Linda Ney, Jean-Luc Wolken, Rajveer Singh et al.

ECS Meeting Abstracts • 2022

The manufacturing process of catalyst coated membranes for polymer electrolyte fuel cells (PEMFC) needs to be transferred to high throughput mass production to meet the increasing demand on the market. After the coating of the catalyst ink, the drying temperature and its profile can change the pore structure and crack appearance of the catalyst layer by influencing the solvent evaporation [1]. Therefore, adjusting the drying parameters to the type of solvents within the catalyst ink can result in beneficial performance gain. Often solvents with low boiling points like isopropanol-water mixtures are used. The rapid evaporation of these solvents could lead to crack formation, which could be avoided by the usage of high boiling point solvents like e.g. ethylene glycol [2,3]. Therefore higher drying temperatures are necessary to ensure a complete removal of the wet components. This leads to the question of the maximum drying temperature which can be applied to speed up the drying process as much as possible. The most temperature sensitive component within the catalyst layer is the ionomer. Drying at high temperatures could lead to degradation and decomposition of the ionomer network within the catalyst layer. However, is the temperature too low, the necessary drying time increases, which would result in higher investment costs for longer drying process lines. Within this study we investigated at first the thermal behavior of short side chain (Aquivion®) and long side chain (Nafion™) ionomer dispersions to analyze their glass transition and melting temperatures with differential scanning calorimetry in the range of 30-400°C. The findings are shown in Figure 1. The glass transition temperature of Aquivion® lies between 154-159°C, whereas Nafion™ is more temperature sensitive with 125-142°C, which is consistent with the literature. In a second step, catalyst layers have been fabricated by screen printing with a catalyst paste including a solvent mixture of ethylene glycol and 1-methoxy-2-propanol [4]. The resulting catalyst layers have platinum loadings of 0.154 mg/cm² on the cathode and 0.05 mg/cm² on the anode side. The drying temperature has been varied between 22°C (ambient air temperature), 110°C, 150°C, 180°C, 200°C and 250°C within a continuous convection dryer. Further, different drying profiles have been applied by comparing to hot plate drying method. All other process parameters have been kept constant. The catalyst layers with different drying temperatures have been tested in-situ by electrochemical operation of the MEA. For Aquivion® as ionomer, the polarization curves are shown in Figure 2 and indicate that drying temperatures above 150°C (glass transition temperature) would lead to significant current density losses at wet and dry conditions. Furthermore, there doesn’t seem to be an optimum drying temperature below the glass transition temperature. Therefore, the best compromise of production throughput and electrochemical performance is reached at a temperature of 150°C, which is near the glass transition temperature of the ionomer. [1] Park H-S, Cho Y-H, Cho Y-H, Jung CR, Jang JH, Sung Y-E. Performance enhancement of PEMFC through temperature control in catalyst layer fabrication. Electrochimica Acta 2007;53(2):763–7. [2] Huang D-C, Yu P-J, Liu F-J, Huang S-L, Hsueh K-L, Chen Y-C et al. Effect of Dispersion Solvent in Catalyst Ink on Proton Exchange Membrane Fuel Cell Performance. Int. J. Electrochem. Sci. International Journal 2011;6:2551–65. [3] Hasegawa N, Kamiya A, Matsunaga T, Kitano N, Harada M. Analysis of crack formation during fuel cell catalyst ink drying process. Reduction of catalyst layer cracking by addition of high boiling point solvent. Colloids and Surfaces A: Physicochemical and Engineering Aspects 2021:127153. [4] Alink R, Singh R, Schneider P, Christmann K, Schall J, Keding R et al. Full Parametric Study of the Influence of Ionomer Content, Catalyst Loading and Catalyst Type on Oxygen and Ion Transport in PEM Fuel Cell Catalyst Layers. Molecules (Basel, Switzerland) 2020;25(7). Figure 1

, Nur Fawwaz Asri, Teuku Husaini et al.

Jurnal Kejuruteraan • 2020

Metallic bipolar plates tendency to have high contact resistance and corrosion after several times of usage affected performance of a cell in PEMFC stack. This study focused on the interfacial contact resistance (ICR) and corrosion resistance of SUS 316 L bipolar plates using Cr‒C and Nb‒C as coating layer, single stack performance in PEMFC were observed by experimental. The Cr‒C and Nb‒C coating layer acted as protective layer between SUS 316 L bipolar plates. Therefore, coating is a method in preventing the bipolar plates surface material from damage in the acidic environment of PEMFC. To develop corrosion-resistant and high conductivity bipolar plates for PEMFC, the coatings bipolar plates were applied to cell fabrication in comparison with bare SUS 316 L bipolar plates. The SUS 316 L bipolar plates size and electrode area were 50 mm2 and 25 mm2, respectively. The experiment was carried out on a prepared assembled single cell bipolar plates with the commercial membranes, conductive carbon papers and gasket. Initial performance of the single cells using Cr‒C and Nb‒C coatings over SUS 316 L bipolar plates were recorded at a cell voltage between 0.4 to 0.5 V, respectively. In comparison, Nb‒C gives good performance of corrosion resistance and the ICR value as low as 10‒12 A/cm2 and 1.22 mΩ cm−2. Additionally, it gives maximum power density of 137 mW/cm2 at the cell voltage 0.51 V. The lifetime durability of the single cell significantly improved from the uncoated current density of 390 mA/cm2 to 450 mA/cm2 with Nb‒C coating layer.

Jingying Ma, Zhihao An, Wenwen Zhang et al.

Analytical Science Advances • 2022

Abstract Optimization of dye decolourization for wastewater and power production are explored in dual‐chamber microbial fuel cells (MFCs) with TiO 2 /CdS photocathodes. The rapid reduction of azo dye methylene blue (MB) and power production were enhanced with TiO 2 /CdS photocathode under illumination. The analysis of electrochemical impedance spectra indicated that the photocatalysis of TiO 2 /CdS accelerated the electron transfer process of photoelectrode reduction. Moreover, the UV‐visible light spectrophotometer showed that the maximum degradation of the MFCs was 98.25%, which illustrated that MB may be cleaved by photoelectrons generated by light irradiation on the illuminated TiO 2 /CdS photocathode. Finally, the power production of MFCs in this work promoted reductive decolourization of the dye MB solution.

Xiaojun Zhao, Xuesong Shen, Yanbo Wang et al.

SAE Technical Paper Series • 2025

<div class="section abstract"><div class="htmlview paragraph">The dynamic behavior of the water and thermal management are critical to stabilize the performance of the proton exchange membrane fuel cell (PEMFC) during severe load changes. In this paper, a fuel cell hybrid electric vehicle (FCHEV) dynamic simulation model is established to evaluate the changes in liquid water and temperature distribution inside the fuel cell stack under a vehicle driving cycle conditions. This paper focuses on analyzing the power generation performance of the stack and the dynamic behavior of internal water and heat transfer following the demand of the vehicle. According to the simulation results, the temperature of MEA and cooling water fluctuates greatly, but the temperature of MEA is always higher than the cooling water temperature by about 1.57 degrees Celsius (average value). Compared to the experimental measurements of temperature, the simulation error for the maximum temperature is 3.4% and the simulation error for the average temperature is 4.4%. The accuracy of the simulation model is less than 5%. Based on the temperature distribution, a fuel cell system temperature control method is proposed, which is helpful to the optimization of the system and control design for the PEMFC system in FCHEV.</div></div>

Rod L. Borup, Adam Z Weber, Deborah J Myers et al.

