Life-cycle greenhouse gas emissions and energy balances of sugarcane ethanol production in Mexico

The purpose of this work was to estimate GHG emissions and energy balances for the future expansion of sugarcane ethanol fuel production in Mexico with one current and four possible future modalities. We used the life cycle methodology that is recommended by the European Renewable Energy Directive (RED), which distinguished the following five system phases: direct Land Use Change (LUC); crop production; biomass transport to industry; industrial processing; and ethanol transport to admixture plants. Key variables affecting total GHG emissions and fossil energy used in ethanol production were LUC emissions, crop fertilization rates, the proportion of sugarcane areas that are burned to facilitate harvest, fossil fuels used in the industrial phase, and the method for allocation of emissions to co-products. The lower emissions and higher energy ratios that were observed in the present Brazilian case were mainly due to the lesser amount of fertilizers applied, also were due to the shorter distance of sugarcane transport, and to the smaller proportion of sugarcane areas that were burned to facilitate manual harvest. The resulting modality with the lowest emissions of equivalent carbon dioxide (CO2e) was ethanol produced from direct juice and generating surplus electricity with 36.8Â kgCO2e/GJethanol. This was achieved using bagasse as the only fuel source to satisfy industrial phase needs for electricity and steam. Mexican emissions were higher than those calculated for Brazil (27.5Â kgCO2e/GJethanol) among all modalities. The Mexican modality with the highest ratio of renewable/fossil energy was also ethanol from sugarcane juice generating surplus electricity with 4.8 GJethanol/GJfossil.

[1]  S. Gheewala,et al.  Impacts of Thai bio-ethanol policy target on land use and greenhouse gas emissions , 2009 .

[2]  Myles Allen,et al.  Uncertainty in the IPCC's Third Assessment Report , 2001, Science.

[3]  Hans-Jürgen Dr. Klüppel,et al.  The Revision of ISO Standards 14040-3 - ISO 14040: Environmental management – Life cycle assessment – Principles and framework - ISO 14044: Environmental management – Life cycle assessment – Requirements and guidelines , 2005 .

[4]  Pål Börjesson,et al.  Good or bad bioethanol from a greenhouse gas perspective – What determines this? , 2009 .

[5]  T. Patzek.  Thermodynamics of the Corn-Ethanol Biofuel Cycle , 2004 .

[6]  B. E. Vaughan,et al.  Ethanol as Fuel: Energy, Carbon Dioxide Balances, and Ecological Footprint , 2005 .

[7]  Mark A. J. Huijbregts,et al.  Biofuels for Road Transport: A Seed to Wheel Perspective , 2008 .

[8]  Jerry D. Murphy,et al.  Is it better to import palm oil from Thailand to produce biodiesel in Ireland than to produce biodiesel from indigenous Irish rape seed , 2009 .

[9]  Shabbir H. Gheewala,et al.  Full chain energy analysis of fuel ethanol from cane molasses in Thailand , 2008 .

[10]  Comité Intersecretarial de Cambio Climático.  Inventario Nacional de Emisiones de Gases de Efecto Invernadero 1990-2002. , 2006 .

[11]  Andrew D. Jones,et al.  Supporting Online Material for: Ethanol Can Contribute To Energy and Environmental Goals , 2006 .

[12]  J Villegas,et al.  Life cycle assessment of biofuels: energy and greenhouse gas balances. , 2009, Bioresource technology.

[13]  D. Pimentel,et al.  Ethanol Production Using Corn, Switchgrass, and Wood; Biodiesel Production Using Soybean and Sunflower , 2005 .

[14]  Keith A. Smith,et al.  N 2 O release from agro-biofuel production negates global warming reduction by replacing fossil fuels , 2007 .

[15]  Hiederer Roland,et al.  Background Guide for the Calculation of Land Carbon Stocks in the Biofuels Sustainability Scheme Drawing on the 2006 IPCC Guidelines for National Greenhouse Gas Inventories , 2010 .

[16]  Wouter Achten,et al.  Life cycle assessment of Jatropha biodiesel as transportation fuel in rural India , 2010 .

[17]  Thu Lan T. Nguyen,et al.  Fossil energy savings potential of sugar cane bio-energy systems , 2009 .

[18]  J. Seabra,et al.  Green house gases emissions in the production and use of ethanol from sugarcane in Brazil: the 2005/2006 averages and a prediction for 2020. , 2008 .

[19]  Ignacio Pichardo Pagaza.  Secretaría de Energía , 1995 .

[20]  S. Polasky,et al.  Land Clearing and the Biofuel Carbon Debt , 2008, Science.

[21]  M. A. Elsayed,et al.  CARBON AND ENERGY BALANCES FOR A RANGE OF BIOFUELS OPTIONS , 2003 .

[22]  Jacinto F. Fabiosa,et al.  Use of U.S. Croplands for Biofuels Increases Greenhouse Gases Through Emissions from Land-Use Change , 2008, Science.

[23]  J. Goldemberg,et al.  The Sustainability of Ethanol Production from Sugarcane , 2008, Renewable Energy.

[24]  Michael Q. Wang,et al.  The Energy Balance of Corn Ethanol: An Update , 2002 .

[25]  Electo Eduardo Silva Lora,et al.  Biofuels: Environment, technology and food security , 2009 .