An overview of these capture strategies is shown in Figure 7.A.1. All three are available, in principle, for all hydrocarbon sources, but relative costs differ, as do the energy-conversion routes that are favored. Gasification is probably the most competitive for high-rank coals, but this may reflect the lack of investment thus far in the development of gasifiers for low-rank coals. Petcoke is similar to a high-rank coal. Biomass may be co-fired with coal or petcoke, but to gasify a combination in which biomass represents a significant fraction of the total thermal input, there may need to be a separate biomass gasifier with its own feed-handling strategies.

CO₂ capture from natural-gas-fired power plants can be accomplished using any of the three strategies. One proposed project design features autothermal reforming of natural gas to make hydrogen, with combustion of the hydrogen

FIGURE 7.A.1 Options for capture of CO₂ from flue-gas and process streams.

Source: IPCC, 2005.