Life cycle modelling and comparative assessment of the environmental impacts of oxy-fuel and post-combustion CO_2 capture, transport and injection processes

摘要

The oxy-fuel combustion CO_2 capture route and post-combustion CO_2 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 CO_2 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 CO_2 capture, transport and injection processes. Next, a comparative life cycle assessment of alternative CO_2 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 CO_2 capture routes employed. Finally, by comparing the results obtained with the most recent LCA studies of post-combustion power generation with CO_2 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