Strategies to reduce the carbon footprint associated with the transportation of urban pruning residues in a metropolitan region

This study assesses greenhouse gas (GHG) emissions associated with the transportation of biomass waste from urban tree pruning in five municipalities of the João Pessoa metropolitan region (Northeast Brazil): João Pessoa, Cabedelo, Santa Rita, Bayeux, and Conde. Transportation was identified as the most impactful stage in the waste management chain, and its reduction offers potential for reducing the carbon footprint. This study considers the current business-as-usual scenario, followed by the substitution of regular diesel fuel with S-10 diesel and biodiesel, and the reduction of travel distances due to local reuse of waste. To this end, the life cycle assessment methodology is applied to quantify GHG emissions throughout 10 years. The results indicate that the transportation of pruning residues in the five municipalities is responsible for the emission of 881,607 tCO ₂ e, with the highest emissions in João Pessoa, followed by Cabedelo, Santa Rita, Bayeux, and Conde. Regarding travel distance reduction, total emissions could decrease to 673,622 tCO ₂ e, representing a 24.6% reduction. The scenario involving the use of S-10 diesel showed a slight increase in the carbon footprint (total supply chain emissions), approximately 3.8% higher, resulting from the increased emissions generated by the operation of the hydrogenation unit. Using biodiesel would result in a 29% reduction in GHG emissions, lowering emissions to 622,310.66 tCO ₂ e. Combining biodiesel with travel distance reduction would result in a 46% reduction, bringing total emissions down to 475,753.85 tCO ₂ e, representing the most considerable reduction in GHG emissions. This is a short-term, low-cost local action recommended through 2030.