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HomeMy WebLinkAboutPort Heiden Wind Resource Assessment - Nov 2005 Page 1 of 15 813 W. Northern Lights Blvd. Anchorage, AK 99503 Phone: 907-269-3000 Fax: 907-269-3044 www.aidea.org/wind.htm Wind Resource Assessment for PORT HEIDEN, ALASKA Site # 2548 Date last modified: 11/04/2005 Prepared by: Mia Devine Elevation: 68 ft Latitude: (NAD27) 56Û 55’ 52” N 56Û 55.867’ Tower Type: 100-foot guyed lattice tower Longitude: (NAD27) 158Û 37’ 11.6” W 158Û 37.193’ Monitor Start: Monitor End: 8/06/2004 In operation INTRODUCTION On September 23, 2003, one anemometer and one wind vane were mounted on a 10-kW Bergey wind turbine tower at a height of 85 feet. The 100-foot tower is a 3-legged guyed lattice tower located next to the city building. A temperature sensor was mounted at a height of 14 feet. This system recorded data intermittently until the logger failed. On August 6, 2004, a new NRG Symphonie data logger was installed. On October 7, 2004, an additional anemometer and wind vane were installed at a height of 85 feet and at a 90 degree offset from the first set of equipment to reduce the effects of the tower on readings from certain directions. For consistency in the data sample, this report focuses on data collected by the Symphonie logger, beginning August 6, 2004. The purpose of this monitoring effort, jointly funded by the Bristol Bay Native Corporation, the Sustainable Energy Council of the Alaska Peninsula (SECAP), and AEA, is to evaluate the feasibility of utilizing utility-scale wind energy in the community. This report summarizes the wind resource data collected and the long-term energy production potential of the site. SITE DESCRIPTION Port Heiden is located about 400 miles southwest of Anchorage on the north side of the Alaska Peninsula. It lies at the mouth of the Meshik River near the Aniakchak National Preserve and Monument. The climate is maritime with cool summers and relatively warm winters. Figure 1 shows the location of the wind monitoring tower relative to the surrounding terrain. Alaska Energy Authority PORT HEIDEN, AK Wind Resource Assessment Page 2 of 15 Figure 1. Topographic Map of Wind Tower Site and Surrounding Area Alaska Energy Authority PORT HEIDEN, AK Wind Resource Assessment Page 3 of 15 Table 1 lists the types of sensors that were mounted on the tower, the channel of the data logger that each sensor was wired into, and where each sensor was mounted on the tower. Table 1. Summary of Sensors Installed on the Met Tower Ch # Sensor Type Height Offset Boom Orientation 1 #40 Anemometer 85 ft NRG Standard 180Û True 2 #40 Anemometer 85 ft NRG Standard 280Û True 7 #200P Wind Vane 85 ft 180Û True 180Û True 8 #200P Wind Vane 80 ft 90Û True 270Û True 9 #110S Temperature 4 m NRG Standard - Layout of Equipment on Tower N NE E SE S SW W NW CH1 CH2 Tower CH7 CH8 In order to install the sensors, the wind tower was tilted down, as shown in the photos below. Figure 2. Installation of Sensors on Wind Tower in Port Heiden Alaska Energy Authority PORT HEIDEN, AK Wind Resource Assessment Page 4 of 15 DATA PROCESSING PROCEDURES AND DEFINITIONS The following information summarizes the data processing procedures that were performed on the raw measured data in order to create an annual dataset of “typical” wind speeds, which could then be used to calculate potential power production from wind turbines. There are various methods and reasons for adjusting the raw data, so the purpose