Post-combustion CO₂ control systems separate CO₂ from the flue gas produced by conventional coal combustion in air.  In this case, CO₂ is exhausted in the flue gas at atmospheric pressure and a concentration of 10-15 volume percent.  This is a challenging application for CO₂ capture because:  (1) the low pressure and dilute concentration dictate a high actual volume of gas to be treated; (2) trace impurities in the flue gas tend to reduce the effectiveness of the CO₂ separation processes; and (3) compressing captured CO₂ from atmospheric pressure to pipeline pressure (1,200 - 2,200 pounds per square inch) represents a large parasitic energy load. 

DOE/NETL’s post-combustion CO₂ control technology R&D includes projects directed at the use of solvents, solid sorbents, and membranes. Amine-based solvent systems are in commercial use for scrubbing CO₂ from industrial flue gases and process gases. However, solvents have not been applied to removing large volumes of CO₂ as would be encountered in a PC-fired utility boiler flue gas.  Solid sorbents can be used to capture CO₂ from flue gas through chemical adsorption, physical adsorption, or a combination of the two effects. Possible configurations for contacting the flue gas with solid sorbents include fixed, moving, and fluidized beds.  Membrane-based capture uses permeable or semi-permeable materials that allow for the selective transport/separation of CO₂ from flue gas.  

DOE/NETL is currently funding multiple post-combustion CO₂ emission control projects within each of these approaches. These R&D efforts are being performed both externally by research organizations and academic institutions, as shown in the table below, and internally through NETL’s Office of Research and Development (ORD), specifically the Separations and Fuels Processing Division and the Office of Computational Dynamics.

The In-House Post-Combustion CO₂ Control webpage provides detailed information regarding NETL’s internal R&D.

Click on a project title in the tables below to get more information.