosphere and the site elevation. The computed quantities include the mean and standard deviation of the hourly values, the recovery rate, the maximum one hour average, the wind power density and the frequency that the wind was observed within a wind speed range (12 mph to 60 mph). These quantities are shown in Table 4.1 and reveal a number of things about the potential for generating energy the site. The quantities in Table 4.1 show the wind resource in this area is limited to a few months during the winter. All of the months from April through November have low mean wind speeds, low percentages of time within a general turbine operating range and low power density values. The lowest is September in which a turbine would operate less than 3% of the time. The winter months are somewhat better with power density values above 100 W/m**2 for December through March. However, values for this month are relatively low compared to other, good wind sites. Wind power density represents the amount of energy that would be available to a unit area each hour. The monthly mean values are shown in Figure 4.1 and highlight the low values through much of the year. The reason for this is that strong winds are seldom observed at this site. The area does get a fairly steady and regular afternoon wind over the summer months but it is not strong enough to provide a significant amount of power. This is highlited further by the maximum one hour values in Table 4.1 that are below 20.0 mph for the months of July through September.
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Table 4.1: Observed and computed power quantities for the wind site at the North Ashland site.
Month
Mean
Std.
Recovery
Max 1Hr
Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May ANN
(mph) 8.5 7.8 8.1 7.1 6.7 7.3 11.5 9.6 10.4 11.5 8.4 8.0 8.7
(mph) 4.24 3.36 3.16 3.06 3.63 6.35 10.12 8.26 8.21 9.50 5.57 4.33 6.49
Rate (%) 100.0 100.0 100.0 100.0 100.0 100.0 95.8 100.0 100.0 100.0 100.0 100.0 99.7
(mph) 28.1 17.5 14.8 16.5 23.4 39.3 45.3 39.5 44.1 46.7 30.9 27.8 46.7
Wind Resource Evaluation: North Ashland
Time in Range (12-60) mph (%) 15.3 8.7 7.8 2.5 5.1 11.0 31.8 25.4 25.0 32.0 16.8 11.7 16.0
Power Den.
Shape
Scale
W/m^2 59 38 39 29 31 96 326 191 213 294 83 55 120
Factor 2.13 2.51 2.77 2.51 1.94 1.16 1.14 1.18 1.29 1.23 1.55 1.96 1.38
Factor 9.6 8.8 9.1 8.1 7.5 7.7 12.0 10.2 11.2 12.3 9.3 9.1 9.5
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Power Density
Power Density (W/m**2)
350 300 250 200 150 100 50 0 Jun
Jul
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Ann
Figure 4.1: Monthly power density for the North Ashland site.
In addition to evaluating these basic power characteristics it is possible to estimate how specific wind turbines might interact with the winds at a particular site. Using the collected wind data and the characteristics of a particular wind turbine it is possible to estimate the amount of power it could produce. This is done by comparing the wind data with a power curve for a specific wind turbine. A power curve is simply the curve that shows the relationship between the wind speed and the amount of power a turbine can produce. An example is provided in Figure 4.2. There are several portions of the curve that are important. At low wind speeds, below the cut-in speed, no energy is produced. Any turbine has a lower threshold below which it won’t operate. This is in part because there is little energy available at these levels. In the middle is a ramp up zone where even a small increase in wind speed results in a larger increase in power. At some point, depending on the type of turbine, the amount of power hits its rated capacity as the blades are pitched to spill energy and protect the turbine. At the upper end, energy production will stop if the winds reach a cut-out speed. This is the speed at which a turbine is shut down. In Table 4.2, energy capacity factors are shown for eight different types of turbines. The capacity factor is the ratio of the amount of energy produce to the amount of energy that could be produced if a turbine ran at its rated capacity all the time. The rated capacity is effectively a theoretical maximum and capacity factors generally range from 0.0 to 0.40. It’s difficult to compare these because of the different turbine characteristics but they are given to provide a range of values that might be expected from this site. In computing these values, it is necessary to adjust the observed data which is measured at 67 feet to
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the hub height of the particular turbine. In this case this is done using a standard assumption that the wind follows a typical power law profile with a coefficient of 0.143. 120
Power Output (% of Rated)
100
80
60
40
20
0 0
10
20
30
40
50
Wind Speed (mph)
Figure 4.1: Sample power curve for a theoretical turbine
The capacity factors in Table 4.2 support the conclusions of the previous sections and indicate that there appears to be little wind energy potential at this site. Even during the highest wind months of December and February capacity factors for the most efficient wind turbines were on the order of 0.25. During the low wind speed months (August through October) the capacity values vary but are generally well below 0.10. During these months a turbine at this particular site could capture less than 5% of what it might under perfect ideal conditions. For some turbines the values are as low as 1.6 % (Sep. with BWC EXCEL). Overall these values indicate little wind power would be available from this site during much of the year.
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Table 4.2: Capacity factors computed for the North Ashland site using observed wind data and characteristics of eight different wind turbines.
Turbine Size (kW) Hub Ht. (ft.) Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May ANN
Vestas 47 660 131 0.071 0.042 0.042 0.027 0.032 0.078 0.230 0.159 0.161 0.219 0.094 0.063 0.101
Vestas 80 2000 262 0.093 0.060 0.061 0.042 0.045 0.090 0.253 0.180 0.183 0.244 0.114 0.082 0.120
Vestas 66 1650 197 0.062 0.036 0.036 0.023 0.028 0.073 0.216 0.148 0.151 0.207 0.083 0.055 0.093
Wind Resource Evaluation: North Ashland
Vestas 7.5 55 59 0.055 0.029 0.029 0.019 0.024 0.071 0.215 0.146 0.148 0.205 0.078 0.049 0.089
BWC EXCEL-S 10 79 0.041 0.023 0.024 0.016 0.019 0.060 0.181 0.121 0.125 0.173 0.059 0.037 0.073
GE Wind 70.5 1500 210 0.085 0.052 0.055 0.036 0.041 0.088 0.253 0.178 0.180 0.243 0.109 0.076 0.116
Vestas 29 225 103 0.077 0.049 0.050 0.033 0.037 0.083 0.237 0.165 0.169 0.227 0.099 0.069 0.107
Mitsubishi 250 100 0.052 0.031 0.031 0.020 0.023 0.068 0.201 0.136 0.141 0.194 0.072 0.046 0.084
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5.0 CLIMATOLOGICAL ANALYSIS Measurements taken over a single one-year period can provide a good estimation of the winds and wind energy potential of a site. However, this is a fairly limited period and is only meaningful if we can place the period into a larger climatological context. For the Ashland monthly mean wind speed values from the Sexton Summit site used for this purpose. While not ideal, wind records from Sexton Summit should show the general climatological significance of this particular observation period. To accomplish this, monthly mean wind speed values and climate normals were obtained from the National Climate Data Center (NCDC). Information about the site and the monthly means and departures for this annual study period can be found in Table 5.1. First, the winds overall were similar to those observed at the North Ashland site for this study period. Sexton Summit had an overall mean of 9.3 mph while the North Ashland site had a mean of 8.7 mph. Much of this difference is likely due to the elevation difference between the sites. Table 5.1 shows that for the first seven months of this study period the winds were slightly below normal at Sexton Summit. Overall, the winds were very close to normal (3.5 %). The highest departures and therefore the highest variability appear to happen during the winter months when changes can occur from month to month. Overall it appears that conditions during this observation period at the North Ashland site were close to normal. Several individual months had departures greater than 10% but over the year these tended to average out.
