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In very high gravity (VHG) fermentation, yeast cells are subjected to a multitude of challenging conditions, including the osmotic pressure exerted by the high sugar content of the wort and the stress factors associated with the high ethanol concentrations present at the end of the fermentation cycle. The response of this biological system to abiotic stresses may be enhanced through biochemical and physiological routes. Silica may play a significant role in regulating the cellular homeostasis of yeast. Alternatively, it is expected that this outcome may be achieved through biochemical responses from the effects of vitamins on yeast cells and the physiological yeast route changing by the culture medium aeration. The objective of this study was to investigate the effects of adding 500 mg L−1 of silica on corn ethanol wort medium and the possibility of supplementing the same wort with vitamins alongside aeration (0.2 v v−1 min−1) as an alternative resource to sustain the fermentation yield rather than adding silica in a fed-batch fermentation cycle with yeast recycling. Upon completion of the five fermentation cycles, yeast samples subjected to the treatment with the addition of silica exhibited a 3.1% higher fermentation yield in comparison to the results observed in the vitamins plus aeration medium bath. Even though greater biomass production (19.1 g L−1) was observed through aerobic yeast behavior in vitaminized supplemented corn medium, the provided silica had a more beneficial effect on yeast stress relief for very high gravity fermentation in a corn hydrolyzed wort with cell recycling. [ABSTRACT FROM AUTHOR]

This study investigates the relationship between corn prices in Brazil and the international market, considering a rise in corn ethanol production in Brazil's Midwest region since 2017. Did the entry of the corn ethanol industry in Brazil affect the relationship between domestic and international corn prices? A cointegration analysis was made with a monthly time series from May 2005 to August 2023 controlling for different exogenous events or shocks that may have affected global agricultural markets. The study's findings indicate a stable long‐term relationship between the international and Brazilian corn prices, with changes in international prices being predictors of variations in Brazilian domestic prices, while the opposite was not statistically supported. The study also found no evidence to support the claim that the entry of the corn ethanol industry into Mato Grosso state in 2017 impacted the prices paid to local producers. Therefore, the increase in Brazilian corn prices cannot be attributed to additional demand for corn by local mills, an important result that contributes to discussions such as food versus fuel and indirect land use change. [ABSTRACT FROM AUTHOR]

Abstract This study investigates the relationship between corn prices in Brazil and the international market, considering a rise in corn ethanol production in Brazil's Midwest region since 2017. Did the entry of the corn ethanol industry in Brazil affect the relationship between domestic and international corn prices? A cointegration analysis was made with a monthly time series from May 2005 to August 2023 controlling for different exogenous events or shocks that may have affected global agricultural markets. The study's findings indicate a stable long‐term relationship between the international and Brazilian corn prices, with changes in international prices being predictors of variations in Brazilian domestic prices, while the opposite was not statistically supported. The study also found no evidence to support the claim that the entry of the corn ethanol industry into Mato Grosso state in 2017 impacted the prices paid to local producers. Therefore, the increase in Brazilian corn prices cannot be attributed to additional demand for corn by local mills, an important result that contributes to discussions such as food versus fuel and indirect land use change.

Yeast recycling, which is a common practice in sugarcane ethanol plants, could be expanded if it could be successfully implemented in corn-based ethanol production. However, the process of recycling the yeast remaining after fermentation is hampered by contaminating microorganisms that reduce the fermentation efficiency and compete with the yeast for the fermentable sugars. Currently, antibiotics are used to control microbial contamination. This study proposes chlorine dioxide and electron beam irradiation as alternative control methods for completely inactivating contaminants and minimizing their effect on recycled yeast. For that, wort sterilization using electron radiation (20 kGy) and treatment with a chemical biocide, namely chlorine dioxide (125 mg kg−1), were compared with non-treated wort. Five fermentation cycles were performed using fed-batch systems with 300 g L−1 of fermentable sugars. The results obtained in this study showed the inactivation of contaminants under the effect of electron beam irradiation, which led to an increase in the productivity, yield, and efficiency of fermentation by 0.21 g L−1h−1, 2.6%, and 4.7%, respectively. However, ClO2 did not show promising results in reducing contamination or improving fermentative parameters. Thus, electron beam irradiation of contaminated wort may be a suitable alternative to chemical biocides and would allow the use of recycled yeast in corn-based ethanol plants.

