Venkatesh Babu K. P., Geethu Varghese, Thadathil Varghese Joseph et al.

Journal of The Electrochemical Society • 2022

Misalignment in the flow field plates of High-Temperature Polymer Electrolyte Membrane Fuel Cell (HT-PEMFC) due to manufacturing tolerances, assembly process, or unavoidable vibration during the cell operation is contemplated its performance and durability. This study investigates the effect of flow field plate misalignment and its concomitant impact with varying the clamping pressures on HT-PEMFC operation. The study considers six degrees of cathode flow field misalignment, varying from 0% to 100% with respect to the anode flow field. Clamping pressures ranging from 1 to 2 MPa are applied to the various cases of misalignment to study their effect on GDL deformation and intrusion into the channels. The structural analysis shows that as the misalignment increases from 0 to 100%, the GDL compression increases from 26.72% to 37.75% for 1 MPa, 40.07% to 56.63% for 1.5 MPa, and 53.43% to 75.51% for 2 MPa, owing to the increase in compression approximately by 41% from their base cases and it is also crucial to note that GDL compression exaggerates at higher clamping pressures. The misalignment results in the sagging of Membrane Electrode Assembly (MEA), and the amplitude of wave nature is proportional to the degree of misalignment and clamping pressure, indicating the misalignment is the sole factor for structural changes. As a result, considerable variance in current distribution and average value is observed, i.e., at operating voltage 0.5 V, the current density drops from 4472.7 to 4264.4, 4420.7 to 4211.8, and 4374.1 to 4161.3 A m −2 from cases 1 to 6 for clamping pressures 1, 1.5, and 2 MPa, respectively, resulting in a 4.7% loss in performance. According to the observations, a misalignment of 60% is tolerable, with minimal performance loss and negligible non-uniformity in cell distributions.

Jie Wang, Yang Wang, Jun Wei et al.

Volume 2: Nuclear Fuel and Material, Reactor Physics and Transport Theory, and Fuel Cycle Technology • 2022

Abstract Reactivity-initiated accident (RIA) is postulated design-basis accidents (DBAs) in light-water reactor (LWR). Moreover, Pellet-cladding mechanical interaction (PCMI) can cause a failure of the cladding in the early transient. In recent RIA regulatory guide released by NRC which points out that PCMI failure threshold depends on total hydrogen content in cladding during RIA. In order to evaluate the performance of independently-developed zirconium alloy under RIA conditions, the mechanical behavior and the fracture of 2 different cladding tubes (CZ, and SR (Stress Relief) Zr-4) with different hydrogen contents are investigated under thermal-mechanical loading conditions representative of PCMI during RIAs. Ring tensile tests are performed at room temperature, 350 °C on 2 different materials containing various hydrogen concentrations up to 1000 wt. ppm. Test results indicate that the ductility of the material decreases with increasing hydrogen content at room temperature due to damage nucleation by hydride cracking, the ductility and strength results of SR Zr-4 have a good agreement with reference paper, confirming the rationality of experimental method applied and reliability of test facilities. According to the results of Zr-4 and CZ, a conclusion can be made is that the ductility of independently-developed zirconium alloy (CZ) is better than Zr-4, which can provide the technical support when licensing.

Muhammad Zeeshan Khan, Muhammad Shahzad Nazir, Muhammad Shoaib Bhutta et al.

Sustainability • 2023

Epoxy resin is extensively used in gas insulated switches as a renewable energy coating due to its exceptional insulation, mechanical characteristics, and environmental friendliness. The higher resistivity of the epoxy resin causes numerous surface charges to accumulate on the surface of the epoxy resin as a result of carrier injection due to the high DC electric field, which may cause insulation failure of the power transmission system. In this study, various concentrations of epoxy resins blended with nano-alumina (nano-Al2O3) at 0 wt%, 1 wt%, 3 wt%, and 5 wt% were created. Afterwards, the epoxy resin and Al2O3 nanocomposites were fluorinated by utilizing a combination of F2 and N2 with a ratio of 20% F2 at 0.05 MPa while maintaining the temperature at 40 °C. In order to improve dispersion, nano- Al2O3 was treated with a silane coupling agent called γ-aminopropyltriethoxysilane (KH550). Additionally, infrared spectroscopy based on the Fourier transform was used to investigate the structure of chemical bonds. Furthermore, the changes in the molecular chains were verified by the FTIR spectra. The DC breakdown strength of epoxy resin\Al2O3 nano-composites showed that breakdown strength significantly improved after gas-phase fluorination. Moreover, 1 wt% nano- Al2O3 showed a higher breakdown strength. The fluorinated layer had a charge-suppressing effect, reducing the charge injected into the polymer matrix of the epoxy-resin matrix and increasing its DC breakdown capability. Thermally stimulated current (TSC) measurements indicate that epoxy resin’s trap energy and trap density are altered by nano- Al2O3 incorporation and fluorination treatment (gas-phase). It was also observed that introducing nano- Al2O3 at a lower concentration (e.g., 1 wt%) can hinder the growth of space charge in the polymer matrix of the epoxy resin, thus enhancing the deep traps’ energy. Furthermore, a fluorination layer containing a strong polarization of C-F bonding would seize the charge injection from electrodes, thus decreasing the conductivity and suppressing the charge injection.

