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

Published Date
Biomass and Bioenergy
July 2008, Vol.32(7):582–595, doi:10.1016/j.biombioe.2007.12.006

Author 

• Isaias C. Macedo ^a,,
• Joaquim E.A. Seabra ^b
• João E.A.R. Silva ^c

• aInterdisciplinary Center for Energy Planning (NIPE), State University of Campinas (Unicamp), CEP 13084-971, Campinas, SP, Brazil
• bCollege of Mechanical Engineering, State University of Campinas, Cidade Universitária “Zeferino Vaz”, CEP 13083-970, Barão Geraldo, Campinas-SP, Brazil
• cCentro de Tecnologia Canavieira (CTC), CEP 13400-040, Piracicaba, SP, Brazil

Received 13 April 2007. Revised 27 November 2007. Accepted 7 December 2007. Available online 14 January 2008. 

Abstract

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.

Keywords

Energy balance

CO₂

Nitrous oxide

Methane

Fertilizers

Diesel consumption

Cane residues

Trash burning

Avoided emissions

Ethanol blends

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Copyright © 2008 Elsevier Ltd. All rights reserved.

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