This study uses energy and greenhouse gas (GHG) balances to evaluate how the scale of sugarcane cultivation affects the performance of a sugarcane bioenergy system generating exportable electricity from bagasse. Small-, medium-, large- and miller-planter systems, with cane field areas of less than 10 ha, 10 – 42 ha, 42 – 2000 ha, more than 2000 ha respectively, were modelled. Each of them also has different combinations of manual and mechanical agricultural operations, resulting in different cane yields. Miller-planter system (fully mechanised) performs best with energy yield ratio of 10.99, GHG emissions in bagasse electricity of 0.0633 kg CO2eq/kWh and avoided life cycle GHG emissions of 82.07% when replacing electricity from coal, whereas small-planter system (fully manual) has the worst performance with energy yield ratio of 6.82, GHG emissions in bagasse electricity of 0.0881 kg CO2eq/kWh and avoided life cycle GHG emissions of 75.03% when substituting electricity from coal. Sensitivity analyses show that relative performances of all sugarcane planter systems both in terms of energy and GHG emissions are not significantly affected by variations in bagasse allocation factor, in sugarcane yield and in fertiliser input (the most energy-intensive and GHG-emitting component). Moreover, they confirm miller-planter system as the overall best performer and indicate that increasing small-planters’ cane yield is the critical measure to improve their energy analysis performance. In terms of the nature of agricultural operations, mechanical operations do not necessarily require more input energy than their manual counterparts, contrary to common belief. This is the case for fertilisation, irrigation and cane loading. Fully mechanised sugarcane production at miller-planter scale is therefore strongly encouraged.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20413号 / 工博第4350号 / 新制||工||1674(附属図書館) / 京都大学大学院工学研究科化学工学専攻 / (主査)教授 宮原 稔, 教授 田門 肇, 教授 山本 量一 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

No description available.

This thesis reports on the research undertaken to minimise energy consumption within the production phase of a product lifecycle through modelling, monitoring and improved control of energy use within manufacturing facilities. The principle objective of this research is to develop a framework which integrates energy data at plant and process levels within a manufacturing system so as to establish how much energy is required to manufacture a unit product. The research contributions are divided into four major parts. The first reviews relevant literature in energy trends, related governmental policies, and energy tools and software. The second introduces an Embodied Product Energy framework which categorises energy consumption within a production facility into direct and indirect energy required to manufacture a product. The third describes the design and implementation of a simulation model based on this framework to support manufacturing and design decisions for improved energy efficiency through the use of what-if scenario planning. The final part outlines the utilisation of this energy simulation model to support a Design for Energy Minimisation methodology which incorporates energy considerations within the design process. The applicability of the research concepts have been demonstrated via two case studies. The detailed analysis of energy consumption from a product viewpoint provides greater insight into inefficiencies of processes and associated supporting activities, thereby highlighting opportunities for optimisation of energy consumption via operational or design improvements. Although the research domain for this thesis is limited to the production phase, the flexibility offered by the energy modelling framework and associated simulation tool allow for their employment other product lifecycle phases. In summary, the research has concluded that investment in green sources of power generation alone is insufficient to deal with the rapid rise in energy demand, and has highlighted the paramount importance of energy rationalisation and optimisation within the manufacturing industry.

