Green house gases emissions in the production and use of ethanol from sugarcane in Brazil: The 2005/2006 averages and a prediction for 2020

This work presents the evaluation of energy balance and GHG emissions in the production and use of fuel ethanol from cane in Brazil for 2005/2006 (for a sample of mills processing up to 100 million tons of sugarcane per year), and for a conservative scenario proposed for 2020. Fossil energy ratio was 9.3 for 2005/2006 and may reach 11.6 in 2020 with technologies already commercial. For anhydrous ethanol production the total GHG emission was 436 kg CO2 eq m(-3) ethanol for 2005/2006, decreasing to 345 kg CO2 eq m(-3) in the 2020 scenario. Avoided emissions depend on the final use: for E100 use in Brazil they were (in 2005/2006) 2181 kg CO2 eq m(-3) ethanol, and for E25 they were 2323 kg CO2 eq m(-3) ethanol (anhydrous). Both values would increase about 26% for the conditions assumed for 2020 mostly due to the large increase in sales of electricity surpluses. A sensitivity analysis has been performed (with 2005/2006 values) to investigate the impacts of the huge variation of some important parameters throughout Brazilian mills on the energy and emissions balance. The results have shown the high impact of cane productivity and ethanol yield variation on these balances (and the impacts of average cane transportation distances, level of soil cultivation, and some others) and of bagasse and electricity surpluses on GHG emissions avoidance. (C) 2008 Elsevier Ltd. All rights reserved.