FIGURE 5.3 Supply function for biomass feedstocks in 2020. High-yield grasses include Miscanthus and normal-yield grasses include switchgrass and prairie grasses.

FIGURE 5.3 Supply function for biomass feedstocks in 2020. High-yield grasses include Miscanthus and normal-yield grasses include switchgrass and prairie grasses.

comparison, costs of gasoline are shown in Figure 5.4 for two different crude oil prices: $60/bbl and $100/bbl (that is, $73 and $113 per barrel of gasoline equivalent). Results are also shown in Table 5.5.

Figure 5.5 shows the net CO2 emissions per barrel of gasoline equivalent produced by various production pathways. The CO2 released during combustion of the fuel is similar among the options, with ethanol releasing less CO2 than is released with either gasoline or synthetic diesel and gasoline. But a large variation in net releases results from the CO2 taken out of the atmosphere when biomass is grown and from the significant differences in CO2 released into the atmosphere during the conversion process. CO2 emissions for corn grain ethanol are slightly lower than those of gasoline. In contrast, CO2 emissions of cellulosic ethanol without CCS are close to zero.

Figure 5.4 shows that FT coal-to-liquid fuel products with and without geologic CO2 storage are cost-competitive at gasoline-equivalent prices below $70/bbl (this represents equivalent crude-oil prices of about $55/bbl) and that prices for MTG are somewhat lower. Figure 5.5 shows that without CCS, both FT and MTG vent a large amount of CO2—over twice that of petroleum gasoline on a



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