Jermaine Chambers, Kaia Gomez, Williamson Gustave

Qeios • 2024

In recent years microbial fuel cells have been studied for their biosensing properties. Consequently, sediment microbial fuel cells (sMFCs) have been found to be able to detect minor oil spills in freshwater. However, it was previously unknown whether sMFC properties as a biosensor would be able to produce the same results in a saltwater environment. Therefore, sMFCs at various external resistances (220 Ω, 300 Ω, 430 Ω, 510 Ω, 1000 Ω and 2000 Ω) were assembled to assess their ability to detect oil in seawater. The results indicated that as oil was added to the cathode of the microbial fuel cells, there was a clear and gradual decrease in the voltage output due to the oil’s interference with oxygen dissolvability in seawater; However, the relationship between the change in voltage and change in time was less linear than the change observed in previous studies, and inconsistent across the different voltages. The variation observed may be due to the absence of a catalyst, such as platinum, which would have sped up the rate of the decrease in voltage. This study illustrates that sediment microbial fuel cells provide a cost effective and environmentally friendly method to detect minor oil spills in seawater.

Amira Suriaty Yaakop, Akil Ahmad, Fida Hussain et al.

International Journal of Chemical Engineering • 2023

Microbial fuel cell (MFC) is a method that is both effective and environmentally friendly for producing renewable electricity. Several studies have shown that one of the major challenges is the generation of electrons as a result of poor exploitation of organic substrates. One of the most talked about issues in modern molecular fusion is the reutilization of biological organic waste in an MFC. In this article, the effective utilization of domestic organic waste as an organic supply for bacterial species to generate energy was highlighted. The findings that were obtained corresponded to the one-of-a-kind MFC operation in which a voltage of 110 mV was generated in a time span of 12 days during operation with an external resistance of 500 ῼ. With an internal resistance of 117 ῼ, the maximum power density and the current density were recorded 0.1047 mW/m2 and 21.84 mA/m2, respectively. According to the results of the biological study, strains of bacteria such as Pseudomonas aeruginosa, Acinetobacter schindleri, and Pseudomonas nitroreducens are the ones responsible for producing energy. In addition, final remarks with proposals for the future have been enclosed.

G. Lota, E. Frackowiak

Fuel Cells • 2010

Abstract We report on the pseudo‐capacitance induced by a nitrogen substituted in the carbon network composite prepared by a simple carbonisation (750 °C) of formaldehyde and melamine in the presence of carbon nanotubes. Nitrogen content in the composites varied from 7.4 to 21.7 wt.%. Such materials have a higher density than activated carbons, hence, they can supply better volumetric capacity. N‐rich composites show an excellent charge propagation at current loads from 500 mA g –1 to 50 A g –1 because of multiwalled nanotubes which play a conducting as well as a supporting role. The electrochemical performance of various composites was investigated in two‐ and three‐electrode cells using acidic (1 mol L –1 H 2 SO 4 ), alkaline (6 mol L –1 KOH), neutral (1 mol L –1 Na 2 SO 4 ) and organic electrolytes (1 mol L –1 TEABF 4 in acetonitrile). Organic and neutral medium is not adapted for N‐rich carbon electrodes of supercapacitor. The detailed electrochemical characterisation pointed out the differences of charge propagation of electrodes with the different polarity.

Devesh D Shreeram, Warunya Panmanee, Cameron T McDaniel et al.

Journal of Industrial Microbiology and Biotechnology • 2018

Abstract Pseudomonas aeruginosa is a metabolically voracious bacterium that is easily manipulated genetically. We have previously shown that the organism is also highly electrogenic in microbial fuel cells (MFCs). Polarization studies were performed in MFCs with wild-type strain PAO1 and three mutant strains (pilT, bdlA and pilT bdlA). The pilT mutant was hyperpiliated, while the bdlA mutant was suppressed in biofilm dispersion chemotaxis. The double pilT bdlA mutant was expected to have properties of both mutations. Polarization data indicate that the pilT mutant showed 5.0- and 3.2-fold increases in peak power compared to the wild type and the pilT bdlA mutant, respectively. The performance of the bdlA mutant was surprisingly the lowest, while the pilT bdlA electrogenic performance fell between the pilT mutant and wild-type bacteria. Measurements of biofilm thickness and bacterial viability showed equal viability among the different strains. The thickness of the bdlA mutant, however, was twice that of wild-type strain PAO1. This observation implicates the presence of dead or dormant bacteria in the bdlA mutant MFCs, which increases biofilm internal resistance as confirmed by electrochemical measurements.

K. Sathish Kumar, Omar Solorza-Feria, Rafael Hernández-Vera et al.

Journal of New Materials for Electrochemical Systems • 2012

A single-chamber microbial fuel cell (SCMFC) with a carbon supported Pt-cathode for the oxygen reduction reaction (ORR), and loaded with a sulfate reducing bacterial consortium as biocatalyst in the anodic chamber was characterized by polarization by variable resistance (VR) and linear sweep voltammetry (LSV) methods. From VR a whole cell configuration maximum volumetric power of 92.5 mW m-3 was attained at a current density of 459 A m-3 and voltage of 0.202 V. The LSV method of whole cell configuration gave a higher maximum power density of 197.5 mW m-3 at current density of 696 mA m-3 at the potential of 0.284V; this disagreement was ascribed to possible reduction of power and potential overshoot with the LSV. There was a fair agreement between internal resistance values of whole cell configuration determined by VR and electrochemical impedance spectroscopy (EIS): 2225 and 2307 Ω , respectively. Yet, internal resistance measured by LSV was 30% lower for the whole cell configuration. Both LSV and EIS show the advantage of reduced potential overshoot; yet, EIS provides more detailed information on equivalent circuit of the cell and resistance contributions of the electrodes, electrolyte and membrane. Further cyclic voltammetry tests gave midpoint potential of -0.215 V vs saturated calomel electrode, a value close to those reported for bacterial cytochromes involved in extracellular electron transfer processes. It is concluded that in spite of particular advantages of some techniques over others, the combination of electrochemical methods can be very valuable for shedding light and internal checking of the main characteristics of a microbial fuel cell.

Kam-Khong Chan, Wei-Eng Thung, Soon-An Ong et al.

IOP Conference Series: Earth and Environmental Science • 2020

Abstract Metal contaminated wastewater effluent from industries has caused several environmental problems and public health due to its toxicity. Conventional heavy metal reduction processes are neither economical nor environmentally friendly. A synergy economical single chamber up-flow membrane-less microbial fuel cell (UFML-MFC) was fabricated to study the feasibility of heavy metal reduction and voltage generation. Cu (II) was used as electron acceptor to explore the mechanism of metal treatment in UFML-MFC. The performances of the UFML-MFC were investigated with 0 mg/L, 5 mg/L and 10 mg/L concentration of Cu (II) in terms of voltage output, chemical oxygen demand (COD) reduction and Cu (II) reduction efficiency and electrode spacing distance. UFML-MFC used carbon felt as anode and cathode material where anode region was filled with 0.2 cm of gravels at anode region. Overall performance deteriorated with increased initial concentration of Cu (II). Voltage generation decreased from 71 mV to 11.1 mV. COD reduction decreased from 56% to 36%. Moreover, the Cu (II) reduction efficiency was reduced from 87.56% to 36.98%. These results showed that the increased concentration of the Cu (II) could potentially reduce the microbial activities. However, UFML-MFC showed that the shorter distance of electrode spacing (anode and cathode) could enhanced the voltage output. These results showed the great ability of integrating UFML-MFC for heavy metal reduction.

