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.