Life cycle modelling and comparative assessment of the environmental impacts of oxy-fuel and post-combustion CO2 capture, transport and injection processes

The oxy-fuel combustion CO2 capture route and post-combustion CO2 capture route involve different energy consumption rates and subsequent environmental impacts. The holistic perspective offered by Life Cycle Assessment (LCA) can help decision makers to compare alternative CO2 capture and storage technologies in a life cycle perspective. This paper, at first, introduces the principles of the dynamic LCA model developed for oxy-fuel combustion and post-combustion power generation with CO2 capture, transport and injection processes. Next, a comparative life cycle assessment of alternative CO2 capture technologies is presented. Results show that, at life-cycle level, the post-combustion and oxy-fuel combustion CCS cases can reduce the life-cycle Global Warming Potential (GWP) by 78.8% and 80.0% respectively compared to conventional power plant without CCS. Other environmental impacts, such as Ecotoxicity, Human toxicity and Acidification, vary significantly with the different CO2 capture routes employed. Finally, by comparing the results obtained with the most recent LCA studies of post-combustion power generation with CO2 capture and storage, it is shown that the plant level, gate-to-gate studies provide significantly variable results and generally overestimate life cycle environmental impacts. (C) 2011 Published by Elsevier Ltd.