Md. Mostaqur Rahman

International Journal of Engineering Materials and Manufacture • 2021

A microbial fuel cell (MFC) is a device that converts bio-chemical energy into electrical energy during substrate oxidation with the aid of microorganisms (bacteria). The energy contained in waste water is converted to the electrical power by the action of bacteria. The principle of MFC is to transfer electrons from the microorganisms to electron acceptor at a higher electrochemical potential. An experimental study was performed to find the most efficient industrial waste water that can produce highest and stable electrical power by the MFC and to determine the removal rate of pollutant from the waste water by the MFC. Two MFC, namely one PEM MFC and two PEM FMC, has been fabricated for this study. The three different waste water samples used were Dyeing Waste Water-1 (DWW-1), Dairy Industry Waste Water (DIWW) and Dyeing Waste Water-2 (DWW-2). The highest rate of voltage generation is achieved when the MFC was operated with DWW-1 (1.06 V), DIWW (0.95 V) and DWW-2(0.644 V), respectively. Based on the graph pattern the DWW-1 provided the best record in terms of electrical energy generation.

Chih-Tang Sah, Fredrik A. Lindholm

Journal of Applied Physics • 1984

This paper analyzes the performance improvements obtainable from extending the traditionally thin back-surface-field (BSF) layer deep into the base of silicon solar cells under terrestrial solar illumination (AM1). This extended BSF cell is also known as the back-drift-field cell. About 100 silicon cells have been analyzed, each with a different emitter or base dopant impurity distribution whose selection was based on physically anticipated improvements. The four principal performance parameters (the open-circuit voltage, the short-circuit current, the fill factor, and the maximum efficiency) are computed using a program which numerically solves the six Shockley equations under AM1 solar illumination at 88.92 mW/cm2, at an optimum cell thickness of 50 μm. The results show that very significant performance improvements can be realized by extending the BSF layer thickness from 2 μm (18% efficiency) to 40 μm (20% efficiency). The immunity of cell performance to recombination defect or impurity center is also improved by a factor of 2 to 3 in the recombination center density. For 20% p+/n/n+ cells with about 20-μs base lifetime, a 20-μm BSF penetration is sufficient. At this or deeper penetrations, interband Auger recombination in the emitter layer becomes the limiting factor and affects mainly the short-circuit current but not the open-circuit voltage which has saturated to about 710 mV.

Raden Darmawan, Sri Rachmania Juliastuti, Nuniek Hendrianie et al.

AIMS Environmental Science • 2021

<abstract> <p>Carcinogenic hexavalent chromium is increasing worldwide due to the increased electroplating, welding and textile industry. On the other hand, molasses, the sugar factory's byproduct with high organic compounds (sugars), may pollute the environment if it is not processed. However, microbial fuel cell (MFC) seems to be a promising technology due to its ability to produce electrical energy from pollutant degradation using microbes while reducing hexavalent chromium to trivalent chromium with less toxicity. Carbon felt was used at both electrodes. This research aimed to determine the effect of modifying the anode with rice bran and cathode with Cu catalyst towards electricity generation and pollutant removal in molasses and reducing Cr (Ⅵ) into Cr (Ⅲ) using tubular microbial fuel cells. Moreover, the effect of mixing Sidoarjo mud and <italic>Shewanella oneidensis</italic> MR-1 as electricigen bacteria toward electrical energy production and pollutant removal was determined. Experiments revealed that the S/CM/AM variable, which only used <italic>Shewanella oneidensis</italic> MR-1 as an electricigen bacteria with both modified electrodes, produced the highest total power density of 530.42 mW/m<sup>2</sup> and the highest percentage of Cr (Ⅵ) reduction of 98.87%. In contrast, the highest microbial population of 66.5 × 10<sup>10</sup> cells/mL, 61.28% of Biological Oxygen Demand (BOD<sub>5</sub>) removal and 59.49% of Chemical Oxygen Demand (COD) were achieved by SSi/CM/AM variable, mixing <italic>Shewanella oneidensis</italic> MR-1 and Sidoarjo mud as an electricigen bacteria with both modified electrodes. Therefore, this study indicates that double chamber tubular microbial fuel cells may be a sustainable solution for managing molasses and carcinogen hexavalent chromium.</p> </abstract>

Triyanto Pangaribowo, Wahyu Mulyo Utomo, Abdul Hamid Budiman et al.

Journal of Robotics and Control (JRC) • 2024

Open cathode proton exchange membrane fuel cells (OC-PEMFC) are devices that produce electrical energy through an electrochemical reaction between hydrogen and oxygen gas. Rapid load changes often lead to fluctuations in the flow of hydrogen entering the OC-PEMFC system. Increased load directly correlates with higher hydrogen gas consumption. However, if there is a delay in adjusting the gas flow rate to changes in load, it can trigger fluctuations in the amplitude and frequency of the output voltage. This fluctuation ultimately disrupts the stability of the power supply to the load, and reducing efficiency. Therefore, this paper presents a novel hybrid system that integrates wavelet and clipping techniques to regulate a more stable hydrogen flow, enhancing efficiency and accuracy under constant load conditions. A wavelet control system is used to mitigate noise, coupled with amplitude limitation through clipping techniques. This control system is implemented in OC-PEMFC model that is validated with experimental data. The performance analysis of this hybrid system reveals a 1.95 % increase in efficiency and attains high accuracy, as evidenced by a low ISE value of 0.028 during interference.

Magdalena Dudek, Andrzej Raźniak, Jarosław Markowski et al.

E3S Web of Conferences • 2023

This article presents the results of experimental investigations on an advanced model of a polymer exchange membrane fuel cell (PEMFC) stack designed to serve as a charging unit for electric vehicle batteries or off-grid distributed power sources. The assembled 720 W PEMFC stack comprises two 360 W modules that can be electrically connected in series or parallel. A liquid cooling system for the PEMFC stack has also been constructed. The dependencies – voltage ( U ) versus current ( I ) and current ( I ) versus electrical power ( P ) – for single modules, as well as for the electrically connected two-module PEMFC stack, are determined. Additionally, the hydrogen utilization versus the electrical power ( P ) of the PEMFC stack is examined. The electrical efficiency of the PEMFC stack varies between 42% and 50%, depending on the electrical power. An adjustable DC/DC converter, operating in two modes (step-down or stepup), is proposed as a device to integrate a lithium-ion (Li-ion) battery pack with approximately 720 W PEMFC stack. The electrical architecture of the integrated system, comprising the PEMFC stack, DC/DC converter, and Li-ion battery pack, is investigated and discussed in this paper. It was found that the electrical efficiency of the proposed DC/DC converter varies depending on the electrical power, reaching a peak efficiency of 95%– 98%. The environmental benefit, in terms of reducing CO 2 emissions when charging the battery, was also identified.

Yuji Okuyama, Tomohiro Kuroha, Yamauchi Kosuke et al.