There has been renewed significance for innovative energy conversion technologies, particularly the heat recovery-to-power technologies for sustainable power generation from renewable energies and waste heat. This is due to the increasing concern over high demand for electricity, energy shortage, global warming and thermal pollution. Among the innovative heat recovery-to- power technologies, the proposed trilateral flash cycle (TFC) is a promising option, which presents a great potential for development. Unlike the Rankine cycles, the TFC starts the working fluid expansion from the saturated liquid condition rather than the saturated, superheated or supercritical vapour phase, bypassing the isothermal boiling phase. The challenges associated with the need to establish system design basis and facilitate system configuration design-supporting analysis from proof-of-concept towards a market-ready TFC technology are significant. Thus, there is a great need for research to improve the understanding of its operation, behaviour and performance. The objective of this study is to develop and establish simulation tools of the TFCs for improving the understanding of their operation, physics of performance metrics and to evaluate novel system configurations for low-grade heat recovery-to-power generation. This study examined modelling and process simulation of the TFC engines in order to evaluate their performance metrics, predictions for guiding system design and parameters estimations. A detailed thermodynamic analysis, performance optimization and parametric analysis of the cycles were conducted, and their optimized performance metrics compared. These were aimed at evaluating the effects of the key parameters on system performances and to improve the understanding of the performance behaviour. Four distinct system configurations of the TFC, comprising the simple TFC, TFC with IHE, reheat TFC and TFC with feed fluid-heating (or regenerative TFC) were examined. Steady-state steady-flow models of the TFC power plants, corresponding to their thermodynamic processes were thermodynamically modelled and implemented using engineering equation solver (ESS). These models were used to determine the optimum synthesis/ design parameters of the cycles and to evaluate their performance metrics, at the subcritical operating conditions and design criteria. Thus, they can be valuable tools in the preliminary prototype system design of the power plants. The results depict that the thermal efficiencies of the simple TFC, TFC with IHE, reheat TFC and regenerative TFC employing n-pentane are 11.85 - 21.97%, 12.32 - 23.91%, 11.86 - 22.07% and 12.01 - 22.9% respectively over the cycle high temperature limit of 393 - 473 K. These suggest that the integration of an IHE, fluid-feed heating and reheating in optimized design of the TFC engine enhanced the heat exchange efficiencies and system performances. The effects of varying the expander inlet pressure at the cycle high temperature and expander isentropic efficiency on performance metrics of the cycles were significant. They have assisted in selecting the optimum-operating limits for the maximum performance metrics. The thermal efficiencies of all the cycles increased as the inlet pressures increased from 2 - 3 MPa and increased as the expander isentropic efficiencies increased from 50 - 100%, while their exergy efficiencies increased. This is due to increased net work outputs that suggest optimal value of pressure ratios between the expander inlets and their outlets. A comprehensive evaluation depicted that the TFC with IHE attained the best performance metrics among the cycles. This is followed by the regenerative TFC whereas the simple TFC and reheat TFC have the lowest at the same subcritical operating conditions. The results presented show that the performance metrics of the cycles depend on the system configuration, and the operating conditions of the cycles, heat source and heat sink. The results also illustrate how system configuration design and sizing might be altered for improved performance and experimental measurements for preliminary prototype development.

