CO₂ Removal

Carbon dioxide (CO₂) capture and sequestration (or storage) (CCS) is increasingly becoming a core supporting technology component of clean coal projects, such as coal gasification facilities, to reduce the overall environmental impact of coal utilization. Historically, the main focus was on sulfur dioxide and particulate emissions, where a typical pulverized coal (PC) or coal gasification power plant was required to incorporate supporting technology to remove sulfur and particulate matter emissions. While it is still not clear what rules or regulations may be put in place for CO₂, it is highly likely that CO₂ emissions from coal-based power plants will be targeted for reduction. This type of regulation could serve as a driver for gasification because of its inherent advantages for CO₂ capture as its overall process scheme can be easily designed (or modified) to allow for economic pre-combustion CO₂ capture.
  
Design for Pre-Combustion CO₂ Capture
The web page on how plant design changes for CO₂ Capture discusses the design requirements for incorporating CO₂ capture into an acid gas removal (AGR) processing unit within an IGCC plant.  While the design selection of a conventional chemical and/or physical solvent based AGR process for gasification will be application specific, both are commercially demonstrated technologies and can be modified for simultaneous or selective hydrogen sulfide (H₂S) and carbon monoxide (CO₂) removal.  To remove a significant amount of CO₂ from a gasification plant (e.g., > 80%), the CO in the syngas stream must first be converted into CO₂ and hydrogen (H₂) via a water-gas-shift process upstream of the AGR plant.

CO₂ Capture and Sequestration Technology Development
DOE has a significant program in CCS.  For gasification, commercial technologies are available for pre-combustion CO₂ capture, for near-term applications.  Mid-term and longer-term technologies under development include:

• Solid sorbents
• Ionic Liquids
• Membranes

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