Life cycle assessment of lignocellulosic ethanol: a review of key factors and methods affecting calculated GHG emissions and energy use.

Lignocellulosic ethanol has potential for lower life cycle greenhouse gas emissions compared to gasoline and conventional grain-based ethanol. Ethanol production 'pathways' need to meet economic and environmental goals. Numerous life cycle assessments of lignocellulosic ethanol have been published over the last 15 years, but gaps remain in understanding life cycle performance due to insufficient data, and model and methodological issues. We highlight key aspects of these issues, drawing on literature and a case study of corn stover ethanol. Challenges include the complexity of feedstock/ecosystems and market-mediated aspects and the short history of commercial lignocellulosic ethanol facilities, which collectively have led to uncertainty in GHG emissions estimates, and to debates on LCA methods and the role of uncertainty in decision making.

[1]  J Villegas,et al.  Life cycle assessment of biofuels: energy and greenhouse gas balances. , 2009, Bioresource technology.

[2]  Seungdo Kim,et al.  Life cycle assessment of corn grain and corn stover in the United States , 2009 .

[3]  A. Aden,et al.  Process Design Report for Stover Feedstock: Lignocellulosic Biomass to Ethanol Process Design and Economics Utilizing Co-Current Dilute Acid Prehydrolysis and Enzymatic Hydrolysis for Corn Stover , 2002 .

[4]  Michael O'Hare,et al.  Greenhouse gas emissions from biofuels' indirect land use change are uncertain but may be much greater than previously estimated. , 2010, Environmental science & technology.

[5]  Humberto Blanco-Canqui,et al.  Energy Crops and Their Implications on Soil and Environment , 2010 .

[6]  T. Foust,et al.  Technoeconomic analysis of the dilute sulfuric acid and enzymatic hydrolysis process for the conversion of corn stover to ethanol , 2009 .

[7]  S. Suh,et al.  On the uncanny capabilities of consequential LCA , 2014, The International Journal of Life Cycle Assessment.

[8]  Deepak Rajagopal,et al.  Implications of market-mediated emissions and uncertainty for biofuel policies. , 2013 .

[9]  Rakesh Agrawal,et al.  Estimation of liquid fuel yields from biomass. , 2010, Environmental science & technology.

[10]  J. Gutiérrez,et al.  Resource economics and coordination among above- and below-ground functional traits of three dominant shrubs from the Chilean coastal desert. , 2015 .

[11]  H. MacLean,et al.  Impacts of pre-treatment technologies and co-products on greenhouse gas emissions and energy use of lignocellulosic ethanol production , 2014 .

[12]  Germán Aroca,et al.  Life cycle assessment of lignocellulosic bioethanol: Environmental impacts and energy balance , 2015 .

[13]  A. Horvath,et al.  Lifecycle greenhouse gas implications of US national scenarios for cellulosic ethanol production , 2012 .

[14]  C. Wyman,et al.  Pretreatment: the key to unlocking low‐cost cellulosic ethanol , 2008 .

[15]  Reinout Heijungs,et al.  LCA of second generation bioethanol: A review and some issues to be resolved for good LCA practice , 2012 .

[16]  John J. Reap,et al.  A survey of unresolved problems in life cycle assessment , 2008 .

[17]  David Zilberman,et al.  Indirect fuel use change (IFUC) and the lifecycle environmental impact of biofuel policies , 2011 .

[18]  F. Creutzig,et al.  Using Attributional Life Cycle Assessment to Estimate Climate‐Change Mitigation Benefits Misleads Policy Makers , 2014 .

[19]  Mikhail Chester,et al.  Attributional and Consequential Life-cycle Assessment in Biofuels: a Review of Recent Literature in the Context of System Boundaries , 2015, Current Sustainable/Renewable Energy Reports.

[20]  Kelly N. Ibsen,et al.  Lignocellulosic Biomass to Ethanol Process Design and Economics Utilizing Co-Current Dilute Acid Prehydrolysis and Enzymatic Hydrolysis for Corn Stover , 2002 .

