Scrubbing CO₂ from Power Plant Flue Gas Using Monoethanolamine (MEA)

CONTEXT

Combustion of fossil fuels is responsible for about 85% of the world’s energy supply and is the most significant source of anthropogenic carbon dioxide (CO₂) emissions worldwide. It is becoming increasingly important to develop economically feasible technology to capture and sequester CO₂ from fossil fuel burning power plants. Although there are several different methods that have been proposed for the capture and separation of CO₂, one of the few methods that has been proven to work on an industrial scale for capture of CO₂ from flue gas is chemical absorption using monoethanolamine (MEA).

"Capturing CO₂ from a power plant is already a commercial process. More than a dozen capture plants exist worldwide, with the CO₂ being sold into commercial markets. Presently, all commercial CO₂ capture plants use processes based on chemical absorption with a monoethanolamine (MEA) solvent. MEA was developed more than 60 years ago as a general, nonselective solvent to remove acid gases, such as CO₂ and H₂S, from natural gas streams. For CO₂ capture from flue gas, the process was modified to incorporate inhibitors that resist solvent degradation and equipment corrosion; also, solvent strength is kept relatively low, resulting in large equipment sizes and high-regeneration energy requirements. Until recently, no efforts were made to adapt and optimize this process for carbon sequestration, although such efforts could produce significant energy and cost savings." http://sequestration.mit.edu/pdf/EST_web_article.pdf

PROCESS

In this method, MEA absorbs CO₂ through chemical reaction in an absorber column. Since the reaction is reversible, the CO₂ can be driven off by heating the CO₂-rich amine in a separate stripper column. The MEA may be recycled through the process.

PROBLEM

Degradation of the MEA leads to increases in material costs, waste disposal costs, and energy demands for the CO₂ capture process. The chemical processes associated with the degradation of the MEA are not completely understood.

RESEARCH OBJECTIVE

Current research at NETL is aimed at developing an increased chemical understanding of the MEA degradation processes. Insight into the mechanisms and chemical pathways associated with MEA degradation may result in decreasing or eliminating its negative effects and will enhance the commercial viability of the process as a solution to CO₂ emissions from fossil-fueled power plants.