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The potential of sweet sorghum as an alternative crop for ethanol production was investigated in this study. Initially, the enzymatic hydrolysis of sorghum grains was optimized, and the hydrolysate produced under optimal conditions was used for ethanol production with an industrial strain of Saccharomyces cerevisiae , resulting in an ethanol concentration of 87 g L −1 . From the sugary fraction (sweet sorghum juice), 72 g L −1 ethanol was produced. The sweet sorghum bagasse was submitted to acid pretreatment for hemicellulose removal and hydrolysis, and a flocculant strain of Scheffersomyces stipitis was used to evaluate the fermentability of the hemicellulosic hydrolysate. This process yielded an ethanol concentration of 30 g L −1 at 23 h of fermentation. After acid pretreatment, the remaining solid underwent an alkaline extraction for lignin removal. This partially delignified material, known as partially delignified lignin (PDC), was enriched with nutrients in a solid/liquid ratio of 1 g/3.33 mL and subjected to simultaneous saccharification and fermentation (SSF) process, resulting in an ethanol concentration of 85 g L −1 at 21 h of fermentation. Thus, from the conversion of starchy, sugary and lignocellulosic fractions approximately 160 L ethanol.ton −1 sweet sorghum was obtained. This amount corresponds to 13,600 L ethanol.ha −1 . [ABSTRACT FROM AUTHOR]

Abstract: The U.S. Energy Independence and Security Act of 2007 mandates the use, if produced, of 6.06 × 1010 L of advanced biofuels by 2022. The objective of this study is to determine the ethanol price necessary for a biorefinery to breakeven when using switchgrass as the single feedstock to produce ethanol. A holistic model that encompasses acquisition of land use services, feedstock production, harvest, harvest machine investment, feedstock logistics (storage, transportation), biorefinery location and size, and biorefinery investment is constructed and used to determine breakeven ethanol price. The model was solved for each of three biomass to ethanol conversion rates (250, 334, and 417 L of ethanol Mg−1 of biomass) and each of three biorefinery investment cost estimates ($2, $4, and $6 × 108 for a biorefinery with annual capacity of 379 × 106 L). Breakeven ethanol prices ranged from $0.44 L−1 with a conversion rate of 417 L of ethanol Mg−1 and an investment cost of $2 × 108, to $0.72 L−1 with a conversion rate of 250 L Mg−1 and an investment cost of $6 × 108. Improving the efficiency of conversion from 250 to 334 L Mg−1 decreases the estimated breakeven cost by $0. 07 L−1. Improved conversion efficiency results in a reduction of the total quantity of feedstock required and in the cost to deliver feedstock. Most of the cost reduction follows from reductions in land required (rent), and biomass harvest, storage, and transportation costs. [Copyright &y& Elsevier]

Abstract: Lignocellulose into fuel ethanol is the most feasible conversion route strategy in terms of sustainability. Oil palm empty fruit bunch (EFB) generated from palm oil production is a huge source of cellulosic material and represents a cheap renewable feedstock which awaits further commercial exploitation. The purpose of this study was to investigate the feasibility of using steam at 0.28 MPa and 140 °C generated from the palm oil mill boiler as a pretreatment to enhance the digestibility of EFB for sugars production. The effects of steam pretreatment or autohydrolysis on chemical composition changes, polysaccharide conversion, sugar production and morphology alterations of four different types of EFB namely fresh EFB (EFB1), sterilized EFB (EFB2), shredded EFB (EFB3) and ground EFB (EFB4) were evaluated. In this study, the effects of steam pretreatment showed major alterations in the morphology of EFB as observed under the scanning electron microscope. Steam pretreated EFB2 was found to have the highest total conversion of 30% to sugars with 209 g kg−1 EFB. This production was 10.5 fold higher than for EFB1 and 1.6 fold and 1.7 fold higher than EFB3 and EFB4, respectively. The results suggested that pretreatment of EFB by autohydrolysis using steam from the mill boiler could be considered as being a suitable pretreatment process for the production of sugars. These sugars can be utilized as potential substrates for the production of various products such as fuel ethanol. [Copyright &y& Elsevier]

Abstract: Ethanol produced from lignocellulosic biomass through a number of conversion pathways presents a more viable alternative to fossil fuels because non-food feedstocks are used. The approaches for ethanol production from biomass, such as wood, can be classified into three general pathways: hydrolysis fermentation (hydrolysis followed by fermentation of the sugars), gasification biosynthesis (gasification followed by biosynthesis to ethanol), and gasification chemical synthesis (gasification followed by catalytic synthesis to ethanol). To compare performance of the three pathways, a black-box system model was utilized with relevant assumptions to analyze their mass and energy conversion efficiencies. Their processing times were also estimated. A comprehensive comparison of the modeling results showed that from a process engineering standpoint, the feasibility of the biomass refining pathways ordered from high to low is gasification chemical synthesis, hydrolysis fermentation, then gasification biosynthesis. Calculations of a performance index, a singular number incorporating the major input and output and processing time of a pathway that was defined, also supported this order. [Copyright &y& Elsevier]