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HomeMy WebLinkAboutKokhanok Wind Resource Report - Mar 2007Kokhanok, Alaska Wind Resource Report Report written by: Douglas Vaught, P.E., V3 Energy, LLC Photo © Doug Vaught Summary Information The wind resource in Kokhanok is superb by any measure – the winds are steady, smooth, low shear, highly directional and high power class. The selected wind site, near the tip of the spit of land jutting into Lake Iliamna (see photo above) is ideal for wind turbine installations as it is V3 Energy, LLC 1 of 28 Kokhanok, Alaska Wind Resource Report relatively far from the village but near an existing overhead power line, is comprised of stable rocky soil, and is in a location unlikely to be desired for other village uses (because of the wind). Meteorological Tower Data Synopsis Wind power class Class 6 – Outstanding Wind speed annual average (30 meters) 7.84 m/s Maximum wind gust (2 sec. average) 40.1 m/s (Nov. 2004) Mean wind power density (50 meters) 763 W/m2 (calculated) Mean wind power density (30 meters) 690 W/m2 (measured) Weibull distribution parameters k = 1.64, c = 8.77 m/s Turbulence intensity 0.0985 (low) Roughness class 0.00 (smooth) Power law exponent 0.0725 (very low wind shear) Data start date August 12, 2004 Data end date June 14, 2006 Community Profile Current Population:179 (2005 State Demographer est.) Pronunciation/Other Names:(KOCK-hone-ack); alt. Kakhonak Incorporation Type:Unincorporated Borough Located In:Lake & Peninsula Borough School District:Lake & Peninsula Schools Regional Native Corporation:Bristol Bay Native Corporation Location: Kokhanok is located on the south shore of Iliamna Lake, 22 miles south of Iliamna and 88 miles northeast of King Salmon. It lies at approximately 59.441600° North Latitude and -154.755140° West Longitude. (Sec. 32, T008S, R032W, Seward Meridian.) Kokhanok is located in the Iliamna Recording District. The area encompasses 21.3 sq. miles of land and 0.1 sq. miles of water. History: This fishing village was first listed in the U.S. Census in 1890 by A.B. Schanz. The community was relo- cated to higher ground a few years ago when the rising level of Iliamna Lake threatened several commu- nity buildings. Culture: The village has a mixed Native population, primarily Alutiiq and Yup'ik. Subsistence activities are the focal point of the culture and lifestyle. The sale or importation of alcohol is banned in the village. Economy: The school is the largest employer in Kokhanok. Commercial fishing has declined since several limited entry permits were sold. Some residents travel to the Bristol Bay area each summer to fish; eight persons currently hold commercial fishing permits. People heavily rely on subsistence activities; many families have a summer fish camp near the Gibraltar River. Salmon, trout, grayling, moose, bear, rabbit, porcupine and seal are utilized. V3 Energy, LLC 2 of 28 Kokhanok, Alaska Wind Resource Report Facilities: Bedrock has made the development of water and sewer facilities difficult. The Village operates a piped water and sewer system that serves 35 households. The water treatment plant is currently being up- graded. The school operates its own well and water treatment facility. Kokhanok generates power only during the summer months; in winter, electricity is purchased