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care, education, or basic shelter for low-income families. Nor does it consider aesthetic issues about different sources of illumination.

Care must be taken in developing such a table because there is some "double-counting" among potential mitigation options. For example, implementation of both the nuclear and the natural gas energy options assumes replacement of the same coal-fired power plants. Thus, simply summing up the emission reductions of all options to give total reduction in emissions would overstate the actual potential. The options presented in Table 6.2 have been selected to eliminate double-counting.

Finally, although there is evidence that efficiency programs can pay, there is no field evidence showing success with programs on the massive scale suggested here. There may be very good reasons why options exhibiting net benefit on the table are not fully implemented today.

Figure 6.3 illustrates the results of different rates of implementation of those options. The many uncertainties in the calculations of both costs and emission reductions have been collapsed into two lines. The line labeled "25% Implementation/High Cost" assumes incomplete implementation of each option (25 percent implementation of feasible opportunities) and the high end of the range of cost estimates for that option (high cost). This line shows a lower bound of what is reasonable to achieve. The line labeled

FIGURE 6.3 Comparison of mitigation options. Total potential reduction of CO2-equivalent
emissions is compared to the cost in dollars per ton of CO2 reduction. Options are ranked from
left to right in CO2 emissions according to cost. Some options show the possibility of reductions
of CO2 emissions at a net savings. See text for explanation.