There has been renewed significance for innovative energy conversion technologies, particularly the heat recovery-to-power technologies for sustainable power generation from renewable energies and waste heat. This is due to the increasing concern over high demand for electricity, energy shortage, global warming and thermal pollution. Among the innovative heat recovery-to- power technologies, the proposed trilateral flash cycle (TFC) is a promising option, which presents a great potential for development. Unlike the Rankine cycles, the TFC starts the working fluid expansion from the saturated liquid condition rather than the saturated, superheated or supercritical vapour phase, bypassing the isothermal boiling phase. The challenges associated with the need to establish system design basis and facilitate system configuration design-supporting analysis from proof-of-concept towards a market-ready TFC technology are significant. Thus, there is a great need for research to improve the understanding of its operation, behaviour and performance. The objective of this study is to develop and establish simulation tools of the TFCs for improving the understanding of their operation, physics of performance metrics and to evaluate novel system configurations for low-grade heat recovery-to-power generation. This study examined modelling and process simulation of the TFC engines in order to evaluate their performance metrics, predictions for guiding system design and parameters estimations. A detailed thermodynamic analysis, performance optimization and parametric analysis of the cycles were conducted, and their optimized performance metrics compared. These were aimed at evaluating the effects of the key parameters on system performances and to improve the understanding of the performance behaviour. Four distinct system configurations of the TFC, comprising the simple TFC, TFC with IHE, reheat TFC and TFC with feed fluid-heating (or regenerative TFC) were examined. Steady-state steady-flow models of the TFC power plants, corresponding to their thermodynamic processes were thermodynamically modelled and implemented using engineering equation solver (ESS). These models were used to determine the optimum synthesis/ design parameters of the cycles and to evaluate their performance metrics, at the subcritical operating conditions and design criteria. Thus, they can be valuable tools in the preliminary prototype system design of the power plants. The results depict that the thermal efficiencies of the simple TFC, TFC with IHE, reheat TFC and regenerative TFC employing n-pentane are 11.85 - 21.97%, 12.32 - 23.91%, 11.86 - 22.07% and 12.01 - 22.9% respectively over the cycle high temperature limit of 393 - 473 K. These suggest that the integration of an IHE, fluid-feed heating and reheating in optimized design of the TFC engine enhanced the heat exchange efficiencies and system performances. The effects of varying the expander inlet pressure at the cycle high temperature and expander isentropic efficiency on performance metrics of the cycles were significant. They have assisted in selecting the optimum-operating limits for the maximum performance metrics. The thermal efficiencies of all the cycles increased as the inlet pressures increased from 2 - 3 MPa and increased as the expander isentropic efficiencies increased from 50 - 100%, while their exergy efficiencies increased. This is due to increased net work outputs that suggest optimal value of pressure ratios between the expander inlets and their outlets. A comprehensive evaluation depicted that the TFC with IHE attained the best performance metrics among the cycles. This is followed by the regenerative TFC whereas the simple TFC and reheat TFC have the lowest at the same subcritical operating conditions. The results presented show that the performance metrics of the cycles depend on the system configuration, and the operating conditions of the cycles, heat source and heat sink. The results also illustrate how system configuration design and sizing might be altered for improved performance and experimental measurements for preliminary prototype development.