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Table 5.1: Monthly mean and departures for winds at Sexton Summit. SEXTON SUMMIT NWS Latitude: 42.60N
Elevation: 3832'
Longitude 123.37W Month
Normal (mph)
Mean (mph)
Departure
1982-1997
2005-2006
(%)
Jun
8.7
8.1
-6.9
Jul
9.0
8.4
-6.7
Aug
8.6
8.3
-3.5
Sep
8.6
7.8
-9.3
Oct
9.1
8.2
-9.9
Nov
10.8
9.9
-8.3
Dec
11.6
13.2
13.8
Jan
11.7
13.0
11.1
Feb
10.9
9.3
-14.7
Mar
9.9
9.9
0.0
Apr
8.1
8.2
1.2
May
8.8
7.5
-14.8
ANN
9.7
9.3
-3.5
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6.0 SUMMARY AND DISCUSSION There are a number of factors that might have an influence on the interpretation of the winds observed over this annual study period in the Ashland area. First, measurements were taken from only one tower and it is possible that other locations might provide better exposure to the prevailing winds. The location of the tower was dictated in part by the constraints of the property boundaries and the terrain. Although care was taken to locate a location with good exposure to all directions, some blocking of the winds from the north is possible. While this is not expected to be a significant factor, the regular winds do come from this direction in the summer. In any case, the site is ideally situated to capture the flows from the southerly direction. A second factor that is important to consider is that observations were collected at only one height. Flow over hills and ridgelines can be very complex and difficult to estimate. These types of flows are influenced by many factors including the density of the air, the exact shape of the mountain and the upper air wind characteristics. Observations taken at a different height above ground would most likely show some differences that might be important to a determination of economic feasibility. In summary, 1) 2)
3) 4)
No problems were encountered during the annual data collection period. One period of icing was detected in December and removed from the records. The observed annual mean wind speed was 8.7 mph. The Ashland area appears to have weak but identifiable seasonal pattern, Winds during the winter can produce periods of adequate resource. During the summer there is a strong diurnal pattern but the peak winds during these periods can be fairly low for long periods. A comparison with a nearby site where a longer history of observations are available suggests that this study period (June 2005-May 2006) was very close to the 16 year normal (1982-1997) During all seasons, the winds come from a direction that is nearly parallel to the Valley
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Appendix A: Topographic Map of the North Ashland site.
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Appendix B: Photograph of the North Ashland site tower looking southeast.
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Appendix C: Site Visit Records and wind gust during period prior to visit. Changes Made Date: 5/24/2005 7/08/2005 8/13/2005 9/08/2005 10/05/2005 11/18/2005 12/10/2005 1/17/2006 2/09/2006 2/26/2006 4/13/2006 5/14/2006 6/19/2006
Plug Y Y Y Y Y Y Y Y Y Y Y
Battery
Time
Y Y Y Y
Y
Gust (mph) 40 28 26 29 44 56 62 56 50 65 38 44
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Comment Site Installed
Site Removed
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Appendix D: Miscellaneous analysis Tables.
STATION – NORTH ASHLAND WIND SPEED FREQUENCY DISTRIBUTION WITH NORMALIZED AVAILABLE ENERGY DATA PERIOD OF RECORD 6/2005 - 5/2006 NORMALIZATION PERIOD - ONE YEAR AVERAGE WIND SPEED FOR PERIOD: 8.7 MPH NORMALIZED AVAILABLE ENERGY: 1058.1 KWH/M**2/YEAR TOTAL HOURS OBSERVED: 8729 SPD MPH 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47
HOURS/ PERIOD 77 308 492 535 647 722 761 769 777 762 724 554 356 180 114 69 74 59 63 50 65 51 36 50 36 43 41 35 54 33 38 29 19 17 21 9 10 11 10 6 8 3 3 2 3 1 1 1
RELFREQ 0.88 3.53 5.64 6.13 7.41 8.27 8.72 8.81 8.90 8.73 8.29 6.35 4.08 2.06 1.31 0.79 0.85 0.68 0.72 0.57 0.74 0.58 0.41 0.57 0.41 0.49 0.47 0.40 0.62 0.38 0.44 0.33 0.22 0.19 0.24 0.10 0.11 0.13 0.11 0.07 0.09 0.03 0.03 0.02 0.03 0.01 0.01 0.01
CUMHRS 8729 8652 8344 7852 7317 6670 5948 5187 4418 3641 2879 2155 1601 1245 1065 951 882 808 749 686 636 571 520 484 434 398 355 314 279 225 192 154 125 106 89 68 59 49 38 28 22 14 11 8 6 3 2 1
CUMRELFREQ 100.00 99.12 95.59 89.95 83.82 76.41 68.14 59.42 50.61 41.71 32.98 24.69 18.34 14.26 12.20 10.89 10.10 9.26 8.58 7.86 7.29 6.54 5.96 5.54 4.97 4.56 4.07 3.60 3.20 2.58 2.20 1.76 1.43 1.21 1.02 0.78 0.68 0.56 0.44 0.32 0.25 0.16 0.13 0.09 0.07 0.03 0.02 0.01
Wind Resource Evaluation: North Ashland
NORMALIZED AVAIL. ENERGY KWH/M**2/YEAR 0.0 0.0 0.2 0.8 2.2 4.7 8.6 13.7 20.7 28.9 37.7 38.4 32.0 20.6 16.3 12.1 15.8 15.1 19.1 17.9 27.1 24.6 20.0 31.7 25.9 35.0 37.5 35.9 61.7 41.9 53.4 45.0 32.4 31.8 43.0 20.1 24.3 29.0 28.6 18.5 26.7 10.8 11.6 8.3 13.3 4.7 5.1 5.4
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STATION – NORTH ASHLAND MONTHLY WIND SPEEDS (MPH) DATA PERIOD OF RECORD 6/2005 -
5/2006
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
NOV
DEC
2005 # OBS
0.0 0
0.0 0
0.0 0
0.0 0
0.0 0
8.5 720
7.8 744
8.1 744
7.1 720
6.7 744
7.3 720
11.5 713
2006 # OBS
9.6 744
10.4 672
11.5 744
8.4 720
8.0 744
0.0 0
0.0 0
0.0 0
0.0 0
0.0 0
0.0 0
0.0 0
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AVG SPD
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
