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Modeling Corn Ethanol and Climate
Author(s) -
Plevin Richard J.
Publication year - 2009
Publication title -
journal of industrial ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.377
H-Index - 102
eISSN - 1530-9290
pISSN - 1088-1980
DOI - 10.1111/j.1530-9290.2009.00138.x
Subject(s) - greenhouse gas , corn ethanol , biorefinery , life cycle assessment , environmental science , biofuel , upstream (networking) , climate change , land use, land use change and forestry , econometrics , production (economics) , ethanol fuel , agriculture , mathematics , economics , computer science , engineering , ecology , waste management , biology , computer network , macroeconomics
Summary New fuel regulations based on life cycle greenhouse gas (GHG) emissions have focused renewed attention on life cycle models of biofuels. The BESS model estimates 25% lower life cycle GHG emissions for corn ethanol than does the well‐known GREET model, which raises questions about which model is more accurate. I develop a life cycle metamodel to compare the GREET and BESS models in detail and to explain why the results from these models diverge. I find two main reasons for the divergence: (1) BESS models a more efficient biorefinery than is modeled in the cases to which its results have been compared, and (2) in several instances BESS fails to properly count upstream emissions. Adjustments to BESS to account for these differences raise the estimated global warming intensity (not including land use change) of the corn ethanol pathway considered in that model from 45 to 61 g CO 2 e MJ −1 . Adjusting GREET to use BESS's biorefinery performance and coproduct credit assumptions reduces the GREET estimate from 64 to 61 g CO 2 e MJ −1 . Although this analysis explains the gap between the two models, both models would be improved with better data on corn production practices and by better treatment of agricultural inputs.