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Impacts of pre-treatment technologies and co-products on greenhouse gas emissions and energy use of lignocellulosic ethanol production

Pourbafrani, Mohammad; McKechnie, Jon; Shen, Timothy; Saville, Bradley A.; MacLean, Heather L.

Authors

Mohammad Pourbafrani

Timothy Shen

Bradley A. Saville

Heather L. MacLean



Abstract

Life cycle environmental performance of lignocellulosic ethanol produced through different production pathways and having different co-products has rarely been reported in the literature, with most studies focusing on a single pre-treatment and single co-product (electricity). The aim of this paper is to understand the life cycle energy use and greenhouse gas (GHG) emissions implications of alternative pre-treatment technologies (dilute acid hydrolysis, ammonia fiber expansion and autohydrolysis) and co-products (electricity, pellet, protein and xylitol) through developing a consistent life cycle framework for ethanol production from corn stover. Results show that the choices of pre-treatment technology and co-product(s) can impact ethanol yield, life cycle energy use and GHG emissions. Dilute acid pathways generally exhibit higher ethanol yields (20 to 25%) and lower net total energy use (15 to 25%) than the autohydrolysis and ammonia fiber expansion pathways. Similar GHG emissions are found for the pre-treatment technologies when producing the same co-product. Xylitol co-production diverts xylose from ethanol production and results in the lowest ethanol yield (200 litres per dry t of stover). Compared to producing only electricity as a co-product, the co-production of pellets and xylitol decreases life cycle GHG emissions associated with the ethanol, while protein production increases emissions. The life cycle GHG emissions of blended ethanol fuel (85% denatured ethanol by volume) range from -38.5 to 37.2 g CO2eq/MJ of fuel produced, reducing emissions by 61% to 141% relative to gasoline. All ethanol pathways result in major reductions of fossil and petroleum energy use relative to gasoline, at least 47% and 67%, respectively. Pathways with electricity as the sole co-product use the least fossil energy All ethanol pathways studied meet the USA Energy Information and Security Act requirement of a 60% reduction in GHG emissions compared to gasoline for classification as a cellulosic biofuel; however, greater reductions are achievable through strategic selection of co-products.

Citation

Pourbafrani, M., McKechnie, J., Shen, T., Saville, B. A., & MacLean, H. L. (2014). Impacts of pre-treatment technologies and co-products on greenhouse gas emissions and energy use of lignocellulosic ethanol production. Journal of Cleaner Production, 78, https://doi.org/10.1016/j.jclepro.2014.04.050

Journal Article Type Article
Acceptance Date Apr 20, 2014
Online Publication Date May 9, 2014
Publication Date Sep 1, 2014
Deposit Date May 27, 2016
Publicly Available Date May 27, 2016
Journal Journal of Cleaner Production
Print ISSN 0959-6526
Electronic ISSN 1879-1786
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 78
DOI https://doi.org/10.1016/j.jclepro.2014.04.050
Keywords Bioethanol; Corn stover; Life cycle assessment; Biorefinery; Co-products; Pre-treatment
Public URL http://eprints.nottingham.ac.uk/id/eprint/33579
Publisher URL http://dx.doi.org/10.1016/j.jclepro.2014.04.050
Copyright Statement Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by-nc-nd/4.0

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Manuscript Pourbafrani et al revised FINAL.pdf (468 Kb)
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Copyright Statement
Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by-nc-nd/4.0





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