MON
200
300
400
500
8.0
7.8
7.4
7.1
6.8
9.2 10.0 10.1 9.4 9.7 9.7 9.0 8.8 8.4 8.0 9.0 8.2 8.5 8.5 8.8 6.2 6.0 6.1 7.2 6.4 8.1 6.8 5.9 5.5 5.1 6.8 6.2 6.2 5.9 5.9 7.0 6.7 6.4 6.0 5.6 8.2 8.3 7.8 7.0 6.1 7.6 7.2 6.6 5.1 5.2 5.9 6.5 5.4 5.0 5.3 7.2 6.8 5.5 6.2 6.2 11.7 11.6 11.1 10.8 10.0
100
700
6.4
5.9
9.4 8.7 8.9 8.4 8.3 9.3 5.5 5.2 4.6 4.8 5.7 5.3 4.0 2.3 4.1 2.3 5.9 4.0 5.2 4.8 5.6 5.6 9.8 10.1
600
6.6
7.9
8.9
10.2 12.6 15.2 11.2 10.9 11.4 11.5 11.2 9.9 8.3 8.5 12.1
9.7 12.2 15.0 11.1 11.3 10.5 11.7 11.2 9.4 7.7 6.6 11.5
8.8 11.1 15.2 10.6 11.6 11.2 11.9 11.2 8.4 6.1 7.0 11.9
8.4 9.8 14.1 9.7 10.5 11.5 11.3 10.9 6.5 7.0 7.3 12.8
9.9 10.7 11.2 11.2 11.1 10.6 10.4 10.0
11.0 13.3 13.9 11.1 10.9 11.8 11.3 11.0 9.8 9.1 9.0 12.9 9.7
9.5 10.9 13.2 8.5 8.6 10.3 9.7 9.5 7.4 8.4 7.6 12.6
9.3
10.8 11.6 11.8 7.5 7.7 9.3 8.4 8.4 7.1 8.7 7.8 12.9
8.5
7.9
7.9
8.0
10.9 9.8 8.6 8.8 11.7 11.7 10.8 8.8 11.3 10.9 10.8 9.9 6.6 7.0 8.0 7.1 7.1 6.7 7.7 8.1 8.4 6.9 5.9 6.6 7.1 5.2 5.2 6.9 6.1 4.5 6.6 7.6 6.3 5.7 6.8 8.0 7.7 7.4 6.0 6.1 7.6 8.0 7.6 7.9 11.9 11.4 11.5 10.5
900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 2400
5/2006
8.8 7.9 9.0 9.8 10.6 11.8 8.0 8.4 9.9 11.1 12.7 13.1 9.7 11.0 12.5 12.7 14.0 13.8 6.9 8.8 10.6 11.2 10.9 11.2 6.3 7.8 8.3 8.9 9.0 10.3 7.3 8.3 9.2 10.1 11.4 11.9 4.6 7.2 8.4 9.1 9.9 10.7 4.6 7.3 8.6 9.6 10.7 11.0 4.1 5.7 7.2 8.4 9.4 9.7 3.7 5.1 5.9 7.7 8.2 9.3 5.8 6.5 7.9 8.7 9.2 8.6 9.4 10.4 10.0 11.7 12.8 13.5
800
STATION – NORTH ASHLAND DIURNAL WIND SPEEDS (MPH) DATA PERIOD OF RECORD 6/2005 -
8.7
9.6 10.4 11.5 8.4 8.0 8.5 7.8 8.1 7.1 6.7 7.3 11.5
AVG SPD
Wind Resource Evaluation: North Ashland
22
NOTE:
N NNE NE ENE E ESE SE SSE S SSW SW WSW W WNW NW NNW CALM TOTAL %
DIR
2.1
0.0 0.0 0.0 0.0 0.1 0.8 0.8 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.2 0.2
16 TO 19
1.8
0.0 0.0 0.0 0.0 0.1 1.1 0.6 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
19 TO 22
1.5
0.0 0.0 0.0 0.0 0.1 0.8 0.5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
22 TO 25
1.4
0.0 0.0 0.0 0.0 0.1 1.0 0.3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
25 TO 28
1.3
0.0 0.0 0.0 0.0 0.1 1.0 0.2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
28 TO 31
0.7
0.0 0.0 0.0 0.0 0.0 0.6 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
31 TO 34
0.3
0.0 0.0 0.0 0.0 0.0 0.3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
34 TO 37
0.3
0.0 0.0 0.0 0.0 0.0 0.3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
37 TO 40
0.1
0.0 0.0 0.0 0.0 0.0 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
40 TO 43
0.1
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
43 TO 46
0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
46 TO 49
0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
49 TO 52
0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
52 TO 55
0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
>= 55
100.0
1.9 0.8 0.6 0.6 2.3 18.5 18.7 3.3 1.3 0.6 0.5 0.5 4.0 20.3 18.8 6.3 0.9
TOTAL %
8.7
3.8 3.0 3.5 3.1 7.6 13.0 9.5 6.9 4.6 4.3 4.3 4.1 6.6 7.6 8.2 8.3
MEAN SPEED (MPH)
MEAN SPEED OF THE TOTAL IN A WIND ROSE MAY DIFFER FROM THE SPEED FREQUENCY DISTRIBUTION FOR A GIVEN PERIOD DUE TO DATA SELECTION. SPEED FREQUENCY DISTRIBUTIONS REQUIRE ONLY A WIND SPEED OBSERVATION BE PRESENT. WIND ROSES, ON THE OTHER HAND, REQUIRE BOTH SPEED AND DIRECTION BE PRESENT FOR EACH OBSERVATION.
3.4
71.5 15.4
13 TO 16 0.0 0.0 0.0 0.0 0.0 0.4 1.0 0.1 0.0 0.0 0.0 0.0 0.0 0.2 0.8 0.8
10 TO 13
0.1 0.0 0.0 0.0 0.0 0.8 2.8 0.5 0.0 0.0 0.0 0.0 0.5 3.5 5.3 1.7
1.8 0.7 0.6 0.6 1.8 11.3 12.3 2.5 1.3 0.6 0.4 0.5 3.5 16.6 12.4 3.6
0 TO 10
SPEED CATEGORIES(MPH)
STATION - NORTH ASHLAND WIND ROSE FOR ALL DATA 8729 OBSERVATIONS DATA PERIOD OF RECORD - 6/2005 - 5/2006
Wind Resource Evaluation: North Ashland
23
0.3
46.2
634.9
103.9 77.6 144.2 36.3 9.9 14.5 3.0 3.4 2.8 5.1 51.7 182.4
ESE
205.0
28.6 53.1 30.0 7.1 9.6 3.9 1.9 2.3 4.1 8.1 9.4 46.9
SE
15.3
2.4 0.8 6.2 0.5 1.0 0.2 0.0 0.0 0.3 0.7 0.5 2.7
SSE
1.5
0.4 0.1 0.2 0.3 0.1 0.0 0.0 0.0 0.0 0.1 0.0 0.1
S
0.6
0.1 0.1 0.2 0.0 0.0 0.1 0.0 0.0 0.0 0.0 0.2 0.0
SSW
0.7
0.2 0.3 0.0 0.0 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.1
SW
0.4
0.1 0.0 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
WSW
8.8
0.4 0.3 1.0 0.9 1.1 0.5 0.4 0.5 1.1 1.5 0.6 0.4
W
56.2
2.3 4.8 3.2 3.7 6.8 5.9 6.3 6.5 6.2 4.6 3.0 2.8
WNW
72.6
2.7 3.2 3.3 5.6 7.7 12.9 12.7 12.7 4.8 2.7 2.5 1.8
NW
AVAILABLE ENERGY IN AN ENERGY ROSE MAY DIFFER FROM THE SPEED FREQUENCY DISTRIBUTION FOR A GIVEN PERIOD DUE TO DATA SELECTION. SPEED FREQUENCY DISTRIBUTIONS REQUIRE ONLY A WIND SPEED OBSERVATION BE PRESENT. ENERGY ROSES, ON THE OTHER HAND, REQUIRE BOTH SPEED AND DIRECTION BE PRESENT FOR EACH OBSERVATION.
0.5
1.4 3.1 31.1 1.4 0.6 0.0 0.0 0.0 0.0 0.1 0.0 8.4
E
NOTE:
0.3
0.0 0.0 0.1 0.0 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0
ENE
2.1
0.0 0.0 0.0 0.3 0.0 0.0 0.2 0.0 0.0 0.0 0.0 0.0
NE
TOT
0.0 0.0 0.0 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.1
NNE
0.8 0.2 0.0 0.2 0.3 0.0 0.0 0.0 0.0 0.2 0.0 0.1
N
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
MON NORM.
STATION – NORTH ASHLAND ENERGY ROSE (TOTALS ARE NORMALIZED AVAILABLE ENERGY (KWH/M**2) DATA PERIOD OF RECORD 6/2005 - 5/2006
31.9
2.4 0.8 1.7 3.8 3.9 4.8 4.3 4.1 1.8 0.6 1.9 1.8
NNW
1077.0
145.8 144.4 221.3 60.1 41.2 42.9 28.9 29.6 21.3 23.7 70.0 247.8
TOTAL
8645
731 668 739 716 739 716 737 738 715 736 712 698
OBS.