from the School District. Transportation: Kokhanok is accessible by air and water. A State-owned 2,920' long by 60' wide gravel airstrip and a sea- plane base serve scheduled and charter air services from Anchorage, Iliamna, and King Salmon. Sup- plies delivered by barge via the Kvichak River must be lightered to shore. There are no docking facilities. The community wants to develop a boat harbor and launch ramp. Skiffs, ATVs and trucks are common forms of local transportation. Climate: Kokhanok lies in the transitional climatic zone. Average summer temperatures range from 40 to 64 F; win- ter temperatures average 3 to 30 F. The record high is 84 F; the record low, -47 F. Precipitation averages 32 inches annually, including 89 inches of snowfall. Wind storms and ice fog are common during winter. (Above information from State of Alaska Department of Commerce, Community, and Economic Develop- ment website, www.dced.state.ak.us) Tower Sensor Information Channel Sensor type Height Multiplier Offset Orientation 1 NRG #40 anemometer 30 m 0.765 0.35 north 2 NRG #40 anemometer 21 m 0.765 0.35 north 7 NRG #200P wind vane 29 m 0.351 350 south 9 NRG #110S Temp C 2 m 0.136 -86.383 N/A Site Information and Location Site number 2257 Site Description Near tip of spit jutting north into Lake Iliamna Latitude/longitude N 59° 26.907’ W 154° 45.835’ Site elevation 23 meters Datalogger type NRG Symphonie Tower type NRG 30-meter tall tower, 152 mm (6 in) diameter V3 Energy, LLC 3 of 28 Kokhanok, Alaska Wind Resource Report V3 Energy, LLC 4 of 28 Kokhanok, Alaska Wind Resource Report Data 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 October was nearly 100%, but during the months of November through April some data was filtered. Temperature data recovery was 100 percent, indicating full functioning of the temperature sen- sor. Because data recovery was so good, data was not synthesized to replace data missing from icing events. 30 m anemometer 21 m anemometer Wind vane Temperature Year Month Records Recovery Records Recovery Records Recovery Records Recovery Rate (%) Rate (%) Rate (%) Rate (%) 2004 Aug 2,812 100.0 2,812 100.0 2,812 100.0 2,812 100.0 2004 Sep 4,320 100.0 4,320 100.0 4,320 100.0 4,320 100.0 2004 Oct 4,462 100.0 4,462 100.0 4,462 100.0 4,464 100.0 2004 Nov 4,291 99.3 4,295 99.4 4,291 99.3 4,320 100.0 2004 Dec 4,371 97.9 4,370 97.9 4,370 97.9 4,464 100.0 2005 Jan 4,357 97.6 4,353 97.5 4,353 97.5 4,464 100.0 2005 Feb 3,957 98.1 3,951 98.0 3,951 98.0 4,032 100.0 2005 Mar 4,427 99.2 4,428 99.2 4,427 99.2 4,464 100.0 2005 Apr 4,266 98.8 4,252 98.4 4,252 98.4 4,320 100.0 2005 May 4,463 100.0 4,463 100.0 4,463 100.0 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 4,464 100.0 4,464 100.0 4,464 100.0 4,464 100.0 2005 Nov 4,285 99.2 4,288 99.3 4,285 99.2 4,320 100.0 2005 Dec 4,383 98.2 4,374 98.0 4,374 98.0 4,464 100.0 2006 Jan 4,275 95.8 4,237 94.9 4,232 94.8 4,464 100.0 2006 Feb 3,878 96.2 3,892 96.5 3,878 96.2 4,032 100.0 2006 Mar 4,213 94.4 4,179 93.6 4,166 93.3 4,464 100.0 2006 Apr 4,234 98.0 4,230 97.9 4,219 97.7 4,320 100.0 2006 May 4,453 99.8 4,458 99.9 4,453 99.8 4,464 100.0 2006 Jun 1,938 100.0 1,938 100.0 1,938 100.0 1,938 100.0 All data 95,417 98.8 95,334 98.7 95,278 98.6 96,622 100.0 V3 Energy, LLC 5 of 28 Kokhanok, Alaska Wind Resource Report Measured Wind Speeds The