O mundo está passando por uma transformação profunda no setor energético. Ao que tudo indica estamos rumando para uma economia baseada em energias renováveis e de baixa emissão de carbono. O programa de bionenergia do Estado de São Paulo é o maior programa de bioenergia do mundo. Dentro desse programa produz-se etanol a partir da cana-de-açúcar, precisamente dos açúcares simples da cana-de-açúcar. O etanol produzido a partir dos açúcares simples da planta é denominado etanol de primeira geração. Entretanto, existe uma nova tecnologia para se produzir etanol a partir da celulose da cana-de-açúcar o etanol de segunda geração que possibilitará aumentar a eficiência energética do processo e fortalecer a competitividade do setor bioenergético nacional. O objetivo desse trabalho é prospectar cenários para o futuro do setor produtivo de etanol em São Paulo tendo em vista o etanol de segunda geração como elemento produtivo adjacente à produção atual de primeira geração. Para isso utilizou-se um modelo de construção de cenários que pressupõe uma detalhada consulta a especialistas, qualificação de variáveis quanto à sua importância e incerteza e identificação de variáveis-chaves. Por fim, foram criadas matrizes e roteiros para os cenários a partir das variáveis-chaves identificadas. Concluiu-se que dos quatro cenários construídos dois são favoráveis, um é desfavorável e um é pouco plausível. A metodologia de geração de variáveis-chaves foi aplicada com sucesso no setor produtivo de etanol. Os cenários criados podem lançar alguma luz possíveis futuros do setor estudado em relação ao etanol de segunda geração. / Nowadays the worlds energy sector is in a process of deep transformation. Apparently the world is going to a renewable energy based matrix, with low carbon emissions. The Sao Paulos bioenergetical program is the biggest renewable energy program in the world. In addition to that, it is also produced in that program ethanol from sugar cane. The ethanol that is produced in that program is made from the simple sugars of sugar cane. This ethanol is named first generation ethanol. However, there is a new technology to produce ethanol from sugar canes cellulose, named second generation ethanol. This important new technology could increase the energetic efficiency of process and make the Brazilians energetic production competitiveness stronger. The objective of this work was to prospect scenarios for the ethanols future in Sao Paulo looking at the second generation ethanol. For that it was used a model of scenario construction that presupposed an exhaustive inquire applied to specialists, qualifying trends related to their importance and uncertainty, and identifying the key parameters. At last, extracting the key parameters, matrices were made, and scripts too, both related to these scenarios. The conclusion was that the methodology for scenarios generation was applied with success on the ethanol industry, and those scenarios were able to illuminate with some light under plausible futures about the second generation ethanol.

Second-generation biofuels have the potential to replace fossil fuels in the energy economy without negatively impacting the food supply. An effective biocatalyst must be able to convert all sugars found in lignocellulosic hydrolysates to biofuels. Few microbes exist in that have both a wide substrate range and high ethanol yields necessary for this process. Mixed culture biotechnology is a promising alternative to the use of single organisms in the production of fuels from lignocellulosic biomass. These systems mimic natural processes for the degradation of lignocellulose and exploit the native capabilities of each microbe. The segregation of metabolic pathways allows for the individual optimization of each step in the process. Preliminary work with a consortium capable of saccharification and fermentation showed promise, but the dynamics were poorly understood. Metabolic modeling is a powerful tool for understanding the interactions between microbes in mixed cultures. The development of accurate models of mixed culture metabolism will help drive the engineering of these systems for industrial applications. In this dissertation, dynamic flux balance analysis is applied to mixed culture systems by combining mathematical reconstructions of pure culture metabolism. By tuning the inoculum to sugar concentration, simulations of Saccharomyces cerevisiae and Escherichia coli mutants engineered to ferment a specific substrate display the potential for improved ethanol production over pure cultures. A framework for translating model predictions to experimental systems was developed for a co-culture of S. cerevisiae and xylose-specific E. coli. The consumption of sugar mixtures was optimized through this method, but the inability of the predicted gains in ethanol production to be replicated in experimental systems reveals the importance of selecting microbes with similar optimal growth conditions. The more compatible microbes S. cerevisiae and Scheffersomyces stipitis were modeled under microaerobic conditions to optimize ethanol production from a mixture of glucose and xylose. To further demonstrate the ability of these systems to ferment lignocellulosic hydrolysates, the effect of furan inhibitors on pure and co-cultures was assessed through modeling and experiment. The work presented here represents the first steps towards engineering and optimizing a microbial consortium for the production of ethanol from lignocellulosic biomass.