8760
744 672 744 720 744 720 744 744 720 744 720 744
Wind Resource Evaluation: North Ashland
24
0.8 0.9 1.6 1.9 1.9 0.6 0.5 0.5 0.7 1.3 1.0 0.6
1.5
2.0 2.4 3.0 6.7 3.8 1.0 1.3 2.0 1.4 2.0 1.9 2.9
3.8
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC TOTAL %
0.7 0.8
1.8 2.0
2005 2006
NNE
N
PERIOD
1.3
0.6 0.9 1.3 1.7 0.3 0.4 1.1 0.4 0.6 0.9 1.1 1.0
0.8 0.6
NE
1.4
0.7 0.6 1.9 2.5 1.6 0.4 0.3 0.4 1.0 0.4 0.8 0.6
0.5 0.7
ENE
4.9
2.6 4.2 10.8 4.4 5.9 1.0 1.2 0.9 1.7 2.7 2.6 3.9
2.0 2.6
E
37.3
18.9 35.4 47.6 41.9 32.0 17.2 18.3 19.5 19.3 15.7 13.6 22.9
18.1 18.9
ESE
37.5
19.2 60.4 41.4 30.3 25.3 9.0 10.3 12.2 20.0 22.2 24.6 25.1
17.6 19.2
SE
6.6
3.6 6.0 13.2 4.7 4.6 1.2 1.1 0.8 1.5 3.8 4.7 5.3
2.6 3.6
SSE
2.8
1.6 3.3 4.3 2.8 2.7 0.1 0.7 0.5 0.7 0.9 1.8 1.8
0.9 1.6
S
1.3
0.7 2.1 1.9 1.7 0.5 0.1 0.0 0.3 0.3 0.8 1.4 0.6
0.5 0.7
SSW
0.9
0.5 0.6 0.8 0.6 0.3 0.3 0.7 0.0 0.0 0.7 1.0 0.4
0.4 0.5
SW
1.1
0.6 1.5 1.6 0.3 1.1 0.3 0.3 0.3 0.6 0.4 1.0 0.4
0.5 0.6
WSW
DIRECTION CATEGORIES
DISTRIBUTIONS IN PERCENT
STATION – NORTH ASHLAND WIND DIRECTION FREQUENCY DISTRIBUTION DATA PERIOD OF RECORD 6/2005 - 5/2006
8.1
4.2 5.7 10.2 10.0 9.9 3.6 1.2 1.5 5.1 6.9 5.1 2.5
3.7 4.2
W
40.9
19.9 39.6 27.7 37.8 48.7 24.3 22.2 21.4 23.5 26.6 19.7 15.0
21.9 19.9
WNW
37.7
17.9 28.0 22.6 37.2 46.5 29.9 33.2 32.3 19.0 10.1 13.7 10.1
21.2 17.9
NW
12.7
6.2 8.6 10.2 15.6 15.1 10.6 7.7 7.0 4.7 4.6 5.8 6.9
6.7 6.2
NNW
0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.0 0.0 0.0 0.1 0.1
0.1 0.0
CALM
8729
744 672 744 720 744 720 744 744 720 744 720 713
5105 12353
TOTAL OBS
Wind Resource Evaluation: North Ashland
Prepared By:
Energy Resources Research laboratory Oregon State University
August 31, 2006
NOTICE This publication was prepared as an account of work sponsored by the Energy Trust of Oregon, Inc. Neither the Energy Trust of Oregon, Inc. nor any of their contractors, subcontractors, or their employees make any warranty, express or implied, or assume any legal liability or responsibility for the accuracy, completeness, usefulness, or reliability of the research data, and conclusions reported herein, or of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. For these reasons and for the reason that the views, opinions, and conclusions contained in this material are those of the contractor.
Wind Resource Evaluation: North Ashland
ii
OREGON ANEMOMETER LOAN PROGRAM
Wind Resource Evaluation: North Ashland
Prepared by: Philip L. Barbour Stel N. Walker, Ph.D. Energy Resources Research Laboratory Department of Mechanical Engineering Oregon State University Corvallis, OR 97331
Sponsor: Energy Trust of Oregon, Inc. 733 SW Oak Street, Suite 200 Portland Oregon,97205
Wind Resource Evaluation: North Ashland
iii
1.0
INTRODUCTION
The Oregon anemometer loan program was established in the fall of 2002 in order to assist landowners in the state evaluate the wind energy potential of their property. The program is funded by a grant from the Energy Trust of Oregon and is administered by the Energy Resources Research Laboratory at Oregon State University. The program involves several steps, beginning with a preliminary evaluation of the site. If estimates of the site show promise then a monitoring system is installed for a fixed duration (typically on year). The site is monitored regularly and the data processed and checked at regular intervals. Upon completion of the first year, the collected wind data is summarized and a report is prepared evaluating the wind data and the wind resource of the location. This report represents the final portion of the project and is designed to give the landowner the information necessary to make an informed choice about the role wind energy might play in their property. The report is separated in to sections with section 2.0 devoted to a description of the site, its location and the type of terrain found there. Section 3.0 includes a summary of the wind data collected during the study period including data quality checks and a characterization of the measured winds. In section 4.0 the wind data is analyzed to determine the amount of power production that might be expected from the site and to examine characteristics that might influence these estimates. This is followed in section 5.0 in which wind data from a nearby site is summarized and used to place the current study period in climatological context. A discussion and summary is then presented in section 6.0
Wind Resource Evaluation: North Ashland
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2.0
SITE DESCRIPTION Site Name: Latitude: Longitude: Elevation: County: Sensor Height: Types of Sensors: Types of Data: Installation Date: Removal Date:
North Ashland 42-13-49 122-44-18 1760 ft. Jackson 67 ft. NRG Maximum #40 wind speed NRG 200 series2 wind vane 10 min. average wind speed (mph) 10 min. std. dev. wind speed (mph) 10 min. wind direction (16 categories) May 24, 2005 @ 1550 PST June 19, 2006 @ 1400 PST
Site Location: Ashland is located in southwestern Oregon along the I-5 corridor. The city sites at the base of a broad valley boarderd by the foothills of the Cascades on the east and the Siskiyou Mountains to the west. The valley extends from Medford southeast towards Ashland. The current site is located just north of the city of Ashland on a small rise. Access to the site is found by turning east off of I-5 at exit 19 and turning southeast on East Ashland Lane. The site was located near the top of the small hill located just to the east. The area is primarily grass land with a few small trees. The tower location is marked on the map included in Appendix A. Pictures of the tower and the local terrain have been included in Appendix B. Project Description: The owner of the site is interested in evaluating the site for possible installation of a small wind turbine for home use. There has been a lot of interest in home wind systems from this area and this site was selected over other sites because it was the site of previous monitoring from 1979 through 1980. That monitoring indicated the site had an annual mean of 8.3 mph at 35 meters. Properties in the area consists of several acres and have room to be equipped with small turbines.
Wind Resource Evaluation: North Ashland
2
3.0
WIND CHARACTERISTICS
In the following sections, several characteristics of the winds at the North Ashland site are examined and discussed. The goals are to evaluate the characteristics that can help explain the physical processes at work at the site and to highlight the properties that are important to assessing the wind energy potential. These evaluations are done using hourly averaged means that have been constructed using the 10 minute means recorded at the site. This is done so that existing analysis programs can be used and is not expected to have any appreciable influence on the interpretation of data. Data Recovery: The amount of data recovered during an observation period is important to characterize and should be examined to determine the confidence of other characteristics. During the initial annual period at this site, there were no problems detected that might influence the collected wind data. A table of site visits and the actions taken has been included in Appendix A. Data were plotted and scanned manually to identify any problems with the site. For the most part, data collection from the site was complete and there were no periods of missing data. Data for several periods were removed from the records because the effects of icing were detected. This was only done for periods with a clear presence of icing and it is possible that other periods with a more limited influence occurred. Icing is identified as prolonged periods with a wind speed of 0.0 mph and a constant direction. For the North Ashland site icing was confined to the month of December.
Data Recovery
Recovery Rate (%)
100 80 60 40 20 0 Jun
Jul
Aug
Sep
Oct
Nov Dec
Jan
Feb
Mar
Apr
May Ann.
Figure 3.1: Data recovery by month for the North Ashland site.
Wind Resource Evaluation: North Ashland
3
Month
Jun
Rec. (%)
Jul
100
Aug
100
Sep
100
Oct
96.77
Nov
100
Dec
100
Jan
95.8
Feb
100
Mar
100
Apr
100
May
100
100
Ann
99.7
Monthly Means: Monthly means are often constructed and used to determine the overall strength of the winds during different periods of the year. Monthly means show that the North Ashland site has slightly higher winds during the winter months but no period of sustained strong winds. All of the months over which the sensor was in place had winds below 12.0 mph. December, February and March were the only months with winds above 10.0 mph. This suggests that even during high wind periods this site has a fairly low wind resource.
