Probabilistic Lifecycle Assessment of Butanol Production from Corn Stover Using Different Pretreatment Methods

Abstract

The recalcitrant nature of lignocelluloses requires a pretreatment process before the fermentative butanol production. The commonly used pretreatment processes, such as steam explosion, sulfuric acid, ammonia fiber explosion, ionic liquid (IL), and biological, require different quantities and types of process chemicals, and produce different quality and quantity of fermentable sugars. This study determines life-cycle greenhouse gas emissions (GHG) these pretreatment methods by developing a system-level process model including corn stover feedstock supply system and the downstream butanol production process. This study further evaluates the uncertainty associated with energy use and GHG emissions for each stage of the entire butanol production chain and provide the future optimization opportunities. Probabilistic results of these analyses describe a distribution of GHG emissions with an average of 18.09–1056.12 gCO2e/MJ and a 95% certainty to be less than 33.3–1888.3 gCO2e /MJ. The highest GHG emissions of IL-pretreatment of 1056.12 gCO2e/MJ reaches to 89.8 gCO2e/MJ by switching IL-recovery from 80 to 99 wt %, which is the most influential parameter for IL-pretreatment. Additionally, credits from excess electricity, butanol yield, nitrogen replacement, and diesel fuel for transportation and harvesting were the most influential parameters. Based on the current state of technologies, apart from ionic liquid and biological pretreatments, other pretreatment processes have similar metrics of sustainability.

Use of ensiled biomass sorghum increases ionic liquid pretreatment efficiency and reduces biofuel production cost and carbon footprint

“…The process equipment data are gathered from similar prior studies. 31,34 Following a rigorous material and energy balance for each unit operation, capital and operating costs as well as material and energy requirements for each stage of the entire biofuel production chain are determined. The economic evaluation parameters and the methods used to determine carbon footprint are documented in the ESI-S2.…”

Life-Cycle Assessment (LCA) of Different Pretreatment and Product Separation Technologies for Butanol Bioprocessing from Oil Palm Frond

“…Baral et al [50], who treated corn stover for butanol production recorded NER of 1.78, 1.80, 1.73, 0.41, and 3.69 from the steam explosion, DA, AFEX, ionic liquid, and biological pretreatments, respectively. When only considering chemical pretreatment methods (DA and AFEX), their NER values were not far different from those that were recorded in this study.…”

“…In general, the process with a high-energy requirement recorded high emissions, which were mostly generated from the energy generation process (CHP system). Baral et al [50] conducted an LCA on the steam explosion, sulfuric acid, ammonia fiber explosion, ionic liquid, and biological pretreatments for butanol production from corn stover. They estimated biogenic CO 2 between 5.21-11.46 kg CO 2 /L butanol, which was only overlapped with the LMAA pretreatment model in this study (10.32 kg CO 2 /L butanol).…”

Microbial Heat and Organic Matter Loss in an Aerobic Corn Stover Storage Reactor: A Model Validation and Prediction Approach Using Lumped-Parameter Dynamical Formulation

“…Moisture contents from 15–20%, on the other hand, have lower dry matter losses effects in biomass storage and reduce safety risks such as self-ignition ( Rentizelas et al, 2009 ). This feedstock variability of corn stover has been demonstrated to be highly sensitive in metrics of sustainability such as life-cycle net energies, carbon dioxide emissions, and the cost of biofuels ( Kim and Dale, 2005 ; Spatari et al, 2005 ; Baral et al, 2017 , 2018 ). The effects of environmental factors in the corn stover properties such as moisture, temperature, and dry matter loss have been researched in field and laboratory studies ( Wendt et al, 2014 , 2018 ; Essien and Richard, 2018 ; Wang et al, 2019 ).…”