CO2 Sequestration through Deep Saline Injection and ...

sequestration by industrial photobioreactor were pursued. Sequestration by the industrial
photobioreactor was pursued because there are very few adverse environmental impacts, the
future market for algal biomass looks strong, it has the potential to make existing technologies
green, and can be easily transferred to several locations. The deep saline aquifer injection was
pursued because it is very common in location and would not require large transport distances
from existing sites, has high storage capacity, has long retention times, does not present
unreasonable environmental risks, and utilizes mature and well known technology.
2. PART II: THE IGCC POWER PLANT
The selected source for CO2 is an integrated gasification combined cycle (IGCC) power plant.
The IGCC combines gasification technology with combined cycle technology. The first step in
the IGCC process is gasification. Gasification converts any hydrocarbon into a synthesis gas (or
syngas) is comprised of mainly of hydrogen (H2) and carbon monoxide (CO) at high temperature
and pressure. In the case under consideration, the hydrocarbon source is coal. Gasification
process produces fewer pollutants in the effluent than combustion and consequently fewer
pollutants in the flue gas streams. Even though it produces fewer pollutants, the syngas must be
cleaned-up to removing the acid gases (such as hydrogen sulfide), particulate matter, Hg and
other undesirable components. This is done primarily to protect the catalysts and materials down
stream from the gasification. With a CO2 capture option, syngas passes through a Water Gas
Shifter (WGS) reactor where steam is introduced to the syngas the CO is converted to CO2 and
more H2.
A Pd membrane can be used to separate hydrogen from the effluent from the WGS and hydrogen
is combusted in a combined cycle gas turbine that produces electricity. Both the syngas
production process and the gas turbine combustion process generate steam that is utilized to
generate electricity by a steam turbine. Advantages of IGCC include the reduction of CO2
emissions, increased efficiency, and flexible fuel supply. Further, IGCC technology with CO2
capture is beneficial for the environment because of the reduction of the emission of pollutants
(e.g., SO2, NOx, particulate matter, and mercury). The collection of sulfur and gasification slag
obtained from the process has byproduct value, which avoids the cost byproduct disposal, and
easier CO2 removal. The energy consumption for CO2 capture is lower in comparison with
conventional power plant. However, the capital cost for IGCC is higher. In addition, IGCC is a
complex process that requires a high degree of component integration [24]. Figure 2 shows the
schematic of IGCC process under consideration.
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