At present, the world's transportation sector is being principally supplied by fossil fuels. However, energy consumption in this sector is drastically increasing and there are concerns with supply, cost, and environmental issues with the continuing use of fossil fuels. Utilizing non-petroleum ethanol in the transportation sector reduces the dependence on oil, and allows for cleaner burning of gasoline. Lignocellulose materials are structurally composed of five types of polymeric sugars, glucan, galactan, mannan, arabinan, and xylan. NREL has developed a quantitative saccharification (QS) method for determining carbohydrate composition. We proposed a new protocol based on the NREL 2006 Laboratory Analytical Procedure "Determination of Structural Carbohydrates and Lignin in Biomass" (Sluiter et al. 2006a) with a slight modification, in which xylose concentration was determined after the secondary hydrolysis by using 1% sulfuric acid rather than 4% sulfuric acid. We found that the current NREL protocol led to a statistically significant overestimation of acid-labile xylan content ranging from 4 to 8 percent. Lignocellulosic biomass is naturally recalcitrant to enzymatic hydrolysis, and must be pretreated before it can be effectively used for bioethanol production. One such pretreatment is a fractionation process that separates lignin and hemicellulose from the cellulose and converts crystalline cellulose microfibrils to amorphous cellulose. Here we evaluated the feasibility of lignocellulose fractionation applicable to the hurds of industrial hemp. Hurds are the remaining material of the stalk after all leaves, seeds, and fiber have been stripped from the plant. After optimizing acid concentration, reaction time and temperature, the pretreated cellulosic samples were hydrolyzed to more than 96% after 24 hours of hydrolysis (enzyme loading conditions of 15 FPU/g glucan Spezyme CP and 60 IU/g glucan Novozyme 188) at the optimal pretreatment condition (> 84% H₃PO₄, > 50 °C and > 1 hour). The overall glucose and xylose yields were 89% (94% pretreatment; 96% digestibility) and 61%, respectively. All data suggest the technical feasibility of building a biorefinery based on the hurds of industrial hemp as a feedstock and a new lignocellulose fractionation technology for producing cellulosic ethanol. The choice of feedstock and processing technology gives high sugar yields, low processing costs, low cost feedstock, and low capital investment. / Master of Science

Master of Science / Department of Agricultural Economics / Jeffery Williams / Ethanol has become an important source of energy for transportation purposes in the U.S. The majority of the feedstock for this ethanol is corn grain. The use of crop residues and perennial grasses has been proposed as an alternative feedstock for ethanol production using cellulosic conversion processes. Commercial scale production of cellulosic ethanol is still on the horizon. In the meantime a wide variety of studies examining both the technical and economic feasibility of cellulosic ethanol production have been conducted. This is the first study that combines both county level cellulosic feedstock production and farmer participation rates to determine the feasibility of supplying it to cellulosic ethanol plants. This research determines the economic feasibility of supplying cellulosic feedstocks to seven potential add-on cellulosic ethanol plants of 25 million gallons per year at seven existing starch ethanol plants in Kansas. The feedstocks considered are corn stover, sorghum stalks, wheat straw, and perennial switchgrass. A mixed integer programing model determines the amount and mix of cellulosic feedstocks that can be delivered to these plants over a range of plant-gate feedstock prices given transportation costs and farm-gate production costs or breakeven prices. The variable costs of shipping are subtracted from the difference between plant-gate price and farm-gate price to find savings to the plant. The objective function of the model minimizes transportation costs which in turn maximizes savings to the plant. The role switchgrass may have as a feedstock given various switchgrass production subsidies is examined. The results indicate the minimum plant-gate price that must be paid to feedstock producers for all plants to have enough cellulosic feedstocks is $75 per dry ton. Switchgrass feedstocks were only a minor portion of biomass supplied and used without a production subsidy. A Biomass Crop Assistance Program payment increased the supply of switchgrass more than other production subsidies.

