Environmental impact assessment of CCS chains - Lessons learned and limitations from LCA literature

Abstract

This study performs an assessment of existing LCA literature to obtain insights into potential environmental impacts over the complete life cycle of fossil fuel fired power plants with CCS. CCS results in a net reduction of the GWP of power plants through their life cycle in the order of 65-84% (PC-CCS), 68-87% (IGCC-CCS), 47-80% (NGCC-CCS), and 76-97% (Oxyfuel). The results show a lower performance for NGCCs on GWP, although in absolute terms, the GWP of NGCCs with CCS appears in the same order of magnitude as PC-CCS (76-245gCO₂eq/kWh vs. 79-275gCO₂eq/kWh in PC-CCS). This is due to upstream emissions in NGCC chains. Deploying CCS in PC, IGCC and NGCC results in relative increases in eutrophication and acidification when comparing to power plants without CCS. The limited available LCA literature on oxyfuel with CCS shows this technology as generating the lowest relative increases in the environmental impact categories. For power plants without CCS, direct emissions account as the main contributor to GWP, acidification and eutrophication while for power plants with CCS, indirect emissions appear as the main contributor to GWP, acidification and human toxicity potential. The highly relative importance of emissions occurring upstream (e.g. coal mining, coal transport, MEA production) and downstream (e.g., CO₂ transport, CO₂ storage) when assessing the environmental performance of power plants with CCS implies the need for optimal designs of CCS chains to also include up- and downstream processes.