ECS Meeting Abstracts • 2017

The FC-PAD (Fuel Cell – Performance and Durability) consortium coordinates national laboratory activities related to fuel cell performance and durability, provides technical expertise, and integrate activities with industrial developers. The national laboratory core teams have the responsibility to carry out foundational research and capabilities development, and provide support for the individual projects’ research efforts. This consortium incorporates National-Laboratory investigators related to durability, transport, and performance, and combines them into one highly coordinated effort. The consortium formalized already existing and effective collaborations amongst the National Laboratories that established leadership in PEMFC performance and durability research and development. The consortium coordinates work under in different Thrust Areas including component thrust areas and cross-cutting thrust areas. The six different thrust areas are: Component Thrust Areas: Electrocatalysts and Supports Electrode Layers Ionomers, Gas Diffusion Layers, Bipolar Plates, Interfaces Cross-cutting Thrust Areas: Modeling and Validation Operando Evaluation: Benchmarking, ASTs, and Contaminants Component Characterization and Diagnostics The structure of FC-PAD utilizes multiple cross-cutting thrust areas from theoretical modeling to characterization including benchmarking new materials that are provided to FC-PAD. The FC-PAD structure brings together world-class scientists into one integrated consortium, yet it provides a flexible structure to strategically use the widely varying expertise. The FC-PAD consortium is examining degradation mechanisms to help develop improved materials and operating strategies. Corrosion of the carbon electrocatalyst support has been measured during drive-cycle operating conditions and increases with increase potential cycling from 0.4 to 0.9 V. Carbon corrosion is one of the major contributors to degradation which leads to changes in the catalyst layer structure and reduces its activity. Reduction in catalyst layer thickness is observed during operation, exacerbated during drive cycles. This reduction can be due to the loss of carbon through carbon corrosion or due to compaction; both effects likely lead to a loss of void volume. Membrane additives which increase membrane life-times, have been measured to migrate into the catalyst layer and appear to be associated with the carbon in the catalyst layers. Low potentials (0.2V) appear to be required to remove membrane fragment adsorbates which decrease catalyst activity. Pt alloy catalysts lose most of their alloying agents during operation; the alloying agents migrated throughout the ionomer. Durability implications of using Pt-X alloy catalysts will be discussed. Results related to the mentioned degradation mechanisms will be presented including characterization from TEM, SEM, XRF, XRD and electrochemical testing. Consortium members include Argonne National Laboratory, Lawrence Berkeley National Laboratory, Los Alamos National Laboratory, the National Renewable Energy Laboratory and Oak Ridge National Laboratory. Acknowledgments This work was funded through the DOE FC-PAD Consortium with thanks to DOE EERE FCTO, Fuel Cell Team Leader: Dimitrios Papageoropoulos

Debajyoti Bose, Mahula Santra, Rama Venkata Siva Prasanna Sanka et al.

International Journal of Energy Research • 2020

Summary In natural environments, voltage gradients can be created in soil or sediments from inherent microbial activity. Present work has utilized sediment microbial fuel cell or s‐MFC for dark flocculent surface sediments to see bioelectricity generation potential at Jaipur, Rajasthan in India. Using a glucose rich substrate media and low external resistance, system generated external voltage of around 500 ± 10 mV, with power density peaking after a week of operation with 2122 ± 80 mW/m 2 and current density of 4.31 mA/m 2 ; s‐MFC reactor components included six graphite based anodes, placed strategically in the sediments, connected in series to a cathode for enhanced system performance. FTIR analysis of the surface sediment showed the presence of complex organic and inorganic compounds that allow stable biofilm formation, which influences power density directly. Such systems provide a novel route to bioremediation using microbial metabolism and can provide remote power generation for oceanographic instruments, biosensors and similar low power devices.

J. I. San Martín, I. Zamora, V. Aperribay et al.

Fuel Cells • 2014

Abstract One of the most outstanding products of fuel cells is electrical power but, currently, there is a reduced number of publications that provide experimental data about the performance of fuel cells when used for supplying Alternating Current (AC) loads. Most of the existing publications provide experimental data only with direct current (DC) loads, or analyze the performance with AC loads using simulation models. For this reason, this paper analyses experimentally the behavior of a proton exchange membrane fuel cell (PEMFC) system when feeding different electrical loads. The system tested is constituted by a PEM fuel cell, a storage battery, electronic converters and electrical loads. In the tests, the fuel cell system supplies power to three different loads: DC, single‐phase AC and three‐phase AC. For these cases, voltage, current, power, power factor and efficiency data are shown, at different load levels. From those parameters, efficiency of the global system is estimated. Finally, as the power quality concept is a topic of increasing importance when supplying electricity, the total harmonic distortion (THD) of the electric signals has also been analyzed.

Xiaohua Zhao, Tian Tian, Min Guo et al.

Journal of Chemical Technology & Biotechnology • 2019

Abstract BACKGROUND The morphology and size of MnO 2 that deposited on a carbon clothelectrode have dramatic effects on the electrochemical properties and cycling life. Currently, MnO 2 and its composite structures with zero‐dimensional (0D) nanospheres, one‐dimension (1D) nanotubes and two‐dimension (2D) nanomesh have been successfully synthesized and employed in MFC. Hence, the development of a three‐dimensional (3D) flexible, cost‐effective and high‐performance anode is of great significance for microbial energy harvesting. RESULT Herein, we have fabricated 3D cauliflower‐like polypyrrole@manganese dioxide (PPy@MnO 2 ) composites, which are successfully grown on carbon cloth (CC) anode by electrodeposition to promote the power production and storage in microbial fuel cells (MFCs). Impressively, the as‐prepared PPy@MnO 2 modified CC anode delivers a power density of 2139.7 ± 17.5 mW m −2 and produces an areal capacitance of 1120 ± 12.8 mF cm −2 , which is 3.58 and 4.84 folds higher than that with bare CC anode, benefiting from the unique cauliflower‐like 3D architecture with increased active centers that host the bacteria for more efficient charge transfer. Electrochemical analyses indicate that the PPy@MnO 2 modified CC electrode has excellent electrochemical activity, capacitive behavior and long‐term cyclabilities with smooth surface morphology and high porosity. CONCLUSION These findings not only provide a facile electrodeposition strategy for PPy@MnO 2 nanoflowers modified CC anode, but also demonstrates its potential for the production and storage of energy simultaneously in MFC application. © 2019 Society of Chemical Industry

Rhushikesh Ghotkar, Ryan J. Milcarek

ASME 2020 Power Conference • 2020

Abstract Direct flame fuel cells were developed in 2004 and there have been many iterations of them ever since. One of the latest iterations are the micro-tubular flame-assisted fuel cells. Even though there has been significant experimental research characterizing the performance and polarization losses of flame-assisted fuel cells, there is no model that describes their polarization losses. A model is thus developed and presented in this paper to assess the polarization losses and performance of flame-assisted fuel cells. Voltage and power density variation with current density are the main parameters that are analyzed in this paper. A model for calculating activation, ohmic and polarization losses is developed. Experimental parameters from previously published work like dimensions of the fuel cell layers, the fuel and oxidizer flow rates, the charge transfer coefficient and the exchange current density are used to optimize the model. The FFC is assumed to be a lumped system and a zero dimensional model is thus developed. The model was able to achieve an accuracy up to 95%, which adds to its credibility. The fuel-rich combustion exhaust composition is predicted using chemical equilibrium analysis for the equivalence ratios of 1.25 to 1.4 with intervals of 0.5 at 800°C. The model predicts that the open circuit voltage decreases from 0.94 to 0.89 for the equivalence ratios of 1.4 to 1.25, respectively, which matches experimental results. The model also predicts that the maximum power density decreases with decrease in equivalence ratio. Negligible activation loss was observed in the results while the ohmic loss didn‘t vary significantly with equivalence ratio. The concentration loss increased with decrease in equivalence ratio, which also matches with experimental results.

