Novel Electrochemical Process for Capture of CO2 From Power Plant Flue Gas

Energy efficient capture of CO₂ released from coal based power plants is a major challenge to reduce greenhouse gas emissions. The existing commercial technologies require substantial energy inputs in the form of heat and vacuum which leads to around 30 % parasitic energy loss. To overcome this problem a novel electrochemical process is developed to efficiently capture CO₂ from flue gas and then release (desorb) pure CO₂ at atmospheric pressure without requiring heat, vacuum, or consumptive chemical usage. The process uses a proprietary resin wafer based Electrodeionization (RW-EDI) technique to shift the pH of the process solution from basic in the capture chamber to acidic in the release chamber. The base/acid pH shift drives the CO₂ capture/release process and catalysts (enzyme or inorganic) are used to enhance kinetics. The goal is to demonstrate 90 % capture of CO₂ from synthetic flue gas (15 % CO₂) and subsequent release of CO₂ with 90 % purity in the released stream. Recent bench-scale experimental results will be presented showing significant progress towards this goal. Water chemistry (CO₂ hydration/dehydration), mass transfer issues (gas-liquid interaction) and kinetic limitations (capture/release rates) associated with the process will be discussed in detail. Funding for this project is awarded by US Department of Energy ARPA-E to Nalco Company and Argonne National Laboratory.