Direct Air Carbon Capture and Sequestration: How It Works and How It Could Contribute to Climate-Change Mitigation

Owing to the small quantity of carbon dioxide (CO 2 ) that can be emitted before we exceed the 1.5°C–2°C target of the Paris Agreement on climate change, we are increasingly likely to require ways of removing significant CO 2 from the atmosphere. In addition to the biological options considered to date such as afforestation and bioenergy with CO 2 capture, direct air carbon capture and sequestration (DACCS) is emerging as a potentially important synthetic CO 2 removal technology. Here, we explain how DACCS works, focusing on two major processes that have been developed into large-scale pilot plants. We discuss cost estimates and operational energy requirements, as well as ecological and ethical considerations. We highlight the role of DACCS in the low-carbon transition by discussing its benefits, while also noting potential trade-offs and uncertainties that deserve further investigation.