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HomeMy WebLinkAboutNaknek Wind Resource Report - Aug 2006 - REF Grant 7013005Naknek, Alaska Wind Resource Report Report written by: Douglas Vaught, V3 Energy LLC, Eagle River, AK Date of report: August 2, 2006 Photo © Doug Vaught General Site Information Site number 2398 Site Description Naknek Latitude/longitude N 58° 44.551’ W 156° 52.739’ Site elevation 53 meters Datalogger type NRG Symphonie Tower type NRG 30-meter tall tower, 152 mm (6 in) diameter Naknek is located near the mouth of the Naknek River on the Bristol Bay coast of the Bering Sea, approximately 485 kilometers southwest of Anchorage. Naknek is serviced by the jet- service capable airport in King Salmon and is connected by road to that community. Naknek Electric Association is the local utility company and provides service to Naknek, South Naknek and King Salmon. The met tower project test site is adjacent to the community landfill approxi- mately half-way between Naknek and King Salmon. V3 Energy LLC 1 of 21 Naknek, Alaska Wind Resource Report Data Synopsis Wind power class (at 50 meters) Class 3 – Fair (site is high class 3) 30 meter average wind speed 6.24 m/s Maximum wind speed 32.9 m/s, 4/21/05, 5:20 pm Mean wind power density (50 meters) 383 W/m2 Roughness Class 2.00 (few trees) Power law exponent 0.181 (moderate wind shear) Data start date July 27, 2004 Most recent data date July 19, 2006 Tower Sensor Information Channel Sensor type Height Multiplier Offset Orientation 1 NRG #40 anemometer 30 m 0.765 0.35 west 2 NRG #40 anemometer 20 m 0.765 0.35 southeast 7 NRG #200P wind vane 27 m 0.351 262 east V3 Energy LLC 2 of 21 Naknek, Alaska Wind Resource Report 9 NRG #110S Temp C 6 m 0.136 -86.383 N/A Quality Control Data was filtered to remove presumed icing events that yield false zero wind speed data. Data that met the following criteria were filtered: wind speed < 1 m/s, wind speed standard deviation = 0, and temperature < 3 °C. Note that data recovery during the months of May through Sep- tember was nearly 100%, but during the months of October through April some data was filtered, with January being the most ice prone as far as data loss is concerned. Temperature data recov- ery was 100 percent, indicating full functioning of the temperature sensor. Ch 1 (30m spd) Ch 2 (20m spd) Ch 7 (vane) Ch 9 (temp) Year Month Records Recovery Records Recovery Records Recovery Records Recovery Rate (%) Rate (%) Rate (%) Rate (%) 2004 Jul 606 100.0 606 100.0 606 100.0 606 100.0 2004 Aug 4,464 100.0 4,464 100.0 4,464 100.0 4,464 100.0 2004 Sep 4,320 100.0 4,320 100.0 4,320 100.0 4,320 100.0 2004 Oct 4,462 100.0 4,453 99.8 4,453 99.8 4,464 100.0 2004 Nov 4,154 96.2 4,145 95.9 4,143 95.9 4,320 100.0 2004 Dec 3,995 89.5 3,995 89.5 3,982 89.2 4,464 100.0 2005 Jan 3,860 86.5 3,842 86.1 3,811 85.4 4,464 100.0 2005 Feb 3,977 98.6 3,981 98.7 3,977 98.6 4,032 100.0 2005 Mar 4,113 92.1 4,231 94.8 4,105 92.0 4,464 100.0 2005 Apr 4,227 97.8 4,244 98.2 4,224 97.8 4,320 100.0 2005 May 4,464 100.0 4,464 100.0 4,464 100.0 4,464 100.0 2005 Jun 4,320 100.0 4,320 100.0 4,320 100.0 4,320 100.0 2005 Jul 4,464 100.0 4,464 100.0 4,464 100.0 4,464 100.0 2005 Aug 4,464 100.0 4,464 100.0 4,464 100.0 4,464 100.0 2005 Sep 4,320 100.0 4,320 100.0 4,320 100.0 4,320 100.0 2005 Oct 4,436 99.4 4,391 98.4 4,391 98.4 4,464 100.0 2005 Nov 4,070 94.2 4,006 92.7 4,000 92.6 4,320 100.0 2005 Dec 4,274 95.7 4,282 95.9 4,145 92.9 4,464 100.0 