Yeast recycling, which is a common practice in sugarcane ethanol plants, could be expanded if it could be successfully implemented in corn-based ethanol production. However, the process of recycling the yeast remaining after fermentation is hampered by contaminating microorganisms that reduce the fermentation efficiency and compete with the yeast for the fermentable sugars. Currently, antibiotics are used to control microbial contamination. This study proposes chlorine dioxide and electron beam irradiation as alternative control methods for completely inactivating contaminants and minimizing their effect on recycled yeast. For that, wort sterilization using electron radiation (20 kGy) and treatment with a chemical biocide, namely chlorine dioxide (125 mg kg−1), were compared with non-treated wort. Five fermentation cycles were performed using fed-batch systems with 300 g L−1 of fermentable sugars. The results obtained in this study showed the inactivation of contaminants under the effect of electron beam irradiation, which led to an increase in the productivity, yield, and efficiency of fermentation by 0.21 g L−1h−1, 2.6%, and 4.7%, respectively. However, ClO2 did not show promising results in reducing contamination or improving fermentative parameters. Thus, electron beam irradiation of contaminated wort may be a suitable alternative to chemical biocides and would allow the use of recycled yeast in corn-based ethanol plants. [ABSTRACT FROM AUTHOR]

Sustainable fuel initiatives in the United States such as the Environmental Protection Agency's Renewable Fuel Standard and the Department of Energy's Sustainable Aviation Fuel Grand Challenge have increased the production of corn ethanol and soybean biodiesel. However, the lack of precise information regarding biomass sourcing at a localized level has hindered accurate understanding of both biofuel costs and environmental impact of these production pathways. By harnessing the power of geospatial analysis and leveraging United States Department of Agriculture (USDA) crop census data, this dataset fills this critical knowledge gap. This dataset offers a novel estimation of geospatial biomass sourcing for biofuel production in the United States by synthesizing 2017 USDA crop census data, biorefinery data from the United States Energy Information Administration, and publicly available information about biomass sourcing for biofuel production. This dataset provides a detailed understanding of biomass use for first generation biofuel production, enabling stakeholders to make informed decisions about resource allocation, investment strategies, and infrastructure development. Furthermore, the county-level granularity of the dataset allows for increased fidelity in the techno-economic assessments and life-cycle analyses of first-generation biofuels in the United States.

High-gravity fermentation, used for ethanol production from sugarcane, corn, and mixed substrates, offers several benefits. Yeast, a rapidly multiplying unicellular microorganism, can be adapted for high sugar and ethanol tolerance on a lab scale. However, different substrates can enhance fermentation efficiency. Our study consisted of two experiments. In the first, we compared simple batch feeding with a fed-batch system for yeast selection in high-gravity fermentation. We ran eight cycles with increasing initial sugar contents (50 to 300 g L−1). No significant differences were observed in the first seven cycles, but in the eighth, the fed-batch system showed lower glycerol and fructose contents and higher cell viability than the simple batch system. In the second experiment, we used the fed-batch system with 300 g L−1 from sugarcane, corn, and mixed wort. The results showed that mixed wort produced higher ethanol contents and greater fermentation efficiency compared to corn and sugarcane as substrates. In conclusion, our findings indicate that the fed-batch system is more suitable for high-gravity fermentation on a lab scale, and the combination of sugarcane juice and corn can enhance fermentation efficiency, paving the way for integrating these substrates in industrial ethanol production.

High-gravity fermentation, used for ethanol production from sugarcane, corn, and mixed substrates, offers several benefits. Yeast, a rapidly multiplying unicellular microorganism, can be adapted for high sugar and ethanol tolerance on a lab scale. However, different substrates can enhance fermentation efficiency. Our study consisted of two experiments. In the first, we compared simple batch feeding with a fed-batch system for yeast selection in high-gravity fermentation. We ran eight cycles with increasing initial sugar contents (50 to 300 g L−1). No significant differences were observed in the first seven cycles, but in the eighth, the fed-batch system showed lower glycerol and fructose contents and higher cell viability than the simple batch system. In the second experiment, we used the fed-batch system with 300 g L−1 from sugarcane, corn, and mixed wort. The results showed that mixed wort produced higher ethanol contents and greater fermentation efficiency compared to corn and sugarcane as substrates. In conclusion, our findings indicate that the fed-batch system is more suitable for high-gravity fermentation on a lab scale, and the combination of sugarcane juice and corn can enhance fermentation efficiency, paving the way for integrating these substrates in industrial ethanol production. [ABSTRACT FROM AUTHOR]

