The objective was to create a feasibility framework for assessing the feasibility of a cellulosic ethanol refinery. In addition, the research aimed to create a base case scenario based on data from literature and conduct sensitivity analysis to determine significant parameters of a cellulosic ethanol refinery. The base case was found to be not feasible in the financial and economic analysis given the assumptions used.

The objective was to create a feasibility framework for assessing the feasibility of a cellulosic ethanol refinery. In addition, the research aimed to create a base case scenario based on data from literature and conduct sensitivity analysis to determine significant parameters of a cellulosic ethanol refinery. The base case was found to be not feasible in the financial and economic analysis given the assumptions used.

This thesis describes a way to achieve higher conversion rates of sugars from lignocellulosic biomass that can then be used for cellulosic ethanol production. Using oat hulls as the biomass, several chemical and physical pretreatment techniques were explored to overcome the recalcitrance and allow access to cellulose and hemicellulose. Experimentation with enzyme cocktails and dosing was done to obtain the highest conversions of cellulose and xylan to produce sugars. High solids-loading of the substrate, 14-16%, enabled higher conversion rates and would amount to lower cost of production in a commercial facility; however, end-product inhibition by the accumulation of inhibitors is also realized. To remove inhibition, a solid-liquid separation step was implemented which allowed enzymes to operate at a higher efficiency. The best combination of pretreatment and enzymatic hydrolysis led to a glucose of 89% and xylose yield of 84%, for trials conducted in a 20L bioreactor.

This thesis describes a way to achieve higher conversion rates of sugars from lignocellulosic biomass that can then be used for cellulosic ethanol production. Using oat hulls as the biomass, several chemical and physical pretreatment techniques were explored to overcome the recalcitrance and allow access to cellulose and hemicellulose. Experimentation with enzyme cocktails and dosing was done to obtain the highest conversions of cellulose and xylan to produce sugars. High solids-loading of the substrate, 14-16%, enabled higher conversion rates and would amount to lower cost of production in a commercial facility; however, end-product inhibition by the accumulation of inhibitors is also realized. To remove inhibition, a solid-liquid separation step was implemented which allowed enzymes to operate at a higher efficiency. The best combination of pretreatment and enzymatic hydrolysis led to a glucose of 89% and xylose yield of 84%, for trials conducted in a 20L bioreactor.

Many recent studies on the relative costs and benefits of biofuels have raised the need for a detailed and rigorous analysis of the operations of a biorefinery that is focused on optimization. The current thesis concentrates on the design and optimization of plants for producing biodiesel and ethanol from cellulosic biomass. We have performed numerical simulations combined with systematic parametric analyses to investigate the effect of various parameters on the overall material and energy balances of each biorefinery. The efficiency of the simulated processes was investigated by introducing and/or estimating various metrics in order to select the more beneficial directions for process improvements. Particular emphasis has been paid on heat integration and the design of highly efficient combined heat and power (CHP) units that generate the steam and electricity needed for the purification of biofuels and their co-products. The first part of the thesis is focused on biodiesel production via transesterification of soybean oil with methanol, under alkali-catalyzed conditions. We have analyzed the performance of several reactor configurations in order to improve the conversion of the reversible transesterification reactions. The effect of the oil to alcohol ratio has also been extensively explored. Furthermore, the energy requirements of the simulated process have been rigorously calculated. Since biodiesel facilities can be used either for small-scale, distributed applications or for large-scale production, we have explored whether it is more energy efficient to burn the glycerol-rich stream in a combined heat and power (CHP) plant, or purify the glycerol and use it a feedstock for producing higher-value chemicals with further biotechnological processes. The second part of the thesis focuses on the production of cellulosic ethanol. Having developed the process model, a detailed parametric analysis was carried out to determine how the energy balances and overall efficiency of the biorefinery were influenced by changes in (a) the composition of the biomass feedstock, and (b) the conversion levels of the hydrolysis and fermentation stages. Furthermore, the requirements of the utility section of the ethanol plant were calculated. The utility section included a combined heat and power unit where by-product streams of the production process were utilized for energy generation. The parametric analysis indicated that these streams were in most cases an insufficient fuel source for meeting the energy requirements of the plant and thus, additional fuel was required (biomass, coal, or natural gas). The calculations of this section indicated a significant trade-off between ethanol production and external energy inputs, thus casting some doubt on the ultimate effectiveness of efforts to develop genetically modified energy crops (with high carbohydrate content) in order to maximize fuel production.

