A major attraction of gasification is that it can convert waste or low-priced

fuels, such as biomass, coal, and petcoke, into high-value chemicals like metha­nol. Biomass holds great appeal for industries and businesses, especially in the

energy sector. For example:

• Downstream flue-gas cleaning in a gasification plant is less expensive than that in a coal-fired plant with flue-gas desulphurization, selective catalytic reducers (SCRs), and electrostatic precipitators.

• Polygeneration is a unique feature of a gasifier plant. It can deliver steam for process, electricity for grid, and gas for synthesis, thereby providing a good product mix. Additionally, for high-sulfur fuel a gasifier plant pro­duces elemental sulfur as a by-product; for high-ash fuel, slag or fly ash is obtained, which can be used for cement manufacture.

• For power generation, an IGCC plant can achieve a higher overall efficiency (38-41%) than can a combustion plant with a steam turbine alone. Gasifica­tion therefore offers lower power production costs.

• Carbon dioxide capture and sequestration (CCS) may become mandatory for power plants. An IGCC plant can capture and store CO2 at one-half of what it costs a traditional PC plant (www. gasification. org). Other applications of gasification that produce transport fuel or chemicals may have even lower CCS costs. Established technologies are available to capture carbon dioxide from a gasification plant, but that is not so for a combustion plant.

• A process plant that uses natural gas as feedstock can use locally available biomass or organic waste instead, and thereby reduce dependence on imported natural gas, which is not only rising sharply in price but is also experiencing supply volatility.

• Gasification provides significant environmental benefits, as described in Section 1.4.2.

• Total water consumption in a gasification-based power plant is much less than that in a conventional power plant (Table 1.5). Furthermore, a plant can be designed to recycle its process water. For this reason, all zero — emission plants use gasification technology.

• Gasification plants produce significantly lower quantities of major air pol­lutants like SO2, NOx, and particulates. Figure 1.8 compares the emission from a coal-based IGCC plant with that from a combustion-based coal-fired

□ NOX

—

“SOX

■ PM

steam power plant and a natural-gas-fired plant. It shows emissions from the gasification plant are similar to those from a natural-gas-fired plant.

• An IGCC plant produces lower CO2 per MWh than a combustion-based steam power plant.