Greenhouse gas emissions and energy balances in bio-ethanol production and utilization in Brazil (1996)

Production of sugar cane in Brazil in the 1996/97 season was 273 million t (harvested wet wt)/year, leading to 13.7 million m3 ethanol and 13.5 million t of sugar. Emissions of greenhouse gases were evaluated for the agronomic/industrial production processes and product utilization including N2O and methane. Up-dating the energy balance from 1985 to 1995 indicated the effect of the main technological trends; apparently, fossil fuel consumption due to the increasing agricultural mechanization is largely off-set by technological advances in transportation and overall conversion efficiencies (agricultural and industrial). Output/input energy ratio in ethanol grew to 9.2 (average) and 11.2 (best values). Net savings in CO2 (equivalent) emissions, due to ethanol and bagasse substitution for fossil fuels, correspond to 46.7 × 106 t CO2 (equivalent)/year, nearly 20% of all CO2 emissions from fuels in Brazil. Ethanol alone is responsible for 64% of the net avoided emissions.