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Characterizing model uncertainties in the life cycle of lignocellulose-based ethanol fuels
Journal article   Peer reviewed

Characterizing model uncertainties in the life cycle of lignocellulose-based ethanol fuels

Sabrina Spatari and Heather L MacLean
Environmental science & technology, v 44(22), pp 8773-8780
15 Nov 2010
PMID: 20979408

Abstract

Lignin - analysis Air Pollution - statistics & numerical data Uncertainty Models, Chemical Greenhouse Effect Lignin - chemistry Ethanol - chemistry Ethanol - analysis Biofuels - analysis Carbon Footprint Air Pollution - analysis Conservation of Natural Resources Crops, Agricultural Vehicle Emissions - analysis
Renewable and low carbon fuel standards being developed at federal and state levels require an estimation of the life cycle carbon intensity (LCCI) of candidate fuels that can substitute for gasoline, such as second generation bioethanol. Estimating the LCCI of such fuels with a high degree of confidence requires the use of probabilistic methods to account for known sources of uncertainty. We construct life cycle models for the bioconversion of agricultural residue (corn stover) and energy crops (switchgrass) and explicitly examine uncertainty using Monte Carlo simulation. Using statistical methods to identify significant model variables from public data sets and Aspen Plus chemical process models,we estimate stochastic life cycle greenhouse gas (GHG) emissions for the two feedstocks combined with two promising fuel conversion technologies. The approach can be generalized to other biofuel systems. Our results show potentially high and uncertain GHG emissions for switchgrass-ethanol due to uncertain CO₂ flux from land use change and N₂O flux from N fertilizer. However, corn stover-ethanol,with its low-in-magnitude, tight-in-spread LCCI distribution, shows considerable promise for reducing life cycle GHG emissions relative to gasoline and corn-ethanol. Coproducts are important for reducing the LCCI of all ethanol fuels we examine.

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#12 Responsible Consumption & Production
#7 Affordable and Clean Energy

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Collaboration types
Domestic collaboration
International collaboration
Web of Science research areas
Engineering, Environmental
Environmental Sciences
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