Corn-based ethanol production has increased dramatically in the past ten years, causing an increase in demand for corn by ethanol producers and an increase in production of ethanol by-products such as distillers' grains. The increase in ethanol production can be attributed to ethanol policy at the state and federal levels. Because of the increase in production of corn-based ethanol, cattle producers face greater competition for a major feed source, corn, and greater supply of an emerging feed source, distillers' grains. The objective of this study is to analyze and quantify the effects of ethanol policy on cattle production. A theoretical model and an econometric model are used to fulfill the objectives of this study. The theoretical model contains an ethanol model and a general livestock model. Results of the theoretical model present the possibilities of ethanol policy affecting cattle production. The econometric model identifies the indirect and direct effects of ethanol policy on cattle production. The results of the econometric model indicate that there is a relationship between ethanol policy, specifically the Renewable Fuel Standard, and cattle production.

Um método de fabricação para eletrodos compósitos impressos à base de grafite e resina poliuretana (EIGPU) foi desenvolvido, iniciando-se pela tinta e processo para a impressão, além da otimização dos parâmetros para garantir a aplicabilidade e maximização da resposta dos mesmos. Os parâmetros otimizados na fabricação da tinta foram a composição de 60% grafite e 40% poliuretana (m/m), a natureza e quantidade de solvente, dimensão do conjunto impresso, quantidade de demãos aplicadas no processo de \"screen-printing\", espessura da máscara adesiva e o tipo de isolante que define os contatos elétricos e a área ativa do eletrodo. Também foi proposto e desenvolvido um procedimento de ativação da superfície do eletrodo, que consiste em uma compressão do compósito, seguido de tratamento eletroquímico da superfície do eletrodo de trabalho, que se mostraram fundamentais para o desempenho adequado do sensor. Os resultados desses estudos inciais foram avaliados usando K3[Fe(CN)6], como sonda eletroquímica. Em seguida, o EIGPU foi avaliado quanto ao seu potencial para determinação de analitos de interesse farmacológico, usando como modelo o paracetamola (APAP) e suas misturasb com cafeína (CAF) em amostras de fármacos (LOD=0,81a, 0,84b(APAP), 1,6b(CAF) µmol L-1); ambiental: Zn2+, Pb2+, Cu2+ e Hg2+ simultaneamente em amostras de etanol combustível (LOD=300, 65, 30, 46 nmol L-1, respectivamente) e biológico: epinefrina (EP) em amostras artificiais de fluido cérebro-espinal sintético (LOD=42,8 e 768 nmol L-1, para DPV e SWV, respectivamente). Para isso, foram usadas Voltametria Cíclica (CV), Voltametria de Pulso Diferencial (DPV), Voltametria de Pulso Diferencial de Redissolução Anódica (DPASV) e Voltametria de Onda Quadrada (SWV). Na determinação dos analitos de interesse ambiental, os eletrodos impressos foram modificados com sílica SBA-15, antes e após organofuncionalização com a espécie benzotiazol-2-tiol. Os compósitos modificados foram preparados substituindo quantidades correspondentes de pó de grafite de modo a obter eletrodos com 5% (m/m) do modificador. Antes de realizar as análises, foram feitas as otimizações dos parâmetros envolvidos em cada técnica escolhida e obtidas as curvas analíticas. Em seguida, o EIGPU foi utilizado na determinação dos analitos nas respectivas matrizes. A quantidade dos analitos presentes nas amostras foi determinada pelo método de adição de padrão, em triplicata. Os resultados foram comparados com aqueles obtidos por Cromatografia Líquida de Alta Eficiência (HPLC) e Espectroscopia de Absorção Atômica (AAS), para as análises farmacêuticas e ambientais, respectivamente. / A method for the fabrication of a graphite polyurethane composite based screen printed electrodes (EIGPU) was proposed by developing a ink and a imprinting procedure after optimizing parameters such as ink composition 60% graphite and 40% polyurethane (m/m), nature and quantity of solvent, dimensions of the electrode set, number of ink layers, deepness of the adhesive mask and nature of the insulating that defines the active electrode area and the electrical contacts. Procedures for activating the electrode surface, by mechanically compressing the ink followed by an electrochemical treatment of the surface were also developed. The results of this phase were evaluated using K3[Fe(CN)6] as an electrochemical probe. Than the EIGPU