process are to produce 1974 estimates of the number of Btu per dollar of final output. These are the estimates shown in Exhibit 47 under the heading "Energy Requirements by Sector." In addition the DSI model provides for separate computation of the energy required for that portion of the dollar cost that is attributable to trade and transportation as opposed to the actual manufacture of the material in question. General coefficients of 5% for trade and 4% for transportation are assigned to basic materials while comparable estimates of 7% for trade and 2% for transportation are assigned to equipment. Since trade and transportation operations have different requirements, these are prorated along with the energy requirements per dollar for the sector itself to derive the estimates shown in the final columns of Exhibit 46. These are estimates of the number of Btu per dollar of final output (1974), including trade and transportation components. 6. Resources Required With respect to specific resource materials required, the only comprehensive treatment found in the references reviewed was in the Johnson Space Center presentation (Ref. A13). A table in that presentation deals with various chemical elements and compounds required for construction of a 10-GW SSPS satellite together with a cumulative computation for 112 10- GW stations. This analysis, shown as Exhibit 48, indicates that the most intensively used material will be aluminum. Over one million metric tons of aluminum will be required for each satellite. The production of each satellite would require from 2.7 to 5.4% of the aluminum demand in the year 2000 for the entire United States, depending on whether low, or high demand projections are used. Alternatively stated, the aluminum requirements for a single satellite would represent 13.2% of known reserves in the United States. Most other materials required do not represent large proportions of either U.S. demand or known reserves. Two notable exceptions are arsenic for which 41,000 pounds would be required per satellite representing 7-9% of U.S. demand but a negligible proportion
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