For all of human history except the past two centuries or so, bioenergy provided nearly all the world’s primary energy. Then, fossil fuels largely replaced bioenergy, but concern about climate change and fossil fuel depletion will force a move back to renewable energy, including bioenergy. The main method used here to study the future of global bioenergy was a literature surview of relevant published papers, with emphasis both on those published after 2020, and those having a global focus. The key finding is that bioenergy is unlikely to greatly increase its share of global energy consumption, for several reasons. Liquid biofuel production for transport is likely to almost disappear as countries progressively phase out internal combustion engine vehicles. Traditional firewood use is also projected to fall. There are also doubts about the technical potential of bioenergy, not only because it must compete with the other uses for biomass—food, fodder, fibre and timber—but also because in many cases its climate change mitigation impact is less than for other approaches, including alternative renewable energy sources. The overall conclusion is that bioenergy will have a minor but still useful role in the future global energy system, but global energy reductions are likely to be more important for climate stability than bioenergy.

Ethanol tolerant Saccharomyces cerevisiae is compulsory for ethanol production in starch based biorefinery, especially during high-gravity fermentation. In this study, adaptive evolution with increased initial ethanol concentrations as a driving force was harnessed for achieving ethanol tolerant S. cerevisiae. After evolution, an outstanding ethanol tolerant strain was screened, which contributed to significant improvements in glucose consumption and ethanol production in scenarios of 300 g/L initial glucose, high solid loadings (30 wt%, 33 wt%, 35 wt% and 40 wt%) of corn, and high solid loadings (30 wt% and 33 wt%) of cassava, compared with the original strain. Genome re-sequencing was applied for the evolved strain, and 504 sense mutations in 205 genes were detected, among which PAM1 gene was demonstrated related to the elevated ethanol tolerance. In sum, this study provided a practical approach for obtaining ethanol tolerant strain and the identified PAM1 gene enhanced our understanding on ethanol tolerant mechanism, as well as provided a target basis for rational metabolic engineering. [Display omitted] • Ethanol tolerant S. cerevisiae was obtained via adaptive evolution; • Intermittent evolution strategy is suitable for obtaining ethanol tolerant yeast; • 50–60 g/L ethanol is an effective stress for obtaining ethanol tolerant yeast; • The ethanol tolerant strain exhibited excellent activity in high-gravity fermentation; • PAM1 gene involves S. cerevisiae 's tolerance to ethanol; [ABSTRACT FROM AUTHOR]

For all of human history except the past two centuries or so, bioenergy provided nearly all the world's primary energy. Then, fossil fuels largely replaced bioenergy, but concern about climate change and fossil fuel depletion will force a move back to renewable energy, including bioenergy. The main method used here to study the future of global bioenergy was a literature surview of relevant published papers, with emphasis both on those published after 2020, and those having a global focus. The key finding is that bioenergy is unlikely to greatly increase its share of global energy consumption, for several reasons. Liquid biofuel production for transport is likely to almost disappear as countries progressively phase out internal combustion engine vehicles. Traditional firewood use is also projected to fall. There are also doubts about the technical potential of bioenergy, not only because it must compete with the other uses for biomass—food, fodder, fibre and timber—but also because in many cases its climate change mitigation impact is less than for other approaches, including alternative renewable energy sources. The overall conclusion is that bioenergy will have a minor but still useful role in the future global energy system, but global energy reductions are likely to be more important for climate stability than bioenergy. [ABSTRACT FROM AUTHOR]

