Modifying carbon feedback by transforming arctic soil into biochar

The escalation of global temperatures has heightened uncertainties in the Arctic, particularly regarding the potential release of greenhouse gases, such as carbon dioxide, through permafrost thawing. This phenomenon is primarily driven by positive carbon feedback, leading to 3.3 times faster Arctic warming rate than the global average. To address this challenge, this study proposes a proactive strategy for substituting Arctic underground soil with biochar to mitigate carbon dioxide emissions. Particularly, utilising carbon dioxide (CO₂) as a reactive feedstock to the pyrolysis system opens up opportunities to produce the functionalized biochar for adsorbing CO₂, simultaneously enhancing energy recovery from other pyrogenic products, such as syngas and biocrude. Moreover, a comprehensive techno-economic analysis allowed to determine optimized pyrolytic conditions for biochar production. Despite the necessity of high reaction temperatures, the utilisation of carbon dioxide demonstrated superior performance in terms of energy recovery and carbon dioxide mitigation. The biochars produced represent a potential of offsetting CO₂ emission, with an estimated decrease rate of 51.6 Gt CO₂ yr⁻¹ by 2100 over the next 75 years. Therefore, this study introduces a strategic approach to mitigate positive carbon feedback and slow global climate change by incorporating CO₂ for the biochar production.