Channel 1 (30-meter) anemometer annual wind speed average for the reporting period is 7.84 m/s and the Channel 2 (20-meter) anemometer wind speed average is 7.66 m/s. 30 m anemometer 21 m anemometer Month Mean Max Std. Dev. Weibull k Weibull c Mean Max (m/s) (m/s) (m/s) (m/s) (m/s) (m/s) Jan 7.73 21.9 4.51 1.72 8.64 7.53 21.7 Feb 10.01 27.2 6.08 1.61 11.11 9.81 26.8 Mar 8.53 27.4 4.86 1.77 9.55 8.35 26.9 Apr 7.22 27.3 4.46 1.64 8.05 7.00 26.7 May 7.09 24.1 4.81 1.41 7.74 6.97 23.6 Jun 7.84 25.3 5.01 1.49 8.60 7.60 24.7 Jul 7.03 19.1 3.49 2.04 7.87 6.79 18.6 Aug 6.68 20.7 3.60 1.86 7.48 6.53 20.2 Sep 7.33 26.8 3.85 1.93 8.22 7.23 26.1 Oct 6.86 25.6 4.22 1.63 7.63 6.77 25.0 Nov 8.46 28.4 4.63 1.87 9.51 8.27 27.4 Dec 9.32 27.2 5.62 1.61 10.34 9.08 26.5 Annual 7.84 28.4 4.79 1.64 8.77 7.66 27.4 V3 Energy, LLC 6 of 28 Kokhanok, Alaska Wind Resource Report Daily wind profile The daily wind profile indicates that the lowest wind speeds of the day occur in the morning hours of 5 a.m. to 7 a.m. and the highest wind speeds of the day occur during the afternoon hours of 1 p.m. to 4 p.m. The daily variation of wind speed is minimal on an annual basis but more pronounced on a monthly basis. V3 Energy, LLC 7 of 28 Kokhanok, Alaska Wind Resource Report Time Series of Wind Speed Averages As expected, the highest winds occur during the winter months and the lowest winds during spring, summer and early autumn, but in the case of Kokhanok, this is relative as the monthly average wind speeds are very good all year round. The unusually low winds measured in Janu- ary 2006 were due to a persistent high pressure system over Alaska that month that yielded calm winds and extremely cold weather Statewide. V3 Energy, LLC 8 of 28 Kokhanok, Alaska Wind Resource Report Wind Shear Profile The power law exponent was calculated at 0.0656 indicating very low wind shear at the Kok- hanok test site. The seasonal wind shear profile graph indicates that higher wind shear occurs in the summer months and lower wind shear in the winter months and that shear is lowest to the east and slightly higher to the southwest, although in all directions the wind shear is very low. The practical application of this data is that a low turbine tower height is possible as there will be only a marginal gain in wind speed/power recovery with additional height. A tower height/power recovery/construction cost tradeoff study is advisable. V3 Energy, LLC 9 of 28 Kokhanok, Alaska Wind Resource Report V3 Energy, LLC 10 of 28 Kokhanok, Alaska Wind Resource Report 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. Weibull parameters are k = 1.64, c = 8.77 m/s. The PDF information is shown visually in another manner in the second graph, the Cumulative Distribution Function. V3 Energy, LLC 11 of 28 Kokhanok, Alaska Wind Resource Report Wind Roses Kokhanok winds are highly directional; the wind frequency rose indicates exclusively easterly and southwesterly winds. This observation is strongly reinforced with reference to the power density rose below. Power producing winds are almost entirely easterly. The practical applica- tion of this information is that the test site on the spit (the location of the Kokhanok’s old airport) is ideal in that easterly winds travel a long fetch of water before traversing the site. If more than one turbine were