was evaluated regarding its potentialities for the determination of analytes with pharmacological interest using paracetamola (APAP) and its mixturesb with caffeine (CAF) in pharmaceutical formulations (LOD=0,81a, 0,84b(APAP), 1,6b(CAF) µmol L-1), environmental relevance as metal ions Zn2+, Pb2+, Cu2+ e Hg2+ determined simultaneously in ethanol fuel samples (LOD=300, 65, 30, 46 nmol L-1, respectively) and biologically important as epinephrine (EP) contained in artificial cerebro-spinal fluid. (LOD=42,8 e 768 nmol L-1, for DPV e SWV, respectively).These applications were achieved by means of Cyclic Voltammetry (CV), Differential Pulse Voltammetry (DPV), Square Wave Voltammetry (SWV) and Differential Pulse Anodic Stripping Voltammetry (DPASV). In the determination of the metal ions in ethanol fuel, the electrodes were modified with SBA-15 silica organofunctionalized with benzothiazol-2-thiol. The composities were prepared by substituting corresponding amounts of graphite powder in order to have 5% (m/m) of the modifier in the final device. Before performing the analysis several parameters were optimized for each case for each technique before measuring the analytical curves. After, the EIGPU was used in the determination of the different analytes in the chosen matrices. The amount of analytes present in the samples was determined using addition method in triplicate. The results were compared with those obtained using high performance liquid chromatography (HPLC) and Atomic Absorption Spectrocopy (AAS), as comparision methods.

Um método de fabricação para eletrodos compósitos impressos à base de grafite e resina poliuretana (EIGPU) foi desenvolvido, iniciando-se pela tinta e processo para a impressão, além da otimização dos parâmetros para garantir a aplicabilidade e maximização da resposta dos mesmos. Os parâmetros otimizados na fabricação da tinta foram a composição de 60% grafite e 40% poliuretana (m/m), a natureza e quantidade de solvente, dimensão do conjunto impresso, quantidade de demãos aplicadas no processo de \"screen-printing\", espessura da máscara adesiva e o tipo de isolante que define os contatos elétricos e a área ativa do eletrodo. Também foi proposto e desenvolvido um procedimento de ativação da superfície do eletrodo, que consiste em uma compressão do compósito, seguido de tratamento eletroquímico da superfície do eletrodo de trabalho, que se mostraram fundamentais para o desempenho adequado do sensor. Os resultados desses estudos inciais foram avaliados usando K3[Fe(CN)6], como sonda eletroquímica. Em seguida, o EIGPU foi avaliado quanto ao seu potencial para determinação de analitos de interesse farmacológico, usando como modelo o paracetamola (APAP) e suas misturasb com cafeína (CAF) em amostras de fármacos (LOD=0,81a, 0,84b(APAP), 1,6b(CAF) µmol L-1); ambiental: Zn2+, Pb2+, Cu2+ e Hg2+ simultaneamente em amostras de etanol combustível (LOD=300, 65, 30, 46 nmol L-1, respectivamente) e biológico: epinefrina (EP) em amostras artificiais de fluido cérebro-espinal sintético (LOD=42,8 e 768 nmol L-1, para DPV e SWV, respectivamente). Para isso, foram usadas Voltametria Cíclica (CV), Voltametria de Pulso Diferencial (DPV), Voltametria de Pulso Diferencial de Redissolução Anódica (DPASV) e Voltametria de Onda Quadrada (SWV). Na determinação dos analitos de interesse ambiental, os eletrodos impressos foram modificados com sílica SBA-15, antes e após organofuncionalização com a espécie benzotiazol-2-tiol. Os compósitos modificados foram preparados substituindo quantidades correspondentes de pó de grafite de modo a obter eletrodos com 5% (m/m) do modificador. Antes de realizar as análises, foram feitas as otimizações dos parâmetros envolvidos em cada técnica escolhida e obtidas as curvas analíticas. Em seguida, o EIGPU foi utilizado na determinação dos analitos nas respectivas matrizes. A quantidade dos analitos presentes nas amostras foi determinada pelo método de adição de padrão, em triplicata. Os resultados foram comparados com aqueles obtidos por Cromatografia Líquida de Alta Eficiência (HPLC) e Espectroscopia de Absorção Atômica (AAS), para as análises farmacêuticas e ambientais, respectivamente. / A method for the fabrication of a graphite polyurethane composite based screen printed electrodes (EIGPU) was proposed by developing a ink and a imprinting procedure after optimizing parameters such as ink composition 60% graphite and 40% polyurethane (m/m), nature and quantity of solvent, dimensions of the electrode set, number of ink layers, deepness of the