Environmental impacts and scale-up efficiency of four carbon capture and storage scenarios

Capture, transportation, and permanent storage of CO₂ is considered pivotal in reaching global net-zero emission targets. Conceptualization and deployment of carbon capture and storage (CCS) value chains require substantial resources with current CCS projects trailing behind expectations. To date few studies address the environmental impacts related to introducing CCS into existing value chains, and even fewer focus on the environmental efficiency of scaling-up CCS projects, despite the need for acceleration. Four scenarios were studied, resembling CCS projects at different capture capacities of 0.3, 1.5, 3.5 and 10 million tonnes of CO₂ per year (mtpa) deployed within a Northern European region. Using attributional life cycle assessment, we demonstrate that permanent carbon storage today may furnish a 47–91% CO₂ net-abatement potential depending on the CO₂ source and geographical location of CCS projects. Despite limited operational data, results appear robust with general low uncertainty. Our environmental assessment show that capturing, conditioning and liquefaction account for the largest emission shares of the studied CCS value chains, ranging from 70 to 80%, which is heavily fluctuated by the carbon emission intensity of regional electricity production. Impacts related to permanent storage activities, such as offshore monitoring and well drilling are limited to less than 2% across all scenarios. Moreover, our study suggests that expanding the spatial geographical scope to accumulated 5000 km has a low influence on the efficiency of CCS value chains regardless of capture rate. Freshwater eutrophication shows the highest burden across the assessed environmental impact categories caused by the electricity production for capture processes. Lastly, we identify net-abatement improvement potential for post-combustion CCS projects at capturing capacities between 1.5 and 10 million tonnes per annum ranging from 10 to 20% for transport-related activities, and 60–68% for capturing processes when assuming net-zero energy scenarios.