Master of Science / Department of Grain Science and Industry / Leland McKinney / The current forage handling equipment in the cellulosic ethanol industry is severely limited by the low bulk densities of baled and ground biomass. Low bulk densities contribute to flowability problems and lack of maximizing trailer capacities. By pelleting we can increase the bulk density and flowability characteristics of forages. The objectives of this research were to evaluate (1) the energy requirements of grinding sorghum stalks, corn stover, wheat straw and big bluestem through two different screen sizes, (2) the energy requirements of pelleting forages from the two grind sizes, and (3) the physical properties of our various end products. The two screen types were found to have significantly different energy consumptions from each other (P<.0001). The majority of the four forage types were also found to have significantly different energy consumptions for grinding from each other (P<.0001). The exception was big bluestem vs. corn (P=.2329). All of the 1/8” vs. 1/8” and 1/8” vs. 3/8” grinds were significantly different from each other (Most P<.0001 and all at least P<.05). 3/8” sorghum was significant against all other 3/8” forage types. No other comparisons were significant for 3/8” vs. 3/8” (All 3/8” sorghum P<.0001). Production rate through the 3/8” screen was almost 3 times that of the 1/8” screen (Average of 400 lb/hr vs. 150 lb/hr). The two screen types were found to have significantly different energy consumptions for pelleting from each other (P<.0001). The four forage types were also found to have significantly different energy consumptions from each other (P<.0001) while the big blue vs. wheat did not. (P=.1192). Particle length for the 1/8” grind ranged from .06 inches to .07 inches, while the 3/8” grind ranged from .08 inches to .12 inches. Pelleting increased bulk density from 6.24 lb/ft3 to 9.99 lb/ft3 for biomass grinds to 31.17 lb/ft3 to 43.77 lb/ft3 for pelleted biomass. Pellet quality ranged from 93% to 98%. A cost analysis indicated that it would take roughly $20 extra per ton for the transportation, pre-processing and storage of pelleted cellulosic biomass than whole corn. This cost is still almost half that of the cost for baled biomass.

The economic feasibility of producing biomass-based fuels requires high-yielding feedstocks to supply biomass to biorefineries. Populus trees are a potential biomass feedstock due to their high yield, but their high water requirement limits productivity under drought conditions. The number of genes controlling drought tolerance, and the long generation time for perennial species, slows cultivar development. Accelerated domestication proposes using the sequenced Populus genome to quickly incorporate target traits into productive clones by transgenesis. Six putative drought tolerance transcription factors: DREB2A, DREB2B, AtMYB, AREB1/ABF2, MYB, and NAC, had been previously identified and manipulated in eastern cottonwood (Populus deltoides). Three constructs of each gene were transformed into a P. deltoides background clone, including constitutive overexpression (OE), drought inducible OE, and knockdown. This greenhouse study examines the effect of these previously transformed constructs on drought tolerance by characterizing leaf abscission, leaf water potential, and growth under drought and well-watered conditions. AREB1/ABF2 constitutive OE lost significantly fewer leaves under drought than the Vector control, and had one of the lowest rates of leaf loss overall. Both DREB2A inducible OE and AREB1/ABF2 constitutive OE plants were more productive than the Vector control under drought conditions. MYB inducible OE was a productive construct and initially appeared to be drought tolerant. It is possible that this construct experienced xylem cavitation early on due to the severity of drought experienced by the large trees containing this construct. DREB2A inducible OE, AREB1/ABF2 constitutive OE, and MYB inducible OE were the most productive constructs as well as being likely to confer drought tolerance. Field trials would be the next step, providing a clearer picture of how these constructs would perform under natural conditions.

