Identifying knowledge gaps in the assessment of biochar's carbon dioxide removal potential: A Canadian case study

Achieving carbon neutrality by 2050, as targeted under the Paris Agreement, requires the deployment of carbon dioxide removal (CDR) strategies such as biochar production (BC), especially in biomass-rich regions. However, its effectiveness as a negative-emission technology depends strongly on process conditions and the sustainability of biomass feedstocks, requiring robust scientific evidence to confirm its CDR potential. Canada, which is well positioned to develop an industrial BC sector and is projected to rely on it for its net-zero strategy on it, was used as a case study to assess the alignment between BC-related scientific literature and its technical CDR potential derived from exploitable organic resources. Results show that Canada has a sustainably exploitable resource of 165,771 kt C under a conservative baseline scenario, dominated by fire-killed trees (73%), followed by crop residues (14%) and harvest residues (5%). According to Puro.earth's protocol, this resource represents a CDR potential of up to 348,146 kt CO 2 -equivalent by BC production, excluding upstream and downstream life cycle emissions. The systematic literature review, based on 150 Scopus-indexed publications, shows that Canadian BC research focuses mainly on secondary forestry residues feedstock and agricultural soil amendment applications. However, only 13 studies address BC production's environmental impacts in Canada. Significant knowledge gaps remain in Canadian literature, including insufficient data on alternative feedstocks (e.g., disturbed forest biomass, crop residues, manure), underexplored applications with market potential (e.g., fossil fuel substitution, materials), and limited environmental assessments across provinces and territories. Despite BC being among the most studied CDR options in Canada, current scientific literature does not adequately support large-scale deployment, highlighting the need for targeted research to inform policy and investment.