Resume

Sugarcane and palm trees are amongst the crops with the highest biofuel yields, which can reach 6 to 7.5 thousand liters of ethanol per hectare per year and 4 to 6 metric tons of oil per hectare per year, respectively. The joint production of biofuels from these crops enhances the sustainability of the ethanol produced. The objective of this work was comparing a traditional sugarcane ethanol production system with a joint production system, in which ethanol and palm biodiesel are produced. This comparative study is based on a life cycle approach (ISO 14.044/2006) and appropriate indicators. Production systems in Cerrado, Cerradão and grassland ecosystem were considered. The energy balance, carbon balance and land use change impact on the carbon balance were evaluated. The joint system includes 100% substitution of diesel for biodiesel, which is used in different cropping stages. A sensitivity analysis of distinct fractions of sugarcane in sugar production was carried out. When all sugarcane is converted into sugar production, ethanol is produced only by molasses. The data were collected by direct field observation methods and by questionnaires applied to facilities in Brazil. Three sugarcane mills situated in São Paulo State and one palm oil refinery located in Para State were surveyed. The information was complimented by secondary sources. Results demonstrated that fossil fuel use and greenhouse gas emissions decreased whereas energy efficiency increased when the joint system was compared to the traditional ethanol production system.  In comparison with the traditional system, the energy balance of the joint production system was 2.64 greater. In addition, the joint production system released 24% lesser GHG emissions than the traditional system. The ecosystem carbon payback time for Cerrado, Cerradão and Degraded Grassland of the joint production system was respectively 5, 10, and -5 years. These are typical land use types of the central Brazilian region for which the joint ethanol production system was conceived.