Techno-Economic Analysis of Postcombustion Processes for the Capture of Carbon Dioxide from Power Plant Flue Gas

Capture and sequestration of CO2 from power plant flue gas have become an important issue in the discussion about global warming. Different concepts of capture are being pursued. The advantage of postcombustion processes, such as processes based on absorption and stripping, is the possibility of retrofitting a state-of-the-art power plant with a capture plant under reasonable effort. Capturing CO2 by using an absorption/stripping process requires energy in the form of electricity and steam both supplied by the power plant. The capture process thereby reduces the overall efficiency of the power plant by up to 13%pts (percentage points). Apart from the development of new solvents, alternative and novel configurations of the process can lower the energy requirements. Three alternative configurations are economically and technically evaluated and compared to a baseline process represented by a standard absorption/stripping process using monoethanolamine (MEA) as a solvent. Savings in cost of CO2-avoided of 2−5% were attained. Regarding the total power required, savings of 4−7% were obtained. The results showed that not the process with the highest energy savings has the lowest cost of CO2-avoided, but that the influence of rising investment costs of more complex configurations cannot be ignored. For a comprehensive analysis of different configurations it is essential to perform both an economic evaluation and a technical study.