A concept called "concentration swing absorption (CSA)" was present to save CO2 regeneration heat requirement. In this process the initial lean-CO2 solvent is executed to form the so-called initial CO2-rich solvent (ICRS) by absorbing CO2, then ICRS is split into the concentrated CO2-rich solvent (CCRS) phase and the diluted phase (mainly water). And only CCRS is regenerated in the stripper. Regeneration characteristics of CCRS were investigated as the first step study of CSA. Results showed that compared to the direct regeneration of ICRS, concentrating ICRS before regeneration cannot only improve the regeneration performance, but also reduce the regeneration temperature. Despite the increase of solvent viscosity hindering the CO2 molecular diffusion of regeneration, ICRS should be concentrated to become the special CCRS with higher concentration beyond its unique critical concentration range. Moreover, based on the energy analysis of CSA considering the reboiler heat duty and energy required to concentrate ICRS by taking 30 wt% monoethanolamine (MEA) as an example, theoretically the overall CO2 regeneration heat requirement may be decreased considerably to 2739.98 kJ/kg of CO2 by about 34.78% in the future when ICRS was concentrated to 60 wa. (C) 2013 Elsevier B.V. All rights reserved.