Economic evaluation of a sodium/limestone double-alkali FGD process

The report fives results of a comparison of results from a recent forced-oxidation limestone flue gas desulfuriation (FGD) process evaluation and those from a conceptual design and economic evaluation of a sodium/limestone double-alkali FGD process, based on recent EPA-sponsored pilot-plant and prototype test work. For a 500-MW new power unit burning 3.5% sulfur coal and meeting the 1979 new source performance standards, the estimated capital investments in 1982 costs are $95 million ($190/kW) for the sodium/limestone double-alkali process and $103 million ($206/kW) for the forced-oxidation limestone process. Estimated first-year annual revenue requirements in 1984 costs for these processes are $26 million and $29 million (9.3 and 10.6 mills/kWh), respectively. Although the sodium/limestone double-alkali process appears to be about 8% lower in capital investment, given the accuracy associated with studies of this type (+ or -10%), it is uncertain if the sodium/limestone double-alkali process has a lower capital investment. In terms of first-year and levelized annual revenue requirements, the sodium/limestone double-alkali process shows a 12% and 14% lower cost, respectively, than the forced-oxidation limestone process and (thus) is marginally less expensive. However, economics for the double-alkali process are more uncertain than those for the other.