Role of biochar toward carbon neutrality

Abstract Carbon neutrality by the mid-twenty-first century is a grand challenge requiring technological innovations. Biochar, a traditional soil amendment which has been used for fertility improvement and contaminant remediation, has revealed new vitality in this context. In this review we highlight the huge potential of biochar application in different fields to mitigate as high as 2.56 × 10 9 t CO 2 e total greenhouse gas (GHG) emissions per year, accounting for 5.0% of the global GHG emissions. Soil applications of biochar as either a controlled-release fertilizer or an immobilization agent offer improved soil health while simultaneously suppressing the emissions of CH 4 and N 2 O. Non-soil applications of biochar also contribute to carbon neutrality in unique ways. Firstly, biochar application as a ruminant feed decreases CH 4 emissions via physical sorption and enhanced activities of methanotrophs. Secondly, biochar can be used as a green catalyst for biorefinery. Besides, biochar as an additive to Portland cement and low impact development (LID) infrastructure lowers the carbon footprint and builds resilience to climate change. Furthermore, biochar can be used as novel batteries and supercapacitors for energy storage purposes. Finally, the high CO 2 adsorption capacity makes it possible for biochar being used as a sorbent for carbon capture, utilization, and storage (CCUS). We advocate that future research should further explore the effectiveness of biochar systems for climate change mitigation in large scale applications, and assess the economic and social viability of local biochar systems to combat climate change. Graphical Abstract