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.