This study aims efficient conversion of cotton stalks to cellulosic ethanol through ionic liquid pretreatment and enhanced enzymatic hydrolysis. Among several ionic liquids, EMIMAc exhibited the most striking impact on cotton stalks with respect to the changes in biomass structure and digestibility. Cotton stalks, which were subjected to EMIMAc pretreatment at 10% (w cotton stalks/w EMIMAc) of biomass loading and 150&deg / C for 30 minutes, were found to be 9 times more digestible than untreated cotton stalks. Besides, glucose and ethanol yields, which were based on the cellulose content of untreated cotton stalks, were found as 67% and 66%, respectively. These yields were insufficient regarding efficient conversion of the cellulosic portion of cotton stalks to glucose and ethanol which is linked to the superior solvation capability of EMIMAc towards biomass. In order to enhance aforementioned yields, EMIMAc pretreatment was conducted at 30% of biomass loading. Though lignin extracted was much lower, higher yields were obtained compared to the former case since 96% of cellulose was recovered upon EMIMAc pretreatment and reduced crystallinity was observed for pretreated biomass. Glucose yield was achieved as 84% even at a substrate loading of 15% (w/v). Additionally, 76% of ethanol yield and 3% (v/v) of ethanol titer were obtained upon fermentation. Accordingly, reduction in biomass crystallinity was satisfactory to improve enzymatic accessibility of the biomass. Besides, EMIMAc maintained its effectiveness as a pretreatment agent upon recycling since no change in terms of hydrolysis of pretreated samples was observed upon EMIMAc recycling for three times.

To overcome the limitations of starch-based and sugar-based ethanol, scientists propose to expand the use of cellulosic ethanol. Cellulosic ethanol is a biofuel produced from wood, grasses, or the non-edible parts of plants. As the U.S. has a large cellulosic biomass production base (Perlack et al., 2006), production of ethanol from cellulosic feedstock and use of ethanol as a substitute for gasoline could help promote rural development, reduce green house gases emissions, and increase energy independence. This study focuses on the cost of producing cellulosic ethanol along with the amount of carbon sequestered and emitted using switchgrass as a feedstock. In the first part of this study, willingness to adopt (WTA) switchgrass is evaluated. The amount of farmland available for growing switchgrass was estimated using Probit and Tobit models of switchgrass production survey data developed in the University of Tennessee’s Department of Agricultural and Resource Economics. The estimated results from these two models show that when switchgrass prices increase, the probability of farmers to grow switchgrass and land acreages used for switchgrass production will increase. In the second part of this study, based on the results of estimated, farmland availability within an optimal draw area of 50 miles of a biorefinery and a switchgrass delivery schedule could be determined from the biorefinery’s perspective considering different bale types and storage methods. A cost minimization programming model was developed to estimate the year-round switchgrass delivery schedule within fifty miles of three selected biorefinery locations in the southeastern U.S. Also in this study, the carbon credit effect was considered in the model. The results from the programming model suggest that with the carbon credit paid to biorefineries, more marginal land will be used for growing switchgrass, and carbon will be sequestered in the soil at a level that exceeds emitted carbon by at least 1.5 times. Lower feedstock costs would be available to the biorefineries if a carbon payment was available to producers for net carbon sequestered.

On the forefront of the recent expansion in biofuels research is the production of cellulosic ethanol, or ethanol produced from a cellulose containing feedstock. Cellulose is a six-carbon polysaccharide found in most plant life and is one of the most abundant organic compounds on the planet. While the first generation of ethanol facilities uses sugar and starch based (corn kernels) plants as their feedstock, the next generation will use cellulosic sources such as wood chips, switchgrass, and forest residues. These cellulosic sources require far less energy and resources to grow and harvest, and are also much more abundant. A cellulosic source widely available in Georgia and much of the southeastern US is southern pine. This study involves the modeling of a complete 2000 dry ton per day pine to ethanol production facility with the AspenTech3 software Aspen Plus, which outputs a mass and energy balance as well as the capital cost of the equipment. A key parameter which affects the competitiveness of cellulosic ethanol is the internal processing energy required to convert the pine to ethanol. As a result, the heat and electrical load of every component within the facility is modeled and then quantified through the Aspen Plus simulation. After this base case energy analysis is developed, various alternate plant configurations are integrated in an attempt to reduce this process energy requirement. The material that is not fermented into ethanol is burned on-site to provide steam and electricity to the plant, as well as excess electricity to be sold to the grid as a byproduct. As the facility processing energy requirement is decreased, more excess electricity is available for sale. The implementation of the alternate distillation scenarios effectively reduce the internal processing energy in a manner as to increase the amount of excess electricity sold to the grid by 13.5%. The additional equipment required in this alternate scenario returns a simple payback period of 1.1 years through the additional revenue of the increased electricity sale.