Haiying Guo, Chunfeng Huang, Xinlei Jia et al.

Environmental Progress & Sustainable Energy • 2023

Abstract Electricity‐generating bacteria are used as the biocatalysts of microbial fuel cells (MFCs). The power‐generating properties of electricity‐generating bacteria play an important role in organic matter degradation and electricity generation of MFCs. However, there are few electricity‐producing bacteria isolated from the anode biofilm of microbial fuel cells containing oily sludge. More importantly, the adaptability of nitrogen‐to‐phosphorus ratio, temperature and pH of the electricity‐generating bacteria were adjusted by controlled variable method. The results of this study showed that the isolated electricity‐producing bacteria ( Citrobacter freundii ) with a rod‐shaped cell, wrinkled surface, about 0.5–1.0 μm in length. The optimal nitrogen‐to‐phosphorus ratio, temperature and pH of MFCs are 5.67:1, 25°C, and pH = 7.5, Its maximum voltage and power density was up to 143.01 mV and 65 mW·m −3 , respectively. Furthermore, the growth rate of the electricity‐producing bacteria is the highest. This lays the foundation for inoculating electricity‐generating bacteria into oily sludge MFCs to improve the oil removal and power generation performance.

E. Gambino, M. Toscanesi, F. Del Prete et al.

Fuel Cells • 2017

Abstract The influence of microelectrogenesis on PAHs degradation and detoxification operated by Pseudomonadaceae, Bacillaceae, Staphylococcaceae and Enterobacteriaceae was investigated in water environment. Single chamber, air‐cathode MFCs and bioreactors were filled with the microbial pool (10 7 –10 8 CFU mL −1 ) inoculated in a 400 mL Winogradsky saline solution containing no other carbon and energy source than naphthalene (80 ppm), phenanthrene (40 ppm), pyrene (40 ppm), benzo(a)pyrene (20 ppm). MFCs and bioreactors operated at 25 °C for thirteen weeks. Power Density (PD) and Current Density (CD) outputs as well as PAHs degradation rate were measured. The toxic effect of PAHs suspension vs. Raphidocelis subcapitata was quantified by EC 1 , EC 20 , EC 50 , LOEC and NOEC calculations. The results showed a significant variability in PD and CD outputs, with highest PD of 300 mW m −3 and 25 mA m −3 . After 5 weeks, the overall PAHs concentration in MFCs decreased of a 90%. COD and TOC removal respectively of 62% and 73% after 11 weeks was achieved in MFC inoculated with bacteria (MFC 2 ). Ecotoxicological tests showed for MFCs a lower toxic effect vs. P. subcapitata when bacteria are present. Microelectrogenesis just sped up microbial metabolism rather than take advantage from the interaction of PAHs with graphite electrodes.

Khalid Zouhri, Reza S. Yassar

ASME 2014 12th International Conference on Fuel Cell Science, Engineering and Technology • 2014

The molten carbonate fuel cell (MCFC) is considered one of the best technologies for stationary power. This is due to its high efficiency, medium–high operating temperature, and low emissions. The MCFC operates at a temperature range from 600oC to 700oC and normally is combined with the gas turbine (GT) as a topping cycle. This work investigates the impact of Platinum/Graphene (Pt/G) on a combined cycle of MCFC-GT by applying the first and second laws of thermodynamics. The maximum work output of the hybrid cycle is ultimately calculated to be 1350 kW. The overall exergy efficiency achieved is 59.82%. Our findings reveal that there is an average 23% gain in the maximum work output, energy and exergy efficiencies when Pt/G is used as the cathode material compared to other materials such as Platinum/Carbon (Pt/C) and Platinum/Carbon cloth (Pt/CC).

Liang Liu, Wen Yi Zhang

Applied Mechanics and Materials • 2013

In this study we investigated the use of a microbial fuel cell (MFC) to abioticlly cathodic decolorization of a model azo dye, Methyl Orange (MO). Experimental results showed that electricity could be continuously generated the MO-fed MFC and MO was successfully decolorized in the cathode. The decolorization rate was highly dependent on the catholyte pH. When pH was varied from 3.0 to 9.0, the k value in relation to MO degradation decreased from 0.298 to 0.016 μmol min -1 , and the maximum power density decreased from 34.77 to 1.51 mW m -2 . Sulfanilic acid and N,N-dimethyl-p-phenylenediamine were identified as the decolorization products of MO by HPLC-MS.

José Luz Silveira, Antonio Carlos Caetano de Souza, Márcio Evaristo da Silva

Journal of Fuel Cell Science and Technology • 2008

Fuel cell as molten carbonate fuel cell (MCFC) operates at high temperatures. Thus, cogeneration processes may be performed, generating heat for its own process or for other purposes of steam generation in the industry. The use of ethanol is one of the best options because this is a renewable and less environmentally offensive fuel, and is cheaper than oil-derived hydrocarbons, as in the case of Brazil. In that country, because of technical, environmental, and economic advantages, the use of ethanol by steam reforming process has been the most investigated process. The objective of this study is to show a thermodynamic analysis of steam reforming of ethanol, to determine the best thermodynamic conditions where the highest volumes of products are produced, making possible a higher production of energy, that is, a more efficient use of resources. To attain this objective, mass and energy balances were performed. Equilibrium constants and advance degrees were calculated to get the best thermodynamic conditions to attain higher reforming efficiency and, hence, higher electric efficiency, using the Nernst equation. The advance degree (according to Castellan 1986, Fundamentos da Fisica/Quimica, Editora LTC, Rio de Janeiro, p. 529, in Portuguese) is a coefficient that indicates the evolution of a reaction, achieving a maximum value when all the reactants’ content is used of reforming increases when the operation temperature also increases and when the operation pressure decreases. However, at atmospheric pressure (1atm), the advance degree tends to stabilize in temperatures above 700°C; that is, the volume of supplemental production of reforming products is very small with respect to high use of energy resources necessary. The use of unused ethanol is also suggested for heating of reactants before reforming. The results show the behavior of MCFC. The current density, at the same tension, is higher at 700°C than other studied temperatures such as 600 and 650°C. This fact occurs due to smaller use of hydrogen at lower temperatures that varies between 46.8% and 58.9% in temperatures between 600 and 700°C. The higher calculated current density is 280mA∕cm2. The power density increases when the volume of ethanol to be used also increases due to higher production of hydrogen. The highest produced powers at 190mA∕cm2 are 99.8, 109.8, and 113.7mW∕cm2 for 873, 923, and 973K, respectively. The thermodynamic efficiency has the objective to show the connection among operational conditions and energetic factors, which are some parameters that describe a process of internal steam reforming of ethanol.

Nathan Coutard, Ahmed Ghedjatti, Sandrine Lyonnard et al.