Monthly Means 14 12
(mph)
10 8 6 4 2 0 Jun
Jul
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Ann
Figure 3.2: Monthly Mean Wind Speed Values for the North Ashland site. Month Mean (mph)
Jun 8.5
Jul 7.8
Aug 8.1
Sep 7.1
Oct 6.7
Nov 7.3
Dec 11.5
Jan 9.6
Feb 10.4
Mar 11.5
Apr 8.4
May
Ann
8.0
8.7
Diurnal Means: The diurnal pattern of winds is an important characteristic for many wind sites and helps illuminate the mechanisms responsible for the winds. In general, a diurnal pattern is associated with a site at which strong thermal influences play a role. These are normally accentuated during the summer months when the daily heating cycle is at its greatest. Diurnal variations can also provide an indication of dependable and predictable winds at a site.
Wind Resource Evaluation: North Ashland
4
As is common for many sites in Oregon, the winds at the North Ashland site show a clear diurnal pattern is present during the summer months and is strong enough to show up in the mean for the annual diurnal average (Fig. 3.3). In general, the diurnal values for summer show that the winds are very light through the night and morning hours and begin to pick up around noon. The magnitude of the winds build until around 1700-1800 and taper off slowly. On average, the winds during these days are in a usable range for about 28% of the time. The winds during these periods are predominantly from the north and are a response to large-scale heating patterns. During the winter months there is a little indication of a diurnal variation but at best it is fairly weak Diurnal Mean Winds 14 Wind Speed (mph)
12 10 AVE Jan
8 6
Jul
4 2 0 1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Hour of Day
Figure 3.3: Diurnal mean wind speed values for the North Ashland site.
Frequency Distribution: How the wind speed at a site is distributed over various wind speed categories is an important indication of the wind resource potential of a site. An ideal site would have winds that blow at a high rate for long periods. This is not normally the case, however, and wind records from a site show a skewed distribution with a higher frequency of winds at lower speeds. For the North Ashland site (Figure 3.4) we see that the distribution is fairly typical with a low frequency of winds at the lowest range, a peak centered between 5.0 to 7.0 mph and a trailing tail at the upper end. In this case the peak is relatively narrow with a single peak that drops off fairly rapidly. This peak would likely be smoother with additional data. The importance of this figure is that it illustrates the amount of time that the winds are within various energy resource ranges. For example, the winds at the North Ashland site are at or above 12.0 mph only about 18 % of the time. This suggests that it would be possible to produce appreciable amounts of energy at the site less than 20 % of the time. In addition, the winds are above 20.0 mph only about 7.0% of the time (the range at which most wind turbines produce their peak amount of power). This suggests that a typical wind turbine would produce optimal output only about 7.0 % of the time. This is Wind Resource Evaluation: North Ashland
5
relatively low for a good wind site and suggests that there is a low frequency of winds at the upper end of the range. This is significant because it is at higher wind speeds where most of the potential power is produced.
Frequency (%)
Relative Frequency 10 9 8 7 6 5 4 3 2 1 0 0
5
10
15
20
25
30
35
40
45
Wind Speed Category Figure 3.4: Wind speed frequency distribution for the North Ashland site.
Wind Rose: How the wind varies with direction is also important to understanding the physical processes that contribute to the local winds at a site and eventually in designing a wind facility. A wind rose is often used to display this information and show the frequency with which the wind occurs in different direction categories. A similar plot can be used to show the strength of the wind from each of the direction categories. For this site (Figure 3.5) it is apparent that the winds come from two main directions, the Southeast and the Northwest. This is basically the orientation of the valley and is not surprising. Viewing the second figure we see that the mean wind speeds for the Southwesterly directions are much higher than for the northerly directions. This is often the case at sites in the Northwest where southerly winds associated with strong storm systems during the winter months produce much of the observed wind. The higher wind speed averages for the southerly directions suggest that this is the direction from which a majority of the energy producing winds will come from.
Wind Resource Evaluation: North Ashland
6
Annual Directional Frequency
Annual Directional Speed 14
Mean Speed (mph)
Frequency (%)
25 20 15 10 5 0
12 10 8 6 4 2 0
N
NE
E
SE
S
SW
W
NW
N
CALM
NE
E
Direction Category
SE
S
SW
W
NW
Direction Category
Figure 3.5: Frequency (%) and average wind speed (mph) for each of 16 wind direction categories
In order to better understand the winds at the site during different times of year; similar plots have been constructed using data from the individual months of January and July. These can be seen in figures 3.6a-d and show the difference between the two periods. JANUARY
JANUARY 25
Mean Speed (mph)
Frequency (%)
30 25 20 15 10 5 0
20 15 10 5 0
N
NE
E
SE
S
SW
W
NW
N
CALM
NE
E
Direction Category
JULY
S
SW
W
NW
W
NW
JULY
35
12
30
10
Mean Speed (mph)
Frequency (%)
SE
Direction Category
25 20 15 10 5
8 6 4 2 0
0 N
NE
E
SE
S
SW
W
NW
CALM
Direction Category
N
NE
E
SE
S
SW
Direction Category
Figure 3.6: Frequency (%) and average wind speed (mph) for each of 16 wind direction categories for the months of January and July for the North Ashland site.
Wind Resource Evaluation: North Ashland
7
4.0
SITE POWER CHARACTERISTICS
In order to evaluate the wind power potential at this site a number of quantities were computed using the collected wind data. As with the wind characteristics, hourly wind data was used to complete this work. The power density calculation requires air density. This is estimated assuming a standard atmosphere and the site elevation. The computed quantities include the mean and standard deviation of the hourly values, the recovery rate, the maximum one hour average, the wind power density and the frequency that the wind was observed within a wind speed range (12 mph to 60 mph). These quantities are shown in Table 4.1 and reveal a number of things about the potential for generating energy the site. The quantities in Table 4.1 show the wind resource in this area is limited to a few months during the winter. All of the months from April through November have low mean wind speeds, low percentages of time within a general turbine operating range and low power density values. The lowest is September in which a turbine would operate less than 3% of the time. The winter months are somewhat better with power density values above 100 W/m**2 for December through March. However, values for this month are relatively low compared to other, good wind sites. Wind power density represents the amount of energy that would be available to a unit area each hour. The monthly mean values are shown in Figure 4.1 and highlight the low values through much of the year. The reason for this is that strong winds are seldom observed at this site. The area does get a fairly steady and regular afternoon wind over the summer months but it is not strong enough to provide a significant amount of power. This is highlited further by the maximum one hour values in Table 4.1 that are below 20.0 mph for the months of July through September.
Wind Resource Evaluation: North Ashland
8
Table 4.1: Observed and computed power quantities for the wind site at the North Ashland site.
Month
Mean
Std.
Recovery
Max 1Hr
Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May ANN
(mph) 8.5 7.8 8.1 7.1 6.7 7.3 11.5 9.6 10.4 11.5 8.4 8.0 8.7
(mph) 4.24 3.36 3.16 3.06 3.63 6.35 10.12 8.26 8.21 9.50 5.57 4.33 6.49
Rate (%) 100.0 100.0 100.0 100.0 100.0 100.0 95.8 100.0 100.0 100.0 100.0 100.0 99.7
(mph) 28.1 17.5 14.8 16.5 23.4 39.3 45.3 39.5 44.1 46.7 30.9 27.8 46.7
Wind Resource Evaluation: North Ashland
Time in Range (12-60) mph (%) 15.3 8.7 7.8 2.5 5.1 11.0 31.8 25.4 25.0 32.0 16.8 11.7 16.0
Power Den.
Shape
Scale
W/m^2 59 38 39 29 31 96 326 191 213 294 83 55 120
Factor 2.13 2.51 2.77 2.51 1.94 1.16 1.14 1.18 1.29 1.23 1.55 1.96 1.38
Factor 9.6 8.8 9.1 8.1 7.5 7.7 12.0 10.2 11.2 12.3 9.3 9.1 9.5
9
Power Density
Power Density (W/m**2)
350 300 250 200 150 100 50 0 Jun
Jul
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Ann
Figure 4.1: Monthly power density for the North Ashland site.