adhesive mask and nature of the insulating that defines the active electrode area and the electrical contacts. Procedures for activating the electrode surface, by mechanically compressing the ink followed by an electrochemical treatment of the surface were also developed. The results of this phase were evaluated using K3[Fe(CN)6] as an electrochemical probe. Than the EIGPU was evaluated regarding its potentialities for the determination of analytes with pharmacological interest using paracetamola (APAP) and its mixturesb with caffeine (CAF) in pharmaceutical formulations (LOD=0,81a, 0,84b(APAP), 1,6b(CAF) µmol L-1), environmental relevance as metal ions Zn2+, Pb2+, Cu2+ e Hg2+ determined simultaneously in ethanol fuel samples (LOD=300, 65, 30, 46 nmol L-1, respectively) and biologically important as epinephrine (EP) contained in artificial cerebro-spinal fluid. (LOD=42,8 e 768 nmol L-1, for DPV e SWV, respectively).These applications were achieved by means of Cyclic Voltammetry (CV), Differential Pulse Voltammetry (DPV), Square Wave Voltammetry (SWV) and Differential Pulse Anodic Stripping Voltammetry (DPASV). In the determination of the metal ions in ethanol fuel, the electrodes were modified with SBA-15 silica organofunctionalized with benzothiazol-2-thiol. The composities were prepared by substituting corresponding amounts of graphite powder in order to have 5% (m/m) of the modifier in the final device. Before performing the analysis several parameters were optimized for each case for each technique before measuring the analytical curves. After, the EIGPU was used in the determination of the different analytes in the chosen matrices. The amount of analytes present in the samples was determined using addition method in triplicate. The results were compared with those obtained using high performance liquid chromatography (HPLC) and Atomic Absorption Spectrocopy (AAS), as comparision methods.

In recent years, the demand for alternatives to fossil fuels has risen dramatically, and ethanol fuel has become an important liquid fuel alternative globally. The most efficient mode of transportation of petroleum-based fuel is via pipelines, and due to the 300% increase in ethanol use in the U.S. in the past decade, a similar method of conveyance must be adopted for ethanol. Low-carbon, low-alloy pipeline steels like X52, X60, and X65 comprise the existing fuel transmission pipeline infrastructure. However, similar carbon steels, used in the ethanol processing and production industry, were found to exhibit stress corrosion cracking (SCC) in ethanol service. Prior work has shown that contaminants absorbed by the ethanol during distillation, processing or transport could be the possible determinants of SCC susceptibility; 200 proof ethanol alone was shown not to cause SCC in laboratory studies. To ensure the safety and integrity of the pipeline system, it was necessary to perform a mechanistic study of SCC of pipeline steel in fuel grade ethanol (FGE). The objective of this work was to determine the environmental factors relating to SCC of X65 steel in fuel grade ethanol (FGE) environments. To accomplish this, a systematic study was done to test effects of FGE feedstock and common contaminants and constituents such as water, chloride, dissolved oxygen, and organic acids on SCC behavior of an X65 pipeline steel. Slow strain rate tests (SSRT) were employed to evaluate and compare specific constituents' effects on crack density, morphology, and severity of SCC of X65 in FGE. SCC did not occur in commercial FGE environments, regardless of the ethanol feedstock. In both FGE and simulated fuel grade ethanol (SFGE), SCC of carbon steel was found to occur at low water contents (below 5 vol%) when chloride was present above a specific threshold quantity. Cl- threshold for SCC varied from 10ppm in FGE to approximately 1 ppm in SFGE. SCC of carbon steel was inhibited when oxygen was removed from solution via N2 purge or pHe was increased by addition of NaOH. During SSRT, in-situ¬ electrochemical measurements showed a significant role of film rupture in the SCC mechanism. Analysis of repassivation kinetics in mechanical scratch tests revealed a large initial anodic dissolution current spike in SCC-causing environments, followed by repassivation indicated by current transient decay. In the deaerated environments, repassivation did not occur, while in alkaline SFGE repassivation was significantly more rapid than in SCC-inducing SFGE. Composition and morphology of the passive film on X65 during static