to be placed in Kokhanok, they should be oriented north-south with a minimum 1.5 rotor diameter placement hub-to-hub. The indication below of 24 percent calm winds is cal- culated with a 4 m/s wind speed threshold, the typical cut-in speed of wind turbines. Wind Frequency Rose (30 meters) V3 Energy, LLC 12 of 28 Kokhanok, Alaska Wind Resource Report Wind Power Density Rose (30 meters) Wind Power Density Rose by Month (30 meters) V3 Energy, LLC 13 of 28 Kokhanok, Alaska Wind Resource Report V3 Energy, LLC 14 of 28 Kokhanok, Alaska Wind Resource Report Turbulence Intensity The turbulence intensity (TI) is quite acceptable for all wind direction, with a mean turbulence intensity of 0.0985 (30 meters) and 0.100 (20 meters), indicating very smooth air. These TIs are calculated with a threshold wind speed of 4 m/s. The spike of relatively high turbulence to the south and southeast in both graphs is due to the infrequent winds from these sectors. The most important TI is for winds from the east. 30-meter Turbulence Intensity 21-meter Turbulence Intensity V3 Energy, LLC 15 of 28 Kokhanok, Alaska Wind Resource Report IEC Turbulence Intensity Standards Turbulence at the Kokhanok project test site is well within International Electrotechnical Com- mission (IEC) standards at all measured wind speeds and from all four quadrants of the wind rose. V3 Energy, LLC 16 of 28 Kokhanok, Alaska Wind Resource Report Turbulence Table Bin Bin Endpoints Records Standard Deviation Mean Standard Deviation Characteristic Midpoint Lower Upper In of Wind Speed Turbulence of Turbulence Turbulence (m/s) (m/s) (m/s) Bin (m/s) Intensity Intensity Intensity 1 0.5 1.5 4729 0.400 0.441 0.180 0.620 2 1.5 2.5 6175 0.409 0.214 0.121 0.335 3 2.5 3.5 6396 0.421 0.144 0.079 0.222 4 3.5 4.5 6665 0.456 0.116 0.059 0.174 5 4.5 5.5 7029 0.529 0.107 0.047 0.154 6 5.5 6.5 7605 0.607 0.102 0.041 0.144 7 6.5 7.5 7526 0.707 0.102 0.038 0.140 8 7.5 8.5 7705 0.798 0.100 0.035 0.136 9 8.5 9.5 7016 0.875 0.098 0.035 0.133 10 9.5 10.5 6397 0.922 0.093 0.035 0.127 11 10.5 11.5 5770 1.005 0.092 0.031 0.123 12 11.5 12.5 4517 1.096 0.092 0.030 0.121 13 12.5 13.5 3511 1.200 0.093 0.028 0.121 14 13.5 14.5 2814 1.317 0.094 0.026 0.120 15 14.5 15.5 2410 1.394 0.093 0.026 0.119 16 15.5 16.5 1882 1.489 0.093 0.025 0.119 17 16.5 17.5 1380 1.604 0.095 0.025 0.120 18 17.5 18.5 1231 1.726 0.096 0.025 0.121 19 18.5 19.5 954 1.811 0.096 0.024 0.119 20 19.5 20.5 638 1.945 0.098 0.023 0.121 21 20.5 21.5 404 2.066 0.099 0.021 0.120 22 21.5 22.5 261 2.212 0.101 0.023 0.124 23 22.5 23.5 167 2.303 0.101 0.021 0.122 24 23.5 24.5 90 2.326 0.097 0.020 0.117 25 24.5 25.5 96 2.484 0.100 0.022 0.122 26 25.5 26.5 55 2.598 0.100 0.022 0.122 27 26.5 27.5 28 2.500 0.093 0.014 0.107 28 27.5 28.5 2 3.150 0.112 0.020 0.133 29 28.5 29.5 0 3.150 0.112 0.020 0.133 V3 Energy, LLC 17 of 28 Kokhanok, Alaska Wind Resource Report Air Temperature and Density Over the reporting period, Kokhanok had an average temperature of 4.5° C. The minimum re- corded temperature during the measurement period was -23.9° C and the maximum temperature was 25.5° C, indicating a wide variability of an ambient temperature operating environment im- portant to wind turbine operations. Consequent to Kokhanok’s cool temperatures, the average air density of 1.268 kg/m3 is approximately four percent