ECS Meeting Abstracts • 2020

Barium zirconate have high chemical stability with CO 2 comparison with barium cerate. Acceptor doped barium zirconate show high proton conductivity [1]. The proton conductivity of yttrium doped barium zirconate is 1×10 -2 Scm -1 at 600 ℃ and it is attracted as the electrolyte of fuel cell and water vapor electrolysis cell. The fuel cell using proton conducting oxide was called to PCFC (proton ceramic fuel cell) and work at the intermediate temperature. PCFC is expected to be the energy conversion device in future because of high efficiency [2] and low production cost [3]. Generally, nickel is used as anode of PCFC. The anode overpotential of nickel is lower than that of the other metals. However, the nickels dissolve to the proton conducting oxide and possibly increase the ohmic resistance of electrolyte. Moreover, the nickel and the electrolyte possibly form the blocking layer such as the complex oxide. Although the proton conductivity of yttrium doped barium zirconate is highest in the zirconate-type proton conductor, BaY 2 NiO 5 is formed between the nickel and the yttrium doped barium zirconate [4] and it might work as the blocking layer of proton. In this study, the reaction product between NiO and BaZr 0.8 M 0.2 O 3-δ ( M =Sc, In, Yb, Y, Gd) were confirmed by X-ray diffraction analysis. In order to clarify the NiO dissolution effect on the proton transport properties of BaZr 0.8 M 0.2 O 3-δ ( M =Sc, In, Lu, Yb, Y), the partial conductivity of the proton and the hole for BaZr 0.8 M 0.2 O 3-δ ( M =Sc, In, Lu, Yb, Y) with NiO were measured at temperature range of 200-600 ℃ by impedance analysis. The current efficiency on the polarization properties, then was examined for the fuel cell system using Acceptor-doped barium zirconate with NiO as electrolyte. Moreover, we investigated the effect of dopants on the ease of cell fabrication. The conventional ceramic tape-casting and firing process for fabricating laminated ceramic electronic devices was used, which is important for practical use. The power generation performance of planer cells fabricated by this process was also measured. The X-ray diffraction patterns of 0.4 mol% NiO doped BaZr 0.8 M 0.2 O 3-δ ( M = Sc, In, Yb, Y, Gd) were measured for the the samples as-sintered and annealed under 1%H 2 at 873K. The peak of the NiO or Ni phase except the barium zircanate phase was observed for 0.4 mol% NiO doped BaZr 0.8 M 0.2 O 3-δ ( M = Sc, In, Yb). On the other hand, the Ba M 2 NiO 5 phase was observed for M =Y, Gd. When the ionic radius of dopant is in excess of the size of Yb, the Ba M 2 NiO 5 was formed as the reaction product between NiO and BaZr 0.8 M 0.2 O 3-δ . The proton conductivity of the series of BaZr 0.8 M 0.2 O 3-δ containing no NiO increased in the order of In<Sc<Lu<Yb<Y. On the other hand, there was no distinct difference of the hole conductivity for dopant. PCFC using BZ M 20 ( M =Lu, Yb, Tm, Y) has an energy efficiency of more than 0.8 at 873 K. The proton conductivity decreased and the hole conductivity did not change for all series of BaZr 0.8 M 0.2 O 3-δ due to NiO dissolution in BaZr 0.8 M 0.2 O 3-δ . Therefore, proton transport number and the efficiency of the fuel cell decrease by addition to NiO. Considering the above, the ytterbium-doped barium zirconate did not form a complex oxide with NiO and might have high proton conductivity. The performance of PCFC using BZYb20 as electrolyte was measured. The maximum power density values at 600 and 700 °C were 0.50 and 0.70 Wcm −2 for the planar cells using BZYb20, respectively. Electrochemical impedance spectroscopy of the cell showed that the ohmic resistance was 0.28 Ωcm 2 at 600 °C, which was approximately three times larger than the resistance value calculated using the bulk conductivity of BZYb20 and the electrolyte thickness and was in agreement with the resistance value of BZYb20 with NiO. [1] K.D. Kreuer et al., Solid State Ionics 145(2001)295-306. [2] Y. Matsuzaki et al., Scientific Reports, 5:12640(2015)1-10. [3] A. Doubois et al., ECS Transaction 78(1) (2017)1963-1972. [4] J. Tong et al., J. Mater. Chem. , 20(2010)6333.

Wenqin Jiang, Jian Zhang, Qiulin Yang et al.

Sustainability • 2024

The Anammox anaerobic fluidized bed microbial fuel cell (Anammox AFB-MFC) exhibits exceptional performance in both nitrogen removal and electricity generation, effectively eliminating ammonia nitrogen (NH4+-N) and nitrite nitrogen (NO2−-N) pollutants. This technology offers the advantages of high efficiency in nitrogen removal and low electricity consumption. By coupling an AFB with an MFC, the Anammox AFB-MFC was developed through the introduction of anaerobic ammonia-oxidizing bacteria (AnAOB) into MFC. Anammox AFB-MFC’s nitrogen removal ability was found to be superior at an influent COD concentration of 200 mg/L, as determined by a study conducted under unchanged conditions. Subsequently, an open and closed-circuit experiment was performed on the Anammox AFB-MFC system while maintaining a COD concentration of 200 mg/L in the influent. Remarkably, the reactor exhibited significantly enhanced nitrogen removal performance when electricity generation occurred. Throughout the entire experimental process, the reactor consistently maintained high nitrogen removal efficiency and electricity production performance. Under optimal experimental conditions, the reactor achieved a remarkable nitrogen removal rate of 91.8% and an impressive output voltage of 439.1 mV. Additionally, the generation of Anammox bioparticles in MFC significantly contributed to efficient pollutant removal. This study elucidates the impact of organic matter on both the nitrogen removal and electricity generation capabilities of Anammox AFB-MFC, as well as highlights the synergistic effect between MFC electricity generation and nitrogen removal in the reactor.

Pengcheng Zhu, Shumin Zhuo, Weiying Zhang et al.

Journal of Applied Polymer Science • 2023

Abstract Microbial fuel cells (MFCs) are a potential biotechnology for simultaneous degradation of organic wastewater and power generation. In this paper, a biocompatible composite is constructed around a copper mesh with sodium alginate/agar and activated carbon (CM‐SA/AC) and acts as an efficient anode for MFCs after being microbe immobilized. The power performance of the MFC with CM‐SA/AC anode is investigated. The results show that the addition of activated carbon is conducive to the immobilization of bacteria on CM‐SA/AC anode and fast start‐up of MFCs. The power density reaches 1088.6 mW/m 2 , which is 2.03 times and 1.75 times that of CM‐SA (without activated carbon) anode and carbon felt anode, respectively. In case of a candied wastewater treatment, the MFC with immobilized CM‐SA/AC anode exhibits a much higher power density (724.5 mW/m 2 ) than that with carbon felt anode (145.0 mW/m 2 ), together with a longer stabilization time and a smaller charge‐transfer resistance. The total removal rate of chemical oxygen demand (COD) reaches 79.4 ± 0.65%. The present study will facilitate the development of inexpensive and biocompatible anodes to facilitate the application of MFCs in wastewater treatment.

Robyn Barbato, Robert Jones, Michael Musty et al.

• 2025

Electrogenic bacteria produce power in soil based terrestrial microbial fuel cells (tMFCs) by growing on electrodes and transferring electrons released from the breakdown of substrates. The direction and magnitude of voltage production is hypothesized to be dependent on the available substrates. A sensor technology was developed for compounds indicative of anthropological activity by exposing tMFCs to gasoline, petroleum, 2,4-dinitrotoluene, fertilizer, and urea. A machine learning classifier was trained to identify compounds based on the voltage patterns. After 5 to 10 days, the mean voltage stabilized (+/- 0.5 mV). After the entire incubation, voltage ranged from -59.1 mV to 631.8 mV, with the tMFCs containing urea and gasoline producing the highest (624 mV) and lowest (-9 mV) average voltage, respectively. The machine learning algorithm effectively discerned between gasoline, urea, and fertilizer with greater than 94% accuracy, demonstrating that this technology could be successfully operated as an environmental sensor for change detection.