of these notes is to document what was done in this situation. The raw data set is available on the Alaska Energy Authority website (www.akenergyauthority.org) so one could perform their own data processing procedures. Units – Since most wind turbine manufacturer data is provided in metric units, those units are used here. 1 meter/second = 2.24 mph = 1.95 knots 1 meter = 3.28 feet 1 ÛC = 5/9 (ÛF – 32) Max/Min Test – All of the 10-minute data values were evaluated to ensure that none of them fell outside of the normal range for which the equipment is rated. Tower Shadow – The tower itself can affect readings from the anemometer at times when the anemometer is located downwind of the tower. To minimize this effect, one data set is compiled from the 2 anemometers depending on the direction of the wind at any given time. Icing – Anomalies in the data can suggest when the sensors were not recording accurately due to icing events. Since wind vanes tend to freeze before the anemometers, icing events are typically identified whenever the 10- minute standard deviation of the wind vane is zero (the wind vane is not moving) and the temperature is at or below freezing. Some additional time before and after the icing event are filtered out to account for the slow build up and shedding of ice. Filling Gaps – Whenever measured met tower data is available, it is used. Two different methods are used to fill in the remaining portion of the year. First, nearby airport data is used if available. A linear correlation equation is defined between the airport and met tower site, which is used to adjust the hourly airport data recorded at the time of the gap. If neither met tower nor airport data is available for a given timestep, the software program Windographer (www.mistaya.ca) is used. Windographer uses statistical methods based on patterns in the data surrounding the gap, and is good for filling short gaps in data. Long-term Estimates – The year of data collected at the met tower site can be adjusted to account for inter-annual fluctuations in the wind resource. To do this, a nearby weather station with a consistent historical record of wind data and with a strong correlation to the met tower location is needed. Turbulence Intensity – Turbulence intensity is the most basic measure of the turbulence of the wind. Turbulence intensity is calculated at each 10-minute timestep by dividing the standard deviation of the wind speed during that timestep by the average wind speed over that timestep. It is calculated only when the mean wind speed is at least 4 m/s. Typically, a turbulence intensity of 0.10 or less is desired for minimal wear on wind turbine components. Wind Shear – Typically, wind speeds increase with height above ground level. This vertical variation in wind speed is called wind shear and is influenced by surface roughness, surrounding terrain, and atmospheric stability. If the met tower is equipped with anemometers at different heights the wind shear exponent, Į, can be calculated according to the power law formula: ¸¸ ¹ · ¨¨ © § ¸¸ ¹ · ¨¨ © § 2 1 2 1 v v H H D where H1 and H2 are the measurement heights and v1 and v2 are the measured wind speeds. Wind shear is calculated only with wind speed data above 4 m/s. Values can range from 0.05 to 0.25. Since wind speeds were not measured at different heights at this location, a typical value of 0.14 is assumed. Scaling to Hub Height – If the wind turbine hub height is different from the height at