(771a) What Chemicals Will We Need to Capture CO2?

A number of solvents are currently being studied in the application of CO₂ capture from post-combustion flue gas streams.  Of these, aqueous amine solutions are the most thoroughly developed and furthest along in process scaling, stemming a long history of experience within the natural gas industry.  Monoethanolamine (MEA) is perhaps the most well-known, thoroughly studied, and readily available amine for post-combustion CO₂ capture.  However, concentrated aqueous MEA solutions likely cannot meet the stringent energy and cost limitations required to economically achieve 90% CO₂ capture at coal-fired power plants. Also in development are piperazine (PZ) and ‘advanced’ amines, which show great potential to improve energy efficiency and stability, but are not yet produced on a scale approaching that of MEA. Among the non-conventional or "designer" non-aqueous solvents, ionic liquids (ILs) have been the most prominent.  However, few non-aqueous solvents have been taken beyond bench-scale activities.  Aqueous and non-aqueous solvents will also be important for pre-combustion CO₂ capture applications.

In the coming decades, as CO₂ capture processes are broadly deployed worldwide, the solvent(s) with the most favorable economics and performance will need to be manufactured in quantities of at least 1 megaton per year, creating at new chemical(s) of global importance. With the ultimate goal of deep reductions in greenhouse gas (GHG) emissions in mind, the processes by which the proposed chemicals for CO₂ capture are manufactured should also be considered in terms of their energy requirements, efficiencies, waste products, and CO₂ emissions. This presentation wil begin to address some of these technical and economic questions by examining the manufacture of amines, ILs and other physical solvents that have been proposed for post-combustion and pre-combustion CO₂ capture, as well as the fundamental building block of all amines, ammonia.