Optimizing ethanol and bioelectricity production in sugarcane biorefineries in Brazil

In sugarcane biorefineries, the lignocellulosic portion of the sugarcane biomass (i.e. bagasse and cane trash) can be used as fuel for electricity production and/or feedstock for second generation (2G) ethanol. This study presents a techno-economic analysis of upgraded sugarcane biorefineries in Brazil, aiming at utilizing surplus bagasse and cane trash for electricity and/or ethanol production. The study investigates the trade-off on sugarcane biomass use for energy production: bioelectricity versus 2G ethanol production. The BeWhere mixed integer and spatially explicit model is used for evaluating the choice of technological options. Different scenarios are developed to find the optimal utilization of sugarcane biomass. The study finds that energy prices, type of electricity substituted, biofuel support and carbon tax, investment costs, and conversion efficiencies are the major factors influencing the technological choice. At the existing market and technological conditions applied in the upgraded biorefineries, 300 PJ y⁻¹ 2G ethanol could be optimally produced and exported to the EU, which corresponds to 2.5% of total transport fuel demand in the EU. This study provides a methodological framework on how to optimize the alternative use of agricultural residues and industrial co-products for energy production in agro-industries considering biomass supply chains, the pattern of domestic energy demand, and biofuel trade.     

Effect of environment and variety on the relationships of wheat grain physical and chemical characteristics with ethanol yield

BACKGROUND: Following the Renewable Transport Fuel Obligation (RTFO), there is an increasing demand for wheat grain for liquid biofuel in the UK. In order to enhance productivity of the bioethanol industry, good quality wheat must be used. RESULTS: A total of 84 grain samples comprising 14 varieties collected from 11 sites in two harvest years were analysed for a range of grain quality parameters and ethanol yield (EY). The grain quality parameters studied were starch and protein concentration, specific weight, grain density, packing efficiency, thousand‐grain weight (TGW), grain length, width, length/width ratio and hardness index. Regression analysis was used to establish the relationships between grain quality parameters and EY. Apart from grain length and density, all grain parameters had significant relationships with EY. In the order of importance, protein concentration, TGW, packing efficiency and specific weight showed good relationships with EY. All other parameters, including starch concentration, showed a poor correlation with EY. EY and the relationship with the grain parameters were affected more by environment than by variety. Some sites gave consistently higher EY than others. When site and variety were considered with TGW and protein, a good prediction of EY could be made (variance accounted for = 87%). CONCLUSION: Combining TGW and protein concentration could be a better indicator of EY than the current practice of specific weight and protein. Copyright © 2011 Society of Chemical Industry     

Modeling the Regeneration of a Polymeric Resin Column Saturated with Ethanol by Air Purge and External Heating

In this work, the regeneration of a polymeric resin column saturated with ethanol with air purge and external heating has been studied. A theoretical model is proposed for describing the mass and heat transfers in the system, and it has been validated with experimental data. This model can be used for simulating the regeneration step in a concentration-thermal swing adsorption process for fuel-grade ethanol production. The model has been used to analyze the process dynamic behavior, and to compare the performance of the regeneration step using external heating and hot air purge.     

Life cycle assessment and environmental life cycle costing analysis of lignocellulosic bioethanol as an alternative transportation fuel

The objective of this paper is to conduct Life Cycle Assessment (LCA) and Environmental Life Cycle Costing (ELCC) studies for lignocellulosic bioethanol blends [E10 and E85 (10% and 85% by volume of bioethanol with gasoline, respectively)] and conventional gasoline (CG). To compare the environmental performance and economic advantage of the selected fuel blends, the impact potentials and the cost of fuel applications per kilometer by a middle size car was evaluated. According the LCA results, one kilometer driven by E10 and E85 fueled vehicles could reduce the greenhouse gas (GHG) emissions by 4.3% and 47% and ozone layer depletion emissions by 3% and 66%, respectively, relative to CG. However, shifting from gasoline to bioethanol increases the emissions that contribute to eutrophication and photochemical ozone depletion. In terms of acidification potential, E85 shows a more favorable result relative to E10 and CG. According to the ELCC analysis, E85 fuel use provides a 23% lower driving cost relative to CG based on a-1 km driving distance. The results showed that E85 seems to be the best alternative in terms of both GHG emission and fuel production cost reduction compare to CG.     

Short communication: Comparison of the newly developed DVE/OEB (2010) system and the National Research Council (2001) model in modeling metabolic characteristics of proteins in dairy cattle

The truly absorbed protein in the small intestine/degraded protein balance (DVE/OEB)₂₀₁₀ system is a recently developed protein evaluation system for ruminants. The objective of this study was to compare the DVE/OEB₂₀₁₀ system with the National Research Council (2001) model in determining the metabolic characteristics of proteins in dairy cattle. The metabolic characteristics of proteins in bioethanol feedstock and their co-products were compared in terms of (1) truly absorbed rumen synthesized microbial protein in the small intestine; (2) truly absorbed rumen undegraded feed protein in the small intestine; (3) endogenous protein in the digestive tract; (4) total truly absorbed protein in the small intestine; and (5) protein degraded balance. The DVE/OEB₂₀₁₀ system predicted 30% more truly absorbed rumen synthesized microbial protein in the small intestine, 4% more truly absorbed rumen undegraded feed protein in the small intestine, 64% more endogenous protein, 9% more total truly absorbed protein in the small intestine, but 27% less degraded protein balance.     

温和碱法预处理甘蔗渣分步糖化乙醇发酵的研究

甘蔗渣是制糖工业的主要废弃物,因其来源广泛,纤维素含量高而成为一种重要的可再生生物资源。本文在对甘蔗渣成分分析的基础上,研究了温和碱法预处理甘蔗渣分步糖化乙醇发酵工艺。甘蔗渣经温和碱法预处理后采用分步糖化发酵来生产乙醇,正交设计试验表明影响甘蔗渣酶解的显著因素为酶添加量,并得到最优酶解条件:酶添加量为25 FPU/g甘蔗渣,温度为50℃,初始pH为4.9。在优化条件下,预处理甘蔗渣的酶解效率可达到74.26%。在甘蔗渣水解液中补加一定营养物后,适合酵母的生长和乙醇的发酵,发酵96 h时,乙醇产量达到39.79 g/L,发酵效率为82.70%,乙醇得率为0.48 g/g。本研究证实了温和碱法预处理甘蔗渣水解液发酵生产乙醇的可行性,为甘蔗渣预处理及用作乙醇发酵原料奠定了坚实的基础。     

基于14C同位素丰度的乙醇汽油中生物乙醇含量的测定

将煤制乙醇与不同来源的生物乙醇按不同体积比加入到汽油中配制成乙醇汽油。考察了采用加速器质谱(AMS)测定放射性同位素14C丰度区分煤制乙醇与生物乙醇的适用性、测定乙醇汽油中生物乙醇含量的准确性以及在国内外4个加速器质谱实验室的再现性。结果表明：利用14C同位素丰度计算生物基含量的方法可以区分煤制乙醇等化石基燃料与生物乙醇等生物基燃料;采用该方法测定一系列乙醇汽油样品中生物基含量,测定值与根据生物乙醇实际添加量计算的理论值的偏差不超过1百分点(绝对值);在4个加速器质谱实验室测定数据的再现性偏差不超过4百分点(绝对值)。