Cradle-to-gate analyses of biochar produced from agricultural crop residues by vacuum pyrolysis

Abstract Agricultural waste, if not managed efficiently, can pose significant environmental threats. Biochar production, a cost-effective solution, offers a potential to significantly reduce carbon dioxide emissions and thereby combat climate change. However, the environmental impact of this process is not uniform and varies depending on the agricultural residue used. These impacts, spanning the entire lifecycle from cultivation to disposal, underscore the necessity of a thorough assessment before biochar can be widely adopted for practical applications. This study employs a cradle-to-gate approach to evaluate the life cycle assessment (LCAs) of producing biochar from various agro-residues, such as rice husk, sugarcane bagasse (SB), and corn cob (CC). The LCA was conducted using SimaPro software, version 9.5.0.1, and the ReCiPe impact assessment method. The results indicate that CC cultivation has the highest impact across most categories, while rice husks exhibit higher water consumption (2.8 × 103 m3). Using diesel, electricity, and fertilizers significantly contributes to global warming potential (GWP). SB shows the most negligible impact during biomass cultivation. However, pyrolysis processes exhibit high implications on various indicators. Applying biochar to soil for carbon sequestration and improvement can reduce GWP. Sensitivity analysis demonstrates a notable reduction in GWP and cumulative energy demand, approximately 10%–24% and 4–11 MWh, respectively. Paddy cultivation and rice husk biochar production have a lesser environmental impact. Changing energy sources during biomass growth and biochar production significantly influences environmental factors.