ECS Meeting Abstracts • 2020

Commercial proton exchange membrane fuel cells (PEMFCs) use platinum as the catalyst, a too scarce and precious metal for sustainable energy supply through PEMFCs. Pt-free catalysts are actively searched for, both at the cathode and at the anode. With huge advancements in current density, lower overpotential and higher stability in the past few years, molecular engineered bio-inspired catalysts hold promise for the next generation of PEMFC [1, 2]. Yet, their implementation in catalytic layers faces nanocomposite formulation issues [3]. Here, we use carbon nanotube immobilized DuBois nickel catalysts to exemplify how self-assembly at the mesoscale affects performances of H 2 oxidation anodes. Copied on the conserved functional features of the active site of hydrogenases, the nickel catalysts created by Dubois et al. [4] show impressive turn-over frequency with no over-potential for hydrogen oxidation in solution. Not only has the central part of the catalyst, but also its outer sphere has a strong influence on the catalytic capacity [5]. Modification of the outer sphere can be used to immobilize the catalyst on a conductive matrix [6-8], a requirement for further implementation in PEMFC [9]. However, long-term ion transport in PEMFC requires creating ion conductive paths in the electrode, a task usually fulfilled by the addition of an ionomer. Although it allowed us to assemble the first fully Pt-free PEMFC [3], the current density was very low when the anode contained ionomer. The electrode microstructure thus appears critical to the system performance, yet it was hardly studied. The figure includes a STEM picture of a carbon nanotube-ionomer mixture showing the thin film formed by the self-organized ionomer, and the schemes of the catalyst structure and of the ionomer structure. Here, we show that molecular engineering coupled with three-dimensional structuring of the carbon electrode plays a major role on the catalytic activity through enhancement of catalyst grafting and substrate/product diffusion inside the electrode. In particular, we compare the effect of Nafion ionomer addition on the performances of bioinspired catalytic layers produced via three distinct surface chemistries [6-9]. We use microscopy as well as small angle neutron scattering techniques to characterize the self-assembly of the ionomer [10] with the carbon nanotubes/catalyst composite. A strong correlation appears between current drop in the presence of ionomer, and absence of ionomer hydrophilic/hydrophobic nanostructure. We propose a model that describes how the surface charge of the functionalized nanotubes drives the structuration of the Nafion ionomer and impacts diffusion of protons and gas to and from catalytic centres. [1] N. Coutard, N. Kaeffer, V. Artero, Chem. Commun ., 2016, 52, 13728-13748. [2] F. Jaouen, D. Jones, N. Coutard, V. Artero, P. Strasser, A. Kucernak, Johnson Matthey Technology Review , 2018, 62, 231-255. [3] P.D. Tran, A. Morozan, S. Archambault, J. Heidkamp, P. Chenevier, H. Dau, M. Fontecave, A. Martinent, B. Jousselme, V. Artero, Chem. Sci., 2015, 6, 2050-2053. [4] M. Rakowski Dubois and D. L. Dubois, Acc. Chem. Res., 2009, 42, 1974–1982 [5] A. Dutta, J.A.S. Roberts, W.J. Shaw, Angew. Chem. Int . 2014, 53, 6487-6491 [6] A. Le Goff, V. Artero, B. Jousselme, P.D. Tran, N. Guillet, R. Metaye, A. Fihri, S. Palacin, M. Fontecave, Science , 2009, 326, 1384-1387. [7] P.D. Tran, A. Le Goff, J. Heidkamp, B. Jousselme, N. Guillet, S. Palacin, H. Dau, M. Fontecave, V. Artero, Angew. Chem. Int. Ed., 2011, 50, 1371-1374. [8] T.N. Huan, R.T. Jane, A. Benayad, L. Guetaz, P.D. Tran, V. Artero, Energy Environ. Sci., 2016, 9, 940-947. [9] S. Gentil, N. Lalaoui, A. Dutta, Y. Nedellec, S. Cosnier, W.J. Shaw, V. Artero, A. Le Goff, Angew. Chem. Int. Ed. , 2017, 56, 1845-1849 [10] L. Rubatat, G. Gebel, O. Diat, Macromolecules 2004, 37, 7772 Figure 1

Ahmet Erensoy, Nurettin Çek

Polymers • 2021

Microbial fuel cells (MFCs) have attracted attention by directly converting the bioelectrochemical energy possessed by the organic materials that make up the biomass into electrical energy. In this study, the relationship between the biofilm formed on the titanium-based anode electrode surface, and the chemical composition of the substrate, the energy source of MFC, was investigated. For this, MFCs were made by using poplar wood shavings rich in organic material as the substrate, titanium-based material as the anode electrode, and natural soil as bacterial habitat. Three types of MFCs containing 1%, 10%, and 20% poplar wood shavings by weight were made and named P1-MFC, P2-MFC, and P3-MFC, respectively. According to electrochemical analysis, P3-MFC provided the highest open circuit voltage with 490 mV value, and the highest power density with 5.11 mW/m2 value compared to other MFCs. According to optical microscopy examinations, there were Bacillus and Coccus species of bacteria in the soil structure, and these bacteria also existed around the fiber of poplar wood shavings in MFCs. Scanning electron microscopy (SEM), energy-dispersive spectrum (EDS), and Fourier transform infrared spectroscopy (FTIR) analysis showed that MFCs formed biofilm in the titanium-based anode, and the chemical composition of this biofilm with poplar tree was similar. As a result, due to the catalysis reactions of bacteria, the titanium-based anode electrode surface was coated with polymer biofilm released from poplar wood shavings.

Haiying Guo, Xie Shuixiang, Huang Chunfeng et al.

Research Square • 2022

Abstract Electricity-generating bacteria as biocatalysts for microbial fuel cells (MFCs), and their species and power generation performance determine the performance of the MFC for pollution control and power generation. For that purpose, an electricity-generating bacteria isolated from the oily sludge MFCs, and adjusted the adaptability of nitrogen-to-phosphorus ratio (3.67:1, 4.67:1, 5.67:1, and 6.67:1), temperature (5 ℃, 10 ℃, 15 ℃, 20 ℃, 25 ℃, 30 ℃, 35 ℃) and pH (pH = 6, 6.5, 7, 7.5, 8). The results of this study showed that electricity-generating bacteria was identified as Bacillus cereus , with a rod-shaped cell, about 0.5-1.0 µm in length. The optimal nitrogen-phosphorus ratio, temperature and pH of MFCs were 4.67:1, 25 ℃ and pH = 7, respectively, and its output voltage was up to 168.05 mV. The study of this functional bacteria will provide beneficial assistance for the improvement of oil removal and power generation performance of oily sludge MFCs.

Daniel J. Fenton, Jeffrey J. Gagliardo, Thomas A. Trabold

ASME 2014 12th International Conference on Fuel Cell Science, Engineering and Technology • 2014

To achieve optimal performance of proton exchange membrane (PEM) fuel cells, effective water management is crucial. Cells need to be fabricated to operate over wide ranges of current density and cell temperature. To investigate these design and operational conditions, the present experiment utilized neutron radiography for measurement of in-situ water volumes of operating PEM fuel cells under varying operating conditions. Fuel cell performance was found to be generally inversely correlated to liquid water volume in the active area. High water concentrations restrict narrow flow field channels, limiting the reactant flow, and causing the development of performance-reducing liquid water blockages (slugs). The analysis was performed both quantitatively and qualitatively to compare the overall liquid water volume within the cell to the flow field geometry. The neutron image analysis results revealed interesting trends related to water volume as a function of time. At temperatures greater than 25°C, the total liquid water volume at start-up in the active area was the lowest at 1.5 A/cm2. At 25°C, 0.1 A/cm2 performed with the least amount of liquid water accumulation. However, as the reaction progressed at temperatures above 25°C, there was a crossover point where 0.1 A/cm2 accumulated less water than 1.5 A/cm2. The higher the temperature, the longer the time required to reach this crossover point. Results from the current density analysis showed a minimization of water slugs at 1.5 A/cm2, while the temperature analysis showed unexpectedly that, independent of current density, the condition with lowest water volume was always 35°C.

