GHG balance of ethanol production in Brazil (J. Seabra
Transcrição
GHG balance of ethanol production in Brazil (J. Seabra
GHG balance of ethanol production in Brazil Joaquim E. A. Seabra [email protected] Analysis for sugarcane products The main objective of the work was the assessment of life cycle energy use and greenhouse gas (GHG) emissions related to cane sugar and ethanol, considering bagasse and electricity surpluses as coproducts. GREET 1.8c.0 model was used to evaluate energy use and GHG emissions in the ethanol life cycle, with recent production parameters of the Brazilian Center-South Region. Some default parameters were changed to better reflect Brazilian conditions. Parameters based on the CTC database (2008/2009 season). Database Pathways ATR mix Chemicals By-products Sugar production ATR eq SUGAR Agr. chemicals Fuels Chemicals Sugarcane production - Farming - Harvesting - Transport By-products Hydrous etOH production Chemicals By-products Anhydrous etOH production Seabra et al. (2011) ATR eq Fuel HYDROUS ETHANOL Ethanol T&D ATR eq Fuel ANHYDROUS ETHANOL Ethanol T&D Fuel use Fuel use ATR balance Seabra et al. (2011) Coproducts Bagasse surplus displancing fuel oil Electricity surplus displacing NG thermoelectricity Coproducts Brazilian SIN Operating Margin in 2008 100% Average fuel mix 80% 60% Other* Diesel 40% Coal Nuclear 20% 0% Natural gas Results Sugar Sugarcane farming Trash burning Field emissionsa Agr. inputs production Sugarcane transportation Sugarcane processing Ethanol T&D Tailpipe emissions Credits Electricityb Bagassec Total Seabra et al. (2011) Ethanol Fossil energy use GHG emissions Fossil energy use GHG emissions (kJ/kg) (g CO2eq/kg) (kJ/MJ) (g CO2eq/MJ) 1,109 88 508 237 37 85 48 85 48 18 31 6.8 3.8 6.7 3.8 1.4 2.6 1.8 0.8 -754 -416 -46 -35 -60 -33 -3.7 -2.7 721 234 80 21.3 40 19 4 22 Sugar Seabra et al. (2011) Emissions savings Sensitivity Different methods to allocate sugarcane emissions between sugar and ethanol. Seabra et al. (2011) Different methods to deal with sugar and ethanol coproducts allocation (electricity and bagasse surplus). Uncertainty analysis Uncertainty analysis Seabra et al. (2011) Sugarcane biorefinery Juice processing Cane juice Steam Ethanol Electricity Cane trash Bagasse Mill’s power plant Electricity Adjacent plant Bagasse surplus Electricity option: Power plant Electricity OR Ethanol option: Biochem. conversion plant Seabra and Macedo (2010) Ethanol Electricity GHG emissions balance Ethanol LC emissions (g CO2eq/MJ) Seabra and Macedo (2010) -19 5 Sensitivity Lifecycle emissions for gasoline and marginal electricity to yield equal net avoided emissions. Seabra and Macedo (2010) Forthcoming Silva et al. (2011) Forthcoming Silva et al. (2011) Ethanol-Biodiesel integration Façon system Soja Óleo Eletricidade Cana Bioetanol Usina integrada Seabra and Souza (2011) Biodiesel Ethanol-Biodiesel integration Fossil energy consumption 150 100 Produção do etanol Transporte 50 kJ/MJ Insumos agrícolas Emissões do solo 0 Queima da palha Cultivo da cana Créditos -50 Total -100 Referência Sistema integrado Ethanol-Biodiesel integration GHG emissions 25 20 Produção do etanol Transporte g CO2 eq/MJ 15 Cultivo da cana 10 Queima da palha Emissões do solo 5 Insumos agrícolas Créditos 0 Total -5 Referência Sistema integrado Thank you Joaquim E. A. Seabra [email protected]
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