This study evaluates how low‐carbon production technologies applicable to ethanol plants may reduce the life‐cycle greenhouse gas emission (GHG) intensities of corn ethanol production in the USA. Results indicate that options focusing on incremental energy efficiency (e.g., combined heat and power) and yield improvements have a limited impact on GHG reductions. To achieve deep decarbonization (>50% GHG reduction compared to current corn ethanol production), a fuel switch from natural gas (NG) to alternative low‐carbon fuels is needed. Replacing 50% of NG demand at ethanol plants with syngas from biomass through gasification or renewable natural gas from animal waste could achieve significant GHG reductions (11.7–23.5 g CO2e/MJ ethanol). Adding multiple technologies, including carbon capture and storage, to existing ethanol plants may further reduce GHG emissions to −18.4 g CO2e MJ−1 ethanol (including land‐use change emissions), which is 120% lower than the carbon intensity of pure gasoline. These results could inform how the ethanol industry could move toward net‐zero ethanol production. © 2022 UChicago Argonne, LLC, Operation of Argonne National Laboratory. Biofuels, Bioproducts and Biorefining published by Society of Industrial Chemistry and John Wiley & Sons Ltd. [ABSTRACT FROM AUTHOR]

Summary: Distillers' dried grains with solubles (DDGS) is an alternative ingredient in poultry diets. However, DDGS has high concentrations of non-starch polysaccharides, which limits its inclusion in broiler diets. The objective of this trial was to evaluate the effect of inclusion level of DDGS in broiler diets from 22 to 42 D of age. A total of 980 22-day-old broilers with an average BW of 923 ± 4 g were distributed in a completely randomized design, with 7 increasing levels of DDGS (0, 10, 40, 70, 100, 130, and 160 g kg−1), with 7 replicate pen per treatment and 20 broilers per pen. The performance parameters evaluated included BWG, feed intake, and FCR. At 42 D of age, 2 broilers per pen were selected to determine blood parameters and then euthanized to evaluate gastrointestinal tract development, carcass yield, and meat quality. The results demonstrated that up to 160 g kg−1 DDGS can be included in broiler diets from 22 to 42 D of age without negative effect on performance, carcass and cut yields, meat quality, and litter characteristics.

Concerns over climate change have led to the promotion of biofuels for transport, particularly biodiesel from oilseed crops and ethanol from sugar and starch crops. However, additional concerns arose on whether the climate change mitigation potential of biofuels is negated by the associated direct land requirements (dLUC) for growing biofuel feedstocks, or by the indirect land requirements (iLUC) that compensate for the diversion of crops from food/feed into fuel, both cases potentially leading to emissions of greenhouse gases. We investigated official data over the last 20-year period to estimate the magnitude of the effects ethanol production in the USA has had on land use domestically and abroad. The data analyzed shows that, over the period, the use of corn for ethanol increased by 118 Mt per year. According to our model, most of it came from the displacement of other uses of corn, mainly feed, which was compensated for by increased feed production elsewhere. Results indicate a relatively low dLUC but a significant iLUC effect, mainly due to the compensation for the foregone feed production as a result of diverting corn into ethanol production. Meeting the renewable-energy target of 15 billion gallons of corn ethanol more than negates the climate benefits from avoided use of gasoline (by 18.0 Mt CO2-eq.), suggesting that promoting corn ethanol for global climate change mitigation may be counter-productive as, despite decreasing domestic emissions, global emissions increase. We suggest that the policy be revised accordingly.

Biodiesel production from soybean has been growing in the United States and although its amount is small by comparison with corn ethanol, its addition to existing demands on land can have nonlinear effects on land use, due to an upward sloping and increasingly inelastic supply of land. It is critical to quantify these effects to inform future policies that may expand production of soy biodiesel. Here we apply a multi-period, partial equilibrium economic model (BEPAM) to determine land use under a validated counterfactual scenario with no biofuel policy or with corn ethanol mandate alone to isolate the extent to which expansion of biodiesel production in the US led to the conversion of Conservation Reserve Program (CRP) acres and other noncropland to crop production, over the 2007–2018 period. We find that the land use change intensity of biodiesel ranged from 0.78 to 1.5 million acres per billion gallons in 2018 which is substantially higher than that of corn ethanol, that ranged from 0.57 to 0.75; estimates at the lower end of these ranges are obtained under the assumption that there is no conversion of permanent pastureland to cropland and better supported by model validation than the upper end of these ranges. The land use change elasticity with respect to changes in land rent was more inelastic for biodiesel than for corn ethanol. The largest levels of expansion in cropland were in Iowa, Minnesota, North Dakota, Kansas, Michigan and Mississippi.