M. H. Tsai, Y. Y. Yan, H. S. Chu et al.

2nd International Conference on Fuel Cell Science, Engineering and Technology • 2003

A 3kW PEMFC power generation system is developed by Energy and Resources Laboratories in 2002. This system integrates hydrogen storage, fuel reformer, power conversion, hot water tank as well as a 3kW PEMFC stack. The power generation efficiency at 30% and total energy efficiency with hot water recovery at 67% are designed. The stack is key component of this system, and its performance is tested and analyzed before it is integrated into the system. This paper presents its performance in I-V polarization curves with controlling parameters such as fuel cell operating temperature, air humidity, hydrogen humidity and stoichimetric ratio of air. Detailed discussions are given for the effect of each parameter on stack’s performance.

A. Andreičiks, I. Steiks, O. Krievs

Latvian Journal of Physics and Technical Sciences • 2013

Abstract In domestic applications the low DC output voltage of a hydrogen fuel cell used as the main power supply or a backup power source has to be matched to the level and frequency of the AC voltage of utility grid. The interfacing power converter system usually consists of a DC/DC converter and an inverter. In this work, a DC/DC step-up converter stage is designed for interfacing a 5kW proton exchange membrane (PEM) fuel cell. The losses of DC/DC conversion are estimated and, basing on the relevant analysis, the most appropriate configuration of converter modules is selected for a DC/DC converter stage of increased efficiency. The authors present the results of experimental analysis and simulation for the selected configuration of four double inductor step-up push-pull converter modules

Shengpeng Chen, Aina Tian, Chaoling Han

Processes • 2023

The commercial proton exchange membrane fuel cell (PEMFC) system needs to be equipped with the capacity to survive a harsh environment, including sub-freezing temperatures. The cold start of PEMFC brings about great technical challenges, mainly due to the ice blockage in the components, which seriously hinders the multi physical transmission process. A multiscale, two-dimensional model was established to explore the gas purging in PEMFC under different electrochemical reaction intensities. The results indicate that the optimal case is obtained by B3-1 with a power density of 0.796 W cm−2, and the power density increases first and then decreases, followed by stoichiometric flow ratio (ξ) changes. It is worth noting that the water mole fraction in the PEM is closely related to the water concentration gradient. However, the differences in the initial water distribution in porous media have little bearing on the condensed water in the gas channel, and the liquid water in the gas diffusion layer (GDL) is preferably carried away ahead of other porous parts. The results also show that the increase in the purge speed and temperature can remove the excess water on GDL and the catalytic layer in a short time. For a nitrogen-based purge, the operating condition in case B3-1 is shown as the best strategy based on the output performance and economic analysis during the shutdown and purge process.

Nurul Najwa Adam Malik, Mohammad Mirza Mohammad Faizal, Husnul Azan Tajarudin et al.

Journal of Physics: Conference Series • 2021

Abstract Electricity constitutes one of the basic energies of our everyday life and approximately 14 % of the global population does not have the access to electricity. An abundance of waste is generated daily wherein food waste constitutes 45 % of the composition. A mediator-less and membrane-less single-chambered microbial fuel cell (ML-MFC) has the potential to serve as a cost-effective solution for food waste treatment and electricity power generation at no additional cost for the substrate. Food waste from E-Idaman Sdn. Bhd. Kedah was utilised in this study to generate electrical energy while focusing on the effect of different yeast extract concentrations on the performance of the ML-MFC. Electrogenic bacterial (EB) culture employed in this study acted as a catalyst for the power generation and was isolated from a previous ML-MFC study. The proximate analysis of food waste observed carbon constituting the greatest composition at 30.02 %. From the conducted preliminary study which compared three different strains of EB to be introduced in the ML-MFC, Bacillus subtillis sp . exhibited the highest specific growth rate, μ , (0.117 g. L −1 /h) and shortest doubling time, Td , (5.93 h). One-factor-at-a-time (OFAT) method was utilised to evaluate the performance of the ML-MFC. 15 g/L yeast extract concentration obtained the greatest power density (628.05 × 10 6 mW/m 2 ), substrate degradation efficiency (12.3 %), COD removal (99 mg/L) and biomass (44.32 mg/L). This showcased that the addition of extra yeast extract concentration into the food waste had boosted the efficiency of EB’s growth resulting in greater consumption of carbon source (removed COD value; bioremediation) in the food waste.

Y. Reyes-Vidal, J. López-Maldonado, F. Castañeda et al.

International Journal of Chemical Reactor Engineering • 2018

Abstract A theoretical model that describe the effect of design and operational conditions on current density distribution in a bioelectrochemical reactor used as microbial electrolysis cell (MEC) is described in this study. This model is proposed considering an approach where a direct electron transfer mechanism from the biofilm to the electrode surface takes place (mechanism present in most of microbial systems) and is governed by a dual donor-acceptor Nernst-Monod bioelectrochemical kinetic expression. The bioelectrochemical reactor is modelled considering two flow electrochemical reactor designs (a reactor design based in literature reports and a modified system proposed by the authors) operating at different flow inlet velocities and electrical overpotentials. Results obtained from the numerical solution shows that flow distribution is an essential aspect that impact the reactor performance, since concentration profiles and electrical potential-current distributions are strongly dependent on flow regime. Modified inlet configuration displays a more homogeneous fluid distribution and this behavior directly affects the mass transport and current density performance, as a result higher current density values are obtained for such configuration. Finally, it is expected that the information obtained from the analysis carried out in this report will provide us with a theoretical basis to realize the construction of a bioelectrochemical reactor prototype to develop the MEC concept.

Y Z Jin, Y C Wu, B Q Li et al.

IOP Conference Series: Earth and Environmental Science • 2019

Abstract We use anhydrous sodium acetate, glucose, lactose and Colocasia antiquorum Schott as anode substrate to study the periodic curve of battery voltage and stable output voltage of different substrates, The results showed that the four kinds of microbial fuel cells with sodium acetate, glucose, lactose and pretreated Colocasia antiquorum Schott as anode substrate had the following power generation periods: 23.98 d, 20.15 d, 18.84 d and 23.52 d, respectively, and the stable voltage at the two ends of the resistance of microbial fuel cells with four different anode substrates are 0.77 V, 0.75 V, 0.65 V and 0.70 V respectively. We found at the same carbon source concentration, MFC with sodium acetate as the substrate has the best electricity production characteristics. When the pretreated Colocasia antiquorum Schott is used as anode substrate, the time for cell voltage to rise from initial value to stable value is the shortest, and as a carbon source, it can also play a dominant role in the process of electric energy collection and utilization.

Yucui Shi, Gang Tang, Shaohong You et al.

Applied Sciences • 2023

Cr (VI) is hazardous to humans and our environment. Leersia hexandra Swartz (L. hexandra) is the first wet chromium hyperaccumulator found in China. This study constructed the L. hexandra constructed wetland-microbial fuel cell (CW-MFC) system to treat Cr (VI) wastewater. It also determined the effects of different dissolved oxygen (DO) concentrations on power generation, pollutant removal, and Cr (VI) reduction. Cathode aeration promoted the voltage output and pollutant removal of the L. hexandra CW-MFC when the DO concentration was 4.5 mg·L−1: the highest voltage was 520 mV, the chemical oxygen demand (COD) removal rate was 93.73%, and the Cr (VI) removal rate was 97.77%. Moreover, the increase in the DO concentration improved the absorption of heavy metal Cr by the substrate and L. hexandra, and promoted the transformation from Cr (VI) to Cr (III). Chromium mostly exists as a residue with low toxicity and low mobility in L. hexandra and the substrate. This proves that the increased DO concentration promotes the redox reaction in the system and plants, reducing Cr (VI) to Cr (III). At the same time, the key micro-organism Geobacter that enhances the performance of the system and Cr (VI) reduction was found. The research results can provide a reference for the subsequent CW-MFC treatment of actual Cr-containing wastewater.