[21]  Barnabas Gikonyo.  Well-to-Wheels Energy Use and Greenhouse Gas Emissions of Ethanol from Corn, Sugarcane and Cellulosic Biomass for US Use , 2015 .

[22]  A. Kendall,et al.  Life cycle inventory development for corn and stover production systems under different allocation methods. , 2013 .

[23]  Robert B. Mitchell,et al.  Soil Carbon Sequestration by Switchgrass and No-Till Maize Grown for Bioenergy , 2012, BioEnergy Research.

[24]  David D. Hsu,et al.  Life cycle environmental impacts of selected U.S. ethanol production and use pathways in 2022. , 2010, Environmental science & technology.

[25]  Gjalt Huppes,et al.  Allocation issues in LCA methodology: a case study of corn stover-based fuel ethanol , 2009 .

[26]  Poritosh Roy,et al.  A Review of Life Cycle Assessment (LCA) of Bioethanol from Lignocellulosic Biomass , 2012 .

[27]  Hong Huo,et al.  Methods of dealing with co-products of biofuels in life-cycle analysis and consequent results within the U.S. context , 2011 .

[28]  Ryan Davis,et al.  Process Design and Economics for Biochemical Conversion of Lignocellulosic Biomass to Ethanol: Dilute-Acid Pretreatment and Enzymatic Hydrolysis of Corn Stover , 2011 .

[29]  J. M. Earles,et al.  Consequential life cycle assessment: a review , 2011 .

[30]  Seungdo Kim,et al.  Energy Requirements and Greenhouse Gas Emissions of Maize Production in the USA , 2014, BioEnergy Research.

[31]  S. Hellweg,et al.  Emerging approaches, challenges and opportunities in life cycle assessment , 2014, Science.

[32]  H. MacLean,et al.  Implications of land class and environmental factors on life cycle GHG emissions of Miscanthus as a bioenergy feedstock , 2014 .

[33]  Geoffrey P. Hammond,et al.  Environmental life cycle assessment of lignocellulosic conversion to ethanol: A review , 2012 .

[34]  Heather L. MacLean,et al.  Impact of cellulase production on environmental and financial metrics for lignocellulosic ethanol , 2013 .

[35]  Michael Q. Wang,et al.  Energy consumption and greenhouse gas emissions from enzyme and yeast manufacture for corn and cellulosic ethanol production , 2012, Biotechnology Letters.

[36]  Francesco Cherubini,et al.  GHG balances of bioenergy systems – Overview of key steps in the production chain and methodological concerns , 2010 .

[37]  Kimberley A Mullins,et al.  Policy implications of uncertainty in modeled life-cycle greenhouse gas emissions of biofuels. , 2011, Environmental science & technology.

[38]  J. R. Hess,et al.  Process Design and Economics for Conversion of Lignocellulosic Biomass to Ethanol , 2011 .

[39]  B. Dale,et al.  Global potential bioethanol production from wasted crops and crop residues , 2004 .

[40]  Michael Q. Wang,et al.  Land-use change and greenhouse gas emissions from corn and cellulosic ethanol , 2013, Biotechnology for Biofuels.

[41]  Madhu Khanna,et al.  Supply of Cellulosic Biofuel Feedstocks and Regional Production Patterns , 2010 .

[42]  Heather L. MacLean,et al.  Exploring impacts of process technology development and regional factors on life cycle greenhouse gas emissions of corn stover ethanol , 2015 .

[43]  Heather L MacLean,et al.  Life cycle evaluation of emerging lignocellulosic ethanol conversion technologies. , 2010, Bioresource technology.

[44]  Robert D. Perlack,et al.  Current and potential U.S. corn stover supplies. , 2007 .

[45]  Edgar G. Hertwich,et al.  Understanding the Climate Mitigation Benefits of Product Systems: Comment on “Using Attributional Life Cycle Assessment to Estimate Climate‐Change Mitigation…” , 2014 .