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Hosseini S.S.,University of Tehran | Aghbashlo M.,University of Tehran | Tabatabaei M.,Agricultural Biotechnology Research Institute of Iran | Tabatabaei M.,Biofuel Research Team BRTeam | And 2 more authors.
International Journal of Hydrogen Energy | Year: 2015

This paper proposes a thermodynamic framework based on exergy and eco-exergy concepts for biological hydrogen production from CO-enriched gas via a locally isolated photosynthetic bacterium Rhodopseudomonas palustris PT. In order to achieve a deeper understanding on the bioreactor performance, exergetic parameters like exergy destruction, exergy efficiency, and sustainability index for the bioreactor were determined using both concepts at different acetate concentrations as a carbon source ranging from 0 to 3 g/ L. The exergetic results based on both concepts remarkably diverged from each other due to the inclusion of the work of information carried by the genomes of living organisms in the eco-exergy concept. The sustainable dosage of sodium acetate was found to be 1.5 g/L for efficient and eco-friendly bioconversion of harmful carbon monoxide to hydrogen and carbon dioxide through the water-gas shift (WGS) reaction. The methodologies applied herein revealed the benefits of applying exergy analysis for the design and optimization of industrial-scale bioreactors to attain more cost-effective and eco-friendly biohydrogen production. Consequently, the photobiological hydrogen production can be taken into account as a sustainable alternative fuel to the non-renewable fossil resources by minimizing the thermodynamics irreversibilities. © 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Source


Hosseini S.S.,University of Tehran | Aghbashlo M.,University of Tehran | Tabatabaei M.,Agricultural Biotechnology Research Institute of Iran | Tabatabaei M.,Biofuel Research Team BRTeam | And 2 more authors.
Energy | Year: 2015

In this study, exergy analysis of batch biohydrogen production through WGS (water-gas shift) reaction using an anaerobic photosynthetic bacteria Rhodospirillum rubrum was carried out for the first time. Various carbon sources including formate, acetate, malate, glucose, fructose, and sucrose were applied to support microbial growth in the presence of CO-rich syngas. The microorganisms utilized carbon monoxide and produced molecular hydrogen concurrently. The process was analyzed based on both conventional exergy and eco-exergy concepts for determining the exergetic parameters i.e., exergy destruction and exergy efficiency. Unlike the exergy efficiency, the exergy destruction based on the eco-exergy concept was remarkably lower than what obtained via the conventional exergy theory. Minimum normalized exergy destruction values of 189.67 and 181.40 kJ/kJ H2 were achieved for acetate as substrate using the exergy and eco-exergy approaches, respectively. In better words, acetate was identified as the most appropriate carbon source for biohydrogen production from the exergy point of view. Finally, the findings of this study confirmed that exergy analysis could be employed as an adaptable framework to determine and compare the renewability of biological hydrogen production using different routes in order to decide on the most suitable approach and conditions. © 2015 Elsevier Ltd. Source


Aghbashlo M.,University of Tehran | Tabatabaei M.,Agricultural Biotechnology Research Institute of Iran | Tabatabaei M.,Biofuel Research Team BRTeam | Karimi K.,Isfahan University of Technology
Energy | Year: 2016

This paper presents an in-depth exergy analysis of the ethanol fermentation process with various forms of fungus Mucor indicus under aerobic and anaerobic conditions to select the most productive and sustainable conditions. Various carbon sources including fructose, glucose, and sucrose as well as the whole and inverted sugar beet and sugarcanes molasses were used during the fermentation. The rational and process exergetic efficiencies were found to be in the range of 65.21%-88.54% and 0.00%-44.31%, respectively. Overall, the exergy-based parameter based on the process outputs could provide useful information about the sustainability and productivity of the fermentation process compared to the rational analysis. More specifically, the inverted sugar beet molasses with MF (mostly filamentous) form of M. indicus under anaerobic cultivation was shown to be the best option for industrial production phase with respect to the productivity and sustainability issues. The results obtained confirmed that the process yield alone cannot perfectly reflect the exact sustainability parameters of the renewable ethanol production systems. Finally, the developed exergetic framework could help engineers to couple biochemical and physical concepts more robustly for achieving the most cost-effective and eco-friendly pathways for bioethanol production. © 2016 Elsevier Ltd. Source


Aghbashlo M.,University of Tehran | Hosseinpour S.,University of Tehran | Tabatabaei M.,Agricultural Biotechnology Research Institute of Iran | Tabatabaei M.,Biofuel Research Team BRTeam | And 2 more authors.
Energy | Year: 2016

The aim of this work was to exergetically optimize the performance of a continuous photobioreactor for hydrogen production from syngas via water gas shift reaction by Rhodospirillum rubrum. To achieve this, a new multi-objective hybrid optimization technique was developed by coupling the elitist NSGA-II (non-dominated sorting genetic algorithm) with the ANFIS (adaptive neuro-fuzzy inference system) to optimize the operational conditions of the photobioreactor. The syngas flow rate and culture agitation speed were independent variables, while rational and process exergy efficiencies as well as normalized exergy destruction were dependent variables. The ANFIS was used to establish an objective function for each dependent variable individually based on the independent variables. The developed ANFIS model was then utilized by the NSGA-II approach to find the optimal operating conditions simultaneously leading to the highest rational and process exergy efficiencies and the lowest normalized exergy destruction. Consequently, the best operating conditions for the photobioreactor were extracted using a Pareto optimal front set consisting of seven optimum points. Accordingly, syngas flow rate of 13.34 mL/min and culture agitation speed of 383.33 rpm yielding process exergy efficiency of 21.66%, rational exergy efficiency of 85.64%, and normalized exergy destruction of 1.55 were found as the best operating conditions. © 2015 Elsevier Ltd. Source


Aghbashlo M.,University of Tehran | Hosseinpour S.,University of Tehran | Tabatabaei M.,Agricultural Biotechnology Research Institute of Iran | Tabatabaei M.,Biofuel Research Team BRTeam | And 3 more authors.
Renewable Energy | Year: 2016

The aim of the present study was to perform an exergy-based multi-objective fuzzy optimization of a continuous photobioreactor applied for biohydrogen production from syngas via the water-gas shift reaction by Rhodospirillum rubrum. For this purpose, the conventional and innovative fuzzy optimization techniques coupled with multilayer perceptron (MLP) neural model to optimize the main exergetic performance parameters of the photobioreactor. The MLP neural model was applied to correlate three dependent variables (rational and process exergy efficiencies and normalized exergy destruction) with two independent variables (syngas flow rate and agitation speed). The developed MLP model was then interfaced with three different multi-objective fuzzy optimization systems with independent, interdependent, and locally modified interdependent objectives. The optimization process was aimed at maximizing the rational exergy and process efficiencies, while minimizing the normalized exergy destruction, simultaneously. Generally, the innovative locally modified interdependent objectives fuzzy system showed a better optimization capabilities compared with the other two fuzzy systems. Accordingly, the optimal syngas photo-fermentation for biohydrogen production in the continuous bioreactor corresponded to the agitation speed of 383.34 rpm and syngas flow rate of 13.35 mL/min in order to achieve the normalized exergy destruction of 1.56, rational exergy efficiency of 85.65%, and process exergy efficiency of 21.66%. © 2016 Elsevier Ltd. All rights reserved. Source

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