The implications of the Paris Agreement on carbon dioxide removal (CDR) - techno-economics, potential, efficiency and permanence of CDR pathways

Tackling the many unprecedented changes observed in the climate requires immediate and deep mitigation efforts, including carbon dioxide removal (CDR). Despite the many different CDR methods proposed in the literature, it is still unclear how, where, and when carbon dioxide (CO2) removal will be deployed in a sustainable, feasible, and efficient manner. Owing to uncertainties about their CO2 removal and scale-up potentials, concerns about their environmental impacts and their competition for bio-geophysical resources, and their socio-economic challenges, the deployment of CDR at scales that are consistent with the Paris Agreement’s 1.5°C objectives is controversial. This thesis investigates the spatio-temporal deployment of portfolios of archetypal CDR technologies and practices — namely afforestation/reforestation, bioenergy with carbon capture and storage (BECCS), biochar, direct air capture of CO2 with storage (DACCS), and enhanced weathering (EW) —, and seeks to provide insights into their techno-economics, potential, efficiency and permanence. We find that the conditions under which CO2 is removed from the atmosphere in an efficient, timely, and permanent manner vary highly across the different CDR methods. Consequently, their roles and values, when deployed to deliver the Paris Agreement’s 1.5°C objectives, also vary with the region and time of deployment. Additionally, international/inter-regional cooperation is emphasised to deploy CDR most cost-efficiently and equitably — by allowing regions well-endowed with CDR potential to trade CDR surplus with regions for which delivering CDR is more difficult, or more costly. However, such cooperation needs to be implemented as immediately as possible to prevent from greater costs, carried mostly by future generations. Importantly, international/inter-regional markets for negative emissions trading are shown to be of important economic value, not only for beneficiaries of CDR, but also for providers. Finally, we find that time preference — the choice of time horizon for defining permanence — in CDR accounting methods impacts the portfolio of CDR methods deployed, with short-term methods favouring the deployment of temporary CDR methods, more affordable but also more liable to the risks of CO2 re-release/non-permanence, and with long-term methods favouring permanent CDR methods, less risky but more expensive.Open Acces