Ethanol Production and the Cost of Fermentable Sugars from Biomass

Laboratory of Renewable Resources Engineering and Department of Agricultural Engineering, Purdue University, West Lafayette, Indiana 47907, USA
Bioresource Technology (Impact Factor: 4.49). 01/1991; 36(1):83-95. DOI: 10.1016/0960-8524(91)90102-P


The current fermentation alcohol industry in the US is based on utilization of glucose and/or starch derived principally from corn. Biomass materials including wood and agricultural residues, newspaper, and other sources of cellulose could provide a source of fermentable sugars for expanding fuel ethanol production. Prospects for the utilization of biomass for conversion to fermentable hexoses and pentoses are continually improving with advances in enzyme technology, specially engineered microorganisms which can ferment pentoses, and improvement in cellulose pretreatments. Technical and economic factors which affect utilization of sugars from biomass are summarized, and the key steps in wet- and dry-milling of corn are described for purposes of comparison. An approach for estimating fermentable sugar costs is presented to gauge the impact of technical improvements on reducing fermentable sugar costs. An analytical framework resulting from this approach facilitates comparison of effects of feedstock costs, by-product credits, differences in technology, and process costs on the cost of fermentable sugars. A systematic strategy for evaluating differences in cost is presented as a tool for making a first comparison of different technologies and feed stock materials for ethanol production. This analysis suggests that fermentable sugars from enzymatic hydrolysis of cellulose must cost no more than 4–5c lb−1 (8·8–11c kg−1), at current conditions, if they are to be economically competitive with fermentable sugars derived from corn.

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Available from: Michael Ladisch, Jan 23, 2015
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    • "Large quantities of ethanol are used as solvent and chemical feed stock in various industries. Although most of the industrial ethanol is currently produced from the catalytic conversion of ethylene, considerable research has been focused on fermentation based ethanol production from various renewable biomass sources (Ladisch and Svarczkopf, 1991; Worley et al., 1992; Sosulski and Sosulski, 1994; Ingledew et al., 1995). Consequently, this technology has been successfully used in Brazil where a large number of cars are run on either Gasohol (76% gasoline and 24% ethanol) or pure ethanol. "
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    ABSTRACT: Among various environmental issues, waste management is a leading area where the effective and intensive utilisation of wastes and obtaining useful products in biological ways are concentrated. Biochemical characterization of sago industry waste shows that it is rich in carbohydrates, in more specific it contains 55-60% of starch. This work deals with the management of waste for bioethanol production. Native microorganisms were used for converting the sago starch into simple sugars. Amongst them, six bacterial strains were found effective for starch degradation. The cofermentation to produce ethanol was carried out in six different sets with 5% load of isolated bacterial strains and later by addition of 1% load of Saccharomyces cerevisiae. All the experiments were carried out in laboratory scale Erlenmeyer flasks, incubated in shaking incubator for five days at 35°C. The results show that the strain 3 yielded a biomass of 17.041 g/L thereby producing 2.01 g/L of ethanol.
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    • "Xylose is the predominant pentose sugar derived from hemicellulose of most hardwood feedstocks, but for agriculture residues and other herbaceous crops, arabinose constitutes a significant amount of the pentose sugars (McMillan and Boynton, 1994). In particular, hemicellulose from corn fiber, a by-product of corn wet milling facilities, contains about 28% of arabinose (Ladisch and Svarczkopf, 1991). C. glutamicum naturally cannot utilize arabinose and xylose, but expression of the araBAD operon from Escherichia coli enables aerobic growth on arabinose as sole carbon source (Kawaguchi et al., 2006; Schneider et al., 2011). "
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    ABSTRACT: Arabinose is considered as an ideal feedstock for the microbial production of value-added chemicals due to its abundance in hemicellulosic wastes. In this study, the araBAD operon from Escherichia coli was introduced into succinate-producing Corynebacterium glutamicum, which enabled aerobic production of succinate using arabinose as sole carbon source. The engineered strain ZX1 (pXaraBAD, pEacsAgltA) produced 74.4mM succinate with a yield of 0.58mol (molarabinose)(-1), which represented 69.9% of the theoretically maximal yield. Moreover, this strain produced 110.2mM succinate using combined substrates of glucose and arabinose. To date, this is the highest succinate production under aerobic conditions in minimal medium.
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    • "The conventional production of ethanol from grain goes through a number of stages to produce ethanol. The key operations are milling (Ladisch et al, 1991; Kwiatkowski et al, 2006; Maes and Delcour, 2001), starch hydrolysis (Lin and Tanaka, 2006; Warren et al, 1994), fermentation (Berg, 2003), centrifugation (Keim and Venkatasubramanian, 1989), ethanol recovery (Warren et al, 1994) and DDGS production (McAloon et al, 2000). Recently, a new wheat milling technology, pearling (or debranning) has been commercialized. "
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    ABSTRACT: A value analysis methodology [Sadhukhan, J., Zhang, N., Zhu, X.X. (Frank), 2003. Value analysis of complex systems and industrial application to refineries. Industrial & Engineering Chemistry Research 42(21), 5165; Sadhukhan, J., Zhang, N., Zhu, X.X. (Frank), 2004. Analytical optimisation of industrial systems and applications to refineries, petrochemicals. Chemical Engineering Science 59(20), 4169; Sadhukhan, J., Smith, R., 2007. Synthesis of industrial systems based on value analysis. Computers & Chemical Engineering 31(5–6), 535] has been presented for investigating into the economic feasibility of biorefineries. The methodology devises a mechanism for systematic design of industrial systems based on comprehensive assessment of value on processing and cost of production, hence marginal contributions from individual processing routes and products. The feasibility of extracting value added products such as arabinoxylans (AX) from wheat bran within a wheat biorefinery principally producing ethanol has been investigated. Site-wide integrated flowsheets have been created by which AX can be extracted after recovering bran from wheat with ethanol production from the remaining wheat. Based on the most promising test case, value analysis shows that creating a market for AX is feasible in terms of production costs if the AX is co-produced with ethanol. A comprehensive value analysis that includes capital investment policies indicates that the required market price for AX to breakeven against conventional biorefineries without value added production is a strong function of plant life and this may vary between 4 and 6 £/kg for a plant life of 5–2 years, respectively. Further, it shows that if a market can be created for AX as a food ingredient with a selling price of 6 £/kg, the ethanol co-produced can be sold at 10% less than from a conventional biorefinery under current economic scenario.
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