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