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Ethanol Industry (ethanol + industry)

Distribution by Scientific Domains

Life Sciences	50%

Selected Abstracts

Effect of acetic acid and pH on the cofermentation of glucose and xylose to ethanol by a genetically engineered strain of Saccharomyces cerevisiae

FEMS YEAST RESEARCH, Issue 4 2010
Elizabeth Casey
Abstract A current challenge of the cellulosic ethanol industry is the effect of inhibitors present in biomass hydrolysates. Acetic acid is an example of one such inhibitor that is released during the pretreatment of hemicellulose. This study examined the effect of acetic acid on the cofermentation of glucose and xylose under controlled pH conditions by Saccharomyces cerevisiae 424A(LNH-ST), a genetically engineered industrial yeast strain. Acetic acid concentrations of 7.5 and 15 g L,1, representing the range of concentrations expected in actual biomass hydrolysates, were tested under controlled pH conditions of 5, 5.5, and 6. The presence of acetic acid in the fermentation media led to a significant decrease in the observed maximum cell biomass concentration. Glucose- and xylose-specific consumption rates decreased as the acetic acid concentration increased, with the inhibitory effect being more severe for xylose consumption. The ethanol production rates also decreased when acetic acid was present, but ethanol metabolic yields increased under the same conditions. The results also revealed that the inhibitory effect of acetic acid could be reduced by increasing media pH, thus confirming that the undissociated form of acetic acid is the inhibitory form of the molecule. [source]

Environmental and economic analysis of the fully integrated biorefinery

GCB BIOENERGY, Issue 5 2009
ELIZABETH D. SENDICH
Abstract Cellulosic biofuel systems have the potential to significantly reduce the environmental impact of the world's transportation energy requirements. However, realizing this potential will require systems level thinking and scale integration. Until now, we have lacked modeling tools for studying the behavior of integrated cellulosic biofuel systems. In this paper, we describe a new research tool, the Biorefinery and Farm Integration Tool (BFIT) in which the production of fuel ethanol from cellulosic biomass is integrated with crop and animal (agricultural) production models. Uniting these three subsystems in a single combined model has allowed, for the first time, basic environmental and economic analysis of biomass production, possible secondary products, fertilizer production, and bioenergy production across various regions of the United States. Using BFIT, we simulate cellulosic ethanol production embedded in realistic agricultural landscapes in nine locations under a collection of farm management scenarios. This combined modeling approach permits analysis of economic profitability and highlights key areas for environmental improvement. These results show the advantages of introducing integrated biorefinery systems within agricultural landscapes. This is particularly true in the Midwest, which our results suggest is a good setting for the cellulosic ethanol industry. Specifically, results show that inclusion of cellulosic biofuel systems into existing agriculture enhances farm economics and reduces total landscape emissions. Model results also indicate a limited ethanol price effect from increased biomass transportation distance. Sensitivity analysis using BFIT revealed those variables having the strongest effects on the overall system performance, namely: biorefinery size, switchgrass yield, and biomass farm gate price. [source]

Sustainability certification of bioethanol: how is it perceived by Brazilian stakeholders?

BIOFUELS, BIOPRODUCTS AND BIOREFINING, Issue 4 2010
David A. Huertas
Abstract This paper investigates whether initiatives for sustainability certification of Brazilian ethanol can be expected to stimulate a change among producers toward more sustainable production , and, if so, what those changes would likely be. Connected to this, several questions are raised including whether producers might prefer to target other markets with less stringent demands, and if certification might lead to structural changes in the sector because producers who lack the capacity to meet the new requirements cannot remain competitive. The analysis of interviews with a diverse group of stakeholders under the guidance of the Technological Innovation Systems framework allowed us identify different actions taken by the Brazilian sugarcane ethanol sector in response to requirements of sustainability. The interviewees agreed that sustainability certification is an important element for the expansion of biofuel production in Brazil. Brazilian stakeholders have created a platform for more competitive sustainable production and have initiated relevant processes in response to the development connected to sustainability certification. Yet, the certification activities have had a limited impact in terms of the number of involved stakeholders. But interview responses indicate that the sector may adapt to new certification requirements rather than leave markets where such requirements become established. Structural changes can be expected if certification requirements as they exist in many initiatives are introduced in unflexible ways. The social importance of the ethanol industry is large in Brazil and some adjustments for certification may be required. The paper concludes by suggesting some actions for the industry. Copyright © 2010 Society of Chemical Industry and John Wiley & Sons, Ltd [source]

Protein feeds coproduction in biomass conversion to fuels and chemicals

BIOFUELS, BIOPRODUCTS AND BIOREFINING, Issue 2 2009
Bruce E. Dale
Abstract Agriculture has changed greatly in the past in response to changing human needs. Now agriculture is being called on to provide raw materials for very large-scale fuel and chemical production. Agriculture will change again in response to this demand and all producers and users of agricultural feedstocks will be affected by this change. For example, livestock feeding practices have already changed in response to the availability of distillers' grains from corn ethanol production. A fuels industry based on herbaceous biomass energy crops will be many-fold larger than the existing corn ethanol industry and will produce its own set of impacts on livestock feeding. We explore here one of these impacts: the availability of large new sources of feed protein from biomass energy crops. In addition to structural carbohydrates, such as cellulose and hemicellulose, herbaceous biomass energy crops can easily be produced with approximately 10% protein, called ,leaf protein'. This leaf protein, as exemplified by alfalfa leaf protein, is superior to soybean meal (SBM) protein in its biological value. Leaf protein recovery and processing fit well into many process flow diagrams for biomass fuels. When leaf protein is properly processed to concentrate it and remove antinutritional factors, as we have learned over the years to do with soybean meal protein, protein in leaf protein concentrate (LPC) will probably be at least as valuable in livestock diets as SBM protein. If LPC is used to meet 20% of total animal protein requirements (i.e., market penetration of 20%) then the potential utilization of leaf protein concentrate could reach as much as 24 million metric tons annually. This leaf protein will replace protein from SBM and other sources. This much leaf protein will reduce by approximately 16 million hectares the amount of land required to provide protein for livestock. Likewise the amount of land required to meet fuel needs will effectively be reduced by 8 million hectares because this land will effectively do ,double duty' by producing needed animal protein as well as feedstocks for fuel production. © 2009 Society of Chemical Industry and John Wiley & Sons, Ltd [source]