exposure tests was studied using X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Results showed stability of an air-formed native oxide under static immersion in neutral (pHe = 5.4) SFGE, and dissolution of the film when pHe was decreased to 4.3. XPS spectra indicated changes in film composition at high pHe (near 13) and in environments lacking sufficient water. In light of all results, a film-rupture anodic-dissolution mechanism is proposed in which local plastic strains facilitates local breakdown of the air-formed oxide film, causing iron to dissolve anodically. During crack propagation anodic dissolution occurs at the crack tip while crack walls repassivate preserving crack geometry and local stress concentration at the tip. It is also proposed that SCC can be mitigated by use of alkaline inhibitors that speed repassivation and promotes formation of a more protective Fe(OH)3 film.

This thesis develops quantitative methods for evaluation and design of large-scale biofuel production systems with a particular focus on bioreactor-based fuel systems. In Chapter 2, a lifecycle assessment (LCA) method is integrated with chemical process modeling to select from different process designs the one that maximizes the energy efficiency and minimizes the environmental impact of a production system. An algae-based ethanol production technology, which is in the process of commercialization, is used as a case study. Motivated by this case study, Chapter 3 studies the selection of process designs and production capacity of highly distributed bioreactor-based fuel system from an economic perspective. Nonlinear optimization models based on net present value maximization are developed that aim at selecting the optimal capacities of production equipment for both integrated and distributed-centralized process designs on symmetric production layouts. Global sensitivity analysis based on Monte Carlo estimates is performed to show the impact of different parameters on the optimal capacity decision and the corresponding net present value. Conditional Value at Risk optimization is used to compare the optimal capacity for a risk-neutral planner versus a risk-averse decision maker. Chapter 4 studies mobile distributed processing in biofuel industry as vehicle routing problem and production equipment location with an underlying pipeline network as facility location problem with a focus on general production costs. Formulations and algorithms are developed to explore how fixed cost and concavity in the production cost increases the theoretical complexity of these problems.

In this work, two groups of carbon supported Pt-Pd catalysts have been prepared in order to investigate the effect of Pd, as a second metal, and surfactants on the catalytic activity towards methanol and ethanol oxidation reactions used in the direct methanol and ethanol fuel cells. In the first group (group a), 1- hexanethiol was used as a stabilizing agent while in the second group (group b), 1,1 dimethyl hexanethiol was utilized. Cyclic voltammetry (CV), chronoamperometry (CA), X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were used in order to determine the nature of the catalysts. The average crystalline size of the metal particles in the catalysts was explored by XRD and TEM. TEM results revealed the uniform distribution of the metal nanoparticles on carbon support with a narrow size distribution in the range of 3.0 to 3.7 nm and the average crystalline sizes of metal particles for group &ldquo / b&rdquo / catalysts were larger than that of group &ldquo / a&rdquo / catalysts which can be explained by the surfactant effect. These results were in good agreement with XRD data. The oxidation states of platinum (Pt(0) and Pt(IV)) and palladium (Pd(0) and Pd(II)) and their ratios were investigated by XPS and for the most active catalyst, catalyst Ib, these ratios were found to be as 6.94 and 13.7, respectively. Electrochemical activities of the catalysts towards methanol and ethanol oxidation reactions were recorded and compared with that of Pt/C and the commercial Pt (ETEK 20 %wt) catalysts. The results indicated that the group &lsquo / b&rsquo / catalyst has greater catalytic activities than that of group &lsquo / a&rsquo / catalysts. Catalyst Ib comes into prominence as the most active catalyst due to its superior characteristics that it possess such as highest extent of alloying with respect to the palladium amount used, active surface area, CO-tolerance, stability and Pt (0) to Pt (IV) and Pd (0) to Pd (II) ratios.