Since 2000, corn ethanol production in the USA has increased significantly – from 1.6 to 15 billion gallons (6.1 to 57 billion liters) – due to supportive biofuel policies. In this study, we conduct a retrospective analysis of the changes in US corn ethanol greenhouse gas emission intensity, sometimes known as carbon intensity (CI), over the 15 years from 2005 to 2019. Our analysis shows a significant decrease in CI: from 58 to 45 gCO2e/MJ of corn ethanol (a 23% reduction). This is due to several factors. Corn grain yield has increased continuously, reaching 168 bushels/acre (10.5 metric tons/ha, a 15% increase) while fertilizer inputs per acre have remained constant, resulting in decreased intensities of fertilizer inputs (e.g., 7% and 18% reduction in nitrogen and potash use per bushel of corn grain harvested, respectively). A 6.5% increase in ethanol yield, from 2.70 to 2.86 gal/bushel corn (0.402 to 0.427 L kg−1 corn), and a 24% reduction in ethanol plant energy use, from 32 000 to 25 000 Btu/gal ethanol (9.0 to 6.9 MJ L−1 ethanol) also helped reduce the CI. The total GHG emission reduction benefits through the reduction in the CI and increased ethanol production volume are estimated at 140 million metric tons (MMT) from 2005 to 2019 in the ethanol industry. Displacement of petroleum gasoline by corn ethanol in the transportation fuel market resulted in a total GHG emission reduction benefit of 544 MMT CO2e during the period 2005 to 2019. © 2021 Argonne National Laboratory. Biofuels, Bioproducts and Biorefining published by Society of Industrial Chemistry and John Wiley & Sons Ltd [ABSTRACT FROM AUTHOR]

The aim of this study was to characterize four corn and sorghum co-products (DDG) in terms of their protein and carbohydrate fractions; we also evaluated the effects of substituting the protein source of the conventional supplement by DDG on consumption and nutrient digestibility in confined finishing cattle. Thirty-six male Nellore cattle with a mean age of 24 months were used. The treatments were: FA: concentrate with corn as an energy source and cottonseed meal as a protein source; DDG50: concentrate with a 50% substitution of the FA protein source by DDG; DDG100: concentrate with 100% substitution of the FA protein source by DDG. The experimental design was completely randomized with three treatments and three replicates (pens) containing four animals per pen. We found that the use of DDG in the finishing phase did not interfere with the animals’ food intake or the digestibility of the nutrients (p > 0.05). Nutrients were used by the animals; therefore, DDGs may be viable substitutes of cottonseed meal. We conclude that the bromatological composition of this co-product is influenced a lot during processing; therefore, the nutritional values of this co-product present in the composition tables may not be true.

The aim of this study was to characterize four corn and sorghum co-products (DDG) in terms of their protein and carbohydrate fractions; we also evaluated the effects of substituting the protein source of the conventional supplement by DDG on consumption and nutrient digestibility in confined finishing cattle. Thirty-six male Nellore cattle with a mean age of 24 months were used. The treatments were: FA: concentrate with corn as an energy source and cottonseed meal as a protein source; DDG50: concentrate with a 50% substitution of the FA protein source by DDG; DDG100: concentrate with 100% substitution of the FA protein source by DDG. The experimental design was completely randomized with three treatments and three replicates (pens) containing four animals per pen. We found that the use of DDG in the finishing phase did not interfere with the animals' food intake or the digestibility of the nutrients (p > 0.05). Nutrients were used by the animals; therefore, DDGs may be viable substitutes of cottonseed meal. We conclude that the bromatological composition of this co-product is influenced a lot during processing; therefore, the nutritional values of this co-product present in the composition tables may not be true. [ABSTRACT FROM AUTHOR]