In addition to evaluating these basic power characteristics it is possible to estimate how specific wind turbines might interact with the winds at a particular site. Using the collected wind data and the characteristics of a particular wind turbine it is possible to estimate the amount of power it could produce. This is done by comparing the wind data with a power curve for a specific wind turbine. A power curve is simply the curve that shows the relationship between the wind speed and the amount of power a turbine can produce. An example is provided in Figure 4.2. There are several portions of the curve that are important. At low wind speeds, below the cut-in speed, no energy is produced. Any turbine has a lower threshold below which it won’t operate. This is in part because there is little energy available at these levels. In the middle is a ramp up zone where even a small increase in wind speed results in a larger increase in power. At some point, depending on the type of turbine, the amount of power hits its rated capacity as the blades are pitched to spill energy and protect the turbine. At the upper end, energy production will stop if the winds reach a cut-out speed. This is the speed at which a turbine is shut down. In Table 4.2, energy capacity factors are shown for eight different types of turbines. The capacity factor is the ratio of the amount of energy produce to the amount of energy that could be produced if a turbine ran at its rated capacity all the time. The rated capacity is effectively a theoretical maximum and capacity factors generally range from 0.0 to 0.40. It’s difficult to compare these because of the different turbine characteristics but they are given to provide a range of values that might be expected from this site. In computing these values, it is necessary to adjust the observed data which is measured at 67 feet to
Wind Resource Evaluation: North Ashland
10
the hub height of the particular turbine. In this case this is done using a standard assumption that the wind follows a typical power law profile with a coefficient of 0.143. 120
Power Output (% of Rated)
100
80
60
40
20
0 0
10
20
30
40
50
Wind Speed (mph)
Figure 4.1: Sample power curve for a theoretical turbine
The capacity factors in Table 4.2 support the conclusions of the previous sections and indicate that there appears to be little wind energy potential at this site. Even during the highest wind months of December and February capacity factors for the most efficient wind turbines were on the order of 0.25. During the low wind speed months (August through October) the capacity values vary but are generally well below 0.10. During these months a turbine at this particular site could capture less than 5% of what it might under perfect ideal conditions. For some turbines the values are as low as 1.6 % (Sep. with BWC EXCEL). Overall these values indicate little wind power would be available from this site during much of the year.
Wind Resource Evaluation: North Ashland
11
Table 4.2: Capacity factors computed for the North Ashland site using observed wind data and characteristics of eight different wind turbines.
Turbine Size (kW) Hub Ht. (ft.) Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May ANN
Vestas 47 660 131 0.071 0.042 0.042 0.027 0.032 0.078 0.230 0.159 0.161 0.219 0.094 0.063 0.101
Vestas 80 2000 262 0.093 0.060 0.061 0.042 0.045 0.090 0.253 0.180 0.183 0.244 0.114 0.082 0.120
Vestas 66 1650 197 0.062 0.036 0.036 0.023 0.028 0.073 0.216 0.148 0.151 0.207 0.083 0.055 0.093
Wind Resource Evaluation: North Ashland
Vestas 7.5 55 59 0.055 0.029 0.029 0.019 0.024 0.071 0.215 0.146 0.148 0.205 0.078 0.049 0.089
BWC EXCEL-S 10 79 0.041 0.023 0.024 0.016 0.019 0.060 0.181 0.121 0.125 0.173 0.059 0.037 0.073
GE Wind 70.5 1500 210 0.085 0.052 0.055 0.036 0.041 0.088 0.253 0.178 0.180 0.243 0.109 0.076 0.116
Vestas 29 225 103 0.077 0.049 0.050 0.033 0.037 0.083 0.237 0.165 0.169 0.227 0.099 0.069 0.107
Mitsubishi 250 100 0.052 0.031 0.031 0.020 0.023 0.068 0.201 0.136 0.141 0.194 0.072 0.046 0.084
12
5.0 CLIMATOLOGICAL ANALYSIS Measurements taken over a single one-year period can provide a good estimation of the winds and wind energy potential of a site. However, this is a fairly limited period and is only meaningful if we can place the period into a larger climatological context. For the Ashland monthly mean wind speed values from the Sexton Summit site used for this purpose. While not ideal, wind records from Sexton Summit should show the general climatological significance of this particular observation period. To accomplish this, monthly mean wind speed values and climate normals were obtained from the National Climate Data Center (NCDC). Information about the site and the monthly means and departures for this annual study period can be found in Table 5.1. First, the winds overall were similar to those observed at the North Ashland site for this study period. Sexton Summit had an overall mean of 9.3 mph while the North Ashland site had a mean of 8.7 mph. Much of this difference is likely due to the elevation difference between the sites. Table 5.1 shows that for the first seven months of this study period the winds were slightly below normal at Sexton Summit. Overall, the winds were very close to normal (3.5 %). The highest departures and therefore the highest variability appear to happen during the winter months when changes can occur from month to month. Overall it appears that conditions during this observation period at the North Ashland site were close to normal. Several individual months had departures greater than 10% but over the year these tended to average out.
Wind Resource Evaluation: North Ashland
13
Table 5.1: Monthly mean and departures for winds at Sexton Summit. SEXTON SUMMIT NWS Latitude: 42.60N
Elevation: 3832'
Longitude 123.37W Month
Normal (mph)
Mean (mph)
Departure
1982-1997
2005-2006
(%)
Jun
8.7
8.1
-6.9
Jul
9.0
8.4
-6.7
Aug
8.6
8.3
-3.5
Sep
8.6
7.8
-9.3
Oct
9.1
8.2
-9.9
Nov
10.8
9.9
-8.3
Dec
11.6
13.2
13.8
Jan
11.7
13.0
11.1
Feb
10.9
9.3
-14.7
Mar
9.9
9.9
0.0
Apr
8.1
8.2
1.2
May
8.8
7.5
-14.8
ANN
9.7
9.3
-3.5
Wind Resource Evaluation: North Ashland
14
6.0 SUMMARY AND DISCUSSION There are a number of factors that might have an influence on the interpretation of the winds observed over this annual study period in the Ashland area. First, measurements were taken from only one tower and it is possible that other locations might provide better exposure to the prevailing winds. The location of the tower was dictated in part by the constraints of the property boundaries and the terrain. Although care was taken to locate a location with good exposure to all directions, some blocking of the winds from the north is possible. While this is not expected to be a significant factor, the regular winds do come from this direction in the summer. In any case, the site is ideally situated to capture the flows from the southerly direction. A second factor that is important to consider is that observations were collected at only one height. Flow over hills and ridgelines can be very complex and difficult to estimate. These types of flows are influenced by many factors including the density of the air, the exact shape of the mountain and the upper air wind characteristics. Observations taken at a different height above ground would most likely show some differences that might be important to a determination of economic feasibility. In summary, 1) 2)
3) 4)
No problems were encountered during the annual data collection period. One period of icing was detected in December and removed from the records. The observed annual mean wind speed was 8.7 mph. The Ashland area appears to have weak but identifiable seasonal pattern, Winds during the winter can produce periods of adequate resource. During the summer there is a strong diurnal pattern but the peak winds during these periods can be fairly low for long periods. A comparison with a nearby site where a longer history of observations are available suggests that this study period (June 2005-May 2006) was very close to the 16 year normal (1982-1997) During all seasons, the winds come from a direction that is nearly parallel to the Valley
Wind Resource Evaluation: North Ashland
15
Appendix A: Topographic Map of the North Ashland site.
Wind Resource Evaluation: North Ashland
16
Appendix B: Photograph of the North Ashland site tower looking southeast.
Wind Resource Evaluation: North Ashland
17
Appendix C: Site Visit Records and wind gust during period prior to visit. Changes Made Date: 5/24/2005 7/08/2005 8/13/2005 9/08/2005 10/05/2005 11/18/2005 12/10/2005 1/17/2006 2/09/2006 2/26/2006 4/13/2006 5/14/2006 6/19/2006
Plug Y Y Y Y Y Y Y Y Y Y Y
Battery
Time
Y Y Y Y
Y
Gust (mph) 40 28 26 29 44 56 62 56 50 65 38 44
Wind Resource Evaluation: North Ashland
Comment Site Installed
Site Removed
18
Appendix D: Miscellaneous analysis Tables.