Samsudeen Naina Mohamed, Radhakrishnan Thota Karunakaran, Matheswaran Manickam

Environmental Progress & Sustainable Energy • 2017

Distillery wastewater is an important potential sources for electricity generation using Microbial Fuel Cell (MFC) because of it has high content of organic waste and can be easily degraded. This study investigated the effect of feed pH and buffering conditions on electricity production and treatment efficiency using distillery wastewater as a substrate in MFC. The anodic chamber was operated with diluted distillery wastewater (4000 ± 20 mg COD/L) at various pH between 5.4 and 10 while the cathode chamber was maintained at pH 7.5. The MFC peak power density of 168 mW/m 2 (580 mA/m 2 ) with COD, color and TDS removal efficiency of 68.2, 26.4, and 15.4%, respectively was achieved at pH 8. Cyclic voltammetry revealed that an exoelectrogenic activity of microorganism was significantly influenced with respect to pH. The effect of buffering salts in the anolyte on MFC performance was also investigated. When the system operating with borate buffer, highest power density of 194.7 mW/m 2 (624 mA/m 2 ) at 100 Ω was achieved. The result indicated that alkaline condition (pH 8) and borate buffer was favored for obtaining maximum power generation and treatment efficiency from distillery wastewater in the MFC. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 663–668, 2018

Areli Ortega-Martínez, Katy Juárez-López, Omar Solorza-Feria et al.

Journal of New Materials for Electrochemical Systems • 2012

The aim of this work was to design and characterize a novel, multiface parallelepiped MFC in the perspective of decreasing the internal resistance (Rint) and increasing the volumetric power (Pv) output. The cell was fitted with a ‘sandwich’ cathode-membrane-anode assemblage in five of its faces, and possessed a ratio electrode surface area-to-volume ξ (csi) of 19 m-1 .
 When the 5 faces of the MFC-P were connected in series, the Rint was 601 Ω with a voltage of 0.52 V. Characterization of the cell with the 5 faces connected in parallel gave a Rint of 62 Ω with a voltage of 0.5 V that corresponded to external resistance of 56 k Ω in the polarization procedure. This result was ascribed to both the changes in cell architecture and decrease of the inter-electrode distance as well as the parallel connection. The Pv of the new MFC-P achieved values of 62 and 570 mW/m3 for series and parallel connection, respectively.
 Molecular ecological techniques were used to analyze the bacterial diversity of biocatalyst used in new design MFC-P. They showed a low species richness and low-to-moderate evenness. The community consisted primarily of δ-Proteobacteria and Firmicutes, bacteria that are recognized to be capable of exocellular electron transfer.

Jonathan Winfield, Paolo Milani, John Greenman et al.

ECS Meeting Abstracts • 2018

The versatility of Microbial fuel cells (MFCs) has meant that the technology can now branch towards a growing variety of applications. One of the big challenges however, has not been the microbial community but the identification of materials that allow the organisms to thrive and ultimately produce power. Paper has recently been adopted as a viable material that functions both structurally and as the medium for proton exchange. To date; the most reported use for paper-based MFCs has been as a diagnostics tool, however it is highly desirable to develop paper MFCs as lightweight, portable power supplies. In a diagnostic role, the paper MFCs reported have been low-power and short-lived (lasting just minutes) which is not suitable if the role were as power supply. There have been reports of longer-term electrical outputs using paper-based MFCs (with air-cathodes) such as origami stacks 1 and 3D-tetrahedron MFCs 2 . However, in both cases the method for feeding was via careful liquid injection. This is all very well in a lab-based environment but in a real-world scenario MFCs might need activating quickly and without delicate feeding requirements. Here it would be advantageous to simply distribute onto pools of liquid and have them passively intake the fuel. The goal of the current study therefore was to look at paper-based MFCs and investigate whether they might be able to passively intake nutrients from the surrounding environment. Two MFC designs were looked at; the first being flat 2D-MFCs with the anode on the underside of the paper, directly in contact with the liquid and the cathode on top, open to air. The second design was 3D-tetrahedron MFCs constructed from standard copier paper but with an absorbent cellulose material incorporated into the base. For all MFCs, air-cathodes were used without platinum or ferricyanide. For the 2D-flat MFCs, two methodologies were tested; the first was to print electrodes on either side of the paper and the second were hand-made, three-layered structures with conductive latex cathodes painted on one side and a sheet of carbon fibre adhered to the other. Each MFC was approximately 2cm x 4cm. In all experiments, there was no inoculation prior to the MFC being placed on puddles of enriched wastewater. The MFCs with printed electrodes reached peak OCV of 300mV which quickly dropped. In closed circuit the current peaked at 2.4 µA before rapidly declining which is clearly unsuitable for real-world use. The reason for the poor performance was the dissolution of the electrode as the liquid displaced the conductive elements as verified by the significant increase in resistance after use. Further work with printed MFCs will investigate incorporating a stabilising material to prevent the electrodes dissolving. The flat hand-made MFCs fared much better. Interestingly the conductive-latex cathodes were more resistive than the printed ones yet the MFCs were superior and more stable over time. These MFCs climbed and stabilised for 4 days at 11 µW (185mV). Different types of paper were trialled including baking, greaseproof and copier and all performed comparably. Further work will investigate stacking multiple flat-MFCs on single sheets of paper. The simple flat-MFCs are promising but for MFCs operating outside and tapping into nutrients in puddles they should ideally have enclosed chambers housing the anode. To trial this, 3D-tetrahedron MFCs with 15mL volume were set up to sit on pools of liquid with the only method of feeding via capillary motion of the absorbent base. The 3D-MFCs with absorbent bases were compared to MFCs with a waterproof coating over their base. Those with the absorbent bottoms immediately generated a current and continued increasing in power for over 2 weeks peaking and stabilising at 40µW (2.7 W/m 3 ). In addition, when fresh nutrient was added to the reservoir (not directly to the MFCs), they responded almost immediately, a factor that could be advantageous if the role were biosensor. The MFCs with plastic coated bases showed no working voltage throughout the period. The output generated by the MFCs relying on a passive feeding mechanism is comparable to that produced by the same MFCs with sealed bases from a previous study (where injection feeding took place 2 ). This output is sufficient to initiate a power management system and broadcast radio signals. These findings are an exciting development because lightweight paper-MFCs could potentially be dropped onto puddles of organic liquid, passively sucking up nutrients from the environment and subsequently broadcasting distress signals. References 1 Fraiwan et al., (2016) Biosens Bioelectron 85: 190-197 2 Winfield et al., (2015) J Mater Chem A 13: 7058-7065

Hodaka Shimohata, Dang Nguyen, Kozo Taguchi

Resourceedings • 2023

Bamboo is a fast-growing plant in Southeast Asia, Africa, and Latin America. Due to its rapid growth, bamboo is considered a problem because it rapidly invades forested areas and alters the original ecosystem. On the other hand, it is regarded as a material that is readily available and very accessible in many countries and has great potential for both ecological and social purposes. Therefore, bamboo was employed as the material for the electrodes of microbial fuel cells in this study. Typically, biochar used for electrodes is chemically activated to remove impurities and increase its surface area. However, chemical treatment of biochar can have a negative impact on the activity of microorganisms. The Bamboo charcoal powder, prepared by heat-treating powdered bamboo for one hour under air at 500°C, contained about 75% carbon and had a porous structure. Therefore, the material could be used as an electrode material for microbial fuel cells without complicated and time-consuming treatment processes. Some of these treatment processes include chemical treatment, and chemically treated biochar may impact the environment. Bamboo charcoal, which does not require this chemical treatment process, is effective as an electrode material for microbial fuel cells. Bokuju, a common kind of drawing ink in Japan and mainly composed of carbon black, was used as a binder for the prepared bamboo charcoal. The reason for using powdered bamboo charcoal with Bokuju is that it is easier to obtain a solid electrode shape by a drying process. We used this electrode in a floating microbial fuel cell and optimized the ratio of Bamboo charcoal powder and Bokuju in the electrode. By evaluating the performance of the microbial fuel cell using the Bamboo charcoal Bokuju electrode, we were able to improve the effectiveness of the electrode material.

