Removing CO2 from the atmosphere? We can do it but huge innovation is required

A new Nature Communications study has shown the potential of Direct Air Carbon Capture and Storage (DACCS), a new technology for removing CO2 directly from the atmosphere, in helping to limit global temperature rise and lowering the costs of achieving the Paris objectives. However, the authors note that these technologies should be used as part of a portfolio of other mitigation solutions and would require major innovation to be feasible at scale. The paper has been co-authored by an international team of researchers from the Euro-Mediterranean Centre on Climate Change, RFF-CMCC European Institute on Economics and the Environment and Politecnico di Milano (Italy), Grantham Institute – Climate Change and the Environment at Imperial College London (United Kingdom) and the MaREI Centre at University College Cork (Ireland).

Technologies to remove excess carbon dioxide from the atmosphere can play an important role in meeting the Paris agreement, as emphasized in IPCC reports such as the special report on 1.5°C. However, existing studies have mostly focused on biological ways to absorb CO2 (such as bioenergy with CO2 storage), which can have adverse effects on food security and ecosystems.

This new study, published in Nature Communications, explores the role of absorbing CO2 directly from the atmosphere using a technology called Direct Air Carbon Capture and Storage (DACCS). The results suggest that DACCS can not only help meet the Paris Agreement targets, but also lower the costs of doing so. However, it cannot be considered an alternative to reducing greenhouse gas emissions, which will require the progressive phase-out of fossil fuel emissions from our socio-economic systems. The authors emphasize that the benefits from DACCS technologies are linked to the rate at which its capacity can be ramped up. Since the technology is not yet ready for large-scale commercial deployment, this rate will be very limited, at least in the near-term.

Therefore, DACCS is not an alternative to reducing emissions but is one of the solutions available in a portfolio that includes other CO2 removal initiatives, the adoption of lifestyles consistent with a low-carbon society and other measures to mitigate and reduce greenhouse gas emissions.

The study is the first to analyse the technologies using two different techno-economic models in an integrated assessment. It describes in detail the critical issues related to energy consumption, costs and the materials necessary for an extensive roll-out of these technologies in global mitigation strategies.

“This first inter-model comparison helps us to provide more robust insights as the results are consistent across the two models used (WITCH, developed at CMCC, and TIAM-Grantham, used at Imperial) which use different approaches to represent the interactions between the economy and the energy system” said co-author Laurent Drouet, scientist at the RFF-CMCC European Institute on Economics and the Environment.

According to the study’s lead-author, Giulia Realmonte, junior scientist at the RFF-CMCC European Institute on Economics and the Environment, “the energy requirements for manufacturing the chemicals to remove carbon-dioxide from the atmosphere are projected to be significant and may limit the amount of installed DACCS. In general, the indirect impacts of large DACCS deployment have to be further studied as they were not fully considered in this study”.

Study co-author Ajay Gambhir, Senior Research Fellow at the Grantham Institute, added that “DACCS is not yet available for large-scale deployment, so it is critical that we simulate its take-up and implications for emissions reductions in detailed studies such as this. However, we can only know its true potential by actually deploying it and carefully monitoring its impacts on emissions, as well as its other implications”.

“The study shows that innovation in new technologies such as direct CO2 capture is needed to solve the climate crises” says Massimo Tavoni, director of RFF-CMCC institute and professor at Politecnico di Milano. “It also shows that this should not distract us from the pressing issue of reducing CO2 emissions as soon as possible. We need to complement investments in low carbon energy with those in green innovation and education”.

Policy-makers should note that DACCS shows considerable potential, which justifies investment in research, development and deployment; however, if we rely too heavily on DACCS and it doesn’t deliver emissions removals at large-scale, then we will overshoot our Paris Agreement targets, possibly quite significantly. The authors conclude that we must continue ratcheting up the mitigation strategies that are already in place to complement these technologies and avoid missing the Paris Agreement targets.

Giulia Realmonte, Laurent Drouet, Ajay Gambhir, James Glynn, Adam Hawkes, Alexandre C. Köberle, and MassimoTavoni “An inter-model assessment of the role of direct air capture in deep mitigation pathwaysNature Communications, DOI: 10.1038/s41467-019-10842-5.

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