Soichiro Hirose, Kosuke Takasugi, Trang Nakamoto et al.

Resourceedings • 2023

Microbial fuel cells (MFCs) are a promising technology for solving energy and water pollution problems. However, to promote the practical application of MFC, it is necessary to solve the problems of power output and electrode cost simultaneously. Therefore, transition metal-based catalysts that can improve air cathode functionality without using platinum catalysts, which are commonly used, are attracting attention. In this experiment, a cobalt-intercalated birnessite-type manganese oxide catalyst was used as the cathode of the MFC. In addition, rice husk charcoal from agricultural waste and Sumi ink were used as cathode materials to reduce cost and improve the physical stability of the electrodes. The conductivity of the Sumi ink is expected to compensate for the low conductivity of manganese oxide. The resulting power density was 5.8 times higher with the catalyst than without. It was also confirmed that the fabricated cathode operated for at least 90 days without maintenance.

N. Xu, X. Guo, J. Fang et al.

Fuel Cells • 2009

Abstract A series of cross‐linked sulphonated poly(sulphide sulphone) (SPSSF) membranes have been prepared via a polyphosphoric‐acid‐catalysed condensation reaction at 180 °C for a period of time (1.5–5.0 h) and the resulting cross‐linking bonds are the highly stable sulphonyl groups. The cross‐linking density could be controlled by regulating the reaction time. Cross‐linking caused significant enhancement in the mechanical properties and large reduction in both water uptake (WU) and methanol permeability. The SPSSF‐60 membrane (the numeral 60 refers to the degree of sulphonation), e.g. had a tensile strength increased from 16 to 27 MPa (wet membranes) after cross‐linking for 5 h, while the WU substantially decreased from 320 to 58 wt.‐% and the methanol permeability decreased from 1.9 × 10 –6 to 2.7 × 10 –7 cm 2 s –1 (30 °C). Single cell test on hydrogen/oxygen revealed that the cross‐linked SPSSF‐50 (1.5 h) membrane displayed higher open circuit voltage (OCV, 1.02 V), higher maximum output power density (1.32 W cm –2 ) and significantly slower OCV decay rate than the uncross‐linked SPSSF‐40 membrane under the same operating conditions despite their similar ion exchange capacities. The cross‐linked SPSSF‐60 (5.0 h) and SPSSF‐50 (1.5 h) membranes showed significantly better fuel cell performance than Nafion 212.

R. Yeetsorn, R. Petrone, D. Hissel et al.

Fuel Cells • 2022

Abstract A voltage decrease in the long‐term operation of hydrogen fuel cell (FC) electric cars under steady settings under constant load and dynamic operating conditions is a performance constraint of concern. Although accelerated stress test (AST) procedures have been sought to diagnose degradation, the AST results of FC stacks have not been reported extensively. The purpose of this article is to discuss the generation of AST of FC stacks based on real load profiles and the consequences of load changes and start‐stop circumstances, which are mostly generated by common driven cycles in urban regions with high driving speeds and traffic jams. The highlight of this study is to analyze the effects of cycle repetition on the aging FC stack, especially the voltage degradation factor, degradation kinetics, and energy consumption. The relation between actual system temperatures in side cells assembled in the FC stacks and material degradation was also analyzed. The results presented high heat accumulation, related to chemical degradation, that occurred during load cycling and may result in membrane thinning and pinholes in the membrane. Temperature cycling corresponded to mechanical degradation generated during the start‐stop cycling test, which may lead to membrane degradations—cracking, tearing, and pinholes.

Natalia Macauley, Rod L. Borup, Rangachary Mukundan et al.