Jakub Drewnowski, Francisco Fernandez-Morales

Sustainability • 2016

Nowadays, pollution caused by energy production systems is a major environmental concern. Therefore, the development of sustainable energy sources is required. Amongst others, the microbial fuel cell (MFC) seems to be a possible solution because it can produce clean energy at the same time that waste is stabilized. Unfortunately, mainly due to industrial discharges, the wastes could contain nitrates, or nitrates precursors such ammonia, which could lead to lower performance in terms of electricity production. In this work, the feasibility of coupling anodic denitrification process with electricity production in MFC and the effect of the nitrates over the MFC performance were studied. During the experiments, it was observed that the culture developed in the anodic chamber of the MFC presented a significant amount of denitrificative microorganisms. The MFC developed was able to denitrify up to 4 ppm, without affecting the current density exerted, of about 1 mA/cm2. Regarding the denitrification process, it must be highlighted that the maximum denitrification rate achieved with the culture was about 60 mg·NO3−·L−1·h−1. Based on these results, it can be stated that it is possible to remove nitrates and to produce energy, without negatively affecting the electrical performance, when the nitrate concentration is low.

Irene Bavasso, Luca Di Palma, Debora Puglia et al.

Polymer Engineering & Science • 2019

Nanocomposite membranes based on polyethersulfone (PES) and nanomagnetite have been investigated with regards to the effect of pretreatments on the electrochemical performance of microbial fuel cells (MFCs). Nanocomposite membranes containing various amounts of Fe 3 O 4 (5, 10, and 20 wt%) were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry, and tensile tests. The application in MFC systems requires also chemical characterizations such as ion exchange capacity, water uptake, and oxygen permeability. The best formulation (PES10) showed electrochemical properties similar to the PES20. With the aim of obtaining a high‐performance membrane with a low filler dosage, a pretreatment procedure (1 h of boiling step in deionized water and 1 h of immersion in 0.5 M of H 2 SO 4 ) was adopted. The results of such pretreatment in terms of maximum power and current density were 10.59 ± 0.72 mW/m 2 and 52.07 ± 0.86 mA/m 2 , respectively. The adoption of a pretreatment avoids the need of higher amount of nanofillers that can affect membrane surface roughness and its processing. Overall, the nanocomposite membranes represent a suitable technology in the MFC process. POLYM. ENG. SCI., 60: 371–379, 2019. © 2019 Society of Plastics Engineers

Cheng Li, Hong Liu

ECS Meeting Abstracts • 2018

Mixed species biofilms have been able to generate current densities of over 20 A/m 2 in microbial fuel cells (MFCs), while also offering advantages in stability, substrate flexibility, and culture maintenance costs. To further increase the current density, a possible approach is to enhance the conductivity of biofilms and thereby the direct extracellular electron transfer within the biofilms and to the anode. While examination of conductivity in microbial samples is still in its relative infancy and conceptual models in terms of conductive mechanisms are still being developed and debated, our study has demonstrated that current-producing mixed species biofilms can exhibit high conductivity across non-conductive gaps. Differential responses observed over varying potentials also suggest that a redox driven conductivity mechanism is dominant in the tested mixed-species biofilms. Considering that some redox conductive organic polymer films possess negative magnetoresistance property (resistivity of a conductive material decreases as the magnetic field strength increases) and magnetic field may stimulate enzyme activity in certain anaerobic wastewater treatment systems, our mixed species biofilms were exposed to low intensity magnetic field to investigate the conductivity change and performance enhancement. Exposure of the biofilms to magnetic field has led to an over 100% increase in biofilm conductance and over 300% increase in current density. Application of the low intensity magnetic field also encouraged the enrichment of Geobacter spp. in biofilms. Short term application of magnetic field also increased the conductivity of anodic biofilms, resembling the negative magnetoresistivity that has not been observed in conductive biofilms before. These results not only enhance our understanding of the electrical conductivity in microbial aggregates, but also inform rational design and operation of microbial-based fuel cells.

Shiladitya Mukherjee, J. Vernon Cole, Kunal Jain et al.

ASME 2009 7th International Conference on Fuel Cell Science, Engineering and Technology • 2008

In Proton Exchange Membrane Fuel Cells (PEMFCs), water management and the effective transport of water through the gas-diffusion-layer (GDL) are key issues for improved performance at high power density and for durability during freeze-thaw cycles. The diffusion layer is a thin (∼150–350μm), porous material typically composed of a web of carbon fibers and particles, and is usually coated with hydrophobic Teflon to remove the excess water through capillary action. In-situ diagnostics of water movement and gas-reactant transport through this thin opaque substrate is challenging. Numerical analyses are typically based on simplified assumptions, such as Darcy’s Law and Leverett functions for the capillary pressure. The objective of this work is to develop a high fidelity CFD modeling and analysis tool to capture the details of multiphase transport through the porous GDL. The tool can be utilized to evaluate GDL material design concepts and optimize systems based on the interactions between cell design, materials, and operating conditions. The flow modeling is based on the Lattice Boltzmann Method (LBM). LBM is a powerful modeling tool to simulate multiphase flows. Its strength is in its kinetic theory based foundation, which provides a fundamental basis for incorporating intermolecular forces that lead to liquid-gas phase separation and capillary effects without resorting to expensive or ad-hoc interface reconstruction schemes. At the heart of the solution algorithm is a discrete form of the well-known Boltzmann Transport Equation (BTE) for molecular distribution, tailored to recover the continuum Navier-Stokes flow. The solution advances by a streaming and collision type algorithm, mimicking actual molecular physics, which makes it suitable for porous media involving complex boundaries. We developed a numerical scheme to reconstruct various porous GDL microstructures including Teflon loading. Single and multiphase LBM models are implemented to compute permeability. Predicted values are in good agreement with measured data. The present modeling approach resolves the GDL microstructures and captures the influence of fiber orientation on permeability and the influence of Teflon loading on the development of preferential flow paths through the GDL. These observations can potentially guide the development of novel GDL materials designed for efficient removal of water.