which the wind resource is measured, the wind resource can be adjusted using the power law formula described above and using the wind shear data calculated at the site. Air Density Adjustment – The power that can be extracted from the wind is directly related to the density of the air. Air density, ȡ, is a function of temperature and pressure and is calculated for each 10-minute timestep according to the following equation (units for air density are kg/m3): Alaska Energy Authority PORT HEIDEN, AK Wind Resource Assessment Page 5 of 15 TR P u U , where P is pressure (kPa), R is the gas constant for air (287.1 J/kgK), and T is temperature in Kelvin. Since air pressure is not measured at the met tower site, the site elevation is used to calculate an annual average air pressure value according to the following equation: P = 1.225 – (1.194 x 10-4) x elevation Since wind turbine power curves are based on a standard air density of 1.225 kg/m3, the wind speeds measured at the met tower site are adjusted to create standard wind speed values that can be compared to the standard power curves. The adjustment is made according to the following formula: 3 1 tan tan ¸¸ ¹ · ¨¨ © §u dards measured measureddardsVV U U Wind Power Density – Wind power density provides a more accurate representation of a site’s wind energy potential than the annual average wind speed because it includes how wind speeds are distributed around the average as well as the local air density. The units of wind power density are watts per square meter and represent the power produced per square meter of area that the blades sweep as they rotate around the rotor. Wind Power Class – A seven level classification system based on wind power density is used to simplify the comparison of potential wind sites. Areas of Class 4 and higher are considered suitable for utility-scale wind power development. Weibull Distribution – The Weibull distribution is commonly used to approximate the wind speed frequency distribution in many areas when measured data is not available. In this case, the Weibull distribution is used to compare with our measured data. The Weibull is defined as follows: kk c v c v c kvP ¸¹ ·¨© §¸¹ ·¨© §  exp)( 1 Where P(v) is the probability of wind speed v occurring, c is the scale factor which is related to the average wind speed, and k is the shape factor which describes the distribution of the wind speeds. Typical k values range from 1.5 to 3.0, with lower k values resulting in higher average wind power densities. Alaska Energy Authority PORT HEIDEN, AK Wind Resource Assessment Page 6 of 15 LONG-TERM REFERENCE STATION Wind data from the Port Heiden Airport weather station, located about 2 miles north of the met tower site, serves as a long-term reference for the wind resource in the area. This data is measured at a height of 7 meters above ground level and at an elevation of 29 meters. Since the airport is close to the met tower site and the surrounding terrain is relatively flat, the patterns in wind resource data between the sites are expected to be similar. Nearly 30 years of wind speeds are shown in Table 2 and Figure 3. The average wind speed over the 30-year period is 5.7 m/s at a height of 7 meters above ground level. The annual wind speed rarely deviates more than 8% above or below this average. Table 2. Average Wind Speeds at 7-m Height at Port Heiden Airport (m/s) Year JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC AVG % of 30-yr Average 1976 5.4 