2006 Jan 4,163 93.3 4,086 91.5 4,082 91.4 4,464 100.0 2006 Feb 3,980 98.7 3,992 99.0 3,973 98.5 4,032 100.0 2006 Mar 4,411 98.8 4,307 96.5 4,304 96.4 4,464 100.0 2006 Apr 4,316 99.9 4,275 99.0 4,275 99.0 4,320 100.0 2006 May 4,442 99.5 4,455 99.8 4,440 99.5 4,464 100.0 2006 Jun 4,320 100.0 4,320 100.0 4,320 100.0 4,320 100.0 2006 Jul 2,676 100.0 2,676 100.0 2,676 100.0 2,676 100.0 All data 101,298 97.5 101,103 97.3 100,723 96.9 103,938 100.0 Monthly Wind Speed Averages The Channel 1 (30-meter) anemometer wind speed average for the reporting period is 6.24 m/s and the Channel 2 (20-meter) anemometer wind speed average is 5.93 m/s. The daily wind pro- file indicates that the lowest wind speeds of the day occur in the morning hours of 4 to 7 a.m. and the highest wind speeds of the day occur during the afternoon and evening hours of 3 to 6 p.m. V3 Energy LLC 3 of 21 Naknek, Alaska Wind Resource Report Ch 1 (30 m) Ch 2 (20 m) Mean Max Std. Dev. Weibull k Weibull c Mean Max Std. Dev. Month (m/s) (m/s) (m/s) (m/s) (m/s) (m/s) (m/s) Jan 6.95 17.8 3.42 2.074 7.800 6.71 16.9 3.32 Feb 7.76 24.7 4.02 2.018 8.756 7.46 23.1 3.92 Mar 6.72 19.2 3.50 1.988 7.563 6.43 21.7 3.28 Apr 6.10 23.7 3.06 2.098 6.892 5.80 21.9 2.95 May 5.78 17.9 2.71 2.253 6.521 5.53 17.5 2.65 Jun 5.35 18.5 2.73 2.057 6.045 5.07 20.0 2.79 Jul 5.02 15.1 2.38 2.202 5.660 4.73 13.9 2.44 Aug 5.22 17.7 2.84 1.916 5.884 4.95 17.1 2.82 Sep 5.88 19.4 2.96 2.090 6.640 5.46 20.9 2.94 Oct 6.27 19.2 3.22 2.036 7.073 5.86 18.9 3.24 Nov 6.70 22.3 3.31 2.101 7.547 6.26 21.5 3.23 Dec 7.32 24.1 3.73 2.072 8.279 7.04 23.6 3.66 Annual 6.24 24.7 3.28 1.984 7.040 5.93 23.6 3.23 V3 Energy LLC 4 of 21 Naknek, Alaska Wind Resource Report Long-term Comparison The graph below of average annual wind speed for the nearby King Salmon airport indicates that 2004 and 2005 experienced possibly low average annual wind speeds when compared to data over the past thirty-two years, although in comparison to the past ten years, the 2004/05 wind speeds recorded at the airport were about average. The discrepancy between earlier data and the past ten years can be attributable to an equipment upgrade approximately ten years ago. Adjust- ing wind data collected during the measurement period against long-term data measurement will be included in a revision to this report. V3 Energy LLC 5 of 21 Naknek, Alaska Wind Resource Report Time Series of Wind Speed Monthly Averages The average wind speed at 30 meters for the measurement period is 6.24 m/s. Typically, the highest winds occur during the winter months of October through March with the lowest winds during the spring-summer-autumn months of April through September. The unusually low winds measured in January 2006 were due to a persistent high pressure system over Alaska that month that yielded calm winds and extremely cold weather Statewide. Probability Distribution Function The probability distribution function provides a visual indication of measured wind speeds in one meter per second “bins”. Note that most wind turbines do not begin to generate power until the wind speed at hub height reaches 4 m/s. The black line in the graph is a best fit Weibull distribu- tion. V3 Energy LLC 6 of 21 Naknek, Alaska Wind Resource Report Wind Shear Profile The power law exponent was calculated at 0.181, indicating moderate wind shear at the Naknek test site. The practical application of this data is that a higher turbine tower height is desirable as there