| Summary: | Sustainable development and climate change are at the forefront of today’s political agendas, as signified by the 2016 Paris Agreement and the 2015 United Nations’ Sustainable Development Goals. Carbon Dioxide Removal (CDR) technologies are being investigated for their contribution to reducing atmospheric greenhouse gas levels. The PhD assesses the potential of biochar systems as a sustainable CDR technology for climate change mitigation at a European scale. The potential sustainability impacts of biochar production and land application are evaluated by applying life cycle approaches to analyse the environmental, economic and social impacts within the overarching Life Cycle Sustainability Assessment (LCSA) framework. Scenario modelling is incorporated to estimate feedstock potentials and the scale of biochar production within Europe, as well as the corresponding levels of carbon sequestration. The research results indicate that gasification biochar systems have potential as CDR technologies, though the uncertainty regarding biochar’s stable carbon fraction remains a significant knowledge gap. The use of ‘wastes’ as the input material is more likely to reduce potential negative impacts in all three sustainability components. Though overall, the current economic climate limits the feasibility of sustainable biochar systems. The results are sensitive to the modelling approach, especially the incorporation of ‘consequential’ elements, which was shown to significantly benefit the outcomes of the environmental and economic assessments. The scenario modelling outputs suggest that large-scale implementation of biochar systems within Europe can contribute an important share of the EU emission reduction targets. However, to incentivise the uptake of biochar and/or to generate policy support, further certainty and evidence of biochar’s impacts following land application is needed. Overall, a single-issue focus is no longer applicable in today’s policy climate. It is important to assess all three pillars of sustainability when evaluating whether a product system/process is capable of contributing to sustainable development. The novel LCSA framework shows potential to assist with such assessments at the micro-level.
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