5.86 5.83 4.7 5.44 4.45 4.34 3.94 4.66 5.5 5.22 5.55 5.1 89% 1977 7.11 6.49 6.61 5.74 4.44 4.78 5.43 5.2 5.55 6.33 6.36 6.14 5.8 102% 1978 5.46 6.52 5.62 5.58 4.65 5.06 5.17 5.57 5.99 5.9 7.8 8.9 5.7 99% 1979 7.55 5.79 5.92 6.13 5.93 4.91 3.95 5.43 5.66 6.06 7.14 7.33 6.0 105% 1980 6.66 5.41 6.92 5.28 6.05 6.64 5.18 4.76 5.47 4.81 4.64 6.61 5.7 100% 1981 5.36 6.93 5.42 4.14 5.39 4.19 5.08 6.52 5.21 6.52 6.61 6.68 5.6 98% 1982 6.09 6.26 6.5 6.07 5.39 5.8 6.8 5.07 5.89 5.88 5.23 5.41 5.9 102% 1983 5.38 4.85 4.9 5.1 5.54 4.2 4.51 4.56 5.83 6.09 5.52 6.92 5.3 92% 1984 5.98 6.29 4.38 5.44 4.55 4.41 4.26 4.41 5.34 5.28 6.54 6.22 5.3 93% 1985 7.43 6.35 6.63 5.53 6.17 4.67 4.46 5.88 5.65 7.66 7.45 6.84 6.2 108% 1986 5.41 6.43 4.78 5.56 6.03 6.41 4.44 5.42 5.95 4.57 6.19 6.33 5.6 98% 1987 6.46 6.23 5.88 5.91 5.36 5.51 4.58 5.33 5.58 6.13 5.26 6.11 5.7 100% 1988 5.89 7 5.78 5.6 4.85 4.82 4.62 5.12 5.78 5.59 5.61 7.24 5.7 99% 1989 7.86 9.07 5.35 5.97 5.9 4.95 4.62 5.33 6.33 7.95 5.77 6.38 6.2 108% 1990 7.39 7.04 4.7 4.62 6.53 5.41 5.24 5.55 6.36 5.48 6.36 6.96 6.1 106% 1991 4.88 7.42 6.43 4.99 7.06 6.44 4.85 5.25 6.27 5.43 4.83 6.68 5.8 101% 1992 5.21 4.88 5.99 4.56 3.73 5.78 4.67 6.12 4.99 5.59 5.3 7.02 5.3 93% 1993 6.6 7.77 6.06 5.25 5.84 4.79 4.92 6.06 6.03 4.51 6.19 6.15 5.8 102% 1994 5.3 5.51 6.88 4.96 4.73 4.88 4.37 4.82 5.79 5.76 8.15 7.04 5.6 98% 1995 5.3 6.7 5.57 4.83 5.79 4.38 5.97 5.03 5.62 6.39 4.47 6.08 5.6 97% 1996 5.03 8.57 6.14 6.08 5.1 6.6 4.37 4.68 6.82 4.99 7.04 6.25 5.9 104% 1997 6.16 4.66 4.92 4.48 5.01 4.65 3.73 5.32 6.05 4.71 5.49 5.88 5.0 87% 1998 4.96 3.72 7.65 7.11 6.49 5.38 4.58 6.57 6.14 6.09 5.64 7.8 6.0 105% 1999 6.3 6.89 5.71 6.49 5.23 4.94 4.87 5.17 5.3 4.96 5.77 6.62 5.7 99% 2000 6.34 9.01 7.01 5.24 5.14 6.06 4.93 5.6 5.82 5.66 6.69 8.58 6.2 108% 2001 6.13 7.12 6.05 6.14 5.99 5.05 5.64 5.1 5.6 6.44 6.35 6.34 6.0 105% 2002 6.9 7.0 6.5 6.3 5.8 4.4 5.3 4.6 6.6 6.6 5.6 6.4 6.0 105% 2003 6.3 5.6 6.0 5.7 5.6 5.5 4.6 4.9 4.7 5.7 7.2 6.5 5.7 99% 2004 5.5 5.7 6.1 5.9 5.2 5.2 4.5 5.1 5.8 6.7 6.7 7.0 5.8 101% AVG 6.12 6.42 5.94 5.42 5.45 5.16 4.81 5.24 5.69 5.81 6.01 6.62 5.7 100% Alaska Energy Authority PORT HEIDEN, AK Wind Resource Assessment Page 7 of 15 5.15.85.76.05.75.65.95.35.36.25.65.75.76.26.15.85.35.85.65.65.95.06.05.76.26.06.05.75.80 1 2 3 4 5 6 7 8 9 10 19761977197819791980198119821983198419851986198719881989199019911992199319941995199619971998199920002001200220032004Average Wind Speed (m/s) Figure 3. Annual Average Wind Speeds at 7-m Height at Port Heiden Airport Weather Station Hourly wind speed measurements from the Port Heiden Airport weather station that are concurrent with recordings from the wind monitoring tower site were purchased from the National Climatic Data Center. Data between these sites was compared and a correlation coefficient of 0.90 was calculated (a value of 1 is perfect). This suggests that, although the actual wind speed values at the two sites are different, the pattern of wind speed fluctuations is similar between the sites. Based on this correlation a long-term estimate of the wind speed at the wind tower site was developed. Alaska Energy Authority PORT HEIDEN, AK Wind Resource Assessment Page 8 of 15 WIND DATA RESULTS FOR WIND TOWER SITE Table 3 summarizes the amount of data that was successfully retrieved from the anemometers at the wind tower site. Table 3. Data Recovery Rates for Met Tower Data Month Data Recovery January 48% February 91% March 100% April 100% May 100% June 