O pinhão-manso (Jatropha curcas L) é uma espécie da família da Euforbiácea que tem se destacado por ser uma planta perene, rústica e com elevada produção de óleo. A avaliação dos efeitos da poda e da irrigação no crescimento e produção do pinhão-manso é relevante para o manejo de um cultivo com essa espécie. Este estudo teve como objetivo principal avaliar os efeitos de diferentes tipos de poda e manejos hídricos no cultivo do pinhão-manso em Piracicaba, SP. O experimento foi conduzido na área experimental do Departamento de Engenharia de Biossistemas (ESALQ/USP), com plantas de quatro anos de idade dispostas em espaçamento 3 x 4 m, totalizando 833 plantas ha-1. Os tratamentos foram arranjados de forma aleatória em blocos compostos de quatro repetições, sendo que os fatores foram constituídos de dois manejos hídricos (irrigado e sem irrigação) e três tipos de poda, sendo P1 (sem poda), P2 (1,5 m de altura x 1,5 m de diâmetro de copa) e P3 (poda a 2 m de altura e 1,5 m de diâmetro da copa). A irrigação teve influência no diâmetro da copa, nas taxas de crescimento absoluto em altura e diâmetro, na taxa de crescimento relativo em diâmetro e nas variáveis produtivas. O fator poda apresentou diferenças em todas as variáveis de crescimento, sendo a poda drástica (P2) a que exibiu as maiores taxas médias de crescimento. As plantas irrigadas apresentaram os maiores rendimentos por planta e por hectare. A análise de ressonância magnética nuclear de hidrogênio (RMN de 1H) revelou que a irrigação e a poda não influenciaram o teor de óleo nas sementes de pinhão-manso. Em relação ao perfil graxo, a irrigação teve influência em plantas submetidas a poda drástica (P2), de modo que a ausência de irrigação favoreceu o maior acúmulo de ácido oleico no óleo. Pela análise energética, observou-se que os fertilizantes foram os insumos com maior participação na demanda energética (42,57 GJ ha-1) para os dois sistemas estudados, seguido dos combustíveis (32,96 GJ ha-1). A área irrigada consumiu 100,4 GJ ha-1, sendo 16% devido ao acionamento do pivô central. A energia bruta dos frutos de pinhão-manso foi de 69,82 e 45,31 GJ ha-1 para o sistema irrigado e o sem irrigação, respectivamente. O balanço energético (BE) para as duas áreas foi negativo e a lucratividade energética (EROI) foi de 0,63 para a área irrigada e 0,49 para a área sem irrigação, evidenciando a ineficiência e a não sustentabilidade do cultivo de pinhão-manso nas condições deste estudo para geração de energia. / Jatropha (Jatropha curcas L) is a species from Euforbiácea family that has been widely studied because of some particular characteristics such as being a perennial plant, its rusticity and the high oil production. The evaluation of pruning and irrigation on growth development and yield of jatropha is very important for the culture management. The objective of this study was to evaluate the effects on jatropha under different types of pruning and water management in Piracicaba, SP. The experiment was conducted in the experimental area of the Department of Biosystems Engineering (ESALQ/USP) during the fourth year crop growing and with 3 x 4 m planting spacing, totalizing 833 plants ha-1. The treatments were randomly arranged in blocks with two water management (irrigation and rainfed) and three pruning types (P1, no pruning; P2, with 1.5 m height x 1.5 m canopy diameter and; P3, with 2.0 height x 1.5 m canopy diameter). In each block, there were three pruning types with 4 blocks in each water management. Irrigation have influenced the canopy diameter values, absolute growth rates for height and canopy diameter, relative growth rate for canopy diameter and yield parameters., pruning management have influenced in all growth parameters, with drastic pruning (P2) representing the highest average growth rates. The irrigation have showed the highest yield per plant and per hectare. The analysis of Nuclear Magnetic Resonance of hydrogen (1H NMR) have shown that the irrigation and pruning have not influenced the oil content on jatropha seeds. Regarding the fatty profile, the irrigation management have influenced only the P2, since that no irrigation have influenced to largest accumulation of oleic acid in the oil. In energy analysis, it was noted that fertilizers were the inputs with the largest participation in energy input (42.57 GJ ha-1) for both water management, followed by fuels (32.96 GJ ha-1). The irrigated area consumed 100.4 GJ ha-1 energy, representing 16% due to the central pivot usage. The gross energy of jatropha fruits was 69.82 and 45.31 GJ ha-1 for irrigated and rainfed system, respectively. The energy balance for the two areas was negative and the energy return over investment, with 0.63 and 0.49 for irrigated and rainfed, respectively, have showed the inefficiency and unsustainability of jatropha cultivation to generate energy.