higher than the standard air density of 1.2223 kg/m3 (14.8° C and 101.02 kPa at 23 m elevation), indicating that Kokhanok, 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 Density Month Mean Min Max Std. Dev. Mean Min Max Std. Dev. (°C) (°C) (°C) (°C) (kg/m³) (kg/m³) (kg/m³) (kg/m³) Jan -5.78 -22.3 5.7 7.81 1.317 1.262 1.403 0.0393 Feb -3.47 -23.9 10.2 7.33 1.306 1.242 1.412 0.0366 Mar -1.66 -15.1 7.3 5.02 1.297 1.255 1.364 0.0243 Apr 1.89 -15.8 16.6 4.93 1.280 1.215 1.367 0.0233 May 8.59 0.5 21.6 2.89 1.249 1.194 1.286 0.0127 Jun 12.34 3.9 24.6 2.76 1.233 1.182 1.270 0.0119 Jul 14.42 10.2 20.7 1.83 1.224 1.198 1.242 0.0078 Aug 14.67 7.2 25.5 2.58 1.223 1.178 1.255 0.0109 Sep 9.89 0.4 16.7 2.83 1.243 1.214 1.286 0.0125 Oct 6.10 -6.9 12.3 3.45 1.260 1.233 1.322 0.0158 Nov -2.21 -18.4 8.3 5.99 1.299 1.250 1.381 0.0291 Dec -0.68 -19.4 7.9 5.50 1.292 1.252 1.387 0.0269 Annual 4.51 -23.9 25.5 8.38 1.268 1.178 1.412 0.0394 V3 Energy, LLC 18 of 28 Kokhanok, Alaska Wind Resource Report Air Density DMap The DMap below is a visual indication of the daily and seasonal variations of air density (and hence temperature). Air densities higher than standard will yield higher turbine power than pre- dicted by turbine power curves, while densities lower than standard will yield lower turbine power than predicted. Density variance from standard is accounted for in the turbine perform- ance predictions. V3 Energy, LLC 19 of 28 Kokhanok, Alaska Wind Resource Report Wind Turbine Performance The turbine performance predictions noted below are based on 100 percent and 90 percent tur- bine availabilities. The 100 percent data is for use as a baseline of comparison, but it is realistic to expect ten percent or more of losses or downtime for wind turbines located in a small, remote community. Note that these performance estimates were predicted with use of Windographer® wind analysis software; power curves provided by manufacturers are not independently verified and are as- sumed to be accurate. The power curves are presented for a standard air density of 1.225 kg/m3 at 15° C temperature and 101.3 kPa pressure at sea level. However, the predictions of power pro- duction are density compensated by multiplying the standard density power output by the ratio of the measured air density to standard air density, accounting for the site elevation. A number of smaller village-scale grid-connected turbines are profiled in this report for compari- son purposes. These turbines were selected because they have market availability and they are deemed to be within a suitable range for consideration of wind power development in a village the size of Kokhanok. Southwest Skystream 3.7: 1.8 kW rated power output, 3.7 meter rotor diameter, stall- controlled. Available tower heights: 10.7 and 33.5 meters. Additional information is available at www.skystreamenergy.com. Bergey Excel-S: 10 kW rated power output, 6.7 meter rotor diameter, stall-controlled. Avail- able tower heights: 18, 24, 30, 37 and 43 meters. Additional information is available at www.bergey.com. V3 Energy, LLC 20 of 28 Kokhanok, Alaska Wind Resource Report Fuhrländer FL30:30 kW rated power output, 13 meter rotor, stall-controlled (power curve provided by Lorax Energy, LLC). Available tower heights: 26 and 30 meters. Additional in- formation is available at