The present work presents a case study where membrane contactors are compared with absorption towers for post combustion CO2 capture and for natural gas sweetening. Simulations are performed using a absorber model which has been validated with experiments in a membrane contactor setup. The design of the membrane contactors is made with emphasis on the constraints in gas and liquid side pressure drop and size limitations of membrane modules, in addition to the common design criteria for industrial absorbers. Results show that absorber size may potentially be reduced by 75%, given that liquid is flowing on the shell side of the membrane units. Natural gas sweetening is a more viable option than post combustion capture due to the potentially large gas side pressure drop and the need for many membrane units in parallel in the latter case.