Renewable Energy Technology Assessments - Kauai Island Utility ...

More documents

Recommendations

Info

Kaua’i Island Utility Cooperative Renewable Energy Technology Assessments 9.0 Wind where ρ is the air density, A is the rotor area intercepting the wind, and V is the upstream wind velocity. Of these, wind velocity is most important. The cubic dependence of wind power on wind speed implies that energy output, and consequently the economics of a wind turbine installation, is highly sensitive to wind speed. A 10 percent change in velocity results in about 30 percent change in available energy; thus wind speed is one of the most critical factors in determining wind energy generation. Wind power density is expressed in Watts per meter squared (W/m 2 ) and incorporates the combined effects of the time variant wind speed and the dependence of wind power on both air density and cube of wind speed. The figures in this report show wind power density categorized by wind power class from 0-7, as discussed in Section 3.8 previously. Average wind speeds vary significantly geographically. Local factors such as high altitude, unobstructed terrain, lofty airflow height, and natural wind tunneling features cause some areas to have inherently higher wind speeds than others. Wind speed is affected by the height above ground level (AGL). Ideally, wind resources assessments are performed at the hub height of the candidate wind turbine (40 to 80 m); however, if measurements at the actual hub height (Z) are not available, wind speed (v) can be extrapolated from other measurement heights. The most common method is the following relation, known as the one-seventh power law: v v 2 1 ⎛ Z = ⎜ ⎝ Z 2 1 ⎞ ⎟ ⎠ 1/ 7 or P2 ⎛ Z 2 ⎞ = ⎜ ⎟ P1 ⎝ Z1 ⎠ For example, based on the one-seventh power law, wind speed and wind power (P) at 30 m above the ground are respectively 17 and 60 percent greater than at 10 m. Although a convenient approximation, the one-seventh power law has no theoretical basis. A custom power law can be applied to a specific site data by measuring wind speed at two or more different heights on the same tower and determining the wind sheer factor (s) for a specific site. Once a sheer factor is known for a site wind speed can be scaled using the following equation: Z v v Z ⎟ ⎛ 2 ⎞ ⎜ 2 = 1 * ⎝ 1 ⎠ The site-specific nature of the wind energy resource underscores the need for well planned assessments. The one-seventh power law may be inadequate because it is only an approximation and the amount of wind energy available is strongly affected by the local terrain. If the wind sheer factor for a specific site is known, a more accurate power estimate can be made from non hub height data. A thorough study of the wind at a 21 March 2005 9-2 Black & Veatch S 3 / 7
Kaua’i Island Utility Cooperative Renewable Energy Technology Assessments 9.0 Wind particular site is advisable before installing wind turbines. Collecting data at multiple hub heights and locations allows for the optimum design and placement of individual turbines in large turbine arrays or on complex terrain. In this report, a wind sheer factor was estimated for each site based on the local topography. The site wind resource is of critical importance to a wind project because it is the fuel for the power plant. Wind generation suffers in notoriety because it is intermittent – subject to the strength and consistency of the wind. Because of this, the best way to ensure a successful project is to collect as much data as possible and make informed decisions at every step of the project development. This data should be compared against historical data for the area for the longest possible time span that data can be obtained. For the purposes of this study, the wind resource has been evaluated using data acquired in three areas: at the western edge of Hanapepe Bay (Port Allen site), at the southern end of a ridge north of Hanapepe (Hanapepe site), in the foothills of Mount Puu Ehu on Hawaiian Home Lands property (Anahola site). Four other areas; Omao, Kokee, Poipu, and Maha’ulepu, are analyzed to a lesser degree using the validated Kauai wind map. It is assumed that a 7 MW wind project would be developed at each site, with the exception of the Kokee site, where only a 2 MW project development is assumed. The wind data analyzed in this study was collected by anemometers mounted at 90 feet (27 m) above ground level on towers near the Anahola and Hanapepe sites, as well as an anemometer mounted at 30 feet (9 m) above ground level near Port Allen. The period of time that the analyses cover is one calendar year for each site: 1994 for both Anahola and Hanapepe, and 1997 for Port Allen. These full-year data sets are enough to create preliminary wind models for these three projects sufficient for this study. However, prior to making the large investment for any of these projects, Black & Veatch advises KIUC to install and collect data from taller towers (preferably at the hub height of the proposed turbines) for a period of not less than one year. In general, wind on Kauai is stronger in the summer than winter, and in the afternoons than in the evening or morning. A figure showing diurnal (hourly) and seasonal wind variations in the Port Allen data (extrapolated to 164 ft, 50 m) is shown in Figure 9-1. 21 March 2005 9-3 Black & Veatch
Page 1 and 2:
11401 Lamar Black & Veatch Corporat
Page 3 and 4:
Page 3 Kaua’i Island Utility Coop
Page 5 and 6:
Principal Investigators: Ryan Pletk
Page 7 and 8:
Kaua’i Island Utility Cooperative
Page 9 and 10:
Page 11 and 12:
Page 13 and 14:
Page 15 and 16:
Page 17 and 18:
Page 19 and 20:
Page 21 and 22:
Page 23 and 24:
Page 25 and 26:
Page 27 and 28:
Page 29 and 30:
Page 31 and 32:
Page 33 and 34:
Page 35 and 36:
Page 37 and 38:
Page 39 and 40:
Page 41 and 42:
Page 43 and 44:
Page 45 and 46:
Page 47 and 48:
Page 49 and 50:
Page 51 and 52:
Page 53 and 54:
Page 55 and 56:
Page 57 and 58:
Page 59 and 60:
Page 61 and 62:
Page 63 and 64:
Page 65 and 66:
Page 67 and 68:
Page 69 and 70:
Page 71 and 72:
Page 73 and 74:
Page 75 and 76:
Page 77 and 78:
Page 79 and 80:
Page 81 and 82:
Page 83 and 84:
Page 85 and 86:
Page 87 and 88:
Page 89 and 90:
Page 91 and 92:
Page 93 and 94:
Page 95 and 96:
Page 97 and 98:
Page 99 and 100:
Page 101 and 102:
Page 103 and 104:
Page 105 and 106:
Page 107 and 108:
Page 109 and 110:
Page 111 and 112:
Page 113 and 114:
Page 115 and 116:
Page 117 and 118:
Page 119 and 120:
Page 121 and 122:
Page 123 and 124:
Page 125 and 126:
Page 127 and 128:
Page 129 and 130:
Page 131 and 132:
Page 133 and 134:
Page 135 and 136:
Page 137 and 138:
Page 139 and 140:
Page 141 and 142:
Page 143 and 144:
Page 145 and 146:
Page 147 and 148:
Page 149 and 150:
Page 151 and 152:
Page 153 and 154:
Page 155 and 156:
Page 157 and 158:
Page 159 and 160:
Page 161 and 162:
Page 163 and 164:
Page 165 and 166:
Page 167 and 168:
Page 169 and 170:
Page 171 and 172:
Page 173 and 174:
Page 175 and 176:
Page 177 and 178:
Page 179 and 180:
Page 181 and 182:
Page 183 and 184:
Page 185 and 186:
Page 187 and 188:
Page 189 and 190: Kaua’i Island Utility Cooperative
Page 239: Kaua’i Island Utility Cooperative
Page 291 and 292:
Page 293 and 294:
Page 295 and 296:
Page 297 and 298:
show all

Renewable Energy Technology Assessments - Kauai Island Utility ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?