given in Exhibit 42 for 20 years. It is interesting to note that the overall ranking of the SSPS would not change in Exhibit 41 even using a 20-year amortization period for capital energies. The total energy subsidy of 21.1% (211 Btu per 1,000 Btu output) would still place it between coal-strip mining and fuel oil although at this point it would be somewhat closer to fuel oil than to the strip mined coal energy subsidy. Note also that Exhibit 42 includes energy subsidies for natural gas (110 Btu) with the gas valued at the wellhead, and in situ coal gasification (105 Btu). These energy sources were excluded from Exhibit 41 because natural gas appears to be a declining source of energy for electric power generation while in situ coal gasification at this point is still highly exploratory. Further examination of Exhibit 41 shows that although the total energy subsidy required for the SSPS is relatively low, the capital energies required are among the highest shown. The capital energy subsidy, i.e., the amount of energy required for initial construction of the power plant divided by its useful life, is approximately 10.3% for the SSPS. The comparable figures are 5.3-7.5% for the fossil fuel technologies and 2.1 and 4.3% for nuclear (LWR) and geothermal, respectively. The capital energy subsidy required for the SSPS is exceeded only by the solar terrestrial system analyzed by DSI. The amount of the original resource wasted either by virtue of being left intact or by inefficiencies in conversion to electrical power is not altogether significant to solar power in which the initial energy source is nominally free. Nevertheless it is tabulated in Exhibit 42. Based on the efficiency chain shown in the ECON study, approximately 13,000 Btu of energy delivered to the solar cells are required for each 1,000 Btu at the busbar on earth. The generally low level of the external subsidy required for the SSPS may be partly attributable to the higher load factor in comparison to most terrestrial fossil fuel systems. As shown in Exhibit 41, the typical load factors for fossil fuels are 80% while the estimated load factor for solar terrestrial is 45%. Even for nuclear and geothermal, load factors of 75-80% are estimated. In all the available literature, load factors for the SSPS have been quoted at 90% or higher. For this analysis, 95% was used.
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