II. TYPES OF SOLAR CONVERSION SYSTEMS The types of solar conversion systems in operation, under construction and planned for the desert Southwest are variable enough that a brief description is presented to enable evaluation of the potential habitat changes created by the systems and thus analysis of the ecological impacts. This section is not designed to offer details of the existing or planned conversion systems for these are available from the contractor’s engineering specifications or from the Department of Energy. This section is limited to direct solar energy conversion systems and does not include home units cr other conversion systems such as wind or ocean thermal. Systems in Existence There are very few functioning solar conversion facilities in existence. Two types that are of interest to this study include the solar powered irrigation pumping facilities which are considered dispersed solar powered conversion systems and the 5MW thermal solar power tower at Sandia Laboratory near Albuquerque, New Mexico which is termed a solar powered central receiving system. The solar powered irrigation pumping systems use parabolic-trough collectors to concentrate solar radiation on a pipe containing oil. The heated oil is used to "power" a pump which moves water for irrigation. The parabolic collectors are each between 1.5 and 3 meters wide and no more than 25 meters long, depending on the system. They track the sun, rotating on a horizontal north-south axis. During tracking the edge of the reflectors come within about 0.5 meters of the ground. The series of reflectors are spaced to avoid shading each other after about 9 AM in the summer. Other times of year, shading may continue later into the day. The sites of the solar powered irrigation systems are small. Neither of the two sites observed near Gila Bend, Arizona and Willard, New Mexico exceeded one hectare. In both cases the substrate of the site had been prepared by scaping and compacting. The Gila Bend site had a builtup, compacted substrate because it was located in the middle of irrigated fields. The 5MW solar thermal test system at Albuquerque, New Mexico consists of an array of reflectors or heliostats which concentrate reflected solar
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