The production of photovoltaic materials requires large amounts of electrical energy. In the case of silicon the energy requirements are so large a silicon solar power satellite would need to operate at least five to six months just to generate enough electricity to make the amount of solar grade silicon used in its solar cells. For gallium arsenide the problem is- less severe but possibly only because its defined production process is advanced state-of-the-art, while the silicon process is present or near-term state of the art. It is likely that the high dollar cost and high energy cost of solar materials is interrelated and when one problem is solved, so will the other. The only problems of serious concern involving a material that appears in both SPS reference concepts are those associated with graphite fiber production. The production growth rate required to meet the combined requirements of the SPS and expected increased demand by the automobile industry could be in the 20-30 percent range sustained for a decade or more. Also, depending on the type of fiber selected, graphite fiber could become one of the highest material cost contributors to the SPS. In all, potential problems were identified for some 20 SPS materials. Further investigations are needed to determine the severity and implications of these problems and to identify and define corrective actions. These investigations will need to consider factors such as the accuracy of resource and reserve estimates, improved raw material acquisition and beneficiation techniques, improved material production processes, materials acquisition/production economics (such as price/demand elasticity, capital investment requirements, and by-product/co-product economics), and strategies to alleviate import dependency. In addition, the SPS materials characterization (materials list) used in this study is incomplete and lacks adequate traceability. A more complete characterization is needed that would improve confidence in analysis results. REFERENCES: (1) "Satellite Power System Concept Development and Evaluation Program," DOE/ER-0023, U.S. Department of Energy and the National Aeronautics and Space Administration,” Washington, DC, October 28, 1978. (2) Teeter, R.R., and Jamieson, W.M., "Preliminary Materials Assessment for the Satellite Power System," DOE/ER-0038, Battelle Columbus Laboratories, Columbus, Ohio, January, 1980.
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