Effect of Feedstock Variability, Feedstock Blends, and Pretreatment Conditions on Sugar Yield and Production Costs

Yudong Li,Erik M Kuhn,Nick Nagle,Ling Tao,Xiaowen Chen,Melvin Tucker

doi:10.3389/fenrg.2021.792216

Yudong Li, Erik M Kuhn + Show 4 more

Open Access

https://doi.org/10.3389/fenrg.2021.792216

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Abstract

Mass production of sustainable biofuels replacing fossil fuels will significantly reduce global greenhouse gas emissions. However, biomass feedstock variability, availability, and affordability pose significant risks for the sustainable production of biofuels in biorefinery plants. To derisk the sustainable production of biofuels, this work investigates the sugar yields and production costs of four different feedstocks as well as their blends, using different pretreatment methods: deacetylation and dilute acid pretreatment (DDA) and deacetylation and mechanical refining pretreatment (DMR). We found that not only feedstock species variability, but also feedstock harvesting techniques have large impacts on both sugar yields and production costs. Single-pass harvested corn stover (SPCS) showed higher sugar yields and lower production costs than multipass harvested corn stover, followed by sorghum and switchgrass. The highest glucose yields of 91% and 95.3%, which corresponds to the lowest sugar production costs of $0.2286/lb. and $0.2490/lb., were observed for SPCS using DDA and DMR, respectively. The difference in sugar yields and production costs due to feedstock variability can be largely mitigated by increasing deacetylation severity, especially in DMR. Higher deacetylation severity resulted in decreased sugar production costs in the case of DMR in contrast to increased costs in the case of DDA. Blending switchgrass and sorghum into corn stover, which can significantly increase the feedstock availability and sustainability, resulted in sugar yields and production costs of roughly the weighted average of those derived from constituent individual feedstocks, respectively. Thus, blending feedstocks of different biomass species is a potential successful strategy for sustainable production of biofuels to replace fossil-derived fuels.

Highlights

The 2016 billion-ton report by the U.S Department of Energy (DOE) predicts that more than 1 billion dry tons of biomass per year will be available in the United States sufficient to produce enough biofuels to displace 30% of -current petroleum consumption (Langholtz et al, 2016)
The results indicate that a linear interpolation can predict the blended feedstock total sugar yield within 4% based on individual feedstock performance
single-pass corn stover (SPCS), multi-pass corn stover (MPCS), and SW are similar in lignin content and total nonsoluble sugars (16.9%–17.8% of lignin and 53.5%–56.5% of nonsoluble glucan and xylan), whereas SG has a lower lignin content of 11.3% and a lower total nonsoluble sugar of 38.8%

Summary

Introduction

The 2016 billion-ton report by the U.S Department of Energy (DOE) predicts that more than 1 billion dry tons of biomass per year will be available in the United States sufficient to produce enough biofuels to displace 30% of -current petroleum consumption (Langholtz et al, 2016). This prediction was not restricted by the feedstock species and its price at the plant gate. Blending different biomass species with different time and location dependence can reduce overall costs and improve sustainability, such as corn stover and sorghum harvested in fall and switchgrass harvested in the winter (Kuhn et al, 2020)

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