CO2 capture processes using aqueous monoethanolamine (MEA) require significant energy expenditure. There are various possible structural modifications which can be implemented to reduce these energy requirements and enhance energy efficiency. However, as the optimal configuration may contain a combination of different modifications a systematic approach is necessary to consider all possibilities. In this study a superstructure including the conventional amine-based CO2 capture configuration and four different types of structural modifications is constructed in the process simulator UniSim (R). Optimization of this superstructure reveals the configuration and operating conditions giving the minimum energy costs, systematically and simultaneously considering all of the possible modifications included. This methodology is applied to a CO2 capture case study to illustrate how the proposed modeling and optimization framework can effectively investigate design options available for improving energy efficiency. (C) 2016 Elsevier Ltd. All rights reserved.