STATION – NORTH ASHLAND WIND SPEED FREQUENCY DISTRIBUTION WITH NORMALIZED AVAILABLE ENERGY DATA PERIOD OF RECORD 6/2005 - 5/2006 NORMALIZATION PERIOD - ONE YEAR AVERAGE WIND SPEED FOR PERIOD: 8.7 MPH NORMALIZED AVAILABLE ENERGY: 1058.1 KWH/M**2/YEAR TOTAL HOURS OBSERVED: 8729 SPD MPH 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47
HOURS/ PERIOD 77 308 492 535 647 722 761 769 777 762 724 554 356 180 114 69 74 59 63 50 65 51 36 50 36 43 41 35 54 33 38 29 19 17 21 9 10 11 10 6 8 3 3 2 3 1 1 1
RELFREQ 0.88 3.53 5.64 6.13 7.41 8.27 8.72 8.81 8.90 8.73 8.29 6.35 4.08 2.06 1.31 0.79 0.85 0.68 0.72 0.57 0.74 0.58 0.41 0.57 0.41 0.49 0.47 0.40 0.62 0.38 0.44 0.33 0.22 0.19 0.24 0.10 0.11 0.13 0.11 0.07 0.09 0.03 0.03 0.02 0.03 0.01 0.01 0.01
CUMHRS 8729 8652 8344 7852 7317 6670 5948 5187 4418 3641 2879 2155 1601 1245 1065 951 882 808 749 686 636 571 520 484 434 398 355 314 279 225 192 154 125 106 89 68 59 49 38 28 22 14 11 8 6 3 2 1
CUMRELFREQ 100.00 99.12 95.59 89.95 83.82 76.41 68.14 59.42 50.61 41.71 32.98 24.69 18.34 14.26 12.20 10.89 10.10 9.26 8.58 7.86 7.29 6.54 5.96 5.54 4.97 4.56 4.07 3.60 3.20 2.58 2.20 1.76 1.43 1.21 1.02 0.78 0.68 0.56 0.44 0.32 0.25 0.16 0.13 0.09 0.07 0.03 0.02 0.01
Wind Resource Evaluation: North Ashland
NORMALIZED AVAIL. ENERGY KWH/M**2/YEAR 0.0 0.0 0.2 0.8 2.2 4.7 8.6 13.7 20.7 28.9 37.7 38.4 32.0 20.6 16.3 12.1 15.8 15.1 19.1 17.9 27.1 24.6 20.0 31.7 25.9 35.0 37.5 35.9 61.7 41.9 53.4 45.0 32.4 31.8 43.0 20.1 24.3 29.0 28.6 18.5 26.7 10.8 11.6 8.3 13.3 4.7 5.1 5.4
19
STATION – NORTH ASHLAND MONTHLY WIND SPEEDS (MPH) DATA PERIOD OF RECORD 6/2005 -
5/2006
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
NOV
DEC
2005 # OBS
0.0 0
0.0 0
0.0 0
0.0 0
0.0 0
8.5 720
7.8 744
8.1 744
7.1 720
6.7 744
7.3 720
11.5 713
2006 # OBS
9.6 744
10.4 672
11.5 744
8.4 720
8.0 744
0.0 0
0.0 0
0.0 0
0.0 0
0.0 0
0.0 0
0.0 0
Wind Resource Evaluation: North Ashland
20
Wind Resource Evaluation: North Ashland
21
AVG SPD
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
MON
200
300
400
500
8.0
7.8
7.4
7.1
6.8
9.2 10.0 10.1 9.4 9.7 9.7 9.0 8.8 8.4 8.0 9.0 8.2 8.5 8.5 8.8 6.2 6.0 6.1 7.2 6.4 8.1 6.8 5.9 5.5 5.1 6.8 6.2 6.2 5.9 5.9 7.0 6.7 6.4 6.0 5.6 8.2 8.3 7.8 7.0 6.1 7.6 7.2 6.6 5.1 5.2 5.9 6.5 5.4 5.0 5.3 7.2 6.8 5.5 6.2 6.2 11.7 11.6 11.1 10.8 10.0
100
700
6.4
5.9
9.4 8.7 8.9 8.4 8.3 9.3 5.5 5.2 4.6 4.8 5.7 5.3 4.0 2.3 4.1 2.3 5.9 4.0 5.2 4.8 5.6 5.6 9.8 10.1
600
6.6
7.9
8.9
10.2 12.6 15.2 11.2 10.9 11.4 11.5 11.2 9.9 8.3 8.5 12.1
9.7 12.2 15.0 11.1 11.3 10.5 11.7 11.2 9.4 7.7 6.6 11.5
8.8 11.1 15.2 10.6 11.6 11.2 11.9 11.2 8.4 6.1 7.0 11.9
8.4 9.8 14.1 9.7 10.5 11.5 11.3 10.9 6.5 7.0 7.3 12.8
9.9 10.7 11.2 11.2 11.1 10.6 10.4 10.0
11.0 13.3 13.9 11.1 10.9 11.8 11.3 11.0 9.8 9.1 9.0 12.9 9.7
9.5 10.9 13.2 8.5 8.6 10.3 9.7 9.5 7.4 8.4 7.6 12.6
9.3
10.8 11.6 11.8 7.5 7.7 9.3 8.4 8.4 7.1 8.7 7.8 12.9
8.5
7.9
7.9
8.0
10.9 9.8 8.6 8.8 11.7 11.7 10.8 8.8 11.3 10.9 10.8 9.9 6.6 7.0 8.0 7.1 7.1 6.7 7.7 8.1 8.4 6.9 5.9 6.6 7.1 5.2 5.2 6.9 6.1 4.5 6.6 7.6 6.3 5.7 6.8 8.0 7.7 7.4 6.0 6.1 7.6 8.0 7.6 7.9 11.9 11.4 11.5 10.5
900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 2400
5/2006
8.8 7.9 9.0 9.8 10.6 11.8 8.0 8.4 9.9 11.1 12.7 13.1 9.7 11.0 12.5 12.7 14.0 13.8 6.9 8.8 10.6 11.2 10.9 11.2 6.3 7.8 8.3 8.9 9.0 10.3 7.3 8.3 9.2 10.1 11.4 11.9 4.6 7.2 8.4 9.1 9.9 10.7 4.6 7.3 8.6 9.6 10.7 11.0 4.1 5.7 7.2 8.4 9.4 9.7 3.7 5.1 5.9 7.7 8.2 9.3 5.8 6.5 7.9 8.7 9.2 8.6 9.4 10.4 10.0 11.7 12.8 13.5
800
STATION – NORTH ASHLAND DIURNAL WIND SPEEDS (MPH) DATA PERIOD OF RECORD 6/2005 -
8.7
9.6 10.4 11.5 8.4 8.0 8.5 7.8 8.1 7.1 6.7 7.3 11.5
AVG SPD
Wind Resource Evaluation: North Ashland
22
NOTE:
N NNE NE ENE E ESE SE SSE S SSW SW WSW W WNW NW NNW CALM TOTAL %
DIR
2.1
0.0 0.0 0.0 0.0 0.1 0.8 0.8 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.2 0.2
16 TO 19
1.8
0.0 0.0 0.0 0.0 0.1 1.1 0.6 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
19 TO 22
1.5
0.0 0.0 0.0 0.0 0.1 0.8 0.5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
22 TO 25
1.4
0.0 0.0 0.0 0.0 0.1 1.0 0.3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
25 TO 28
1.3
0.0 0.0 0.0 0.0 0.1 1.0 0.2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
28 TO 31
0.7
0.0 0.0 0.0 0.0 0.0 0.6 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
31 TO 34
0.3
0.0 0.0 0.0 0.0 0.0 0.3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
34 TO 37
0.3
0.0 0.0 0.0 0.0 0.0 0.3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
37 TO 40
0.1
0.0 0.0 0.0 0.0 0.0 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
40 TO 43
0.1
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
43 TO 46
0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
46 TO 49
0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
49 TO 52
0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
52 TO 55
0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
>= 55
100.0
1.9 0.8 0.6 0.6 2.3 18.5 18.7 3.3 1.3 0.6 0.5 0.5 4.0 20.3 18.8 6.3 0.9
TOTAL %
8.7
3.8 3.0 3.5 3.1 7.6 13.0 9.5 6.9 4.6 4.3 4.3 4.1 6.6 7.6 8.2 8.3
MEAN SPEED (MPH)
MEAN SPEED OF THE TOTAL IN A WIND ROSE MAY DIFFER FROM THE SPEED FREQUENCY DISTRIBUTION FOR A GIVEN PERIOD DUE TO DATA SELECTION. SPEED FREQUENCY DISTRIBUTIONS REQUIRE ONLY A WIND SPEED OBSERVATION BE PRESENT. WIND ROSES, ON THE OTHER HAND, REQUIRE BOTH SPEED AND DIRECTION BE PRESENT FOR EACH OBSERVATION.
