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The sustainability of the second-generation biofuels requests to confirm that the energy produced from lignocellulosic biomass is significantly greater than the energy consumed in the process. As lignocellulosic biomass does not affect the food supply, sugarcane bagasse was analyzed as a raw material for second-generation biofuels production. Exergy analysis serves as a unified and effective tool to evaluate the global process efficiency. Exergy analysis evaluates the performance of sugarcane bagasse and its sustainability in the bioethanol production process. In this work, four ethanol production topologies using the typical daily amount of residual biomass produced by the sugar industry were compared. The exergy analysis concept is effective in screening design alternatives with the lowest environmental impact for second-generation bioethanol fuel production from renewable resources. This study was executed by the use of the Aspen Plus® program and other software developed by the authors.

This paper presents an effective computational scheme using metaheuristic techniques for the optimization of an integrated biodiesel production process from microalgae Chlorella vulgaris. Ten decision variables were optimized including temperatures and pressures of the five process reactors and the number of stages and feed stage of the three considered distillation columns. The model is a multiobjective formulation involving economic and environmental objectives. The economic objective function is aimed at maximizing the total annual income. The objective function associated with the environmental impact is to minimize the produced greenhouse gases. Process data were obtained from the simulation software Aspen Plus. Models for determining the properties for new substances missing in the database, such as fatty acids present in the microalgae, were considered to improve the predictions of the raw material properties. The free software Symyx Draw was used for the creation of all the components that were no...

Abstract One of the largest potential feedstock for ethanol is lignocellulosic biomass, principally agricultural residues. Cellulosic ethanol can be made from the stems, leaves, bagasse, stalks and trunks of plants which are not used for human-food production. However, there are significant economic challenges facing the second generation of biofuels. Consequently, application of process engineering is necessary to improve the overall process efficiency. Therefore, the main objective of this paper is to apply energy and exergetic analysis together with process integration methodologies coupled with process simulation as a unified and effective tool for the evaluation of converting lignocellulosic biomass to ethanol. In this paper, bioethanol production from acid-pretreated bagasse using different process configurations that include sequential hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF), and simultaneous saccharification and co-fermentation (SSCF) were analyzed.

Abstract Nowadays, there is a tremendous global interest in the biofuels production. However, first generation biofuels have been debated about that energy-crop compete with food crops and thus cause food deficiency and price increases. In this sense, researchers have started looking for potential feedstock for ethanol such as lignocellulosic biomass (e.g., sugarcane bagasse), which does not affect food security. In this paper, the integrated use of sugarcane bagasse is analyzed as raw material for second generation of biofuels production. This case study implements a design and process integration to compare several biorefinery topologies using the typical mass flow rate of residual biomass produced by the sugar industry (1200 ton per day). Based on evaluation of chemical composition of bagasse (cellulose, hemicellulose, and lignin) several process schemes for integral utilization of biomass were proposed. This paper is the first part of the study on the exergy, life cycle analysis (LCA) and economic analysis of sugarcane bagasse for sustainable biofuels production using Aspen Plus™ software. Part 1 presents the exergy and life cycle analysis developed while part 2 describes economic analysis and selection of an optimal configuration with minimal environmental impact, by means of the combined use of raw material and energy integration.

The fast development of the world's bioethanol industry initiated debates on “food versus fuel” and the industry's environmental impact. Lignocellulosic biomass does not compete with food crops because it utilizes waste resources; however, the processing of a renewable energy source usually involves the consumption of non-renewable resources. To justify the production of second generation biofuels it is necessary to confirm that the energy produced from the lignocellulosic biomass is greater than the energy consumed in the ethanol production. The exergy analysis provides a unified and effective tool for the evaluation of the global process efficiency. This methodology requires an analysis of each stage of the production process. In this work, the stage of enzymatic hydrolysis was chosen as a case study because it is a decisive step in production process performance. The exergy analysis concept has been applied to evaluate two types of enzymatic hydrolysis reactors of lignocellulosic biomass for the production process of second generation bioethanol fuels from renewable resources, with the support of ASPEN-HYSYS® and other software developed by the authors.