A recent study by DeCicco et al. (Climatic Change 138:667–680, 2016) claims that corn used for ethanol should not be considered to be inherently biogenically carbon-neutral because not all that corn was grown additional to the level otherwise. By assessing the extent of carbon neutrality of corn for ethanol using the reference point baseline approach and historical data that study concluded that the carbon intensity of US corn ethanol is 27% higher than that of gasoline. We develop a framework to determine the carbon neutrality of corn for ethanol by assessing the additional carbon uptake by crops using an anticipated baseline approach. We also apply this framework to determine the additional corn produced for ethanol and include the direct life cycle carbon emissions of only that portion of corn in the direct life cycle carbon intensity of corn ethanol. We implement this framework by integrating an economic model of the agricultural sector in the USA with a biogenic carbon model and life cycle analysis to quantify biogenic carbon uptake and direct life cycle emissions with and without corn ethanol expansion over the 2007–2027 period. We find that the combined biogenic carbon emissions and direct life cycle carbon emission intensity of corn ethanol (not including indirect land use related emissions) is 21% lower than gasoline. The lower value of this carbon intensity of corn ethanol compared with gasoline is robust to a wide range of parametric assumptions. [ABSTRACT FROM AUTHOR]

Distillers' dried grains with solubles (DDGS) is an alternative ingredient in poultry diets. However, DDGS has high concentrations of non-starch polysaccharides, which limits its inclusion in broiler diets. The objective of this trial was to evaluate the effect of inclusion level of DDGS in broiler diets from 22 to 44 D of age. A total of 980 22-day-old broilers with an average BW of 3 6 4 g were distributed in a completely randomized design, with 7 increasing levels of DDGS (0, 10, 40, 70, 100, 130, and 160 g kg-1), with 7 replicate pen per treatment and 20 broilers per pen. The performance parameters evaluated included BWG, feed intake, and FCR. At 42 D of age, 2 broilers per pen were selected to determine blood parameters and then euthanized to evaluate gastrointestinal tract development, carcass yield, and meat quality. The results demonstrated that up to 160 g kg-1 DDGS can be included in broiler diets from 22 to 42 D of age without negative effect on performance, carcass and cut yields, meat quality, and litter characteristics. [ABSTRACT FROM AUTHOR]

Background and objectives: The coproduct of ethanol industry, dried distiller's grains with solubles (DDGS), has phosphorus content in excess of the animal diet requirement, which leads to excess P in manure and causes environmental concerns. The objective of this study is to determine the technical and economic feasibility of recovering this excess P as a coproduct. Findings: The amount of P was observed to reduce from 9.26 to 3.25 mg/g (db) of DDGS, which is consistent with the animal diet requirement of 3–4 mg P/g animal diet. For an existing dry grind plant of 40 million gallon ethanol capacity, an additional fixed cost of $5.7 million was estimated, with an operating cost increase of $1.29 million/year. Conclusions: The total phosphorus recovered from the plant was estimated as 1,676 kg P/day, with an estimated operating cost of $2.33/kg P recovered. Significance and novelty: Approximately 37 million MT of DDGS is produced annually as animal food containing excess P, which is a serious concern for the environment. This study provides with an economically feasible solution to recover the excess P as a coproduct, which has a potential to be used as fertilizer on more than 56,000 acres of land annually, growing corn and soybean. [ABSTRACT FROM AUTHOR]

Sustainable fuel initiatives in the United States such as the Environmental Protection Agency's Renewable Fuel Standard and the Department of Energy's Sustainable Aviation Fuel Grand Challenge have increased the production of corn ethanol and soybean biodiesel. However, the lack of precise information regarding biomass sourcing at a localized level has hindered accurate understanding of both biofuel costs and environmental impact of these production pathways. By harnessing the power of geospatial analysis and leveraging United States Department of Agriculture (USDA) crop census data, this dataset fills this critical knowledge gap. This dataset offers a novel estimation of geospatial biomass sourcing for biofuel production in the United States by synthesizing 2017 USDA crop census data, biorefinery data from the United States Energy Information Administration, and publicly available information about biomass sourcing for biofuel production. This dataset provides a detailed understanding of biomass use for first generation biofuel production, enabling stakeholders to make informed decisions about resource allocation, investment strategies, and infrastructure development. Furthermore, the county-level granularity of the dataset allows for increased fidelity in the techno-economic assessments and life-cycle analyses of first-generation biofuels in the United States., (© 2024 The Authors. Published by Elsevier Inc.)