Seyed M Ghoreyshi, Meinhard T Schobeiri

Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy • 2020

In the Ultra-High Efficiency Gas Turbine Engine, UHEGT (introduced in our previous studies) the combustion process is no longer contained in isolation between the compressor and turbine, rather distributed within the axial gaps before each stator row. This technology substantially increases the thermal efficiency of the engine cycle to above 45%, increases power output, and reduces turbine inlet temperature. Since the combustion process is brought into the turbine stages in UHEGT, the stator blades are exposed to high-temperature gases and can be overheated. To address this issue and reduce the temperature on the stator blade surface, two different approaches are investigated in this paper. The first is indexing (clocking) of the fuel injectors (cylindrical tubes extended from hub to shroud), in which the positions of the injectors are adjusted relative to each other and the stator blades. The second is film cooling, in which cooling holes are placed on the blade surface to bring down the temperature via coolant injection. Four configurations are designed and studied via computational fluid dynamics (CFD) to evaluate the effectiveness of the two approaches. Stator blade surface temperature (as the main objective function) along with other performance parameters such as temperature non-uniformity at rotor inlet, total pressure loss over the injectors, and total power production by rotor are evaluated for all configurations. The results show that indexing presents the most promising approach in reducing the stator blade surface temperature while producing the least amount of total pressure loss.

Sofia Babanova, Jason Jones, Sujal Phadke et al.

Water Environment Research • 2019

Abstract Microbial fuel cells (MFCs) have long held the promise of being a cost‐effective technology for the energy‐neutral treatment of wastewater. However, successful pilot‐scale demonstrations for this technology are still limited to very few. Here, we present a large‐scale MFC system, composed of 12 MFCs with a total volume of 110 L, successfully treating swine wastewater at a small educational farm. The system was operated for over 200 days in continuous mode with hydraulic residence time of 4 hr. Very stable electrochemical and waste treatment performance was observed with up to 65% of chemical oxygen demand (COD) removed and a maximum treatment rate of 5.0 kg COD/m 3 .day. Robust microbial enrichment was performed and adapted to metabolize and transform a diversity of compounds present. The Net Energy Recovery (NER = 0.11 kWhr/kg COD) is not only competitive with conventional cogeneration processes, but is in fact sufficient to sustain the operational energy requirements of the system. Practitioner points This study demonstrates the design and operation of a large‐scale microbial fuel cells (MFC) system for continuous treatment of swine wastewater. The system achieved a high chemical oxygen demand removal rate within a short hydraulic residence time. This study moves one‐step closer to applying MFC technology for real wastewater treatment.

Yucui Shi, Gang Tang, Shaohong You et al.

Frontiers in Environmental Science • 2022

Cr(VI) is toxic to the human body and environment. As a suitable wastewater treatment with low energy requirement technology, constructed wetland-microbial fuel cells (CW-MFCs) can treat Cr(VI) wastewater while generating electricity. In this study, CW-MFC and constructed wetland systems were developed to purify Cr(VI) wastewater. The removal mechanism of Cr(VI) was examined by electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy. The results demonstrated that the average pollutant removal efficiency of the CW-MFC system is 2.99–8.13% higher than that of the constructed wetland system, and the maximum power density is 505.61 mW m −2 . Moreover, the XPS and EPR analyses demonstrated that Cr in substrates and Leersia hexandra Swartz primarily is in the form of Cr(III). Moreover, in plants and substrates, the Cr(III) content of the CW-MFC system was higher than that of the control, and the bioconcentration and translocation factors were 0.23 and 0.05 higher than those in the control group, respectively. Therefore, the CW-MFC system can efficiently remove Cr(VI) and promote the accumulation and transport of Cr. Microbial community diversity in the CW-MFC was significantly higher than CW. The abundance of electrogenic bacteria Geobacter and metal dissimilatory reducing bacteria Acinetobacter in CW-MFC is higher than that in CW. To summarize, the study results provide a theoretical basis for the mechanism study of Cr(VI) wastewater treatment using CW-MFC systems.

Kieu Thi Quynh Hoa, Phung Minh Hieu, Vy Tuan Anh et al.

Vietnam Journal of Biotechnology • 2022

Sulfate/sulfide-containing wastewater is a widespread environmental contaminant resulting from human activities. These pollutants have negative impact on natural ecosystems and human beings. Biological sulfate/sulfide removal can be achieved by reducing sulfate to sulfide with sulfate-reducing bacteria and then oxidizing sulfide to elemental sulfur (So) with sulfide oxidizing bacteria. In sulfate/sulfide contaminant wastewater lacking electron acceptor for sulfide oxidization, excess sulfide will be produced and accumulated in the treatment system. Therefore, microbial fuel cells (MFCs) have been shown to be a promising technique for the removal of sulfate/sulfide pollutants in wastewater. In this study, a lab-scale MFCs has been developed based on the activity of sulfate-reducing bacterium Desulfovibrio. sp. The results showed that sulfate and sulfide removal efficiencies of 74 - 82% (78 ± 2,5%) and 80.8 - 89.1% (~85,6 ± 3,1%) were achieved, respectively, from the 5th day to the 14th day of operation. The voltage of 0.02V and power density of 7.2 to 7.8 mW/m2 was obtained. In this study, sulfide oxidizing-based MFC integrated with sulfate-reducing bioreactor, representing the feasibility of simultaneous sulfate/sulfide pollutants removal and electricity generation in MFCs. This provides a promising treatment system to scale up for its actual applications in sulfate/sulfide removal.

Banu Taşkan, Ergin Taşkan, Halil Hasar

Environmental Progress & Sustainable Energy • 2020

Abstract The aim of this study is to increase the electricity generation capacity of sediment microbial fuel cell (SMFC) using sewage sludge as a substrate source in anode media via an attractive electrode material. For this purpose, several electrochemical and molecular techniques have been employed to evaluate the performance of SMFC. The max power density and charge transfer resistance of SMFC running on sewage sludge were 187 mW/m 2 and 84.7 Ω, respectively. The polymerase chain reaction‐denaturing gradient gel electrophoresis (PCR‐DGGE) analysis indicated that bacteria in anode biofilm belonged to the Clostridia , d‐proteobacteria , g‐proteobacteria , and b‐proteobacteria . Scanning electron microscopy and fluorescence in situ hybridization observations demonstrated that a viable biofilm was formed on the anode surface and the abundance of bacteria was significantly higher than archaea. Consequently, this study showed that sewage sludge could be used as a substrate in the anode media of SMFC for producing high power density.