http://www.fuhrlaender.de/ and http://www.lorax-energy.com/. Entegrity eW-15:65 kW rated power output, 15 meter rotor, stall-controlled (power curve pro- vided by Entegrity Energy Systems). Available tower heights: 25 and 31 meters. Additional information is available at http://www.entegritywind.com/. V3 Energy, LLC 21 of 28 Kokhanok, Alaska W V3 Energy, LLC ind Resource Report 22 of 28 Vestas V15: 75 kW rated power output, 15 meter rotor, stall-controlled (power curve provided by Powercorp Alaska LLC). Available tower heights: 25, 31 and 34 meters. Additional infor- mation is available at http://www.pcorpalaska.com/. Northwind 100/20: 100 kW rated power output, 20 meter rotor (19 meter rotor blades with 0.6 meter blade root extensions added), stall-controlled (power curve provided by Northern Power Systems). Available tower heights: 25 and 32 meters. Additional information is available at http://www.northernpower.com/. Kokhanok, Alaska Wind Resource Report Turbine Power Output Comparison (100% availability) Annual Net Average Net HubHeightHub Height Wind Speed Time At Zero OutputTime At Rated OutputAverage Net Power OutputEnergyOutputCapacity Factor Turbine (m) (m/s) (%) (%) (kW) (kWh/yr) (%) Southwest Skystream 3.7 10.7 7.37 18.8 20.9 0.88 7,71148.9Southwest Skystream 3.7 33.5 7.92 17.6 23.6 0.96 8,42253.4Bergey Excel-S 18 7.63 11.5 10.1 3.81 33,37638.1Bergey Excel-S 30 7.86 12.4 10.5 3.96 34,70239.6Fuhrländer FL30 26 7.80 10.9 6.8 15.1 132,55945.9Fuhrländer FL30 30 7.86 11.2 7.0 15.3 134,06146.4Entegrity eW-15 60 Hz 25 7.78 24.6 10.3 25.3 221,97839.0Entegrity eW-15 60 Hz 31 7.88 24.3 10.6 25.9 226,84439.8Vestas V15 25 7.78 28.7 6.8 25.3 221,58533.7Vestas V15 31 7.88 28.2 7.0 25.9 226,99634.6Northern Power NW 100/20 25 7.78 24.6 9.2 37.4 327,96337.4Northern Power NW 100/20 32 7.90 24.3 9.4 38.4 336,19338.4Capacity Factor <20% Capacity Factor >20%, <30% Capacity Factor >30%, <40% Capacity Factor >40%, <50% Capacity Factor >50% Assumed turbine losses for predictions of average power output, annual energy output, and average capacity factor: Downtime (%) 0Array (%) 0Icing/soiling (%) 0Other (%) 0Total (%) 0Note: Calculated for the data period 8/12/04 to 6/14/06 V3 Energy, LLC 23 of 28 Kokhanok, Alaska Wind Resource Report Turbine Power Output Comparison (90% availability) Annual Net Average Net HubHeightHub Height Wind Speed Time At Zero OutputTime At Rated OutputAverage Net Power OutputEnergyOutputCapacity Factor Turbine (m) (m/s) (%) (%) (kW) (kWh/yr) (%) Southwest Skystream 3.7 10.7 7.37 18.8 20.9 0.80 6,96344.2Southwest Skystream 3.7 33.5 7.92 17.6 23.6 0.87 7,60648.2Bergey Excel-S 18 7.63 11.5 10.1 3.44 30,14134.4Bergey Excel-S 30 7.86 12.4 10.5 3.58 31,33835.8Fuhrländer FL30 26 7.80 10.9 6.8 13.7 119,71041.4Fuhrländer FL30 30 7.86 11.2 7.0 13.8 121,06741.9Entegrity eW-15 60 Hz 25 7.78 24.6 10.3 22.9 200,46135.2Entegrity eW-15 60 Hz 31 7.88 24.3 10.6 23.4 204,85636.0Vestas V15 25 7.78 28.7 6.8 22.8 200,10730.5Vestas V15 31 7.88 28.2 7.0 23.4 204,99331.2Northern Power NW 100/20 25 7.78 24.6 9.2 33.8 296,17333.8Northern Power NW 100/20 32 7.90 24.3 9.4 34.7 303,60634.7Capacity Factor <20% Capacity Factor >20%, <30% Capacity Factor >30%, <40% Capacity Factor >40%, <50% Capacity Factor >50% Assumed turbine losses for predictions of average power output, annual energy output, and