100% July 89% August 47% September 95% October 99% November 98% December 100% Annual Avg 89% Table 4 and Table 5 summarize the wind resource data measured at the wind tower site as well as the estimated long-term data for this site. Table 4. Measured Wind Speeds at 26-m Height at Wind Tower Location, Aug 2004 - July 2005 (m/s) Hour Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual 0 7.1 7.9 8.7 6.1 6.4 5.1 4.6 6.3 7.1 7.4 8.5 8.1 7.0 1 7.8 8.1 8.4 6.0 5.9 5.3 4.8 6.4 6.8 7.7 8.4 8.4 7.0 2 7.9 8.2 7.9 6.0 6.3 5.1 4.8 6.2 6.8 8.4 9.1 8.3 7.1 3 7.8 7.9 8.1 5.7 5.9 5.4 4.6 5.7 6.8 8.3 9.3 8.1 7.0 4 7.9 8.5 8.4 5.3 5.9 5.1 4.2 5.9 6.6 8.0 9.3 8.0 6.9 5 7.7 8.8 8.4 5.3 6.3 5.3 4.3 6.1 6.9 8.2 9.3 8.2 7.1 6 6.9 8.9 8.2 5.3 6.4 5.2 4.5 5.3 7.1 8.2 9.6 8.3 7.0 7 7.0 8.7 8.0 5.2 6.3 5.0 4.1 5.2 6.9 8.2 9.5 8.8 6.9 8 6.9 8.4 8.3 5.2 6.3 5.4 4.3 5.9 6.7 8.2 9.1 9.0 7.0 9 7.4 8.1 8.4 5.7 6.8 6.1 4.6 6.6 6.7 8.2 9.0 9.2 7.2 10 8.6 8.4 8.7 6.3 7.3 6.7 4.8 6.2 7.2 8.6 8.1 9.5 7.5 11 8.6 8.5 9.3 6.5 7.8 7.1 5.2 6.4 7.2 9.1 8.2 9.7 7.8 12 8.3 8.6 9.3 6.6 8.0 7.6 5.8 6.6 7.1 9.3 8.5 9.2 7.9 13 7.5 8.4 9.2 7.1 8.3 7.9 6.1 6.5 7.4 9.6 8.2 9.0 7.9 14 6.9 8.5 9.2 7.7 8.5 8.3 6.0 7.2 7.4 9.6 8.5 9.3 8.1 15 6.8 8.1 9.5 7.8 8.6 8.1 6.4 7.4 7.4 8.8 8.1 9.1 8.0 16 6.9 8.5 9.0 7.9 8.5 7.7 6.3 7.2 7.5 8.3 8.0 8.6 7.9 17 6.8 8.6 8.8 7.8 8.3 7.2 6.0 7.1 7.6 7.9 7.9 8.3 7.7 18 6.5 8.8 8.3 7.5 7.7 6.8 6.1 7.1 7.3 7.1 8.2 9.0 7.5 19 6.5 9.1 7.9 7.0 7.6 6.6 5.8 7.2 7.1 7.2 8.3 9.1 7.5 20 5.5 8.8 7.8 6.7 7.1 6.3 5.2 6.9 7.0 7.4 8.3 8.8 7.1 21 6.4 8.3 7.7 6.4 6.5 5.6 5.0 6.2 7.3 7.7 8.7 8.9 7.1 22 6.9 8.4 8.2 6.2 6.2 5.2 4.6 6.0 7.0 7.9 9.1 8.6 7.0 23 6.8 8.2 8.5 6.3 6.2 5.4 4.6 6.2 7.1 7.6 9.1 8.4 7.0 Avg 7.2 8.4 8.5 6.4 7.0 6.2 5.1 6.4 7.1 8.2 8.7 8.7 7.3 Alaska Energy Authority PORT HEIDEN, AK Wind Resource Assessment Page 9 of 15 Table 5. Estimated Long-term Wind Speeds at 26-m Height at Wind Tower Location (m/s) Hour Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual 0 7.7 6.7 7.1 6.0 5.6 5.7 5.0 5.6 5.4 6.7 8.1 7.6 6.4 1 7.5 6.8 7.0 6.2 5.6 5.4 5.0 5.5 5.6 6.5 8.0 7.5 6.4 2 7.2 6.2 6.9 5.7 5.6 5.2 4.8 5.2 5.5 6.6 8.4 7.5 6.2 3 7.1 7.1 7.2 5.8 5.8 5.0 4.8 5.1 5.0 6.6 8.5 7.9 6.3 4 6.8 6.9 6.8 5.6 5.7 5.0 4.6 4.9 5.5 6.6 8.5 7.6 6.2 5 6.8 6.8 7.0 5.7 5.4 5.1 4.5 4.9 5.5 6.8 8.3 7.6 6.2 6 6.8 6.6 7.0 5.4 5.7 5.0 4.5 4.9 5.7 7.0 8.4 7.6 6.2 7 7.1 6.4 7.0 5.2 5.6 5.5 4.7 4.7 5.7 6.9 8.3 7.7 6.2 8 6.5 6.1 6.9 6.0 6.0 6.1 5.2 5.4 5.6 7.4 7.9 8.2 6.4 9 6.8 7.0 7.2 6.2 6.8 6.3 5.3 5.9 5.9 7.8 8.1 8.4 6.8 10 6.4 6.4 7.5 7.0 7.3 6.9 5.7 6.2 6.9 8.1 8.0 8.9 7.1 11 7.1 7.1 8.0 7.5 7.6 7.4 5.9 6.4 7.4 8.4 8.4 8.6 7.5 12 7.7 7.6 8.8 8.3 8.3 7.5 6.2 6.6 7.8 8.6 8.7 8.6 7.9 13 8.3 8.2 8.6 9.0 8.7 7.9 6.7 6.7 7.9 8.8 8.9 8.7 8.2 14 7.9 8.7 9.1 9.3 8.9 8.2 6.9 6.9 7.8 9.0 8.7 8.6 8.3 15 8.5 8.7 9.4 9.1 9.1 8.3 7.0 7.1 8.2 8.9 8.9 8.8 8.5 16 7.9 7.7 9.1 9.0 8.7 8.1 7.0 7.6 8.0 8.3 8.7 8.2 8.2 17 7.5 7.6 8.6 9.1 8.6 7.9 6.7 7.3 7.8 8.0 8.6 7.9 8.0 18 7.5 6.9 8.2 8.9 8.3 7.8 6.6 7.2 7.5 7.2 8.3 8.3 7.7 19 7.5 6.9 7.8 8.1 8.1 7.2 6.3 6.9 6.6 7.1 8.0 8.4 7.4 20 7.3 6.8 7.0 7.1 6.9 6.4 5.9 6.3 6.0 6.4 8.1 8.1 6.9 21 7.3 7.1 7.3 6.6 6.5 5.8 5.5 5.9 5.7 6.7 8.1 8.1 6.7 22 7.5 6.7 7.0 6.5 5.9 5.5 4.9 5.6 5.6 6.7 8.4 8.4 6.5 23 7.5 6.7 6.9 6.3 5.5 5.6 5.0 5.6 5.5 6.9 7.8 7.9 6.4 Avg 7.3 7.1 7.6 7.1 6.9 6.4 5.6 6.0 6.4 7.4 8.3 8.1 7.0 0 1 2 3 4 5 6 7 8 9 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecWind Speed (m/s)0 2 4 7 9 11 13 16 18 20 Wind Speed (mph)Aug 04 - July 05 