D Chatzikonstantinou, A Tremouli, K Papadopoulou et al.

Waste Management & Research: The Journal for a Sustainable Circular Economy • 2018

In this study, the use of a dual-chamber microbial fuel cell for the production of bioelectricity from a food residue biomass (FORBI) product was investigated. Food residue biomass was produced by drying and shredding the pre-sorted fermentable fraction of household food waste collected door-to-door in the Municipality of Halandri, Athens, Greece. Different organic loads of food residue biomass expressed as chemical oxygen demand (COD) were examined (0.7, 0.9, 1.4, 2.8, 6 and 14 g COD L −1 , respectively). It was observed that an increase of the initial concentration of the final extract resulted in a corresponding increase in the operating time. The microbial fuel cell potential increased from 33.3 mV to 46 mV as the concentration was increased from 0.7 to 14 g COD L −1 . The best performance in terms of maximum power density (29.6 mW m −2 ) corresponding to a current density of 88 mA m −2 was observed for 6 g COD L −1 . Setting the external resistance at its optimal value (R ext = 2 kΩ) as determined by polarisation experiments, P yield drastically increased to 13.7 and 17.3 Joule (g FORBI) −1 in two consecutive cycles. The results demonstrate that readily biodegradable substrates, such as food residue biomass, can be effectively used for enhanced bioelectricity harvesting in a microbial fuel cell.

Anna Salvian, Daniel Farkas, Marina Ramirez-Moreno et al.

npj Clean Water • 2024

Abstract Efficient wastewater treatment monitoring is vital for addressing water scarcity. Microbial fuel cells (MFCs) have emerged as real-time biosensors for biochemical oxygen demand (BOD) in urban wastewater. Discrepancies in signal generation may arise due to changes in the composition and metabolism of mixed-culture electroactive biofilms stemming from different wastewater compositions. In this study, 3D-printed MFC-based biosensors were employed to assess the BOD of sterile complex artificial wastewater and untreated urban wastewater. Alterations in the microbial composition of the anode were evaluated using 16S rRNA sequencing and metagenomics analysis. Results show that MFC-based biosensors can be effectively recalibrated for diverse types of wastewater, maintaining consistent sensitivity (0.64 ± 0.10 mA L mg −1 m −2 with synthetic wastewater and 0.78 ± 0.13 mA L mg −1 m −2 with urban wastewater) and limit of detection (49 ± 8 mg L −1 for synthetic wastewater and 44 ± 7 mg L −1 for urban wastewater). Crucially, pre-sterilization, conductivity adjustments, and nitrogen purging of wastewater are not required before its introduction into the biosensor. However, the presence of native aerobic microorganisms in the wastewater might affect the current output. Metagenomics and taxonomic analyses revealed that the alterations in biofilm composition are predominantly in response to the varied chemical and microbiological compositions of different substrates. Despite variations in anodic biofilm composition, the MFC-based biosensor maintains a relative error comparable to the standard BOD test. This highlights the resilience and flexibility of the biosensor when directly used with a variety of wastewater types before full biofilm adjustment.

Henan Li, Guohong Liu, Chao Li et al.

Research Square • 2021

Abstract Six 60-L benthic microbial electrochemical systems (BMES) were built for the bioremediation of river sediment. Carbon mesh anodes with honeycomb-structure supports were compared with horizontal anodes, and the system was tested using different cover depths and anode densities. The pollutant removal, electricity generation, and electrochemistry of the six BMES with different anodes was examined using the Ashi River (Harbin, China) as a case study. Total organic carbon (TOC) and total nitrogen (TN) removal from sediments in BMES with three-dimensional anodes were 20%~30% and 20%~33% higher for the other reactors. Moreover, the honeycomb-structure of the anode also resulted in higher power density and improved humus removal.

Segundo Rojas Flores, Orlando Pérez-Delgado, Nazario Naveda-Renny et al.

Environmental Research, Engineering and Management • 2022

The large amount of molasses that are generated in sugar-processing companies are not always redistributed for commercialization in by-products. Because of this, the present research uses these wastes as fuel in low-cost, lab-scale, single-chamber microbial fuel cells. Zinc and copper electrodes were used as electrodes and 100 mL of molasse in the chamber as fuel, managing to generate current and voltage peaks of 1.73 ± 0.13 mA and 0.953 ± 0.142 V. In monitoring the conductivity of the substrate, a maximum peak of 111.156 ± 8.45 mS/cm was observed, and a slightly acidic pH was observed throughout the monitoring. It was possible to obtain a power density of 5.45 ± 0.31 W/cm2 for a current density of 308.06 mA/cm2, while the yeast count showed a logarithmic curve throughout the monitoring. Finally, the molecular technique identified 100% of the special C. boidinii present in the anodic electrode. This research will give great benefits to sugar companies because they will be able to generate electricity using the molasses that cannot generate by-products.

I. Khazaee, M. Mohammadiun

International Journal of Applied Mechanics and Engineering • 2013

A complete three-dimensional and single phase model for proton exchange membrane (PEM) fuel cells was used to investigate the effect of using different channels geometry on the performances, current density and gas concentration. The proposed model was a full cell model, which includes all the parts of the PEM fuel cell, flow channels, gas diffusion electrodes, catalyst layers and the membrane. Coupled transport and electrochemical kinetics equations were solved in a single domain; therefore no interfacial boundary condition was required at the internal boundaries between cell components. This computational fluid dynamics code was employed as the direct problem solver, which was used to simulate the three-dimensional mass, momentum, energy and species transport phenomena as well as the electron- and proton-transfer process taking place in a PEMFC. The results showed that the predicted polarization curves by using this model were in good agreement with the experimental results and a high performance was observed by using circle geometry for the channels of anode and cathode sides. Also, the results showed that the performance of the fuel cell improved when a rectangular channel was used.

Tukendra Kumar, Satya Eswari Jujjavarapu

Journal of Chemical Technology & Biotechnology • 2023

Abstract BACKGROUND The experimental process for optimizing microbial fuel cell (MFC) design under different electrode geometries is restricted. An MFC can be defined as a bio‐electrochemical system (BES) that facilitates the direct conversion of the chemical energy stored in organic matter into electrical energy by harnessing the metabolic activity of microorganisms. Computational fluid dynamics (CFD) tools allow the simulation and evaluation of electro‐analysis phenomena such as cyclic voltammetry and chemical reactions, which can help the optimization of the BESs. In this study, MFC is designed to provide the maximum peak current and efficiency for the applied voltage on various working (or anode) electrode geometries (i.e. hexagonal, square, pentagonal, circular, triangular, rectangular, and rhombus). RESULTS The CFD simulation results demonstrate that a configuration with a larger perimeter value and surface area (i.e. hexagonal design) of the working electrode shows a higher peak current (2422.75 mA) than other configurations. The experimental findings supported the simulation result and reveal that a hexagonal electrode containing a MFC setup produces a maximum power density of 22.41 ± 0.32 mW m −3 and a current density of 41.58 ± 0.35 mA m −2 . The MFC operation demonstrated adequate bioelectricity generation of 540 ± 03 mV on Day 4 of operation at 1000 Ω. Additionally, maximum reduction in chemical oxygen demand (76.13 ± 0.5%) and coulombic efficiency (76.03 ± 0.4%) was achieved for synthetic wastewater using a hexagonal MFC. CONCLUSION Based on these fundamental discoveries, the CFD simulation and its experimental validation considerably drag focus toward the possibility of employing COMSOL Multiphysics software for system improvement of different MFC system applications. © 2023 Society of Chemical Industry (SCI).