Uma análise do setor sucroalcooleiro nacional revela sua autossuficiência energética que com investimentos adequados, pode evoluir para transformar tal característica em benefício por meio de exportação de energia elétrica. Atualmente, os sistemas de cogeração das usinas de etanol operam com bagaço-de-cana; no entantoesse quadro deve ser alterado devido ao grande aumento de disponibilidade de palha gerada no campo. Um acordo firmado entre o Governo do Estado de São Paulo e UNICA, que limita e condiciona queimadas durante a colheita na região ratifica essa condição. O presente estudo se propõe a estimar e discutir impactos ambientais associados à cogeração de energia elétrica em destilarias autônomas para situações diversas de operação do ciclo Rankine, modelo de termodinâmico adotado para representar o funcionamento daquele sistema. Para atender a tais propósitos foram verificadas diferentes condições de pressão de operação da caldeira (20, 45, 67, 80 e 100 bar), teor de umidade da palha (10%, 15%, 25%, 35% e 50%), e taxa de adição dessa biomassa (10%, 20%, 30%, 40% e 50%) com relação ao total gerado no campo. A coordenação simultânea dessas variáveis resultou na formulação de cento e vinte e cinco cenários de análise. Os cenários foram analisados a partir de Análise Energética (Análise Termodinâmica de 1ª e 2ªLeis) e Avaliação de Ciclo de Vida (ACV). AACVocorreusob enfoque do tipo \"berço-aoportão\", e seguiu diretrizes metodológicas descritas na norma ABNT NBR ISO 14044. Adotou-se como unidade funcional para o estudo \"produzir10 t de etanol anidro (99,5% w/w)\". O sistema de produto compreende atividades realizadas nas etapas agrícola (de produção de cana-de-açúcar e palha) e industrial (obtenção de etanol e cogeração). A análise ocorreu em termos da geração específica de eletricidade, e de perfil de impactos ambientais, definido em termos dos potenciais de Mudanças Climáticas, Acidificação Terrestre, Eutrofização Aquática, e de Formação de Oxidantes Fotoquímicos e de Material Particulado.Os resultados obtidos indicam que a eficiência energética aumenta com a elevação das funções de estado do vapor superaquecido que é injetadona turbina. Em termos de desempenho ambiental, observou-se redução sistêmica de efeitos adversos com o aumento da eficiência do ciclo termodinâmico. Os resultados também ratificaram como condição mais favorável em termos de desempenho ambiental aquela em que 50% da palha gerada no campo, com 10% de umidade, é aproveitada como fonte de energia térmica na caldeira, produzindo vapor superaquecido a 100 bar. / Analyzing the sugar-alcohol sector in Brazil, one can perceive that it is self-sufficient in energy terms and that, with adequate investments, it can evolve to transform this characteristic into a benefit through the export of electricity. Currently, the cogeneration systems of the ethanol plants operate with bagasse. However, this picture should be changed due to the large increase in availability of straw generated in the field. An agreement signed between the Government of the State of São Paulo and the federation of ethanol and sugar mills (UNICA) that limits and conditions burnings during harvesting in the region ratifies this condition. This study estimates and discusses environmental impacts associated with the cogeneration of power in autonomous distilleries for typical operational conditions of the Rankine cycle, a thermodynamic model adopted to represent the operation of that system. In order to meet these purposes, different boiler operating pressure (20, 45, 67, 80 and 100 bar), moisture content of the straw (10%, 15%, 25%, 35% and 50%), and rate of biomass feeding (10%, 20%, 30%, 40% and 50%) in relation to the total generated in the field have been verified.The simultaneous coordination of these variables resulted in the formulation of one hundred and twenty-five analysis scenarios, which were investigated in terms of Energy Analysis (Thermodynamic Analysis of 1st and 2nd Laws) and Life Cycle Assessment (LCA). The LCA was carried out under a \"cradle-to-gate\" approach and followed the methodological guidelines described in ABNT NBR ISO 14044. It was adopted as a Functional Unit for the study \"to produce 10 t of anhydrous ethanol (99.5% w/w) \". The product system comprises activities that occur in the agricultural (production of sugarcane and straw) and industrial (synthesis of ethanol and cogeneration) stages. The analysis took place in terms of the specific generation of electricity, and of environmental impact profiles have been defined in terms of the potential of Climate Change, Terrestrial Acidification, Aquatic Eutrophication, and Formation of Photochemical Oxidants and Particulate Material. The results indicate that the energy efficiency increases with the increase of the state functions of the steam that is injected into the turbine. Regarding the environmental performance, it was observed a systemic reduction of adverse effects with the increase of the efficiency of the thermodynamic cycle. The results also confirmed that the most favorable condition in terms of environmental performance is that one which 50% of the straw produced in the field, with 10% humidity, is used as a source of thermal energy in the boiler, producing superheated steam at 100 bar.

O setor florestal apresenta grande importância econômica no Brasil, representando uma significativa parcela no PIB, nas exportações e na geração de empregos. As florestas fornecem matéria prima para a produção de energia ou celulose e são avaliadas, normalmente, por um enfoque econômico, que, isoladamente, não traz a sustentabilidade do setor. Para se avaliar a sustentabilidade, análises sistêmicas e de fluxo de material são algumas das alternativas. O fluxo de material fornece subsídios às metodologias que abordam os diversos aspectos da sustentabilidade, como por exemplo, a análise de energia, a síntese de emergia e análises integradas de aspectos sociais, econômicos e ambientais. Tendo em vista a importância da área florestal e a falta de estudos que permitam uma avaliação sistêmica dessa atividade, esse trabalho teve por objetivo avaliar a sustentabilidade energética de um sistema de produção. Para