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Life cycle assessment of Brazilian sugarcane products: GHG emissions and energy use



Sugarcane is currently the main renewable energy source in Brazil. Due to the importance of the cane industry and its contribution to a wide range of biobased energy and other products, LCA studies regarding cane-derived products are needed to assess their environmental benefits. The main objective of this work was the assessment of life cycle energy use and greenhouse gas (GHG) emissions related to cane sugar and ethanol, considering bagasse and electricity surpluses as coproducts. We performed an overall balance for the Brazilian Center-South Region, adopting different methods to evaluate sugar and ethanol production separately. The GREET 1.8c.0 model was used for the ‘well-to-wheels’ calculations but adapted to the comprehensive set of Brazilian parameters that best represent the Center-South Region. For the reference case, fossil energy use and GHG emissions related to sugar production were evaluated as 721 kJ/kg and 234 g CO2eq/kg, respectively. For the ethanol life cycle, these values were 80 kJ/MJ and 21.3 g CO2eq/MJ. Special attention was paid to the variation of some parameters among producing units based on data collected by industry. The consequent uncertainties in ethanol life cycle emissions were assessed through a Monte Carlo analysis based on assigned distribution of probability curves for eleven selected parameters and informed by partial statistical data available from industry for distribution generation. Projections were also made for 2020 scenario parameters based on the best in current class technologies and technological improvements deemed commercially possible today. Published in 2011 by John Wiley & Sons, Ltd