Examination of the fine detail under WBS Item 1.4 of Table 2 shows that the cost of raw land is $50 million. The perimeter safety fence was shown to have a diameter DF = 13.0 km. Hence, the cost of land in the hazard zone between rectenna and fence is only $14.2 million. Since this is negligible compared to the other costs, we henceforth neglect the fifth term of Eq. 13, for which the coefficient e has the value $0.3 million. We now have a four term cost equation which, on dividing through by Pg, the power delivered to the grid, becomes The right side of Eq. 15 is a function only of the Hansen parameter, h, and the rectenna intercept level. Using Eq. 15, the cost per kilowatt has been evaluated for rectenna intercept levels between 0.5 and 8.0 mW/cm2, and for values of h from 0 to 4.0. The results are shown in the family of curves in Fig. 1. The operating condition for the reference system, $2110/kW, is shown by the encircled point lying very close to the h = 2.4 curve, but not at the minimum. It is clear that by decreasing the rectenna diameter to yield an intercept level of 3.4 mW/cm2, instead of 1.0 mW/cm2, the cost of power from the reference system could be reduced to about $1990/kW, although somewhat less power would be delivered to the grid. By designing for a unifom illumination over the spacetenna the cost of power may be further reduced to an absolute minimum of about $1910/kW, as shown by the curve for h = 0. This would have be be increased to about $1930/kW to account for the cost of the added hazard zone area* that was disregarded in neglecting the fifth term in Eq. 13. This is a full 8.5% less than the cost of power for the reference system. It is of interest to determine the actual power delivered to the grid at each of the minima of the curves in Fig. 1, and then to compute total system cost in each case. Pg may be calculated from the second part of Eq. 12 after determining r)B either by interpolation or by direct computation. The results are given in Table 3, which includes a column for sidelobe level, and are shown graphically in Fig. 2. It appears that grid power decreases monotonically with the parameter h. Total system cost, however, at first decreases, reaches a minimum, and then begins to increase. This absolute minimum in overall cost is slightly less than $9.9 billion and occurs at h = *The perimeter fence must be increased in diameter from 13 to 22 km in order to include much of the first sidelobe. The cost of the neglected fifth term then increases from $14 to $109 million, or about 1% of the total cost.
RkJQdWJsaXNoZXIy MTU5NjU0Mg==