Fig. 25. Construction system elements of construction systems are being identified (Fig. 25), and technology activities are being initiated as funding becomes available. Continued development and evaluation of space construction techniques is a critical area to the assessment of the Solar Power Satellite concept. Fortunately, a modest technology program is underway, and hopefully it can be expanded in the near future. At an appropriate stage of development, these techniques and devices will require evaluation in space. 3. COST CONSIDERATIONS Cost projections for any advanced energy system are very difficult to develop. All such estimates require assumptions related to technological advancement over an extended period of time. Nevertheless, the evaluation of a potential system requires such projections, and a number of cost estimates have been developed during the course of studying the Solar Power Satellite concept over the past several years. Capital costs for the Solar Power Satellite were estimated by four independent study teams in the 1976-77 interval. Estimated costs ranged from $1400/kW to more than $7000/kW. The primary contributors to this wide variance were different estimated costs of the photovoltaic cells, which varied from $130/kW to $921/kW, and construction time, which varied from 1 to 6 years. Improved definition of the satellite, ground receiver, space transportations system, and construction process resulted in estimates of $2000/kW to $2700/kW capital costs. These costs do not translate into electrical energy cost in the same proportion to their capital costs as do conventional plants. Solar power satellites do not require fuel, produce no wastes, promise high-capacity factors because of their passive nature, and appear to be relatively inexpensive to maintain and operate in the space environment. Consideration of these factors and capital costs on the order of $2500/kW result in an electricity cost at the ground receiver output of 1.5 cents/MJ (5.5 cents/kWh). Two of the major cost elements of the Solar Power Satellite are the solar cell
RkJQdWJsaXNoZXIy MTU5NjU0Mg==