Cong Xu, Lorenz T. Biegler, Myung S. Jhon

AIChE Journal • 2006

Abstract An H 2 Polymer Electrolyte Membrane (PEM) Fuel Cell power generation system composed of three subsystems: fuel reforming, fuel cell stack, and post combustion is examined. The system is simulated and optimized with a fuel cell model integrated within the process flow sheet. A case study optimization of the entire power generation system is presented and the influence of heat integration on the optimization is demonstrated. Our objectives are to maximize the energy and system efficiencies as well as the system profit. Here, optimization formulations with heat integration are used to realize our objectives, which explore the synergy between optimization and heat integration. Our results showed that we can achieve an energy efficiency as high as 58.30% and a system efficiency as high as 28.35%. For comparison, we provide results obtained from sequential process optimization followed by heat integration. The gain from the synergy is mostly exemplified in the profit maximization study, where the profit increases by almost 27.15% in the best case. Finally, we obtain optimization results that include feed vaporization of water to steam as a comparison for the heat integration. These results demonstrate the importance of simultaneous optimal heat integration for fuel cell‐based processes. © 2006 American Institute of Chemical Engineers AIChE J, 2006

Vahid Rezaee, Arash Houshmand

Bulletin of the Polytechnic Institute of Iași. Electrical Engineering, Power Engineering, Electronics Section • 2022

Abstract In this study, the performance analysis of waste heat recovery systems in a power generation system consisting of 13000 Proton Exchange Membrane Fuel Cells (PEMFC) in a stack has been investigated. Organic Rankine Cycle (ORC) and Kalina Cycle System 11 (KCS11) as bottoming cycles to convert generated waste heat of stack into electricity were compared with each other in a defined hybrid system. The improvement of system with an exact energy and exergy analysis after utilizing the waste heat in the hybrid system has been analyzed. Results show that the energy efficiency of combined system using Organic Rankine Cycle and Kalina Cycle System 11 increase by about 5% and 1.75% respectively. In addition, exergy analysis results indicate that exergy efficiency of combined system using Organic Rankine Cycle and Kalina Cycle System 11 increases by about 4% and 1.5% respectively. The total exergy destruction rate obtained for the hybrid power systems is 235.5 kW when ORC is used and 329.7 kW when KCS11 is used respectively. Results show that in presented systems ORC has higher energy and exergy efficiencies than KCS11 but different used working fluids and equipment of systems must also be considered from an economical point of view.

Yifeng Zhang, Booki Min, Liping Huang et al.

Applied and Environmental Microbiology • 2009

ABSTRACT Electricity generation from wheat straw hydrolysate and the microbial ecology of electricity-producing microbial communities developed in two-chamber microbial fuel cells (MFCs) were investigated. The power density reached 123 mW/m 2 with an initial hydrolysate concentration of 1,000 mg chemical oxygen demand (COD)/liter, while coulombic efficiencies ranged from 37.1 to 15.5%, corresponding to the initial hydrolysate concentrations of 250 to 2,000 mg COD/liter. The suspended bacteria found were different from the bacteria immobilized in the biofilm, and they played different roles in electricity generation from the hydrolysate. The bacteria in the biofilm were consortia with sequences similar to those of Bacteroidetes (40% of sequences), Alphaproteobacteria (20%), Bacillus (20%), Deltaproteobacteria (10%), and Gammaproteobacteria (10%), while the suspended consortia were predominately Bacillus (22.2%). The results of this study can contribute to improving understanding of and optimizing electricity generation in microbial fuel cells.

Chetan Laddha

ADIPEC • 2023

Abstract Ammonia is a dense energy carrier with high energy density and established supply chain for transport, and storage of hydrogen. Ammonia is a common commodity used in the fertiliser and chemical sector and has a potential to become an affordable and sustainable energy carrier to meet growing demand for industrial decarbonisation. The transport of hydrogen over long distances require an efficient and cost competitive carrier. Potential options for hydrogen carrier are ammonia, liquid organic hydrogen carrier (LOHC), liquid hydrogen, compressed hydrogen, and methanol. This paper describes an innovative ceramics-based solid oxide fuel cell technology for conversion of ammonia into fossil fuel parity energy at a thermal efficiency of 85%. The technology is based on proton conducting ceramics (PCC) electrochemical pathway which eliminates NOx emissions by design and ammonia slippage by catalyst performance and reactor design. The technology has been developed over 7 years, between 2016 to 2022, and the ammonia utilisation capabilities has been proven through demonstrations conducted for O&G and industrial companies. The technology uses low-cost and widely available ceramics-based catalyst. The technology is particularly suited for industrial decarbonisation because of the ability to yield high efficiency and the ability to produce low-cost heat at 700C and hydrogen as byproducts.

Myong-Hwan Kim, Seung Eul Yoo, Youngmo Goo

ECS Meeting Abstracts • 2016

In generally, Bipolar plate is vital component of PEM fuel cells, which supplies fuel and oxidant to reactive sites, removes reaction products, collects produced current and provides mechanical support for the cells in the stack. At the present, the bipolar plate for fuel cell vehicle is metallic separators formed of metallic materials such as stainless steel. The existing bipolar plate includes a land(contacting) portion directly bonded to the gas diffusion layer(GDL) and a channel portion that serves as a supply passage of reaction gases and an exhaust passage of water between land portions. In the typical separator, the land portion and the channel portion are disposed in a longitudinal direction and a flow field area in which the channel portion is formed both have a longitudinal structure. Also, the land portion and the channel portion are distinctly separated from each other.However, in the case of a typical separator, this non-uniformity causes a concentration difference between the area that the channel portion contacts and the area that the land portion contacts among the whole area of the MEA where the electrochemical reaction occurs and the performance of fuel cell is decreased.In this paper, a porous separator with various structures for a fuel cell, which causes the high diffusion of reactant gases was studied for increasing the performance of fuel cell. Also, we conducted an analysis of the properties(contact resistance, corrosion etc.), machinability(uniformity of thickness, change of hole structure etc.) and performance according to hole and pitch structure.In conclusions, the porous separator with optimum structure shows the performance above 200mA/cm 2 at 0.6V in comparision with the typical separator. It is considered to be minimize concentration differences between area in a gas diffusion layer and achieve uniform electrochemical reaction and electricity generation over the whole reaction are, by improving the structure of a flow field in which reactant gases flow.

Lanka Tata Rao, Satish Kumar Dubey, Arshad Javed et al.

Journal of Electrochemical Energy Conversion and Storage • 2020

Abstract Paper-based membraneless microfluidic fuel cell (PMMFC) has emerged as an alternative to conventional fuel cells. Extraction of optimum energy yield from these PMMFCs requires selection and study of various design and operating parameters. In this context, this paper presents reliability analysis and robust design of PMMFC composed of air-breathing graphite electrodes using multiple concentrations of formic acid and sulfuric acid as fuel and electrolyte, respectively. Combinations of four different grades of pencils are employed to prepare the electrodes using various pencil strokes. PMMFC is analyzed for two different orientations—horizontal and vertical, and the maximum power outputs were recorded. In order to analyze the combined effects of different factors governing the performance of PMMFC, a statistical approach of full factorial design is utilized to perform analysis of mean (ANOM), analysis of variance (ANOVA), signal to noise ratio (SNR), and desirability study. The response equations in terms of coded values of the factors are also derived. Rigorous desirability study, with the optimized parameters, concludes that the best desirability values for the horizontal and vertical arrangements of PMMFC are 0.8842 and 0.92768, respectively. Overall, this study helps to develop reliable, robust, and efficient PMMFC for many realistic applications.

Abdelkader Hilmi, Timothy Geary, Adam Franco et al.