Farmers will supply the raw ingredients for the emerging cellulosic ethanol industry. The long-term relationship between a farmer and a processing firm is expected to be contractual. A processing firm has an incentive to sign long-term contracts to ensure a cost-efficient level of raw ingredient supply. However, farmers generally prefer to operate with either no contract or a short-term contract in order to maintain options for adjustments in future acreage allocations due to changes in relative prices. Of interest in this research is to understand the incentives of farmers and calculating the efficient level of the “inflexibility premium”, which a processing firm must provide to a farmer when a long term contract is signed. A stochastic dynamic programming model is solved and with the help of Microsoft Excel numerically evaluated to illustrate the marginal inflexibility premium is increasing with contract length and the level of price variability, and is decreasing with the size of acreage adjustment costs.

Farmers will supply the raw ingredients for the emerging cellulosic ethanol industry. The long-term relationship between a farmer and a processing firm is expected to be contractual. A processing firm has an incentive to sign long-term contracts to ensure a cost-efficient level of raw ingredient supply. However, farmers generally prefer to operate with either no contract or a short-term contract in order to maintain options for adjustments in future acreage allocations due to changes in relative prices. Of interest in this research is to understand the incentives of farmers and calculating the efficient level of the “inflexibility premium”, which a processing firm must provide to a farmer when a long term contract is signed. A stochastic dynamic programming model is solved and with the help of Microsoft Excel numerically evaluated to illustrate the marginal inflexibility premium is increasing with contract length and the level of price variability, and is decreasing with the size of acreage adjustment costs.

Farmers will supply the raw ingredients for the emerging cellulosic ethanol industry. The long-term relationship between a farmer and a processing firm is expected to be contractual. A processing firm has an incentive to sign long-term contracts to ensure a cost-efficient level of raw ingredient supply. However, farmers generally prefer to operate with either no contract or a short-term contract in order to maintain options for adjustments in future acreage allocations due to changes in relative prices. Of interest in this research is to understand the incentives of farmers and calculating the efficient level of the “inflexibility premium”, which a processing firm must provide to a farmer when a long term contract is signed. A stochastic dynamic programming model is solved and with the help of Microsoft Excel numerically evaluated to illustrate the marginal inflexibility premium is increasing with contract length and the level of price variability, and is decreasing with the size of acreage adjustment costs. / Land and Food Systems, Faculty of / Graduate

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.

As the global demand for energy rises, there are significant efforts to find alternative energy sources. In the United States (US), these efforts are primarily motivated by a desire to increase energy security and reduce the potential impacts on climate change caused by carbon dioxide emissions from the burning of fossil fuels. Biofuels are considered a potential partial solution, which are being encouraged through public policy. Cellulosic ethanol is a biofuel that is required in increasing amounts over time as part of the Renewable Fuel Standards. Thus, researchers are exploring the environmental impacts of using this biofuel on a large scale. This dissertation research performed an environmental evaluation using the Life Cycle Assessment technique on Bioenergy Sorghum, a crop which was specifically produced as an energy crop, used in a conversion process (MixAlco version 1) that can produce cellulosic ethanol. Results indicate that the conversion process is highly optimized with minimal environmental concerns. Analysis of the crop production, however, demonstrate that further investigation is warranted regarding the depletion of natural resources and emissions from the fertilizers and pesticides/herbicides, due to large scale production of energy crops. A new policy is proposed to support the sustainable, environmentally responsible development of cellulosic ethanol in the US.