2.1 Typical Site
NRG towers, 40 m tall were used at three sites. Most of the other sites were on existing radio towers. Seawest, a developer based in California, started a project of resource assessment in the Northern Texas Panhandle and Eastern New Mexico. AEI purchased towers and data collection equipment from Seawest at sites 13 and 14. The landowner retained the tower and equipment at site 15, however AEI upgraded the data logger, installed more sensors, and maintained the site.
Two anemometers were installed at 10, 25 and 40 m (180 deg apart), wind direction at 10, 25, and 40 m, and solar horizontal and vertical (Li-Cor) and temperature at 3 m. Where data were collected at heights above 40 m, two anemometers were placed at the higher levels and one anemometer at the lower levels. At some of the sites, there is only 1 wind vane at 40 m, and at the SeaWest sites, there was a wind vane at 50 m. (Appendix 1).
Stations information on towers, booms, sensors, etc. and topographic maps (7.5 minute quadrangle maps) are kept at AEI. The sites with existing radio towers, as expected, were at higher elevations in the local region, except for Matagorda. While these existing radio towers have better territory
coverage from exposed locations, they are often not in the best location for wind resource assessment. Wind resource assessment at optimum locations, such as ridge lines and mesas, is still left to developers. In fact, wind farms in West Texas have been installed on a ridge line near Big Spring and on a mesa near McCamey, even though the general region is a class 2 wind area.
Site 6, Amarillo: Tower is located on SPS property about 3 miles north of the Harrington Power Plant. Terrain is relatively flat with short grass and a center pivot irrigation system 1/4 mile east.
Site 7, Hueco Mountains: The Hueco Mountains are a small range east of El Paso trending primarily north-south in El Paso and Hudspeth Counties. This site was placed on state land as the General Land Office is actively seeking potential sites for development of wind power projects. The site, close to the county line, is remote and access is difficult. The site is a broad hill in the mountain range, open to East-West winds, with higher hills and a major transmission line within 1/2 mile. The area is mostly rock with very little vegetation. Anchor holes were drilled into the surface rock and the anchors were cemented into the holes for the 40 m tower. Installation of the tower failed during the first attempt to lift it into place, with the subsequent loss of 15 m of the tower. This section was replaced and the site was operational November, 1994. An antenna extension was required for proper communication with a U.S. cellular service provider rather than the stronger provider in Mexico.
Site 8, Guadalupe Pass: The Delaware Mountains, extend from the New Mexico border, south to Van Horn in Culberson County. At the northern end is the peak, El Capitan of the Guadalupe Mountains, which is much higher and forces the east-west winds across the Delaware range. There is a desert basin to the west and elevation declines towards the east. The little vegetation is sparse clumps of grass and yucca.
Site 9, Matagorda: The tower is located about 1 mile from Matagorda within 300 yards of the inland waterway and about 5 miles from the Gulf of Mexico. As expected, this site shows the most degradation from salt spray/humidity. Sealed extruded metal tubing, painted mounting booms and all stainless materials were used in place of standard equipment. The site is level with a ground cover of sawgrass and very small bushes (< 3 m).
Site 10, Blue Grove: Blue Grove is around 10 miles south of Henrietta. The Texas Utilities (TU) microwave tower is in the middle of an oil field and is well exposed in all directions. The ground cover is Johnson grass with some scrub oak (4 m) more than 50 m to the north and 100 m to the southeast. The microwave antenna is within 4 m of the sensors at 50 m.
Tower access is very limited since TU radio personnel must be involved. Tower climbing is restricted to use TU safety equipment. Damaged sensors are noted by TU radio personnel within days and reported by e-mail to AEI. This is faster than the weekly call-in/verification. This demonstrates that a good working relation between field workers interested in a project and the data collection group is important in reducing downtime.
