Resumo:
The Brazilian road transport sector is one of the main contributors to greenhouse gas (GHG) emissions, accounting for approximately 206 MtCO2eq (10.7% of total emissions) in 2023. Although it still relies heavily on fossil fuels, the use of biofuels in recent decades has been associated with a significant mitigation of these emissions. This study aimed to estimate the sector’s GHG emissions between 1970 and 2023, analyzing the main stages of the fuel life cycle, fleet evolution, emission profiles by fuel type, and the influence of land use change (LUC). Life Cycle Assessment (LCA) was applied using an attributional approach and “well-to-wheel” system boundaries to develop inventories for ethanol pathways (sugarcane and corn) and biodiesel (soybean oil and beef tallow). The analysis was divided into five periods, allowing the evaluation of technological and regulatory changes. The results indicate a substantial reduction in biofuel emission factors, particularly for sugarcane ethanol, whose emission factor decreased from 40.45 to 14.44 gCO2eq/MJ. The agricultural stage was identified as the main source of emissions, contributing on average 83.5% for sugarcane ethanol, 76% for corn ethanol, and 73.9% for soybean biodiesel. The reduction in fuel consumption intensity in light-duty vehicles led to a decrease in emission intensity from 16 to 2 tCO2eq/unit, accompanied by a reduction in energy intensity from 0.18 to 0.03 MJ/unit. Despite this, fleet growth led to an increase in total sector emissions. LUC had a limited impact on ethanol (2.2%), but a significant effect on soybean biodiesel, increasing life cycle emissions by an average of 67.1%. It is estimated that the use of biofuels avoided approximately 1.1 GtCO2eq in emissions, equivalent to two years of net emissions from the agriculture sector, three years from the energy sector, or twelve years from the industrial processes and waste sectors in Brazil. It can be concluded that biofuels play a central role in mitigating emissions in the road transport sector, and their effectiveness depends on continuous improvements in the agricultural stage and technological advances in the industrial stage.