Highlights • Pretreatment strategies for DDGS have been reviewed. • Acid pretreatment shows the most promising results for sugar release. • Byproducts of pretreatment methods are also analyzed. • Ammonia and steam pretreatments produce lesser furfurals but also less sugars. Abstract Distillers' dried grains with solubles (DDGS) is the by-product of bioethanol production from starch-rich grains through dry-mill fermentation. In this study, dilute sulfuric acid hydrolysis, aqueous ammonia, and steam explosion as the pre-treatment methods were optimized. The central composite response surface methodology (RSM) design was used for optimization of dilute acid pretreatment, aqueous ammonia pretreatment. The steam explosion trials were evaluated. The results show that the dilute acid pretreatment at 121 °C is the most effective way of obtaining simple fermentable sugars (0.382 g/g DDGS). The levels of furfural and HMF was also 5.2 mg/g DDGS) and 1.6 mg/g DDGS, respectively, in the dilute sulfuric acid pretreated DDGS. On the other hand, maximum sugar yield for ammonia pretreatment was 0.129 g/g DDGS and 0.055 g/g DDGS for the steam pretreatment, while no significant amounts of furfural and HMF were observed for these two pretreatment methods. [ABSTRACT FROM AUTHOR]

Highlights • Seven strategies were employed to produce ethanol from mixed CF and CS. • Three corn to CS ratios were applied for ethanol production from mixed CF and CS. • The performance of different integration methods varies with the ratio of CF to CS. • Highest ethanol titer of 99.3 g/L was obtained when the ratio of CF:CS was 20%:10%. • Mixing liquefied CF with 6 h hydrolyzed CS led to the highest ethanol productivity. Abstract This work investigated all possible process integration strategies for ethanol production from corn and dilute acid pretreated corn stover (CS) as mixed substrates. Three corn to pretreated CS ratios (20%:10%, 10%:20% and 5%:25%) were examined. When the ratio of corn to pretreated CS was 20%:10%, the process integration strategy that mixed corn with CS hydrolysate for liquefaction followed by SSF resulted in the highest ethanol titer of 99.3 g/L. Mixing liquefied corn with pretreated CS for hydrolysis/saccharification followed by fermentation was the best strategy for the other two ratios. The strategy of mixing liquefied corn with pretreated CS for 6 h hydrolysis followed by fermentation showed the highest productivity for all the tested ratios. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The liquefied corn was mixed with DDGS hydrolysate for ethanol fermentation. • Sugars in the DDGS were further utilized by mixed fermentation with corn. • Mixed fermentation reduced feedstock cost and enhanced overall ethanol production. • Ethanol yield was increased to 465.5 kg/tonne corn after mixing with treated DDGS. • Cellulose conversion was increased to 86.7% for SSF with DA treated DDGS and corn. Abstract The dry milling ethanol industry produces Distillers' Dried Grains with Solubles (DDGS) as major co-products, which are composed of unhydrolyzed and unfermented polymeric sugars. Ethanol fermentation with the mixture of DDGS and corn has the potential to reduce cost, further utilize sugars in the DDGS and increase overall ethanol production in current dry grind process. In the current study, DDGS was pretreated with dilute alkali, liquid hot water (LHW) and dilute acid (DA). The pretreated DDGS was enzymatically hydrolyzed at 30% (w/w) solid loading and the resulting hydrolysate was mixed with liquefied corn (30%, w/w) at different ratios (0:1, 1:5, 1:2, 1:1 and 1:0 w/w) for simultaneous saccharification and fermentation (SSF). Compared with 30% corn only, SSF with LHW treated DDGS and corn (1:1) resulted in 12.6% increase in ethanol production with 69.3% increase in cellulose conversion, while DA treated DDGS resulted in 15.1% increase in ethanol production with 86.5% increase in cellulose conversion. This work implies that sugars within DDGS can be further converted in regular corn process after appropriate pretreatment. Feedstock cost can be reduced and the overall ethanol production can be enhanced by this strategy, which is beneficial to corn ethanol production in dry-mill process. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Efficiency of engineered yeast to convert fructose to d -psicose was 26.6%. • 50 MT/h corn processing facility estimated to produce 29,835 MT/yr d -psicose. • Minimum selling price of d -psicose with an IRR of 15% was calculated as $1.29/kg. Abstract The objective of this study was to analyze the processing and technoeconomic feasibility of coproduction of d -psicose and ethanol in a modified dry grind ethanol process. The yeast strain was constructed by expressing d -psicose 3-epimerases (DPE) in Sachharomyces cerevisiae. The strain was capable of converting d -fructose to d -psicose at 55 °C with a conversion efficiency of 26.6%. A comprehensive process model for modified dry grind ethanol plant with 396,000 MT/yr corn processing capacity was developed using SuperPro Designer. Predicted ethanol and d -psicose yields were 390.4 L and 75.3 kg per MT of corn, with total annual production of 154.6 million L and 29,835 MT respectively. The capital investment for the plant was estimated as 150.3 million USD with total operating cost of 85.2 million USD/yr. The unit production cost and minimum selling price of d -psicose with an internal rate of return of 15% were calculated as $0.43/kg and $1.29/kg respectively. [ABSTRACT FROM AUTHOR]

