Removal of CO2 from gas streams can be achieved by a number of separation techniques including absorption into a liquid solvent, adsorption onto a solid, cryogenic separation and permeation through membranes. Among these techniques absorption into a liquid solvent is the most suitable process for high volumes of synthesis gas stream. CO2 separation processes with chemical solvents (alkanolamines) are industrialized since the seventies and the licensors are directed these last years toward specific solvent formulations: primary or secondary amines and anti-corrosion additives, tertiary amines with promoters or activators and with antifoaming additives. Mixing of chemical solvents, such as tertiary amines and a relatively small amount of the primary amine, aims to combine the advantages of the two solvents: the target of such mixed chemical solvents is to achieve a better absorption capacity, to avoid the solvent degradation and to limit the corrosion. The physical solvents (methanol, propylene carbonate, N-methyl-pyrrolidone (NMP), Selexol) are known for their chemical stability and for a non-induced corrosion effect. Moreover, their high absorption capacities make them interesting for bulk removal. However, methanol needs low operating temperatures because of its higher volatility. High volatility is a disadvantage with regard to the potential solvent losses. It is then necessary, before compression and storage of CO2, to add downstream the regeneration column, a wash water system and distillation columns to recover the remaining methanol in the CO2 stream. Methanol and NMP solvent requires refrigeration system to meet relatively low temperatures. Refrigeration system uses electricity for the compression of the refrigeration media, which means higher energetic penalty for the process than cooling water. Mixing chemical and physical solvents (hybrid solvent), allows an increased CO2 absorption capacity compared to chemical solvent alone. Solubility of carbon dioxide in primary or secondary amines is improved by the addition of NMP [6]. Solubility of carbon dioxide is compared in a mixture of MDEA and methanol, and in methanol [7]. Physical solvent polarity and permittivity are significant on the ionization of the species and on reaction kinetics. However, the kinetics of CO2 absorption by physical solvents and amines, in aqueous solution forms or not are still unknown. In this work we consider the electrical and steam consumptions of two chemical and two physical absorption processes using AMP 30 mol% in aqueous solution, a mixture of MEA 5 mol% and MDEA 25 mol% in aqueous solution, NMP and methanol, for the CO2 capture from a synthesis gas (50 kg/s and 24 bars). Chemical absorption is an interesting choice for post-combustion capture because of much lower CO2 partial pressure in the flue gas sent to the stack. Physical absorption is favored by a high CO2 partial pressure in the case of a pre-combustion separation. We choose for this study a physical absorption process with methanol.