Much of the research in the area of carbon dioxide recovery and storage focuses on minimizing the energy required for CO2 capture, as this step corresponds to the major cost contribution of the overall process (capture, transportation, injection). Out of the three traditional methods of CO2 capture (absorption, adsorption and membrane processes), absorption is considered to be the best available technology for post-combustion application. However, amine absorption requires 4-6 GJ/tonne of recovered CO2, in a large part due to significant energy consumption associated with the regeneration step. In this paper, we perform a systematic analysis of the separation performances and associated energy cost of a single-stage membrane module. First, the operational limits are identified in terms of permeate composition and CO2 recovery ratio via a systematic parametric study for CO2/N-2 mixtures. The energy consumption of the capture step is then evaluated and compared with the performance of amine absorption. Next, the search for an optimal strategy in terms of compression energy for a combination of membrane capture and CO2 injection has been addressed. The results allow the identification of an optimal membrane pressure ratio for a given set of conditions. (c) 2005 Elsevier Ltd. All rights reserved.