average capacity factor: Downtime (%) 5Array (%) 0Icing/soiling (%) 3Other (%) 2Total (%) 9.69 (factors are multiplicative) Note: Calculated for the data period 8/12/04 to 6/14/06 V3 Energy, LLC 24 of 28 Kokhanok, Alaska WV3 Energy, LLC ind Resource Report 25 of 28 Annual Fuel Cost Avoided for Energy Generated by Wind Turbine vs. Diesel Generator Fuel Price (USD/gallon) Turbine AnnualEnergyOutput(kW-hr/yr) FuelQuantityAvoided(liters)FuelQuantityAvoided(gallons) $1.75 $2.00 $2.25 $2.50 $2.75 $3.00 $3.25Turbine HubHeight (m)Southwest Skystream 3.7 6,963 2,109 557 $975 $1,114 $1,253 $1,393 $1,532 $1,671 $1,810 10.7Southwest Skystream 3.7 7,606 2,303 608 $1,065 $1,217 $1,369 $1,521 $1,673 $1,825 $1,978 33.5Bergey Excel-S 30,141 9,128 2,411 $4,220 $4,823 $5,425 $6,028 $6,631 $7,234 $7,837 18Bergey Excel-S 31,338 9,490 2,507 $4,387 $5,014 $5,641 $6,268 $6,894 $7,521 $8,148 30Fuhrländer FL30 119,710 36,252 9,577 $16,759 $19,154 $21,548 $23,942 $26,336 $28,730 $31,125 26Fuhrländer FL30 121,067 36,663 9,685 $16,949 $19,371 $21,792 $24,213 $26,635 $29,056 $31,477 30Entegrity eW-15 60 Hz 200,461 60,706 16,037 $28,065 $32,074 $36,083 $40,092 $44,101 $48,111 $52,120 25Entegrity eW-15 60 Hz 204,856 62,037 16,388 $28,680 $32,777 $36,874 $40,971 $45,068 $49,165 $53,263 31Vestas V15 200,107 60,599 16,009 $28,015 $32,017 $36,019 $40,021 $44,024 $48,026 $52,028 25Vestas V15 204,993 62,078 16,399 $28,699 $32,799 $36,899 $40,999 $45,098 $49,198 $53,298 31Northern Power NW 100/20 296,173 89,691 23,694 $41,464 $47,388 $53,311 $59,235 $65,158 $71,082 $77,005 25Northern Power NW 100/20 303,606 91,942 24,288 $42,505 $48,577 $54,649 $60,721 $66,793 $72,865 $78,938 32Notes: 1. Kokhanok electrical energy production efficiency assumed to be 12.5 kW-hr/gal 2. Assumes 90% wind turbine availability with no diversion of power to a thermal or other dump load 3. Assumes linear diesel generator fuel efficiency (i.e., 1:1 tradeoff of wind turbine kW-hr to diesel genset kW-hr) 4. Calculated for the data period 8/12/04 to 6/14/06 Kokhanok, 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 26 of 28 Kokhanok, Alaska Wind Resource Report Wind Speed Conversion Chart, m/s to mph m/s mph m/s mph m/s mph m/s mph m/s mph 0.5 1.1 10.5 23.5 20.5 45.9 30.5 68.2 40.5 90.6 1.0 2.2 11.0 24.6 21.0 47.0 31.0 69.3 41.0 91.7 1.5 3.4 11.5 25.7 21.5 48.1 31.5 70.5 41.5 92.8 2.0 4.5 12.0 26.8 22.0 49.2 32.0 71.6 42.0 93.9 2.5 5.6 12.5 28.0 22.5 50.3 32.5 72.7 42.5 95.1 3.0 6.7 13.0 29.1 23.0 51.4 33.0 73.8 43.0 96.2 3.5 7.8 13.5 30.2 23.5 52.6 33.5 74.9 43.5 97.3 4.0 8.9 14.0 31.3 24.0 53.7 34.0 76.1 44.0 98.4 4.5 10.1 14.5 32.4 24.5 54.8 34.5 77.2 44.5 99.5 5.0 11.2 15.0 33.6 25.0 55.9 35.0 78.3 45.0 100.7 5.5 12.3 15.5 34.7 25.5 57.0 35.5 79.4 45.5 101.8 6.0 13.4 16.0 35.8 26.0 58.2 36.0 80.5 46.0 102.9 6.5 14.5 16.5 36.9 26.5 59.3 36.5 81.6 46.5 104.0 7.0 15.7 17.0 38.0 27.0 60.4 37.0 82.8 47.0 105.1 7.5 16.8 17.5 39.1 27.5 61.5 37.5 83.9 47.5 106.3 8.0 17.9 18.0 40.3 28.0 62.6 38.0 85.0 48.0 107.4 8.5 19.0 18.5 41.4 28.5 63.8 38.5 86.1 48.5 108.5 9.0 20.1 19.0 42.5 29.0 64.9 39.0 87.2 49.0 109.6 9.5 21.3 19.5 43.6 29.5 66.0 39.5 88.4 49.5 110.7 10.0 22.4 20.0 44.7 30.0 67.1 40.0 89.5 50.0 111.8 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 27 of 28 Kokhanok, 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 28 of 28