will be an appreciable marginal gain in wind speed/power recovery with additional height. A tower height/power recovery/construction cost tradeoff study is advisable. V3 Energy LLC 7 of 21 Naknek, Alaska Wind Resource Report Wind Roses Naknek winds are not especially directional; the wind frequency rose indicates north, west, east and south components of wind. This observation is reinforced with reference to the power den- sity rose below. Power producing winds are chiefly north, south and east with lesser power winds from west and northeast. The practical application of this information is that a site should be selected with adequate freedom from ground interference in all directions and if more than one turbine is installed, the turbines should be adequately spaced apart to prevent downwind (from the power producing winds) interference problems between the turbines. V3 Energy LLC 8 of 21 Naknek, Alaska Wind Resource Report Wind Power Density Rose (30 meters) Wind Power Density Rose by Month (30 meters) V3 Energy LLC 9 of 21 Naknek, Alaska Wind Resource Report Turbulence Intensity The turbulence intensity (TI) is quite acceptable for all wind direction, with a mean turbulence intensity of 0.102 (Channel 1) and 0.108 (Channel 2), indicating relatively smooth air. These TIs are calculated with a threshold wind speed of 4 m/s. The spike of relatively high turbulence to the east in the first graph is not observed in the second graph. This is due to placement of the 30 meter level anemometer in relation to the wind vane. As indicated below, turbulence at the Nak- nek project test site is well below International Energy Agency (IEA) standards at all measured wind speeds and from all four quadrants of the wind rose. V3 Energy LLC 10 of 21 Naknek, Alaska Wind Resource Report 30-meter turbulence intensity 20-meter turbulence intensity V3 Energy LLC 11 of 21 Naknek, Alaska Wind Resource Report Extreme Wind Analysis By probability, Naknek winds are expected to exceed 37.4 m/s at least once every 25 years and 39.0 m/s every 50 years. Note, however, that these graphs were generated with only three points and should be used with caution for design purposes. V3 Energy LLC 12 of 21 Naknek, Alaska Wind Resource Report Air Temperature and Density Over the reporting period, Naknek had an average temperature of 3.0° C. The minimum re- corded temperature during the measurement period was -36.6° C and the maximum temperature was 26.3° C, indicating a wide variability of an ambient temperature operating environment im- portant to wind turbine operations. Consequent to Naknek’s cool temperatures, the average air density of 1.272 kg/m3 is approximately four percent higher than the standard air density of 1.225 kg/m3 (at 20° C), indicating that Naknek, due to its cool annual temperature average and low elevation, has denser air than the standard air density used to calculate turbine power curves. This density variance from standard is accounted for in turbine performance predictions in this report. Temperature Air Density Month Mean Min Max Std. Dev. Mean (°C) (°C) (°C) (°C) (kg/m3) Jan -10.3 -36.6 7.8 10.48 1.336 Feb -4.1 -33.7 8.4 8.93 1.305 Mar -3.9 -21.8 11.1 7.16 1.303 Apr -0.2 -20.7 22.1 6.38 1.285 May 8.5 -4.2 26.3 5.21 1.246 Jun 12.0 1.0 24.7 4.04 1.230 Jul 13.9 4.4 24.3 3.18 1.222 Aug 15.8 5.7 26.3 3.59 1.214 Sep 10.0 -0.9 19.7 3.45 1.239 Oct 4.0 -10.4 14.8 4.74 1.266 Nov -5.3 -25.3 8.8 8.34 1.310 Dec -3.0 -26.8 8.0 6.70 