ECS Meeting Abstracts • 2017

Stratified catalyst layers can increase fuel cell performance compared to standard flat catalyst layers 1,2 due to improved mass transport because of their irregular thickness and porosity. Stratified catalyst layer structures are expected to have enhanced performance in mass transport region due to improvements in water removal from the catalyst layer. Custom electrodes are fabricated with a custom designed spray coating procedure and catalyst ink recipe. Results from multiple fabrication approaches will be discussed to achieve the electrode structure with the highest performance. One approach used involves a topographical patterning of the catalyst layer, and is based on Ion Power proprietary manufacturing techniques. The second approach uses glass epoxy masks during the spray coating process to create a patterned electrode on the GDL with varying thickness. The mask dimensions mirror the bipolar plate flow-field at the cathode, exposing either the land or channel regions. This way the two extreme cases were investigated and the resulting performance compared. The application of more catalyst material in the channels was found to be more beneficial than when applied in the land regions, likely due to rapid reaction times via better access of the incoming reactant gases through the channels. However, the presence of a thicker catalyst layer under the channel may be an issue for product water removal and oxygen diffusion at high current densities. The best performance was observed when in addition to applying the catalyst preferentially in the channels, a carbon-ionomer filler was used in the land region. The filler is used for both mechanical stabilization of the catalyst layer and to improve ionic and electronic conductivity within the catalyst layer. Two ionomer to carbon (I/C) ratios were tested in the carbon-ionomer filler. The high I/C ratio matches the I/C ratio of the Pt/C ink and is equal to 0.9. This case achieved a significant improvement in the kinetics of the catalyst, but had no effect on mass transport. When the I/C ratio was reduced to 0.6 in the carbon-ionomer filler, there was a visible improvement in mass transport. This is likely due to lower ionomer content which results in less water retention in the catalyst later. In order to better understand the performance mechanisms taking place, the effect of adding hydrophobic agents in the carbon filler is examined. This includes the addition of Polytetrafluoroethylene (PTFE) and Fluorinated ethylene propylene (FEP) to further support water removal at high current densities. Finally, the effect of using thin membranes will be discussed, as by stratifying the catalyst layer, much of the proton conduction occurs in a limited portion of the membrane. Membrane electrode assemblies (MEAs) using 25 micron thick membranes will be compared to significantly thinner membranes of 5 and 10 microns. Acknowledgments This research is supported by DOE Fuel Cell Technologies Office, through the Fuel Cell Performance and Durability (FC-PAD) Consortium; Fuel Cells program manager: Dimitrios Papageorgopoulos. References 1. T. E. Springer, M. S. Wilson, and S. Gottesfeld, J. Electrochem. Soc. , 140 ( 12) , 3513–3526 (1993). 2. R. Borup and T. Rockward, US Dep. Energy Annu. Merrit Rev., Project ID: FC052 (2015). https://www.hydrogen.energy.gov/pdfs/review15/fc052_rockward_2015_p.pdf

Yue Wang, Haitao Wang, Kejian Li

Volume 2: Nuclear Fuel and Material, Reactor Physics and Transport Theory, and Fuel Cycle Technology • 2022

Abstract IN617 was considered the primary material candidate for the IHX in the VHTR. Researching microstructure evolution during high-temperature creep of IN617 helped understand its fracture laws and guide IHX operation under creep loading. Creep tests of IN617 were conducted under 19 MPa, 24 MPa, 27 MPa, and 38 MPa at 950 °C. Creep rupture mechanisms of IN617 were discussed by correlating creep performance, microstructure characteristics and fracture-surface morphology. The results indicated that DRX, creep voids and brittle-phase precipitation were found under different stresses during microstructure observation, which would cause the specimen ductile rupture, intergranular rupture and brittle rupture, respectively. Specifically, under the highest stress 38 MPa, DRX occurred and grain size was decreased greatly to 11.1 μm from 99.7 μm. Fine grains were easy to migrate, causing significant plastic deformation and ductile rupture of specimens. With stress decreased to 27 MPa, grain boundaries became vulnerable and intergranular rupture occurred because intergranular carbides dissolved and their pinning effect was weakened. As stresses were lowered to 24 MPa and 19 MPa, nitrogen was diffused into specimens and brittle nitrides precipitated into continuous networks along GBs. The internal cracking of nitride networks caused brittle rupture. Meanwhile, steady creep rates were increased, and creep rupture lives were shortened greatly, especially under 19 MPa.

Lorena Peñacoba-Antona, Carlos Andres Ramirez-Vargas, Colin Wardman et al.