ECS Meeting Abstracts • 2023

Introduction The molten carbonate fuel cell (MCFC) has emerged as one of the promising alternatives for carbon capture from industrial and power generation CO 2 sources. MCFC technology is less energy-intensive compared to conventional amine scrubbing that requires a significant amount of energy (steam) for solvent regeneration process. MCFC has been commercially used for distributed power generation, however its use in carbon capture applications has been limited to development activities and a few demonstrations during the past decades. The electrochemical reactions taking place during cell operation involve the CO 2 transfer from cathode to anode in the form of carbonate ions resulting in a gas stream with high CO 2 concentration on the anode exhaust. Therefore, MCFC stack systems can be combined with conventional combustion-powered generators (coal and/or natural gas-based power plants) for simultaneous CO 2 separation, power and hydrogen generation. CO 2 capture applications will typically take in flue gas from industrial furnaces, coal and gas fired combined cycle plants as the cathode inlet gas stream having low CO 2 concentrations ranging from 4% to 10% by volume and high CO 2 utilization (>90%). These CO 2 -lean conditions may pose a challenge for attaining good mass-transfer performance and life stability, therefore innovative approaches are needed in terms of hardware design and cathode structure to achieve long-term stability. FCE has tested numerous single cells (250 cm 2 ) and technology stacks (30 kW) under carbon capture operating conditions (4-8% CO 2 in the cathode inlet as opposed to >12% in baseline MCFC systems) to understand impact of design parameters on performance, life, and to investigate design solutions for further enhancement. Figure 1 highlights the effect of cathode water content on CO 2 utilization. It appears that differences exist between the ideal and measured CO 2 utilizations, indicating that less CO 2 is transferring from the cathode to anode than expected. This CO 2 transference reduction becomes more pronounced with higher water concentration, suggesting that a species other than CO 3 2- ion, likely hydroxide (OH - ion), may be generated and transported through the electrolyte matrix. This paper will review the cathode material stability and electrochemical performance under long-term carbon-capture operation. The effect of parameters such as water content, gas composition, utilization, and electrolyte chemistry, as well as approaches to enhance the CO 2 capture efficiency and life, will be discussed. Figure 1

Samuel Simon Araya, Søren Juhl Andreasen, Søren Knudsen Kær

Journal of Fuel Cell Science and Technology • 2014

As fuel cells are increasingly commercialized for various applications, harmonized and industry-relevant test procedures are necessary to benchmark tests and to ensure comparability of stack performance results from different parties. This paper reports the results of parametric sensitivity tests performed based on test procedures proposed by a European project, StackTest. The sensitivity of a Nafion®-based low temperature PEMFC stack's performance to parametric changes was the main objective of the tests. Four crucial parameters for fuel cell operation were chosen; relative humidity (RH), temperature, pressure, and stoichiometry at varying current density. Furthermore, procedures for polarization curve recording were also tested both in ascending and descending current directions.

Takuya Tsujiguchi, Misaki Kojima, Takanori Iwakami et al.

ECS Transactions • 2013

A hyperbranched polymer was used as a catalyst stabilizer for use in a direct formic acid fuel cell, DFAFC, to obtain a high performance with a low catalyst loading. The catalyst ink was prepared by the mixing of Pd nanoparticles stabilized by a hyper branched polymer (H-Pd) and carbon black, which was then calcinated at 300 oC and 500 oC in flowing nitrogen to investigate the effect of the stabilizer residual on the catalytic activity for the formic acid oxidation. It was found that the catalytic activity of the H-Pd was 6 times higher than that of Pd black with a 500 oC calcination. In this condition, a cluster of Pd nanoparticles was observed. By using this catalyst as an anode catalyst of the DFAFC, a 6 times higher power density could be obtained compared to the case using Pd black.

Scott A Mauger, Min Wang, Samantha Medina et al.

ECS Meeting Abstracts • 2019

Industrial production of polymer electrolyte membrane fuel cell (PEMFC) electrodes will rely on continuous roll-to-roll (R2R) coating methods to meet the rates needed for mass production. 1–5 R2R production commonly uses solution coating methods to coat liquids onto a moving substrate at linear speeds over 100 m/min. 6 There are many coating methods, which have different coating physics and require different ink formulations. For PEMFC catalyst layers these differences may result in different morphologies and performance. As production of fuel cell vehicles and power systems increases there is a need to understand the process science of fuel cell manufacturing. Here we present the results of a study comparing fuel cell catalyst layers coated using two R2R coating methods: slot-die and gravure, shown in Figure 1. These two methods were selected because the physics of applying the liquid to the substrate is very different between the two cases. Also, they have different viscosity and wet-film thickness ranges, which may make one method better suited to certain materials or catalyst loadings. In slot die coating, the pre-metered liquid is fed through the cavity of a metal die and extruded onto the substrate, as shown in Figure 1a. In gravure coating, an engraved metal roller is used to transfer the liquid from a pan to the substrate (Figure 1b). In both of these methods the coated liquid film then consolidates into the final dry film. These methods are quite different than common lab-scale coating methods like ultrasonic spraying or hand painting where ink is repeatedly applied to the same area to build up the thickness of the catalyst layers. Pt/C catalysts layers were coated directly onto carbon-fiber gas diffusion media to create gas diffusion electrodes (GDEs), without the use of a decal transfer process. These GDEs were assembled into membrane electrode assemblies (MEAs) by hot pressing to Nafion membranes. In situ performance and other electrochemical diagnostics were used to determine the influence of coating method on catalyst layer electrochemical properties. Electron microscopy was utilized to understand the influence of coating method on electrode morphology and its influence on electrochemical properties. We also explored the influence of solvent ratio to understand the potential coupling between ink formulation and coating methodology. Through this work we demonstrate R2R-coated GDEs with performance equal to ultrasonic spray-coated GDEs and a 200x increase in production rate. This demonstrates that R2R coating methods are suitable for mass-production of high-performance fuel cells. It also lays a foundation for further process science studies. (1) Mauger, S. A.; Neyerlin, K. C.; Yang-Neyerlin, A. C.; More, K. L.; Ulsh, M. Gravure Coating for Roll-to-Roll Manufacturing of Proton-Exchange-Membrane Fuel Cell Catalyst Layer. J Electrochem Soc 2018 , 165 (11), F1012–F1018. https://doi.org/10.1149/2.0091813jes. (2) Bodner, M.; García, H. R.; Steenberg, T.; Terkelsen, C.; Alfaro, S. M.; Avcioglu, G. S.; Vassiliev, A.; Primdahl, S.; Hjuler, H. A. Enabling Industrial Production of Electrodes by Use of Slot-Die Coating for HT-PEM Fuel Cells. Int. J. Hydrog. Energy 2019 . https://doi.org/10.1016/j.ijhydene.2018.11.091. (3) Steenberg, T.; Hjuler, H. A.; Terkelsen, C.; Sánchez, M. T. R.; Cleemann, L. N.; Krebs, F. C. Roll-to-Roll Coated PBI Membranes for High Temperature PEM Fuel Cells. Energy Environ. Sci. 2012 , 5 (3), 6076–6080. https://doi.org/10.1039/c2ee02936g. (4) Ding, X.; Didari, S.; Fuller, T. F.; Harris, T. A. A New Fabrication Technique to Manufacture an MEA Using Direct Coating of Nafion® onto Catalyzed GDL. In 218th ECS Meeting ; ECS, 2010; pp 255–265. https://doi.org/10.1149/1.3484523. (5) Ding, X.; Didari, S.; Fuller, T. F.; Harris, T. A. L. Membrane Electrode Assembly Fabrication Process for Directly Coating Catalyzed Gas Diffusion Layers. J. Electrochem. Soc. 2012 , 159 (6), B746. https://doi.org/10.1149/2.103206jes. (6) Ding, X.; Liu, J.; Harris, T. A. L. A Review of the Operating Limits in Slot Die Coating Processes. AIChE J. 2016 , 62 (7), 2508–2524. https://doi.org/10.1002/aic.15268. Figure 1

Antonio Molinero, Juan Carlos Oller, José Miguel Barcala et al.