Site 11, Mirando City: This site is 2 miles south of Mirando City and about 40 miles east of Laredo on a broad ridge with the elevation declining to the east to the Gulf and to the west to the Rio Grande River. The vegetation is thick mesquite (3 m). There are radio antennas almost continuously from 50 to 100 m. There is a major transmission line 4 miles to the north.
Site 12, Maryneal: This site is 1/2 mile west of Maryneal. This was to be a 100 m tower but construction was halted at 50 m due to a lack of interest in rental space for antennas. One problem was that the large anti-torsion brackets kept us from mounting the booms at 50 m, so they were installed at 45 m. This site is located in a wheat field and the east-west average elevation is around 100 m above the land one mile to the south. There are large power users in the area.
Site 13, Dalhart: This site is on the Pitchfork ranch, 14 miles north of Dalhart. The area is very flat plains with short grass The original configuration had the logger placed in a storage bin below the ground, with a hardened cover (cow proof). The disadvantage was the container filled with water during the rain storms. The logger was moved to the tower, as at the other sites.
Site 14, White Deer: This site on the 6666 ranch, 6 miles west of White Deer. This area is also flat grassland, with a playa 3/4 mile to the west.
Site 15, Quay County, NM: This site on Mesa Redonda is 10 miles south of Tucumcari, NM. The mesa is C shaped with the open face of the C facing North and the tower is located on the southern side in the middle of the mesa. This was the most difficult site to maintain and reach, requiring a 4 wheel drive vehicle. The land owner also restricted access during periods of poor weather due to increased damage to the road. This also meant that routine maintenance had to scheduled when owner�s vehicle was available. AEI has since purchased a 4 wheel drive pickup and can now access the site when the road is dry.
Site 16, Denver City: This was a site on SPS property at the power substation 3 miles east of Denver City. This tower is a four sided angle iron with the vertex of the tower faces pointing to the main compass points. Access to this site must be coordinated with SPS. Tower is located in an oil field in flat terrain. There is a tree wind break (4 m evergreens) 1/8 mile to the east and an old power plant (12 m height) 140 m west.
Site 20, Alice: This communications tower is located 10 miles north of Alice. This is a four faced tower, 150 m tall, with 3 ft face width. Terrain is flat, with lots of mesquite trees (2-3 m tall within 10 m of tower base). Radio shed immediately to south of tower base is 3 m tall.
Site 21, La Paloma: This site is on a ranch/game reserve on a Texas Department of Public Safety radio tower eight miles west of Sarita. Tower is located in a flat field (0.5 m tall thin grass within guy wire radius around tower base) in the middle of cultivated wheat/sorghum fields to north and east. Radio shed, 3 m tall, is southeast of tower. There are cattle feed pens 300 m southwest of the tower.
Site 22, Raymondville: Tower is located on the maintenance grounds of the Texas Department of Transportation on the north side of Raymondville. Storage/garage buildings are 40 m to the southwest (4 m tall). The radio shed, 3 m tall, is south of the tower.
Site 23, Rio Grande City: This site is 10 miles north of Rio Grande City. The Rio Grande Valley has lots of cactus, mesquite-like shrub (3 m) and little else. The tower is located on a low east-west ridgeline with good exposure in all directions.
Site 24, Carta Valley: This site is 5 mile south of Carta Valley and around 30 miles northeast of Del Rio. The tower is on one of a series of fingers of land that is around 70 m above the land to the south. The surface is hard and rocky with little grass cover and some shrubs (4 m). This site has limited access through the Department of Public Safety site supervisor in Del Rio. There are large numbers of wasps/hornets in the area so seals in the metal security box are inspected/replaced at each visit.
Site 25, Corpus Christi: Site is located on the Padre island, 10 miles southeast of Corpus Christi on land owned by the General Land Office. Land has clumps of sawgrass (0.25 m) with the ocean to the east and the intercoastal waterway to the west. Setting anchors into sand with a high water table was difficult. Tower, NRG 40 m, is adapted for a marine environment and is painted alternating orange and white for high visibility due to the Naval Air Station and Coast Guard flight paths.