Made available in DSpace on 2014-06-11T19:29:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-04-13Bitstream added on 2014-06-13T20:38:20Z : No. of bitstreams: 1 colombari_fm_me_sjrp.pdf: 821418 bytes, checksum: 6fa62a325554a5e7485ea5403112c41e (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O material lignocelulósico do qual o bagaço é formado contém principalmente açúcares polimerizados na forma de celulose e hemiceluloses, e compostos fenólicos polimerizados na forma de lignina. Tais polímeros podem ser hidrolisados via química e/ou enzimática, dando origem a, entre outros compostos, açúcares fermentescíveis. O objetivo desse trabalho foi investigar alguns tratamentos físico-químicos aplicados ao bagaço de cana de açúcar que favoreçam o aumento da liberação de açúcares fermentescíveis por hidrólise enzimática, com a mínima produção possível de compostos inibidores da fermentação alcoólica. Diferentes condições de pré-tratamento foram testadas, como utilização de H2SO4 ou NaOH em diferentes concentrações, concomitantemente com a utilização de tratamentos combinados de ozônio, ultrassom e micro-ondas. Os resultados mostraram que tais processos promoveram certa desestruturação do complexo lignocelulósico da parede celular do bagaço, a qual foi relacionada com a concentração de compostos fenólicos e açúcares redutores. O bagaço pré-tratado foi então submetido à ação de enzimas celulolíticas e o teor de açúcares redutores totais formados foi analisado. As condições nas quais maiores quantidades destes açúcares foram liberados foram: H2SO4 0,1 M, irradiado por ultrassom durante 5 minutos (81,7 ± 0,2 mg de glicose por grama de bagaço) e H2SO4 0,1 M saturado com ozônio, irradiado por micro-ondas por 4 minutos (86,0 ± 0,2 mg de glicose por grama de bagaço), que representam um ganho significativo frente aos 6,8 ± 0,2 mg de glicose por grama de bagaço não tratado. As análises por Calorimetria Exploratória Diferencial (DSC) e por Espectrofotometria no Infravermelho (FTIR-ATR) possibilitaram comparar as modificações no sistema estrutural da parede... / The lignocellulosic material of which the sugarcane bagasse is made contains, mainly, polymerized sugars as cellulose and hemicelluloses and polymerized phenolic compounds as lignin. These polysaccharides can be hydrolyzated chemically or enzymatically, giving rise to, among other compounds, fermentable sugars. The aim of this work is to investigate some physicochemical treatments applied to the sugarcane bagasse that favors the release of the maximum amount of fermentable sugars by enzymatic hydrolysis, with a minimal production of alcoholic fermentation inhibitor compounds. Different pre-treatment conditions were tested as different concentrations of sulfuric acid or sodium hydroxide concomitantly with the combinated treatments of ozone, ultrasound and microwaves. Results showed that such processes promoted certain disruption of lignocellulosic complex of the bagasse cell wall, which was related to the concentration of phenolic compounds and reducing sugars. Then, the bagasse was subjected to the action of cellulolytic enzymes and the reducing sugars content was quantified. The conditions in what the maximum amount of these sugars were released were: H2SO4 0.1 M, irradiated by ultrasound for 5 minutes (81.7 ± 0,2 mg/g bagasse) and H2SO4 0.1 M irradiated by microwaves for 4 minutes (86.0 ± 0,2 mg/g bagasse), that represents a significative gain compared to untreated bagasse. Strucural analysis by Differential Scanning Calorimetry (DSC) and Fourier-Transform Infrared Spectrophotometry Atennuated Total Reflectance (FTIR-ATR) analysis allowed comparing the structural modifications in the wall after the pretreatments, indicating that ultrasound pretreatments were effective for hemicelluloses desestruturation and decrease in the cellulose crystallinity index while microwave pretreatments were... (Complete abstract click electronic access below)