Combining on-road measurements and life-cycle carbon emissions of flex-fuel vehicle

The impact of the transport sector on global greenhouse gas emissions has triggered the development of regulations to limit carbon dioxide emissions. The measurement process for vehicle emissions is based on laboratory type-approval tests, which results in gap compared with on-road usage profiles. Although recently introduced vehicle technologies have increased energy efficiency, regulatory restrictions on carbon dioxide emissions necessitate additional solutions. The use of biofuels, such as ethanol, fosters carbon dioxide emissions mitigation in developing countries, such as Brazil. Flex-fuel vehicles are an important alternative technology for the transition to zero-emission vehicles. In addition to vehicle emissions, the fuel production chain also has emissions which depend on the efficiency of the process and feedstock origin. Consequently, this study focuses on flex-fuel vehicles by quantifying the gap between certification and real-world driving energy consumption and by calculating the well-to-wheel impacts accounting for user behaviour choices when refuelling the vehicles. The results show 15.1 and 24.2 % higher fuel consumption in real driving conditions compared to laboratory tests using gasoline and ethanol, respectively. The analysis of the impacts on a well-to-wheel basis confirms the effectiveness of ethanol in mitigating the impacts at the energy production stage. Based on the fuels used in this study, first-generation ethanol leads to a 58 % reduction in carbon dioxide emissions compared with gasoline. Considering second-generation ethanol, the difference increases to up to 73 % lower emissions than gasoline. These results contribute to increasing consumer awareness, which plays an important role in mitigating environmental impacts.