Biofuels have been used as an energy source for heating and cooking since the beginning of time. However, recent changes in the demand for energy, and in particular, renewable energy, have spurred the growth of liquid biofuel industries in developed countries. Many developing countries, including South Africa have the potential to produce biofuels with benefits extending into the economic and social spheres. Despite government commitments and targets, the South African biodiesel and bio-ethanol industries have stalled in the starting blocks. This research aims to assess the reasons why. South Africa does not have the climate to compete with Brazil in bio-ethanol production and the scope for bioethanol is limited by environmental factors. However our neighbours show significantly more promise in this area. Biodiesel production is more likely to be commercially viable due to the country’s ability to grow oil crops and the need for the by-products. Despite the availability of land for cultivation of energy crops, the required technology and suitable infrastructure, progress has been slow. Uncertainty, high risk and misdirected government interventions have hampered investment in the sector and those involved in biofuel projects are very negative about the government’s ability to stimulate the industry. Consequently, they are looking towards importing feedstock material and exporting the biofuel. This will create a limited number of jobs, but will be energy and carbon negative, and will not aid rural development. Currently there is no medium or large scale virgin oil to biofuel producer operating in the country and the start-up dates for projects are beyond 2013. The WVO biodiesel industry has grown rapidly in the last five years but is limited to small scale operators with limited benefit potential. With the exception of Brazil, other world leaders in biofuels are facing heavy criticism and the mechanisms used to initially boost the industry have very limited application in South Africa. The benefits of biofuel production in South Africa are plentiful and align well with social need and development goals. / Thesis (MBA)--North-West University, Potchefstroom Campus, 2013.

Biofuels have been used as an energy source for heating and cooking since the beginning of time. However, recent changes in the demand for energy, and in particular, renewable energy, have spurred the growth of liquid biofuel industries in developed countries. Many developing countries, including South Africa have the potential to produce biofuels with benefits extending into the economic and social spheres. Despite government commitments and targets, the South African biodiesel and bio-ethanol industries have stalled in the starting blocks. This research aims to assess the reasons why. South Africa does not have the climate to compete with Brazil in bio-ethanol production and the scope for bioethanol is limited by environmental factors. However our neighbours show significantly more promise in this area. Biodiesel production is more likely to be commercially viable due to the country’s ability to grow oil crops and the need for the by-products. Despite the availability of land for cultivation of energy crops, the required technology and suitable infrastructure, progress has been slow. Uncertainty, high risk and misdirected government interventions have hampered investment in the sector and those involved in biofuel projects are very negative about the government’s ability to stimulate the industry. Consequently, they are looking towards importing feedstock material and exporting the biofuel. This will create a limited number of jobs, but will be energy and carbon negative, and will not aid rural development. Currently there is no medium or large scale virgin oil to biofuel producer operating in the country and the start-up dates for projects are beyond 2013. The WVO biodiesel industry has grown rapidly in the last five years but is limited to small scale operators with limited benefit potential. With the exception of Brazil, other world leaders in biofuels are facing heavy criticism and the mechanisms used to initially boost the industry have very limited application in South Africa. The benefits of biofuel production in South Africa are plentiful and align well with social need and development goals. / Thesis (MBA)--North-West University, Potchefstroom Campus, 2013.

