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

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.