Effects of Biochar Production and Application on Greenhouse Gas Emissions: a Meta-Analysis and Life Cycle Carbon Footprint Assessment

This paper evaluates the carbon footprint and emission reduction potential of agricultural straw pyrolysis biochar production and application from a life cycle and meta-analysis perspective.The system includes stages such as straw acquisition (planting, transportation), pyrolysis co-production (construction, operation, wastewater treatment, energy use), biochar transportation, and field application (carbon sequestration, soil GHG reduction).Results show that straw cultivation contributes most to GHG emissions.However, through fossil energy substitution and biochar's carbon sequestration, GHG reductions of 206.62 to 1364.10 kg CO2-eq per functional unit are achieved.Without considering energy substitution and carbon sequestration, the emission reduction potential of straw biochar is comparable to that of wood residues and sludge.However, when these factors are accounted for, the system's emission reduction potential increases significantly.Biochar application boosts crop yields by 18% to 31%.Substituting excessive nitrogen fertilizer with biochar further enhances emission reduction.Meta-analysis indicates emission reductions of 30.55%, 22.82%, and 21.34% for rice, wheat, and maize straw-derived biochar, respectively.Sensitivity analysis suggests that reducing energy consumption in wastewater treatment and pyrolysis can minimize environmental impact.Central and Eastern China are ideal for rice straw biochar, Northern and Northwestern China for wheat straw, and Northeastern and Northern China for maize straw.Hebei, Shandong, and Henan should be prioritized as pilot provinces for promotion.