Long-term Estimate Month m/s mph m/s mph Jan 6.9 15.5 6.0 13.3 Feb 8.1 18.1 5.8 12.9 Mar 8.2 18.2 6.2 13.9 Apr 6.1 13.7 5.7 12.9 May 6.7 15.1 5.6 12.6 Jun 6.0 13.4 5.3 11.8 Jul 4.9 10.9 4.6 10.3 Aug 6.1 13.8 4.9 11.0 Sep 6.8 15.2 5.2 11.7 Oct 7.9 17.6 6.0 13.5 Nov 8.3 18.6 6.7 15.1 Dec 8.4 18.7 6.6 14.7 Avg 7.0 15.7 5.7 12.8 Long-term EstimateAug 04 - July 05 Figure 4. Monthly Average Wind Speeds at Wind Tower Site (26m Height) As shown, the highest wind month is typically November and the lowest wind month is typically July. As shown below, the diurnal variation is more pronounced during the summer months than the winter months, with winds typically lowest in the morning and increasing in the afternoon. Alaska Energy Authority PORT HEIDEN, AK Wind Resource Assessment Page 10 of 15 0 1 2 3 4 5 6 7 8 9 0 2 4 6 8 10121416182022 Hour of DayWind Speed (m/s)8/04 to 7/05 Longterm Estimate 0 1 2 3 4 5 6 7 8 9 0 2 4 6 8 10 12 14 16 18 20 22 Hour of DayWind Speed (m/s)Longterm Estimate - July Longterm Estimate - January Figure 5. Hourly Average Wind Speeds at Wind Tower Site (26m Height) A common method of displaying a year of wind data is a wind frequency distribution, which shows the percent of the year that each wind speed occurs. Figure 6 shows the measured wind frequency distribution as well as the best matched Weibull distribution (c = 8.3, k= 1.8). 0 2 4 6 8 10 12 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Wind Speed (m/s)Percent of TimeMeasured Weibull Bin m/s Measured Hours Bin m/s Measured Hours 0 209 15 136 1 392 16 102 2 589 17 69 3 752 18 47 4 881 19 39 5 872 20 32 6 846 21 22 7 777 22 12 8690 23 6 9559 24 5 10 483 25 3 11 414 26 1 12 370 27 1 13 276 28 0 14 177 29 0 Total: 8,760 Figure 6. Wind Speed Frequency Distribution of Wind Tower Data The cut-in wind speed of many wind turbines is 4 m/s and the cut-out wind speed is around 25 m/s. The frequency distribution shows that a large percentage of the wind in Port Heiden falls within this operational zone. Table 6 shows the annual wind rose at the wind tower site versus the wind rose at the Port Heiden airport. The predominant wind energy direction at both the wind tower and the airport is SE, with summer winds coming from the SW. Table 6. Annual Wind Rose for Wind Tower Site and Airport Site Met Tower Site Wind Rose, Aug 04 – July 05 Annual Wind Rose from Airport, 1973-2002 Legend Percent of Total Wind Energy Percent of Total Time NRG Systems SDR Version 5.03 N EW S 0 3 6 9 N NE E SE S SW W NW Average Distribution January July Alaska Energy Authority PORT HEIDEN, AK Wind Resource Assessment Page 11 of 15 Table 7 breaks the annual wind rose at the wind tower site into monthly wind roses. Table 7. Monthly Wind Roses for Wind Tower Site Aug 2004 Sept 2004 Oct 2004 N EW S N EW S N EW S Nov 2004 Dec 2004 Jan 2005 N EW S N EW S N EW S Feb 2005 Mar 2005 Apr 2005 N EW S N EW S N EW S May 2005 June 2005 July 2005 N EW S N EW S N EW S Alaska Energy Authority PORT HEIDEN, AK Wind Resource Assessment Page 12 of 15 Table 8 summarizes the monthly turbulence intensity at the wind tower site. The turbulence intensity of 0.10 to 0.16 is considered moderate and unlikely to contribute to excessive wear of wind turbines. Table 8. Monthly Turbulence Intensity at Wind Tower Site Month Turbulence Intensity Jan 0.11 Feb 0.10 Mar 0.12 Apr 0.12 May 0.12 Jun 0.12 Jul 0.12 Aug 0.12 Sep 0.11 Oct 0.11 Nov 0.10 Dec 0.11 Annual Avg 0.11 Figure 7. Turbulence Intensity by Direction, Aug 2004 - July 