ECS Meeting Abstracts • 2022

An airship, or dirigible balloon, is an aircraft that gains its lift from a gas less dense than air, like helium. For traction, airships have two or more propellers normally attached to a gondola that is suspended under the balloon. At present, they are used for hovering long times without the need for a high speed, like for aerial observation, advertising, or as camera platforms. In our laboratory, the airship is being used as a platform for testing hydrogen fuel cell systems for aerial applications. The airship used in this communication is a 3 m 3 polyurethane's inflatable zeppelin, with radio control, and three electrical propellers (Fig. 1a). A hydrogen fuel cell system has been developed and integrated with the gondola for powering the propellers and electronics. The fuel cell is a 15 W PEMFC stack prototype able to work fully under passive feeding conditions (Fig. 1b). In addition, three supercapacitors have been implemented, that are recharged by the fuel cell, for eventual larger power demands up to 40 W. Hydrogen is stored in two metal hydride canisters with 2g capacity to provide 30 W h energy enough for a few hours autonomy. In addition, for fuel cell parameters monitoring, different sensors have been implemented that provide voltages of the individual cells, current, and temperatures. The sensors are connected to Arduino board, and measurements are continuously monitored by a Labview software with wifi. Boost dc-dc conversion provides 7V voltage power to feed the motors. The stack prototype allows for different testing configurations, using cells in series and parallel connection to change power characteristics with different voltage and current. Results of the testing are provided in this communication. Acknowledgement: The work is partially financed by the ELHYPORT project (PID2019−110896RB-I00), Spanish Ministry of Science and Innovation. Figure 1

, Thanaphorn Hakhen

• 2014

This research presents the application of model predictive control (MPC) to control a proton exchange membrane fuel cell (PEMFC). Firstly, the steady state analysis of PEMFC is considered to select its suitable operating conditions based on cell electrical characteristics. Then, the effect of input parameters on cell voltage and temperature is analyzed to investigate the dynamic behavior of PEMFC that is important for control design. It is found that the cell voltage and cell temperature depend on the inlet molar flow rates and temperature of hydrogen and air, and operating current density. To obtain an efficient control system, the control structure design of the PEMFC is considered to specify a good choice of the controlled and manipulated variables. An analysis of the steady-state relative gain array (RGA) is used for pairing of the controlled and manipulated variables. The result shows that the inlet molar flow rates of hydrogen and air are manipulated variables to regulate the cell temperature and partial pressure of hydrogen, respectively. Finally, a model predictive control (MPC) is developed and designed for controlling the cell temperature and partial pressure of hydrogen. Basically, MPC requires the process model used in its control algorithm. The PEMFC model is known to be complicated and involves uncertain parameters. Thus, an offline robust model predictive control (robust MPC) based on a linear time-varying (LTV) model is proposed for PEMFC control. The simulation results show that the robust MPC shows better control performance than conventional MPC because the robust MPC can guarantee robust stability.

H.‐P. Schmid, J. A. Wünning

Fuel Cells • 2004

Abstract Primary energy savings and CO 2 reduction is one of the key motivations for the use of fuel cell systems in the energy sector. A benchmark of domestic cogeneration by PEMFC with existing large scale power production systems such as combined steam‐gas turbine cycle, clearly reveals that only fuel cell systems optimising overall energy efficiency (> 85%) and electrical efficiencies (> 35%) show significant primary energy savings, about 10%, compared with the best competing technology. In this context, fuel processing technology plays a dominant role. A comparison of autothermal and steam reforming concepts in a PEMFC system shows inherent advantages in terms of efficiency at low complexity for the latter. The main reason for this is that steam reforming allows for the straightforward and effective use of the anode‐off gas energy in the reformer burner. Consequently, practical electrical system efficiencies over 40% seem to be achievable, most likely by steam reformers. FLOX®‐steam reforming technology has reached a high state of maturity, offering diverse advantages including: compact design, stable anode off‐gas usage, high efficiency, as well as simple control behaviour. Scaling of the concept is straightforward and offers an opportunity for efficient adaptation to smaller (1 kW) and larger (50 kW) units.

P Rama, R Chen, R Thring

Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy • 2005

A mathematical multi-species modelling framework for polymer electrolyte fuel cells (PEFCs) is presented on the basis of fundamental molecular theory. Characteristically, the resulting general transport equation describes transport in concentrated solutions and also explicitly accommodates for multi-species electro-osmotic drag. The multi-species nature of the general transport equation allows for cross-interactions to be considered, rather than relying upon the superimposition of Fick's law to account for the transport of any secondary species in the membrane region such as hydrogen. The presented general transport equation is also used to derive the key transport equations used by the historically prominent PEFC models. Thus, this work bridges the gap that exists between the different modelling philosophies for membrane transport in the literature. The general transport equation is then used in the electrode and membrane regions of the PEFC with available membrane properties from the literature to compare simulated one-dimensional water content curves, which are compared with published data under isobaric and isothermal operating conditions. Previous work is used to determine the composition of the humidified air and fuel supply streams in the gas channels. Finally, the general transport equation is used to simulate the crossover of hydrogen across the membrane for different membrane thicknesses and current densities. The results show that at 353 K, 1 atm, and 1 A/cm 2 , the nominal membrane thickness for less than 5 mA/cm 2 equivalent crossover current density is 30 μm. At 3 atm and 353 K, the nominal membrane thickness for the same equivalent crossover current density is about 150 μm and increases further to 175 μm at 383 K with the same pressure. Thin membranes exhibit consistently higher crossover at all practical current densities compared with thicker membranes. At least a 50 per cent decrease in crossover is chieved at all practical current densities, when the membrane thickness is doubled from 50 to 100 μm.

M. Muthukumar, P. Karthikeyan, V. Lakshminarayanan et al.

Applied Mechanics and Materials • 2014

The geometrical and flow parameters are governing the performance of the Proton Exchange Membrane Fuel Cell (PEMFC). The flow channels are used for distributing the reactants uniformly throughout the active area of fuel cell. Among different flow field designs, the serpentine flow field can give better performance to the PEM fuel cell. This paper numerically investigates the effects of the serpentine flow field with different number of passes. The 2 pass, 3 pass and 4 pass serpentine flow field designs of same rib size and channel size were modelled and analyzed using commercially available software package. From the polarization curves and performance curves drawn using the numerical results, the performance of three flow channel designs were compared and the maximum power densities of each design were found

