pay back the energy consumed during all phases of the construction process has to be accounted for to assure that the power produced substantially exceeds the resources consumed during construction and the energy debit required to replace them. For example, the propellants required to place SSPS in orbit or the production of solar cells are an energy tax against the system and will have to be accounted against system performance. In addition, the total energy system required for the building and operation of SSPS will have to be structured to identify and quantify the energy sources and links within the system. Preliminary estimates indicate that this energy tax against the SSPS can be met by less than one year of operation. In addition to the necessity of viewing and analyzing SSPS in the context of the total energy balance and assessing its net impact, the net effect of SSPS on the economy will have to be determined. The demand for human and material resources will be significant and it will be necessary to establish the magnitudes of these demands and to predict the economic consequences of a decision to implement an operational SSPS system. Certain assumptions will have to be made as to manufacturing costs and processes, for example, the degree of automation. These assumptions need to be translated into the demand for capital, management, and labor inputs. Consideration must also be given to likely industry structures, e.g., whether the solar cell production facility has to be a monopoly or whether it should be carried out by industrial enterprises. The capital requirements for these enterprises must also be estimated whenever they are not built in to the development budget. The demand for raw materials required for the building of the SSPS system, and in particular, those materials which might be rare or exotic must be forecast. The present estimates indicate that any material required for an SSPS will not exceed 2% of the annual supply available to the United States. An estimate should also be made of what might happen to the prices of these materials in the face of increased demand. The fundamental raw materials - hydrogen, oxygen, aluminum and silicon - are among the most abundant although there are materials, such as platinum, samarium, and cobalt which will be required in limited quantities. Clearly the supply of these materials is not likely to run out; however, there may be rarer materials required such as gallium for diodes which is today available in limited quantities. The prices for certain of these items will not necessarily rise in the face of a substantial requirement. In fact, the increases in demand for certain materials may lead to a drastic reduction in price due to changes in production processes that may be required to meet the higher demands. By carrying the system installation projections one step further, it will be possible to calculate the raw materials requirements of the system elements. These requirements should be readily available, and, in many instances, the choice of materials will have a major effect on performance. Substantial published information exists on known and forecast reserves of raw materials which will form the basis of comparison. Price trends can be estimated by examining analogous cases for raw
RkJQdWJsaXNoZXIy MTU5NjU0Mg==