Publication Details

Title : Life-Cycle Energy Use and Greenhouse Gas Emission Implications of Brazilian Sugarcane Ethanol Simulated with the GREET Model (abstract)
Publication Date : August 1, 2008
Publication Journal : International Sugar Journal 2008, Vol. 110, No. 1317
Authors : M. Wang, M. Wu, H. Huo, J. Liu
Abstract : By using data available in the open literature, we expanded the Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation (GREET) model developed by Argonne National Laboratory to include Brazilian-grown sugarcane ethanol. With the expanded GREET model, we examined the well-to-wheels (WTW) energy use and greenhouse gas (GHG) emissions of sugarcane-derived ethanol produced in Brazil and used to fuel light-duty vehicles in the United States. Results for sugarcane ethanol were compared with those for petroleum gasoline. The sugarcane-to-ethanol pathway
evaluated in the GREET model comprises fertilizer production, sugarcane farming, sugarcane transportation, and sugarcane ethanol production in Brazil; ethanol transportation to U.S. ports and then to U.S. refueling stations; and ethanol use in vehicles. Our analysis shows that sugarcane ethanol can reduce GHG emissions by 78% and fossil energy use by 97%, relative to petroleum gasoline. The large reductions can be attributed to use of bagasse in sugarcane mills, among other factors. To address the uncertainties involved in key input parameters, we developed and examined several
sensitivity cases to test the effect of key parameters on WTW results for sugarcane ethanol. Of the total GHG emissions associated with sugarcane ethanol, the five major contributors are open-field burning of sugarcane tops and leaves, N2O emissions from sugarcane fields, fertilizer production, sugarcane mill operation, and sugarcane farming. Brazil is going to phase out open-field burning in the future. This action will certainly help further reduce GHG emissions of sugarcane farming, together with reductions in emissions of criteria pollutants such as Nox and particulate matter with diameters smaller than 10 microns. The eventual elimination of open-field burning in sugarcane plantations will result in additional GHG emission reductions by sugarcane ethanol of up to 9 percentage points.

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Title : Updated Sugarcane and Switchgrass Parameters in the GREET Model
Publication Date : October 10, 2011
Authors : J. B. Dunn, J. Eason, M Q. Wang
Abstract : The feedstock from which a biofuel derives can have a significant effect on its life-cycle energy consumption and emissions of greenhouse gases (GHG). The aim of this document is to describe our approach to developing GREET parameters for key facets of sugarcane and switchgrass feedstocks that affect their life-cycle air emissions and energy consumption from the field (including the upstream energy to manufacture agricultural inputs such as fertilizer) to the conversion facility gate in the case of switchgrass. For sugarcane ethanol, we also revise aspects of the fuel's life cycle pertaining to the conversion facility including ethanol yield and embodied energy in the sugarcane mill buildings and equipment. A summary of data sources for corn stover and forest residue are provided elsewhere (Han et al. 2011). Note that although this document discusses switchgrass in the context of ethanol production, this crop could also be a feed to a process that directly produces hydrocarbon fuels, such as fast pyrolysis.

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