2005 0.10 0.110.11 0.12 0.12 0.12 0.12 0.12 0.14 0.14 0.11 0.11 0.13 0.16 0.14 0.11 0.100.10 The air temperature can affect wind power production in two primary ways: 1) colder temperatures lead to higher air densities and therefore more power production, and 2) some wind turbines shut down in very cold situations (usually below -25ÛC). Since the temperature sensor at the wind tower was not functioning properly, the following information comes from data recorded at the Port Heiden airport weather station. Between January 2001 and August 2005, the temperature dropped below -25ÛC for about 1 hour and was below -20ÛC for about 13 hours. -1.3 1.1 -2.8 2.3 9.3 13.3 11.4 15.8 9.2 5.2 1.9 -2.6 -5 0 5 10 15 20 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecTemperature (deg C) Figure 8. Monthly Average Temperatures in Port Heiden Alaska Energy Authority PORT HEIDEN, AK Wind Resource Assessment Page 13 of 15 POTENTIAL POWER PRODUCTION FROM WIND TURBINES Table 9 lists a number of parameters used to characterize the power production potential of a particular site. Table 9. Summary of Power Production Potential of Met Tower Site Average Wind Power Density (30m) 490 W/m2 Wind Power Class 5-6 Rating Excellent Various wind turbines, listed in Table 12, were used to calculate the energy production at the met tower site based on the long-term wind resource data set. Although different wind turbines are offered with different tower heights, to be consistent it is assumed that any wind turbine rated at 100 kW or less would be mounted on a 30-meter tall tower, while anything larger would be mounted on a 50-meter tower. The wind resource was adjusted to these heights based on the standard wind shear of 0.14. The wind resource was also adjusted for local air density. Table 10 summarizes the estimated energy production from various wind turbines at the met tower site. Table 10. Gross Annual Energy Production from Different Wind Turbines at Met Tower Site (kWh) Month Proven 2.5kW Proven 6kW Bergey 10 kW FL30 Entegrity FL100 NW100 FL250 V27 V47 Jan 847 2,147 2,339 10,645 17,819 34,809 28,515 79,642 72,500 240,127 Feb 693 1,763 1,910 8,762 14,596 28,484 23,343 65,447 59,454 197,511 Mar 836 2,152 2,417 10,828 17,544 34,512 28,354 79,193 72,654 246,969 Apr 644 1,657 1,745 8,225 13,038 25,590 20,840 59,714 54,583 187,440 May 682 1,774 1,935 8,919 13,804 27,378 22,366 64,177 58,658 203,360 Jun 572 1,487 1,597 7,320 11,263 22,506 18,416 53,020 48,383 165,982 Jul 456 1,222 1,272 6,202 8,752 17,492 14,174 42,975 39,125 142,568 Aug 556 1,461 1,542 7,264 11,063 21,878 17,898 51,833 47,546 166,276 Sep 566 1,486 1,600 7,442 11,084 22,192 18,072 52,914 48,340 170,126 Oct 733 1,886 1,985 9,423 14,946 29,289 23,825 68,265 62,539 214,067 Nov 881 2,248 2,367 11,277 18,612 35,918 29,362 84,447 76,267 257,599 Dec 912 2,323 2,534 11,605 19,303 37,705 30,887 86,460 78,743 261,782 Annual 8,378 21,607 23,243 107,911 171,825 337,751 276,053 788,086 718,792 2,453,808 Annual kWh/m^2 853 878 573 782 956 950 949 1,108 1,204 1,339 Table 10 also lists the annual energy production per square meter of swept area (kWh/m 2). This allows one to directly compare the efficiency of one wind turbine against another, as shown in Figure 1. 