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Cassava (Manihot esculenta) is a woody bush extensively cultivated as an annual crop in tropical and subtropical regions for its edible starchy tuberous root, a major source of carbohydrates. The main residue from its cultivation is the cassava stalk, which is normally used as soil fertilizer or in culture propagation. The main goal of this paper is to evaluate two routes (biochemical and thermochemical) for bioenergy production (ethanol and synthesis gas—electricity) using cassava stalk as raw material. A detailed techno-economic and energy assessment is carried out based on the simulation approach of both conversion routes to determine the production costs of main products and the overall energy efficiency of the processes. The electricity production costs vary from 0.008 to 0.037 USD/MJ, whereas the ethanol production costs range from 1.11 to 2.02 USD/L (including subsidies). The change in the production costs was observed due to the assumptions of the model, e.g., cassava stalk, transportation, and enzyme costs. The overall energy efficiency of the gasification and ethanol fermentation was 68.7 and 25.1%, respectively. [ABSTRACT FROM AUTHOR]

Abstract: In this paper a techno-economic analysis for bioethanol production in Africa for Tanzania case is presented. It is shown conversion pathways from sugar cane juice and molasses, at three levels of technological schemes, where the first one includes a selection of widely conventional technologies, the second level with a more sophisticated fermentation technology and the third level using a different broth and solid treatment for ethanol production. A simulation procedure was taking into account in order to evaluate the conversion pathways schemes using different scenarios of raw material pretreatment, using Aspen Plus software, that include productivity analysis and energy requirements for each process configuration. Also an economical evaluation of each technology level and each scenario is shown. A comparison and discussions for each technological level and each scenario for bioethanol production in Tanzania is presented. These results served as the basis to draw recommendations on technological and economic feasibility aspects for the implementation of a national biofuel production programme in Africa. The study helped to identify the best technological schemes for producing fuel-grade alcohol from the various raw materials analysed. [Copyright &y& Elsevier]

Fuel ethanol production has become one of the most studied processes in the last two decades because of the need to decrease its production cost and improve its energetic performance. The most promising raw material is lignocellulosic biomass because of its negligible cost and high availability. On the other hand, most research has focused on single steps and has not considered the whole process design. Aspen Plus allowed designing this kind of process while considering relevant aspects such as raw material composition and kinetic models of chemical and biological transformation. In this study fuel ethanol from rice hulls has been simulated considering the kinetic parameters for acid pretreatment, detoxification, and fermentation with the aim of assessing the energy performance of the process. In addition, the economic evaluation was accomplished using Aspen Process Economic Analyzer with the objective of calculating the production cost. It was found that the dilute acid pretreatment had a higher ethanol yield (347.25 L/t) and lower energy consumption (86.75 MJ/L) than liquid hot water pretreatment. However, the latter pretreatment had a lower production cost (US$0.4367/L); although when energy cogeneration and electricity sales were included in the analysis, dilute acid pretreatment became the most economic technology with a lower production cost (US$0.1918/L). [ABSTRACT FROM AUTHOR]

Abstract: Current fuel ethanol research and development deals with process engineering trends for improving biotechnological production of ethanol. In this work, the key role that process design plays during the development of cost-effective technologies is recognized through the analysis of major trends in process synthesis, modeling, simulation and optimization related to ethanol production. Main directions in techno-economical evaluation of fuel ethanol processes are described as well as some prospecting configurations. The most promising alternatives for compensating ethanol production costs by the generation of valuable co-products are analyzed. Opportunities for integration of fuel ethanol production processes and their implications are underlined. Main ways of process intensification through reaction–reaction, reaction–separation and separation–separation processes are analyzed in the case of bioethanol production. Some examples of energy integration during ethanol production are also highlighted. Finally, some concluding considerations on current and future research tendencies in fuel ethanol production regarding process design and integration are presented. [Copyright &y& Elsevier]

