Life cycle assessment of corn stover production for cellulosic ethanol in Quebec

Abstract

Whitman, T., Yanni, S.F. and Whalen, J.K. 2011.Life cycle assessment of corn stover production for cellulosic ethanol in Quebec. Can. J. Soil Sci.91: 997–1012. The province of Quebec has a target of 5% ethanol (EtOH) content in fuel by 2012, which means the province will require about 400 million L of ethanol per year based on current consumption. Current research is focused on “second generation biofuels” such as cellulosic EtOH, which can be produced from agricultural by-products like corn stover. A life cycle assessment (LCA) evaluates the “cradle to gate” impact of corn stover feedstock production for cellulosic EtOH production in three corn-producing regions in Quebec for two impact categories: energy and greenhouse gas (GHG) impacts. The modelled system boundaries include in-field processes: corn stover production, collection, transport, soil organic carbon (SOC) loss, and N2O emissions, as well as background processes: herbicide, fertilizer, seed, and fuel production and transport. Sensitivity analyses vary the percentage of corn stover collected, contrast a multiple-pass with a one-pass stover-grain collection system, and compare mass, economic and system expansion allocation methods. Total energy impact is 931–1442 MJ t−1 dry stover collected under 15% stover collection, with stover harvest, transport, and field operationscontributing most strongly to the total impact. Total GHG emissions from corn stover production and transport of stover to the ethanol facility are320–488kg CO2e t−1 dry stover under 15% stover collection, with SOC loss, N2O emissions, and stover harvest contributing the most to the total impact. Sensitivity analysis reveals that the energy and GHG impacts of stover production are strongly influenced by the mass of stover collected, the use of a one-pass system, and the choice of allocation methods. Scaling-up results from the modelled system suggest that 100% of Quebec's EtOH targets could technically be supplied using corn stover feedstock, but this may come at the expense of GHG emissions and soil health.

Spatially Explicit Life Cycle Analysis of Cellulosic Ethanol Production Scenarios in Southwestern Michigan

“…Once the corn stover left the feedstock production portion of the system, two different coproduct treatment methods, mass allocation and sub-division, were applied in GaBi to all feedstock production inputs in order to generate results for impacts due only to corn stover. Of the more commonly used co-product treatment methods, mass allocation typically attributes the most environmental burden to stover while sub-division attributes the least [21][22][23]. The mass allocation factor for stover in this study was 33 %, and it was applied to production inputs as well as EPIC modeling data input.…”

Modelling Soil Organic Carbon Changes Under Different Maize Cropping Scenarios for Cellulosic Ethanol in Europe

“…Some case studies in the USA have reported an environmental GHG benefit of no-till maize-and stover maize-derived ethanol compared to gasoline-fueled vehicles by LCA analysis [26,27]. In the first case, the no-till adoption was estimated to sequester 377-681 kg C ha −1 year −1 while, in the second, no SOC variation was accounted for Whitman et al [28], conducting a life cycle assessment of corn stover production for cellulosic ethanol in Quebec, showing that soil Fig. 1 Total amount of dry matter annually available (Mt d.m.…”

“…However, Whittaker et al [28] remarked that the inclusion of SOC changes in LCA analysis may reduce GHG emission savings by 133 % if the effect of cereal straw removal is properly taken into account. In a recent paper, Liska et al [29] noted that life cycle emissions will probably exceed the US legislative mandate of 60 % reduction in GHG emissions compared with gasoline (under the next US biofuel targets), if 6 t ha −1 year −1 of maize stover will be removed over 5 to 10 years.…”

A life cycle assessment of environmental and economic balance of biochar systems in Quebec

“…A LCA was carried out by Whitman et al [13] to evaluate corn stover feedstock production for cellulosic EtOH production in three corn-producing regions in Quebec for energy and greenhouse gas (GHG) impacts. In this study, in-field processes such as corn stover production, collection, transport, soil organic carbon (SOC) loss, and N 2 O emissions, as well as background processes of herbicide, fertilizer, seed, and fuel production and transport were considered as the system boundaries.…”