0 20 40 60 80 100 120 140 160 180 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecPower Production (kWh/m^2)Proven 2.5kW Proven 6kW Bergey 10 kW FL30 Entegrity FL100 NW100 FL250 V27 V47 Figure 9. Comparison of Power Production per Square Meter of Swept Area from Various Wind Turbines Alaska Energy Authority PORT HEIDEN, AK Wind Resource Assessment Page 14 of 15 Table 11 summarizes the gross capacity factor of the wind turbines per month. Gross capacity factor is the amount of energy produced based on the given wind resource divided by the maximum amount of energy that could be produced if the wind turbine were to operate at rated power during that entire period. The gross capacity factor could be further reduced by up to 10% to account for transformer/line losses, turbine downtime, soiling of the blades, icing of the blades, yaw losses, and extreme weather conditions. Table 11. Gross Capacity Factor of Different Wind Turbines at Met Tower Site Month Proven 2.5kW Proven 6kW Bergey 10 kW FL30 Entegrity FL100 NW100 FL250 V27 V47 Jan 46% 48% 31% 48% 36% 47% 38% 43% 43% 49% Feb 41% 44% 28% 43% 33% 42% 35% 39% 39% 45% Mar 45% 48% 32% 49% 36% 46% 38% 43% 43% 50% Apr 36% 38% 24% 38% 27% 36% 29% 33% 34% 39% May 37% 40% 26% 40% 28% 37% 30% 35% 35% 41% Jun 32% 34% 22% 34% 24% 31% 26% 29% 30% 35% Jul 25% 27% 17% 28% 18% 24% 19% 23% 23% 29% Aug 30% 33% 21% 33% 23% 29% 24% 28% 28% 34% Sep 31% 34% 22% 34% 23% 31% 25% 29% 30% 36% Oct 39% 42% 27% 42% 30% 39% 32% 37% 37% 44% Nov 49% 52% 33% 52% 39% 50% 41% 47% 47% 54% Dec 49% 52% 34% 52% 39% 51% 42% 46% 47% 53% Annual 38% 41% 27% 41% 30% 39% 32% 36% 36% 42% CONCLUSION This report provides a summary of wind resource data collected from August 2004 through July 2005 in Port Heiden, Alaska. The data was compared to long-term trends in the area. Based on correlations with the long-term weather station at the Port Heiden airport, estimates were made to create a long-term dataset for the Port Heiden wind tower site. This information was used to make predictions as to the potential energy production from wind turbines at that site. It is estimated that the long-term annual average wind speed at the wind tower site is 7.0 m/s at a height of 26 meters above ground level. Taking the local air density into account, the average wind power density for the site is 490 w/m2. This information means that Port Heiden has a Class 5 to 6 wind resource, which is excellent for wind power development. Alaska Energy Authority PORT HEIDEN, AK Wind Resource Assessment Page 15 of 15 Table 12. Wind Turbine Models Used in Power Production Analysis Proven 2.5 kW http://www.provenenergy.com Tower Height: 30 meters Swept Area: 9.6 m2 Turbine Weight: 190 kg Proven 6 kW http://www.provenenergy.com Tower Height: 30 meters Swept Area: 23.8 m2 Turbine Weight: 500 kg Bergey 10 kW www.bergey.com Tower Height: 30 meters Swept Area: 38.5 m2 Weight: not available Fuhrlander FL30 30 kW www.lorax-energy.com Tower Height: 30 meters Swept Area: 133 m2 Weight (nacelle & rotor): 410 kg Entegrity 66 kW www.entegritywind.com Tower Height: 30 meters Swept Area: 177 m2 Weight (drivetrain & rotor): 2,420 kg Fuhrlander FL100 100 kW www.lorax-energy.com Tower Height: 30 meters Swept Area: 348 m2 Weight (nacelle & rotor): 2,380 kg Northern Power NW100/19 100 kW www.northernpower.com Tower Height: 30 meters Swept Area: 284 m2 Weight (nacelle & rotor): 7,086 kg Fuhrlander FL250 250 kW www.lorax-energy.com Tower Height: 50 meters Swept Area: 684 m2 Weight (nacelle & rotor): 4,050 kg Vestas V27 225 kW (refurbished, various suppliers) Tower Height: 50 meters Swept Area: 573 m2 Weight: not available Vestas V47 660 kW www.vestas.com Tower Height: 50 meters Swept Area: 1,735 m2 Weight: not available