Table 3.3 Characterization Parameters for Plant Site and Fuel Cycle performed for NASA by Boeing? and Rockwell.® The satellite power system consists of three basic elements: the first two, in geosynchronous orbit at 36,000 km, are the solar collector, which receives energy from the sun and converts it to electrical energy, and a microwave antenna, which transmits that energy to the third element, an earth-based rectifying antenna (rectenna). The reference system is sized for 5 GW of DC power output to a conventional utility grid. The satellite has one end-mounted antenna, as illustrated in Fig. 3.1. The satellite consists of a planar solar array structure of graphite composite material. Two conversion options (Fig. 3.2) are presently being considered: one is the use of single-crystal gallium aluminum arsenide (GaAlAs) solar cells with a concentration ratio of 2; the other is the use of single-crystal silicon (Si) solar cells with no concentration. The size of the solar array is dictated primarily by the efficiency chain of the various elements in the system. Figure 3.3 shows the end-to-end efficiency chain for the GaAlAs and silicon cell options. The satellite is designed to provide 5 GW of DC power to the utility busbar, and with an overall efficiency of approximately 7%, it is necessary to size the solar arrays so that approximately 70 GW of solar energy will be intercepted. The efficiency assumed is the minimum efficiency, including the worstcase summer solstice factor (0.9675), the seasonal variation (0.91), and the end-of-life (30-year) solar cell efficiency (assuming annealing in the silicon case). For the GaAlAs case, the end-of-life (30-year) concentrator reflectivity is 0.83. Since only half of the intercepted solar energy is reflected by the concentrators, the equivalent lifetime average efficiency is 0.915. The GaAlAs option is a five-trough configuration with a solar blanket area of 26.52 km?, a reflector area of 53.04 km?, and an overall planform area of 55.13 km?. The silicon option has the solar blanket with no concentration, resulting in a blanket area of 52.34 km? and a planform area of 54.08 km?. Table 3.4 lists the cell and planform power characteristics for each cell type. Physical System Characteristics Plant Configuration Thermodynamic Cycle Characterist ics Capacity Factor Environmental Controls Mass & Energy Balances Environmental Residuals Air-Borne Emissions - Liquid Effluents - Solid Wastes - Radionuclides - Waste Heat Capital and Operating Costs Construction Schedule Construction Cash Flow Direct and Indirect Capital Cost O&M Costs Decommissioning Costs Natural and Human Resource Requirements Fuel Use Water Use Land Use Construction Labor Operating Labor
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