3.4
71.5 15.4
13 TO 16 0.0 0.0 0.0 0.0 0.0 0.4 1.0 0.1 0.0 0.0 0.0 0.0 0.0 0.2 0.8 0.8
10 TO 13
0.1 0.0 0.0 0.0 0.0 0.8 2.8 0.5 0.0 0.0 0.0 0.0 0.5 3.5 5.3 1.7
1.8 0.7 0.6 0.6 1.8 11.3 12.3 2.5 1.3 0.6 0.4 0.5 3.5 16.6 12.4 3.6
0 TO 10
SPEED CATEGORIES(MPH)
STATION - NORTH ASHLAND WIND ROSE FOR ALL DATA 8729 OBSERVATIONS DATA PERIOD OF RECORD - 6/2005 - 5/2006
Wind Resource Evaluation: North Ashland
23
0.3
46.2
634.9
103.9 77.6 144.2 36.3 9.9 14.5 3.0 3.4 2.8 5.1 51.7 182.4
ESE
205.0
28.6 53.1 30.0 7.1 9.6 3.9 1.9 2.3 4.1 8.1 9.4 46.9
SE
15.3
2.4 0.8 6.2 0.5 1.0 0.2 0.0 0.0 0.3 0.7 0.5 2.7
SSE
1.5
0.4 0.1 0.2 0.3 0.1 0.0 0.0 0.0 0.0 0.1 0.0 0.1
S
0.6
0.1 0.1 0.2 0.0 0.0 0.1 0.0 0.0 0.0 0.0 0.2 0.0
SSW
0.7
0.2 0.3 0.0 0.0 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.1
SW
0.4
0.1 0.0 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
WSW
8.8
0.4 0.3 1.0 0.9 1.1 0.5 0.4 0.5 1.1 1.5 0.6 0.4
W
56.2
2.3 4.8 3.2 3.7 6.8 5.9 6.3 6.5 6.2 4.6 3.0 2.8
WNW
72.6
2.7 3.2 3.3 5.6 7.7 12.9 12.7 12.7 4.8 2.7 2.5 1.8
NW
AVAILABLE ENERGY IN AN ENERGY ROSE MAY DIFFER FROM THE SPEED FREQUENCY DISTRIBUTION FOR A GIVEN PERIOD DUE TO DATA SELECTION. SPEED FREQUENCY DISTRIBUTIONS REQUIRE ONLY A WIND SPEED OBSERVATION BE PRESENT. ENERGY ROSES, ON THE OTHER HAND, REQUIRE BOTH SPEED AND DIRECTION BE PRESENT FOR EACH OBSERVATION.
0.5
1.4 3.1 31.1 1.4 0.6 0.0 0.0 0.0 0.0 0.1 0.0 8.4
E
NOTE:
0.3
0.0 0.0 0.1 0.0 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0
ENE
2.1
0.0 0.0 0.0 0.3 0.0 0.0 0.2 0.0 0.0 0.0 0.0 0.0
NE
TOT
0.0 0.0 0.0 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.1
NNE
0.8 0.2 0.0 0.2 0.3 0.0 0.0 0.0 0.0 0.2 0.0 0.1
N
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
MON NORM.
STATION – NORTH ASHLAND ENERGY ROSE (TOTALS ARE NORMALIZED AVAILABLE ENERGY (KWH/M**2) DATA PERIOD OF RECORD 6/2005 - 5/2006
31.9
2.4 0.8 1.7 3.8 3.9 4.8 4.3 4.1 1.8 0.6 1.9 1.8
NNW
1077.0
145.8 144.4 221.3 60.1 41.2 42.9 28.9 29.6 21.3 23.7 70.0 247.8
TOTAL
8645
731 668 739 716 739 716 737 738 715 736 712 698
OBS.
8760
744 672 744 720 744 720 744 744 720 744 720 744
Wind Resource Evaluation: North Ashland
24
0.8 0.9 1.6 1.9 1.9 0.6 0.5 0.5 0.7 1.3 1.0 0.6
1.5
2.0 2.4 3.0 6.7 3.8 1.0 1.3 2.0 1.4 2.0 1.9 2.9
3.8
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC TOTAL %
0.7 0.8
1.8 2.0
2005 2006
NNE
N
PERIOD
1.3
0.6 0.9 1.3 1.7 0.3 0.4 1.1 0.4 0.6 0.9 1.1 1.0
0.8 0.6
NE
1.4
0.7 0.6 1.9 2.5 1.6 0.4 0.3 0.4 1.0 0.4 0.8 0.6
0.5 0.7
ENE
4.9
2.6 4.2 10.8 4.4 5.9 1.0 1.2 0.9 1.7 2.7 2.6 3.9
2.0 2.6
E
37.3
18.9 35.4 47.6 41.9 32.0 17.2 18.3 19.5 19.3 15.7 13.6 22.9
18.1 18.9
ESE
37.5
19.2 60.4 41.4 30.3 25.3 9.0 10.3 12.2 20.0 22.2 24.6 25.1
17.6 19.2
SE
6.6
3.6 6.0 13.2 4.7 4.6 1.2 1.1 0.8 1.5 3.8 4.7 5.3
2.6 3.6
SSE
2.8
1.6 3.3 4.3 2.8 2.7 0.1 0.7 0.5 0.7 0.9 1.8 1.8
0.9 1.6
S
1.3
0.7 2.1 1.9 1.7 0.5 0.1 0.0 0.3 0.3 0.8 1.4 0.6
0.5 0.7
SSW
0.9
0.5 0.6 0.8 0.6 0.3 0.3 0.7 0.0 0.0 0.7 1.0 0.4
0.4 0.5
SW
1.1
0.6 1.5 1.6 0.3 1.1 0.3 0.3 0.3 0.6 0.4 1.0 0.4
0.5 0.6
WSW
DIRECTION CATEGORIES
DISTRIBUTIONS IN PERCENT
STATION – NORTH ASHLAND WIND DIRECTION FREQUENCY DISTRIBUTION DATA PERIOD OF RECORD 6/2005 - 5/2006
8.1
4.2 5.7 10.2 10.0 9.9 3.6 1.2 1.5 5.1 6.9 5.1 2.5
3.7 4.2
W
40.9
19.9 39.6 27.7 37.8 48.7 24.3 22.2 21.4 23.5 26.6 19.7 15.0
21.9 19.9
WNW
37.7
17.9 28.0 22.6 37.2 46.5 29.9 33.2 32.3 19.0 10.1 13.7 10.1
21.2 17.9
NW
12.7
6.2 8.6 10.2 15.6 15.1 10.6 7.7 7.0 4.7 4.6 5.8 6.9
6.7 6.2
NNW
0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.0 0.0 0.0 0.1 0.1
0.1 0.0
CALM
8729
744 672 744 720 744 720 744 744 720 744 720 713
5105 12353
TOTAL OBS