tanto, elaborou-se um modelo para determinar o fluxo de material, referente aos insumos utilizados indiretamente nas operações mecanizadas do sistema de produção: mão-de-obra, combustível e depreciação material do maquinário. Através desse modelo avaliou-se o cenário básico, que utiliza calcário na correção da acidez do solo e suas alternativas: cinzas e biossólido. Com base nesses resultados, avaliou-se o sistema através da análise de energia e da síntese de emergia. A análise de energia aborda os fluxos energéticos dos insumos aplicados e o dos produtos obtidos, possibilitando a determinação da lucratividade energética (EROI), o ganho líquido (balanço de energia) e a intensidade energética do sistema de produção. A síntese de emergia contempla os recursos naturais renováveis e os não-renováveis, além dos recursos adquiridos no mercado. Essa análise e síntese estabeleceram os fluxos de recursos, identificando seus principais fatores de produção e os indicadores que têm potencial de uso na tomada de decisão de empresas florestais. Utilizou-se da análise de sensibilidade para avaliar o efeito dos fatores de produção na sustentabilidade do sistema. Os resultados obtidos mostraram que o sistema de produção apresenta uma maior sustentabilidade energética quando comparado com os sistemas de produção menos intensificados. Para a análise de energia, o combustível foi o fator com maior participação na energia de entrada, com os fertilizantes e herbicidas na sequência. Na síntese de emergia, um recurso renovável, evapotranspiração, foi o principal fator. Quando considerou-se os fatores exógenos ao sistema na síntese, o combustível, os fertilizantes e os corretores de acidez foram os principais. Nas duas metodologias, a colheita foi a operação mais demandante de recursos e as alternativas ao calcário pioraram o desempenho energético do sistema. Ressalta-se que as avaliações dessas alternativas não consideraram os benefícios indiretos em não se descartar os resíduos utilizados no ambiente, indicando um caminho para novos estudos. Para se elevar a sustentabilidade, deve-se melhorar a eficiência da colheita e reduzir o uso de insumos com menor redução proporcional da produtividade. Ambas as metodologias deveriam ser consideradas na avaliação de sistemas produtivos, pois tratam de uso de recursos ambientais e exógenos e quantificam a intensidade energética dos produtos, permitindo comparações. / The forestry sector is very important to the Brazilian economy, representing a significant share of the GDP, exports and employment generation. Forests supply raw material for energy and cellulose production and are usually evaluated through an economical approach, which, alone, does not reflect the sustainability of the sector. In order to evaluate sustainability, system and material flow analyses are some alternatives. The material flow gives subsidy to methodologies that approach the several aspects of sustainability, such as, energy analysis, emergy synthesis and analysis integrating social, economic and environmental aspects. Due to the importance of the forestry sector, the lack of studies that systemically evaluate this activity, this study aimed to evaluate the energetic sustainability of a production system. So, one elaborated a model to determine the material flow, regarding the inputs indirectly applied in the mechanized operations in the production system: labor, fuel and material depreciation of machinery. This model evaluated the basic scenario, which uses lime to control soil acidity, and its alternatives: ashes and sludge. Based on the obtained results, the system was evaluated through energy analysis and emergy synthesis. The energy analysis approaches the energy flows of the applied inputs and the obtained products, propitiating the determination of the energetic profitability (EROI), the net gain (energy balance) and the energetic intensity of the production system. The emergy synthesis ranges the renewable and non-renewable natural resources, besides those acquired in the market. This analysis and this synthesis establish the resource flows and identified the main production factors and present indicators with potential use in the decision making of forestry enterprises. The sensitivity analysis evaluated the effect of the production factors in the system's sustainability. The obtained results showed that the studied production system presents higher energetic sustainability than some systems with less intensification. In the energy analysis, fuel was the main factor in the energy input, followed by fertilizers and herbicides. In the emergy synthesis, evapotranspiration, a renewable resource, was the main factor. Considering the factors exogenous to the system, fuel, fertilizers and soil acidity correctors were the main ones. In both methodologies, harvesting was the more demanding operation and the alternatives to liming decreased the energetic performance of the system. One should highlight that in the evaluating of both alternatives, no indirect benefit was considered, such as the avoidance of dumping those materials. This indicates new possibilities of studies. In order to increase sustainability, one should improve the harvest efficiency and reduce use of the agricultural inputs with less proportional reduction of the yield. Both methodologies should de considered in the evaluation of productive systems since they approach the use of environmental and exogenous resources; they quantify the intensity of products and allow comparisons among systems.