Submitted by Fabio Guimaraes (fabiolguimaraes@gmail.com) on 2011-12-13T01:59:43Z No. of bitstreams: 1 PreçosdeEtanolnoBrasil_UmaAnaliseEspacial_FabioGuimaraes_MPAgro2011_Revisada.pdf: 1787727 bytes, checksum: 9ab0396e6fbf3ad4ddaa71d2dbc2cc3e (MD5) / Approved for entry into archive by Gisele Isaura Hannickel (gisele.hannickel@fgv.br) on 2011-12-13T14:32:54Z (GMT) No. of bitstreams: 1 PreçosdeEtanolnoBrasil_UmaAnaliseEspacial_FabioGuimaraes_MPAgro2011_Revisada.pdf: 1787727 bytes, checksum: 9ab0396e6fbf3ad4ddaa71d2dbc2cc3e (MD5) / Made available in DSpace on 2011-12-13T16:09:33Z (GMT). No. of bitstreams: 1 PreçosdeEtanolnoBrasil_UmaAnaliseEspacial_FabioGuimaraes_MPAgro2011_Revisada.pdf: 1787727 bytes, checksum: 9ab0396e6fbf3ad4ddaa71d2dbc2cc3e (MD5) Previous issue date: 2011-11-22 / The introduction of flex-fuel technology resulted in an expressive increase of ethanol consumption in Brazil, competing directly with gasoline throughout gas stations. Nevertheless, unlike gasoline, ethanol suffers from seasonal cycles of sugarcane harvesting, proving to be insufficient to attend demand, incurring in high prices in off-season periods. Besides these factors, the growth in use of ethanol as fuel lacks clear public policies that would encourage the market, as well as structured logistics that would allow for the disposal of the product at a low cost. This study aims to demonstrate how ethanol and gasoline prices behave spatially in Brazil. It was observed that ethanol prices paid by consumers were lower the closer to production areas and higher with greater distances, until they turned disadvantageous for consumers in some states where the parity of ethanol prices against gasoline overcame the technical limit of 70%. It was also observed that the different seasonal cycles from the two production areas in the country define seasonal patterns in consumption of ethanol or gasoline, based on the 70% parity. The results indicate that stocks and product flows depend not only on logistic conditions, but also on seasonal combinations of the producing areas. Finally, this work intends to understand how and to what degree production prices in the state of São Paulo state relate to the prices that consumers pay in other regions of the country. This study demonstrates that the speed in price transmission is not related to distance, but rather, that logistic factors and the specific characteristics of each market are the major determinants of the behavior of consumer prices with relation to changes in production prices in the state of São Paulo. / A introdução da tecnologia flex-fuel resultou em um expressivo aumento do consumo de etanol no Brasil, tornando-o principal concorrente da gasolina nos postos de combustíveis. Apesar disso, diferentemente da gasolina, a oferta de etanol sofre com a sazonalidade da safra de cana de açúcar, mostrando-se insuficiente para atender a demanda, incorrendo em altos preços nos períodos de entressafra. Além destes fatores, a expansão do uso de etanol como combustível enfrenta a ausência de políticas públicas claras que incentivem o mercado, assim como uma estrutura logística que permita o escoamento do produto a baixos custos. O presente trabalho buscou demonstrar como se comportam espacialmente os preços de etanol e gasolina no Brasil. Observou-se que os preços de etanol combustível ao consumidor foram menores quanto mais próximos das regiões produtoras e maiores conforme se distanciam, até se tornarem desvantajosos para o consumidor de alguns estados na medida em que a paridade de preços frente à gasolina supera o limite técnico de 70%. Observou-se também que a sazonalidade distinta das duas regiões produtoras do país define padrões sazonais de áreas que predominantemente consomem etanol ou gasolina, conforme a paridade de 70%. Este resultado indica que a necessidade de estoques e fluxos de produtos depende não apenas das condições logísticas, mas também da combinação da sazonalidade das regiões produtoras. Por fim, intencionou-se entender como e em que proporção os preços ao produtor do estado de São Paulo relacionam-se com os preços ao consumidor de outras regiões do país. Este estudo demonstrou que a velocidade de transmissão dos preços não está relacionada com a distância e que fatores logísticos e características específicas de cada mercado são os principais determinantes do comportamento dos preços ao consumidor em relação às alterações nos preços ao produtor do estado de São Paulo.

