Deploying direct air capture at scale: How close to reality?

Abstract

The role of negative emissions in achieving deep decarbonization targets has been demonstrated through Integrated Assessment Models (IAMs). While many studies have focused on bioenergy with carbon capture and storage (BECCS), relatively little attention has been given to direct air capture (DAC) in IAMs beyond assessing the role of low-cost DAC with carbon storage (DACCS). In this study, we employ an economy-wide model to more fully explore the potential role of DAC, considering the full range of cost estimates ($180–$1000/tCO2), DAC units supplied by either dedicated renewables or grid electricity, and both the storage of captured CO2 (DACCS) or its utilization (DACCU) to produce fuels. Our results show that the deployment of DAC is driven by its cost and is dominated by DACCS, with little deployment of DACCU. We analyze the technical and policy conditions making DACCS compete with BECCS, investigating scenarios in which BECCS is limited and there is no emissions trading across countries. With an international emissions trading system (ETS), we find that Africa takes advantage of its large and cheap renewable potential to export emissions permits and contributes more than half of total global negative emissions through DAC. However, DAC also proves essential when no ETS is available, particularly in Asian countries due to scarce and expensive access to land and bioenergy. Our analysis provides a comprehensive evaluation of the impact of DAC on the power system, economy, and land use.