1.299 Annual 3.0 -36.6 26.3 10.52 1.272 V3 Energy LLC 13 of 21 Naknek, Alaska Wind Resource Report Turbine Performance Predictions The turbine performance predictions noted below are idealized: they assume 100% turbine avail- ability and that the manufacturer-provided power curve is accurate. The power curves are calcu- lated for a standard air density of 1.225 kg/m3, however the predictions of power production are density compensated by multiplying the standard density power output by the ratio of the meas- ured air density to standard air density. Vestas V15: 75 kW output, 15 meter rotor, stall-controlled (power curve provided by Powercorp Alaska LLC) V3 Energy LLC 14 of 21 Naknek, Alaska Wind Resource Report Northwind 100/20: 100 kW output, 20 meter rotor (root blade extenders added to the 100/19 model), stall-controlled (power curve provided by Northern Power Systems) Vestas V27: 225 kW output, 27 meter rotor, pitch-controlled (power curve provided by Alaska Energy Authority) V3 Energy LLC 15 of 21 Naknek, Alaska W V3 Energy LLC ind Resource Report 16 of 21 Fuhrländer FL250: 250 kW output, 29.5 meter rotor, stall-controlled (power curve provided by Lorax Energy Systems) Vestas RRB 47/600: 600 kW output, 47 meter rotor, pitch-controlled (power curve provided by Vestas RRB, India) Naknek, Alaska Wind Resource Report Turbine Power Output Comparison Manufacturer Vestas Northern Power Systems Vestas Fuhrländer Vestas RRBModel E15 NW100/20 V27 FL250 47/600Rated Power 75 kW 100 kW 225 kW 250 kW 600 kW Maximum Power Output 75 kW 104 kW 225 kW 300 kW 600 kW HubHeight (m)Mean Wind Speed (m/s) Capacity Factor (%) AnnualEnergyOutput(kW-hr/yr) Capacity Factor (%) AnnualEnergyOutput(kW-hr/yr) Capacity Factor (%) EnergyOutput(kW-hr/yr) Capacity Factor (%) EnergyOutput(kW-hr/yr) Capacity Factor (%) EnergyOutput(kW-hr/yr) 25 6.0717.9 117,50022.9 200,40032 6.3220.0 131,20025.2 220,50026.7 525,500 42 6.6729.7 585,60029.8 652,20050 6.9131.8 626,80031.9 698,60031.1 1,635,70060 7.1733.4 1,754,700Capacity Factor <20% Capacity Factor >20%, <30% Capacity Factor >30%, <40% Capacity Factor >40%, <50% Capacity Factor >50% V3 Energy LLC 17 of 21 Naknek, Alaska WV3 Energy LLC ind Resource Report 18 of 21 Fuel Cost Avoided for Electrical Energy Generation by Diesel Genset Fuel Price (dollars delivered) Turbine Annual Energy Output(kW-hr/yr) FuelQuantityAvoided(gallons) $2.00 $2.25 $2.50 $2.75 $3.00 $3.25 $3.50HubHeight (m)Vestas E15117,500 7,581 $15,161 $17,056 $18,952 $20,847 $22,742 $24,637 $26,532 25131,200 8,465 $16,929 $19,045 $21,161 $23,277 $25,394 $27,510 $29,626 32NPS NW100/20 200,400 12,929 $25,858 $29,090 $32,323 $35,555 $38,787 $42,019 $45,252 25220,500 14,226 $28,452 $32,008 $35,565 $39,121 $42,677 $46,234 $49,790 32Vestas V27 525,500 33,903 $67,806 $76,282 $84,758 $93,234 $101,710 $110,185 $118,661 32585,600 37,781 $75,561 $85,006 $94,452 $103,897 $113,342 $122,787 $132,232 42626,800 40,439 $80,877 $90,987 $101,097 $111,206 $121,316 $131,426 $141,535 50Fuhrländer FL250 652,200 42,077 $84,155 $94,674 $105,194 $115,713 $126,232 $136,752 $147,271 42698,600 45,071 $90,142 $101,410 $112,677 $123,945 $135,213 $146,481 $157,748 50Vestas RRB 47/600 1,635,700 105,529 $211,058 $237,440 $263,823 $290,205 $316,587 $342,969 $369,352 501,754,700 113,206 $226,413 $254,715 $283,016 $311,318 $339,619 $367,921 $396,223 60Note: Naknek Electric Association energy production efficiency = 15.5 kW-hr/gal Note: Assumes 100% turbine availability