Life Cycle Assessment of Direct Air Carbon Capture and Storage with Low-Carbon Energy Sources

Abstract

Direct air carbon capture and storage (DACCS) is an emerging carbon dioxide removal technology, which has the potential to remove large amounts of CO2 from the atmosphere. We present a comprehensive life cycle assessment of different DACCS systems with low-carbon electricity and heat sources required for the CO2 capture process, both stand-alone and grid-connected system configurations. The results demonstrate negative greenhouse gas (GHG) emissions for all eight selected locations and five system layouts, with the highest GHG removal potential in countries with low-carbon electricity supply and waste heat usage (up to 97%). Autonomous system layouts prove to be a promising alternative, with a GHG removal efficiency of 79-91%, at locations with high solar irradiation to avoid the consumption of fossil fuel-based grid electricity and heat. The analysis of environmental burdens other than GHG emissions shows some trade-offs associated with CO2 removal, especially land transformation for system layouts with photovoltaics (PV) electricity supply. The sensitivity analysis reveals the importance of selecting appropriate locations for grid-coupled system layouts since the deployment of DACCS at geographic locations with CO2-intensive grid electricity mixes leads to net GHG emissions instead of GHG removal today.