O etanol está consolidado como combustível para movimentação de veículos leves no Brasil e, nos últimos 40 anos, apenas a cultura de cana-de-açúcar tem sido explorada comercialmente para a produção deste combustível. Por outro lado, o desenvolvimento agrícola vem proporcionando safras recordes de grãos nas últimas décadas. A produção de milho se destaca pelo aumento da produtividade, podendo ser semeado como cultura principal ou como cultura de inverno em rotação com a soja. O sorgo, por sua vez, pode atuar como um substituto do milho, apresentando maior rusticidade e tolerância à seca. Dada essa conjuntura, usinas de etanol do Mato Grosso se associaram a produtores de milho e sorgo para incluir novas matéria-primas no processo de produção de combustíveis, compartilhando uma mesma unidade industrial, denominada Usina Integrada ou Usina Flex. No contexto atual, o desenvolvimento de novas tecnologias e setores produtivos exige a consideração de suas potenciais implicações energéticas e ambientais. A Avaliação de Ciclo de Vida (ACV) é uma ferramenta da gestão ambiental usada para avaliar impactos ambientais potenciais associados a produtos, processos e serviço. Sua principal característica é se prestar a essa avaliação de forma sistêmica, levando em conta todas as etapas do seu ciclo de vida. O objetivo deste trabalho foi avaliar e comparar os desempenhos ambiental e energético da produção de etanol a partir dos ativos agrícolas cana-de-açúcar, milho e sorgo, no contexto de usina autônoma integrada, segundo a abordagem do ciclo de vida. Para tanto, estudos de ACV foram conduzidos para cada um dos três produtos, seguindo as diretrizes das normas ABNT NBR ISO 14.040:2009 e ABNT NBR ISO 14.044:2009. Para a análise ambiental aplicou-se o método de Avaliação de Impacto do Ciclo de Vida (AICV) ReCiPe midpoint e, para a análise energética, o método Demanda de Energia Cumulativa foi utilizado, seguido pelo cálculo dos Índices de Retorno Energético sobre o Investimento (EROI) para cada combustível. A unidade funcional dos estudos foi 1 m³ de etanol hidratado e o sistema de produto incluiu a produção de insumos, produção da matéria-prima agrícola, produção de etanol, cogeração e etapas de transporte. Os resultados da análise ambiental demonstraram que o etanol de cana-de-açúcar apresenta melhor desempenho do que o etanol de milho e de sorgo em um número maior de categorias de impacto. As análises energéticas demonstraram que o uso de cavaco de madeira na etapa de cogeração dos processos de produção de etanol de milho e sorgo traduziu-se em ganhos energéticos, mas o etanol de cana-de-açúcar ainda apresenta um desempenho melhor por utilizar o bagaço para cogeração. Em termos de EROI, o etanol de cana-de-açúcar disponibilizou 9,77 unidades de energia para cada unidade consumida, o etanol de milho disponibilizou 2,68 e o etanol de sorgo disponibilizou 3,10. / Ethanol is consolidated as fuel to drive light vehicles in Brazil, but for the past 40 years, only the cultivation of sugarcane has been commercially exploited for the production of this fuel. On the other hand, agricultural development has provided high yields of grain in recent decades. Corn production is distinguished by increased productivity, and can be sown as main crop or as a winter crop in rotation with soybeans. Sorghum, in turn, has a higher roughness and tolerance to drought and can act as a substitute for corn. Given this situation, ethanol plants in Mato Grosso were associated with corn and sorghum producers to include new raw materials in the fuel production process, sharing the same plant, called Integrated Plant or Plant Flex. However, the development of new technology and production sectors requires consideration of its potential energy and environmental implications. The Life Cycle Assessment (LCA) is management tool used to evaluate potential environmental impacts associated with products, processes and services. Its main feature is to provide such an assessment in a systematic way, taking into account all stages of their life cycle. The objective of this study was to evaluate and compare the environmental and energy performance of ethanol production from sugarcane, corn and sorghum in the context of integrated autonomous plant, according to the life cycle approach. For that, LCA studies were conducted for each of the three products, following the guidelines of the standards ISO 14040: 2009 and ISO 14044: 2009. For environmental analysis the method of Life Cycle Impact Assessment (LCIA) Recipe midpoint was applied and for energy analysis Cumulative Energy Demand method was used, followed by the estimate of the Energy Return On Investment (EROI) for each fuel. The functional unit of the studies was 1 m³ of hydrous ethanol and the product system includes the production inputs, production of agricultural raw material, production of ethanol, cogeneration and transport stages. The results of the environmental analysis showed that the ethanol sugarcane performs better than the ethanol maize and sorghum in a greater number of impact categories. Energy analyzes have shown that the use of wood chips in cogeneration stage of corn ethanol production processes and sorghum has resulted in energy savings, but the ethanol sugarcane still performs better by using bagasse for cogeneration. In terms of EROI, the sugarcane ethanol provided 9.77 units of energy for every unit consumed, corn ethanol provided 2.68 and sorghum ethanol provided 3.10.