The causal basis for many of the relationships in models used to estimate the indirect effects of U.S. biofuels on global agricultural markets has not been adequately established. This paper addresses this gap by examining causal interactions among corn market variables through which the indirect effects of U.S. corn use for ethanol would be transmitted. Specifically, structural break and causal analyses of U.S. corn supply, uses, trade, and price are performed using quarterly data for marketing years 1986 to 2017. The structural break analysis identifies three breaks in corn use for ethanol that reflect the policy-driven evolution of U.S. corn ethanol production and other market factors. The causality analysis finds that U.S. corn use for ethanol is not a driver of the corn price and net corn exports. Changes in corn supply and domestic corn use are found to be the key factors in accommodating the large increase in corn use for ethanol between 2003 and 2010. These results mean that common assumptions linking U.S. corn ethanol production to large reductions in corn availability and exports, and higher global corn prices merit reconsideration.

The generation of bioenergy from thin stillage in a corn ethanol mill provides a new perspective for the use of by-products in a circular economy concept. Alternative technological routes for the corn ethanol by-products energy and nutrients recovery must be investigated to assess present and future decision-making toward economic and environmental indicators. The theoretical biogas production from an up-flow anaerobic sludge blanket (UASB) reactor in a corn-ethanol mill and the potential thermal and electrical power generation along with the avoided greenhouse gas (GHG) emissions were estimated for a large-scale industrial facility. This work aimed to assess the anaerobic digestion (AD) contribution to techno-economic indicators of a corn ethanol mill in three scenarios: 1) Standard corn-to-ethanol mill; 2) AD-CHP - thin stillage AD to produce biogas and its burning in a combined heat and power (CHP) system; 3) AD-BU - biogas purification to obtain and commercialize biomethane. The existent Brazilian market and fuels and biofuel policies place the system without AD in a slightly better position when analyzing financial indicators related to investment return. In contrast, the global energy and mass balances considering thin stillage AD showed that in the AD-CHP scenario, processing 1 ton of thin stillage would produce 10.37 m³ of biogas, which could generate 119.9 MJ of heat and 24.7 kWh of electricity in a CHP system, favoring a greener energy scenario. The energy recovered from biogas returns to the industry, supplying 7.15% of the heat required for steam production and 52.74% of the electricity requirement for industrial processing. As a renewable energy source, biogas would replace fossil sources for energy generation avoiding GHG emissions. Extrapolating the results of the present work to the Brazilian national scale, the biogas yield from the corn-to-ethanol industry would be 179.68 million m³ , the thermal energy generation from biogas could mitigate 125,574.42 ton CO 2eq , and the electricity replacement could mitigate 58,193.02 ton CO 2eq. Besides the mentioned energy generation and environmental benefits, the financial indicators for the examined scenarios showed that the Brazilian market and public policies related to biogas/biomethane are constraints to overcoming to larger adoption of AD by the corn-to-ethanol industry. [Display omitted] • Biogas production could be an option for corn-to-ethanol mill's. • Thermal energy could supply 7.15% of the heat required for steam production. • Electric energy could supply 52.74% of the requirement for the mill. • All the studied scenarios are profitable. [ABSTRACT FROM AUTHOR]