Guruviah Velayutham, Srinivas Sribollepalli, P Kalingamuthu

ECS Meeting Abstracts • 2014

Gas diffusion layer (GDL) plays a very important role in the function of fuel cell performance. Therefore, the requirements of an ideal GDL include diffusion and distribution of reactants to the catalyst layers, good in plane and thro plane conductivity. Depending on the reactants and operating current densities, the GDL must provide an optimum hydrophobicity and hydrophilicity for gas distribution, water and thermal management (1-3). In order to improve the stability of fuel cell stack, a complete understanding of GDL properties are essential. In the present work, AvCarb MGL370 carbon paper and AvCarb 1071 carbon cloth is used as a substrate material. The effect of PTFE content on the substrate and micro-porous layer on the fuel cell performance is compared in both hydrogen/oxygen and hydrogen/air. The properties of GDL were characterized by experimental setup developed in house for the measurement of gas diffusion coefficient. The properties were also measured using Capillary Flow Porosity meter. The percentage of PTFE on the substrate is varied for both carbon paper as well as carbon cloth ranging from 5 to 20%, however the concentration of PTFE in the micro layer is fixed. The experiments are conducted by keeping constant PTFE loading in the substrate while the concentration PTFE in the micro layer is varied from 15 to 30%. The PEMFC cells were tested at 65 o C and at ambient pressure with relative humidity of hydrogen and air kept at 90% and 80%, respectively. The results were analyzed from the polarization curves. The long-term stability of the cell is evaluated by operating the cell at constant current density. PTFE content in the substrate as well as micro porous layer is important for the performance of fuel cell. The current density achieved in the hydrogen/oxygen is about 1.25A/cm2 at 0.6V, while the same electrode when operated with hydrogen air is 0.5A/cm2 at the same operating voltage (GDL1). Alteration of both substrate and micro-layer PTFE concentration improve the performance to 1.6A/cm2 and 0.7A/cm2 at 0.6V for hydrogen/oxygen and hydrogen/air respectively (GDL2),Fig.1. The effect of hot pressing condition on both carbon cloth as well as carbon paper is also discussed. The pressing pressure conditions varied from 40 to 120kg/cm2. In this paper the performance of both carbon paper and carbon cloth is discussed with respect to PTFE content and pressing conditions. Fig.1: The effect of PTFE content in the substrate and micro layer, ambient pressure, temperature of operation 65 o C, H 2 /O 2 - 100/80%, flow rate H 2 /O 2 is 300/400cc References: 1. G. Velayutham, J. Kaushik , N.Rajalakshmi , K.S.Dhathathreyan , Fuel Cell 7, 314-318 (2007) 2. G. Velayutham, International Journal of Hydrogen Energy 36(22), 14845-14850, (2011) 3. E.Passalacqua , G.Squadrito, F.Lufrano , A.Patti, L.Giorgi . J Appl Electrochem , 31, 449-54 ( 2001)

Yunqi Li, Danping Xiong, Yuwei Liu et al.

Nanotechnology Reviews • 2019

Abstract The catalysts performance degradation is a crucial issue in decay of the polymer electrolyte membrane fuel cell (PEMFC). The effect of Nafion content, dispersity of Pt nanoparticles and selected types of carbon support on the degradation of electrochemical surface area (ECSA) and double layer capacitance (DLC) were experimentally discussed by accelerated stress test (AST). The catalyst with 20wt% Nafion content exhibited better catalyst performance. i.e ., the less DLC and ECSA degradation during AST. Catalysts with well Pt dispersity showed superior %ECSA (the percentage change of ECSA) retention. The heat-treated catalysts exhibited the lowest ECSA and DLC degradation rate due to the larger Pt particle and high carbon corrosion resistance. Moreover, a multi-order model describing the correlation between ECSA and DLC degradation was proposed, providing a vital reference for quantitatively investigating ECSA and DLC degradation in the catalysts with different catalysts structural parameters.

Hegazy Rezk, Ahmed Fathy

Sustainability • 2020

The output power of a fuel cell mainly depends on the operating conditions such as cell temperature and membrane water content. The fuel cell (FC) power versus FC current graph has a unique maximum power point (MPP). The location of the MPP is variable, depending on the operating condition. Consequently, a maximum power point tracker (MPPT) is highly required to ensure that the fuel cell operates at an MPP to increase its performance. In this research work, a variable step-size incremental resistance (VSS-INR) tracking method was suggested to track the MPP of the proton exchange membrane (PEMFC). Most of MPPT methods used with PEMFC require at least three sensors: temperature sensor, water content sensor, and voltage sensor. However, the proposed VSS-INR needs only two sensors: voltage and current sensors. The step size of the VSS-INR is directly proportional to the error signal. Therefore, the step size will become small as the error becomes very small nearby the maximum power point. Accordingly, the accuracy of the VSS-INR tracking method is high in a steady state. To test and validate the VSS-INR, nine different scenarios of operating conditions, including normal operation, only temperature variation, only variation of water content in the membrane, and both variations of temperature and water content simultaneously, were used. The obtained results were compared with previously proposed methods, including particle swarm optimization (PSO), perturb and observe (P&O), and sliding mode (SM), under different operating conditions. The results of the comparison confirmed the superiority of VSS-INR compared with other methods in terms of the tracking efficiency and steady-state fluctuations.

Yang Zhao, Xue Li, Shubo Wang et al.

ECS Meeting Abstracts • 2019

Direct membrane deposition is introduced as a novel polymer electrolyte membrane fabrication method. This method is extended to fabricate a high-performance membrane electrode assembly for polymer electrolyte membrane fuel cell with poly (arylene ether sulfone) nanofibers as effective membrane reinforcements. The nanofibers are directly electrospun onto gas diffusion electrodes. By spray-coating ionomer dispersion into the pore space of nanofiber mats, composite membranes of 15 μm thickness are fabricated. The introduction of the electrically and ionically insulating nanofibers do not hamper the cell performance. At 80 ℃ and 75% relative humidity, the power density of the fuel cell employing direct membrane deposition, 2.85 W/cm 2 , is about 1.36 times higher than that of the reference fuel cell (2.09 W/cm 2 ) with Nafion ® 211. Its cell resistance (28 mΩ·cm 2 ) is much lower than that of the membrane electrode assembly fabricated by the catalyst coating membrane method (46 mΩ·cm 2 ). The performance differences between two fabrication methods are systematically analyzed by electrochemical impedance spectroscopy. Even though the thickness of the polymer electrolyte (15 μm) is much lower than that of Nafion ® 211, it shows much higher internal short resistance because of the existence of nanofibers.

, Dinesh Kumar Madheswaran

Green and Low-Carbon Economy • 2023

This article explores the potential and limitations of Sediment Microbial Fuel Cells (SMFCs) and their deployment for sustainable energy production and environmental remediation. SMFCs use naturally occurring redox gradients in sediments to produce bioelectricity, making them advantageous over conventional energy sources due to their affordability, simplicity, and ability to operate in various environments with minimum maintenance requirements. However, their low power output density restricts their practical applicability. The article discusses the controllable and uncontrollable factors that affect SMFC performance and their influence on SMFC functionality, electrode material, external resistance, electrode spacing, electrode design, electrode immersion dimensions, and catalyst. The article highlights the challenges facing SMFC deployment, particularly in large-scale businesses, such as the need for more scientific literature on SMFCs and inadequate focus on energy metrics.

Richard T. Meyer, Bin Yao

ASME 2006 Fourth International Conference on Fuel Cell Science, Engineering and Technology, Parts A and B • 2005

Recent trends and advances in hydrogen/air Proton Exchange Membrane Fuel Cells (PEMFC) are incorporated into a dynamic control oriented model. This type of model is important for development of control systems for PEMFC powered transportation where unpredictable and widely varying changes in power demand can be expected. Self humidification and low pressure operation are the two major changes to past systems. As a result, a high pressure air compressor, air cooler, and inlet gas humidifiers are no longer required. Also, the likelihood of cathode flooding is reduced. The overall fuel cell model consists of four basic sub-models: anode, cathode, fuel cell body, and cooling. Additionally, the oxidant supply blower, cooling pump, and cooling fan are explicitly incorporated. Mass and energy conservation are applied to each using a lumped parameter control volume approach. Empirical modeling is minimized as much as possible, however it is necessary for model manageability in a control context. Interactions between each subsystem and balance of plant components are clearly defined. The overall model is capable of capturing the transient behavior of the flows, pressures, and temperatures as well as net output power. The influence of the charge double layer effect on transient performance is also explored. Numerical simulations of the system are presented which illustrate the usefulness of the model. Finally, future control work is described.