This work investigated a model biorefinery for producing phenolic compounds extract, ethanol and xylitol from spent blackberry pulp (SBP). The biorefinery was investigated according to four potential scenarios including mass and heat integrations as well as cogeneration system for supplying part of the energy requirements in the biorefinery. The investigated SBP had 61.54% holocellulose; its total phenolic compounds was equivalent to 2700 mg of gallic acid/100 g SBP, its anthocyanins content was 126.41 mg/kg of SBP and its total antioxidant activity was 174.8 μmol TE/g of SBP. The economic analysis revealed that the level of integration in the biorefinery significantly affected the total production cost. The sale-to-total-production-cost ratio indicated that both, mass and heat integrations are of importance relevance. The cost of supplies (enzymes and reagents) had the most significant impact on the total production cost and accounted between 46.72 and 58.95% of the total cost of the biorefinery. [ABSTRACT FROM AUTHOR]

In this work, the technical, economic, and environmentalviabilityof the growth, harvest, drying, and extraction of oil from Chlorella vulgariswas evaluated. A flue stream from a ricehusk processing plant was taken as the substrate for microalgae growthand the production of 1 ton/h of microalgae oil. The mass and energybalances were calculated using Aspen Plus Software. The economic assessmentwas developed using Aspen Process Economic Analyzer Software. Theenvironmental impact evaluation was carried out using the waste reductionalgorithm (WAR). The yields of the process were 0.37 kg of oil/kgof dry microalgae and 0.63 kg of cake/kg of dry microalgae. The productioncosts were 0.56 USD/kg of oil and 0.33 USD/kg of cake. The potentialenvironmental impact was 0.003 PEI/kg of product. The results indicatesignificant mitigation of smog formation potential because gases areused to generated value-added products. [ABSTRACT FROM AUTHOR]

Abstract: Glycerol as a low-cost by-product of the biodiesel industry can be considered a renewable building block for biorefineries. In this work, the conversion of raw glycerol to nine added-value products obtained by chemical (syn-gas, acrolein, and 1,2-propanediol) or bio-chemical (ethanol, 1,3-propanediol, d-lactic acid, succinic acid, propionic acid, and poly-3-hydroxybutyrate) routes were considered. The technological schemes for these synthesis routes were designed, simulated, and economically assessed using Aspen Plus and Aspen Icarus Process Evaluator, respectively. The techno-economic potential of a glycerol-based biorefinery system for the production of fuels, chemicals, and plastics was analyzed using the commercial Commercial Sale Price/Production Cost ratio criteria, under different production scenarios. More income can be earned from 1,3-propanediol and 1,2-propanediol production, while less income would be obtained from hydrogen and succinic acid. This analysis may be useful mainly for biodiesel producers since several profitable alternatives are presented and discussed. [Copyright &y& Elsevier]

Abstract: In this work technical and economic analyses were performed to evaluate the glycerol transformation into Polyhydroxybutyrate using Bacillus megaterium. The production of PHB was compared using glycerol or glucose as substrates and similar yields were obtained. The total production costs for PHB generation with both substrates were estimated at an industrial scale. Compared to glucose, glycerol showed a 10% and 20% decrease in the PHB production costs using two different separation schemes respectively. Moreover, a 20% profit margin in the PHB sales price using glycerol as substrate resulted in a 166% valorization of crude glycerol. In this work, the feasibility of glycerol as feedstock for the production of PHB at laboratory (up to 60% PHB accumulation) and industrial (2.6US$/kgPHB) scales is demonstrated. [Copyright &y& Elsevier]

Ethanol dehydration plays a crucial role during fuel ethanol production process, especially when costs of the overall process are considered. For product recovery step from fermentation broth, several technologies have been proposed. These technologies include conventional distillation followed by dehydration methods like azeotropic distillation, extractive distillation vacuum distillation, and adsorption with molecular sieves. In this work, the effect that the type of separation system has on ethanol production costs was evaluated using process simulators. Among the studied configurations, adsorption with molecular sieves was the dehydration scheme with the best performance despite its higher capital costs (US$ 12.809.706) compared to azeotropic and extractive distillation (US$ 9.547.963 and 9.525.920, respectively). From energy viewpoint, adsorption using molecular sieves requires 2,325.5 kcal/kg of product, while 2,555.3, 2,958.6, and 3,682.7 kcal/kg are required for extractive, azeotropic and vacuum distillation, respectively. Additionally, dehydration with molecular sieves do not involve solvents or entrainers (i.e. benzene, cyclohexane, ethylenglycol), which finally remain in wastewater and in product stream as traces; thus, this technology is cleaner and more environmentally friendly. [ABSTRACT FROM AUTHOR]