Naknek, Alaska Wind Resource Report Temperature Conversion Chart °C to °F °C °F °C °F °C °F -40 -40 -10 14 20 68 -39 -38.2 -9 15.8 21 69.8 -38 -36.4 -8 17.6 22 71.6 -37 -34.6 -7 19.4 23 73.4 -36 -32.8 -6 21.2 24 75.2 -35 -31 -5 23 25 77 -34 29.2 -4 24.8 26 78.8 -33 -27.4 -3 26.6 27 80.6 -32 -25.6 -2 28.4 28 82.4 -31 -23.8 -1 30.2 29 84.2 -30 -22 0 32 30 86 -29 -20.2 1 33.8 31 87.8 -28 -18.4 2 35.6 32 89.6 -27 -16.6 3 37.4 33 91.4 -26 -14.8 4 39.2 34 93.2 -25 -13 5 41 35 95 -24 -11.2 6 42.8 36 96.8 -23 -9.4 7 44.6 37 98.6 -22 -7.6 8 46.4 38 100.4 -21 -5.8 9 48.2 39 102.2 -20 -4 10 50 40 104 -19 -2.2 11 51.8 41 105.8 -18 -0.4 12 53.6 42 107.6 -17 1.4 13 55.4 43 109.4 -16 3.2 14 57.2 44 111.2 -15 5 15 59 45 113 -14 6.8 16 60.8 46 114.8 -13 8.6 17 62.6 47 116.6 -12 10.4 18 64.4 48 118.4 -11 12.2 19 66.2 49 120.2 V3 Energy LLC 19 of 21 Naknek, Alaska Wind Resource Report Wind Speed Conversion Chart m/s to mph m/s mph m/s mph m/s mph 0.5 1.1 10.5 23.5 20.5 45.9 1.0 2.2 11.0 24.6 21.0 47.0 1.5 3.4 11.5 25.7 21.5 48.1 2.0 4.5 12.0 26.8 22.0 49.2 2.5 5.6 12.5 28.0 22.5 50.3 3.0 6.7 13.0 29.1 23.0 51.4 3.5 7.8 13.5 30.2 23.5 52.6 4.0 8.9 14.0 31.3 24.0 53.7 4.5 10.1 14.5 32.4 24.5 54.8 5.0 11.2 15.0 33.6 25.0 55.9 5.5 12.3 15.5 34.7 25.5 57.0 6.0 13.4 16.0 35.8 26.0 58.2 6.5 14.5 16.5 36.9 26.5 59.3 7.0 15.7 17.0 38.0 27.0 60.4 7.5 16.8 17.5 39.1 27.5 61.5 8.0 17.9 18.0 40.3 28.0 62.6 8.5 19.0 18.5 41.4 28.5 63.8 9.0 20.1 19.0 42.5 29.0 64.9 9.5 21.3 19.5 43.6 29.5 66.0 10.0 22.4 20.0 44.7 30.0 67.1 Distance Conversion m to ft m ft m ft 5 16 35 115 10 33 40 131 15 49 45 148 20 66 50 164 25 82 55 180 30 98 60 197 V3 Energy LLC 20 of 21 Naknek, Alaska Wind Resource Report Selected definitions (courtesy of Windographer® software by Mistaya Engineering Inc.) Wind Power Class The wind power class is a number indicating the average energy content of the wind resource. Wind power classes are based on the average wind power density at 50 meters above ground, according to the following table. Source: Wind Energy Resource Atlas of the United States (http://rredc.nrel.gov/wind/pubs/atlas/tables/A-8T.html) Wind Power Class Description Power Density at 50m (W/m 2) 1 Poor 0-200 2 Marginal 200-300 3 Fair 300-400 4 Good 400-500 5 Excellent 500-600 6 Outstanding 600-800 7 Superb 800-2000 Windographer classifies any wind resource with an average wind power density above 2000 W/m2 as class 8. Probability Distribution Function The probability distribution function f(x) gives the probability that a variable will take on the value x. It is often expressed using a frequency histogram, which gives the frequency with which the variable falls within certain ranges or bins. Wind Turbine Power Regulation All wind turbines employ some method of limiting power output at high wind speeds to avoid damage to mechanical or electrical subsystems. Most wind turbines employ either stall control or pitch control to regulate power output. A stall-controlled turbine typically has blades that are fixed in place, and are designed to ex- perience aerodynamic stall at very high wind speeds. Aerodynamic stall dramatically reduces the torque produced by the blades, and therefore the power produced by the turbine. On a pitch-controlled turbine, a controller adjusts the angle (pitch) of the blades to best match the wind speed. At very high wind speeds the controller increasingly feathers the blades out of the wind to limit the power output. V3 Energy LLC 21 of 21