Submitted by Livia Mello (liviacmello@yahoo.com.br) on 2016-09-12T19:51:02Z No. of bitstreams: 1 DissLKKM.pdf: 7338947 bytes, checksum: 70c85b6c9b1fe86fc7445b6006cfd2a9 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-15T13:25:24Z (GMT) No. of bitstreams: 1 DissLKKM.pdf: 7338947 bytes, checksum: 70c85b6c9b1fe86fc7445b6006cfd2a9 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-15T13:25:29Z (GMT) No. of bitstreams: 1 DissLKKM.pdf: 7338947 bytes, checksum: 70c85b6c9b1fe86fc7445b6006cfd2a9 (MD5) / Made available in DSpace on 2016-09-15T13:25:36Z (GMT). No. of bitstreams: 1 DissLKKM.pdf: 7338947 bytes, checksum: 70c85b6c9b1fe86fc7445b6006cfd2a9 (MD5) Previous issue date: 2016-03-04 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Two mathematical models of a Direct Ethanol Fuel Cell (DEFC) considering both an ideal (complete ethanol oxidation) and a realistic behavior (partial oxidation with by-products) were implemented in 3D geometries, adapted from SOUSA et al. (2008), using ANSYS CFX. The ideal model considers the cleavage of the C-C bond in the ethanol molecule, leading to a complete oxidation with CO2 and water as products, whereas the realistic model leads to partially oxidized products (acetic acid and acetaldehyde) through a dissociative adsorption mechanism on the catalyst surface. Kinetic parameters of the realistic model were readjusted from the original work (SOUSA et al., 2008) by experimental data fitting in order to calculate surface coverages of the adsorbed species. Model assumptions are: laminar flow, steady-state, isothermal, homogeneous and isotropic porous materials. Analysis of velocity, pressure and concentration profiles were performed in five different anode flow designs: serpentine, double serpentine, parallel, interdigitated and spot. Results have shown that, within the anode flow designs evaluated, the DEFC containing the interdigitated design presented a better performance, measured by the current density vs. cell potential curve. Cell performance was evaluated between anode overpotentials of 0 to 0,5 V. Different inlet velocities were tested to assess how the solution permeates through the porous layers. A qualitative analysis was also performed with a non-isothermal ideal DEFC model to investigate how each anode flow design contributes to heat removal in the fuel cell. Results showed that heat was better removed in the double serpentine and serpentine anode flow designs. / Dois modelos matemáticos de células a combustível de etanol direto (DEFCs), considerando tanto o comportamento ideal (oxidação completa do etanol) quanto o realístico (oxidação parcial, com formação de subprodutos) foram implementados em geometrias 3D, adaptados de SOUSA et al. (2008), utilizando o software ANSYS CFX. O modelo realístico leva em consideração a oxidação parcial devido à dificuldade na quebra da ligação C-C do etanol em catalisadores mistos de Pt, levando à formação de acetaldeído e ácido acético como subprodutos através de um mecanismo de adsorção dissociativa na superfície catalítica. Alguns dos parâmetros foram reajustados dos seus valores originais ao ser empregada uma maior precisão numérica no método de solução do sistema de equações das frações de cobertura. Foram adotadas as hipóteses de escoamento laminar, estado estacionário, condições isotérmicas e materiais porosos isotrópicos e homogêneos. Através da análise de perfis de velocidade, pressão e concentração na célula, foram investigadas diferentes geometrias dos canais de escoamento: serpentina, dupla serpentina, paralelo, interdigitado e grade. Resultados mostraram que, dentre as geometrias avaliadas, a célula contendo a geometria interdigitada apresentou melhor desempenho nos dois modelos empregados. O desempenho foi determinado pelos valores de densidade de corrente obtidos entre 0 e 0,5 V do sobrepotencial anódico. Adicionalmente, foram realizadas avaliação qualitativa da distribuição de temperatura através do modelo ideal e testes com diferentes velocidades de entrada. Resultados apontaram remoção de calor mais eficiente nas geometrias dupla-serpentina e serpentina.