Frontiers in Microbiology • 2022

A METland is an innovative treatment wetland (TW) that relies on the stimulation of electroactive bacteria (EAB) to enhance the degradation of pollutants. The METland is designed in a short-circuit mode (in the absence of an external circuit) using an electroconductive bed capable of accepting electrons from the microbial metabolism of pollutants. Although METlands are proven to be highly efficient in removing organic pollutants, the study of in situ EAB activity in full-scale systems is a challenge due to the absence of a two-electrode configuration. For the first time, four independent full-scale METland systems were tested for the removal of organic pollutants and nutrients, establishing a correlation with the electroactive response generated by the presence of EAB. The removal efficiency of the systems was enhanced by plants and mixed oxic–anoxic conditions, with an average removal of 56 g of chemical oxygen demand (COD) m bed material –3 day –1 and 2 g of total nitrogen (TN) m bed material –3 day –1 for Ørby 2 (partially saturated system). The estimated electron current density ( J ) provides evidence of the presence of EAB and its relationship with the removal of organic matter. The tested METland systems reached the max. values of 188.14 mA m –2 (planted system; IMDEA 1), 223.84 mA m –2 (non-planted system; IMDEA 2), 125.96 mA m –2 (full saturated system; Ørby 1), and 123.01 mA m –2 (partially saturated system; Ørby 2). These electron flow values were remarkable for systems that were not designed for energy harvesting and unequivocally show how electrons circulate even in the absence of a two-electrode system. The relation between organic load rate (OLR) at the inlet and coulombic efficiency (CE; %) showed a decreasing trend, with values ranging from 8.8 to 53% (OLR from 2.0 to 16.4 g COD m –2 day –1 ) for IMDEA systems and from 0.8 to 2.5% (OLR from 41.9 to 45.6 g COD m –2 day –1 ) for Ørby systems. This pattern denotes that the treatment of complex mixtures such as real wastewater with high and variable OLR should not necessarily result in high CE values. METland technology was validated as an innovative and efficient solution for treating wastewater for decentralized locations.

O A Alo, I O Otunniyi, HCVZ Pienaar

IOP Conference Series: Materials Science and Engineering • 2019

Abstract Conductive polymer composites (CPCs) are very promising candidate materials for bipolar plates (BPs) in polymer electrolyte membrane fuel cells (PEMFCs). However, a major challenge facing application of CPCs in PEMFC BPs is the difficulty in achieving high electrical conductivity while maintaining adequate mechanical strength. Therefore, a good balance between electrical conductivity and mechanical strength is critical in the development of high-performance CPC BPs. In this study, CPCs consisting of polypropylene (PP)/epoxy blend filled with graphite were investigated for application as BP material, which will combine electrical conductivity and mechanical strength that meet the performance requirements for PEMFC BPs. The CPCs, with 30 – 80 wt% graphite powder, were produced by melt mixing followed by compression molding. The morphology, in-plane electrical conductivity, and flexural strength of the composites were investigated using the scanning electron microscopy, four-point probe method, and three-point bending test, respectively. The results obtained were compared with the technical targets for PEMFC BPs by the United States Department of Energy (DOE). All the PP/epoxy/graphite composites exhibited flexural strength that satisfies the DOE target of > 25 MPa while the composite with 80 wt% graphite content showed the best in-plane electrical conductivity.

Yannick Garsany, Megan B. Sassin, Benjamin D. Gould et al.

ECS Meeting Abstracts • 2017

The performance of PEMFCs has been linked to the porosity of the catalyst/carbon/ionomer composite in the cathode catalyst layer (CL), and this can be controlled to some degree by the equivalent weight (EW) of the ionomer.(1) Here, we study impact on PEMFC performance when the cathode CL contains a low equivalent weight (LEW) ionomer having short-side-chains (SSCs). Inks for the CLs are prepared using Pt/C electrocatalysts and either 27 wt.% Aquivion® SSC perfluorosulfonic acid ionomers (i.e. Aquivion® ionomer 980 EW, 830 EW and 700 EW) or a standard 33 wt.% long-side chain (LSC) Nafion® 1100 EW ionomer. The Pt/C/ionomer ink is directly deposited onto the Nafion proton exchange membrane by direct ultrasonic spray deposition to form catalyst-coated membranes (CCMs). The effects of ionomer EW on the surface area, pore structure and morphology of the prepared cathode CLs are surveyed by nitrogen adsorption and scanning electron microscopy (SEM). The CCMs are assembled into membrane electrode assemblies (MEAs), and the performance of the resulting MEAs are analyzed by I-V polarizations at different cell operating temperatures (i.e. 95, 80, 70 and 40°C) and relative humidity (i.e. 100, 70, 50 and 25% RH) in both air and oxygen environments. Cyclic voltammetry is used to determine the cathode CLs Pt ECSA and Pt utilization. In situ electrochemical impedance spectroscopy is used to understand the polarization losses in the cells, particularly in the mass transport region where electrode porosity has a large impact on flooding. Figure 1 compares the average polarization curves measured for 5 MEAs employing the SSC ionomer in their cathode CLs (i.e. Aquivion® 830 EW) to 5 MEAs employing the LSC ionomer in their cathode CLs (i.e. Nafion® 1100EW) at 80°C fed with ambient pressure air humidified at 100 % and 50 % RH. In the kinetic region (i.e. E ≥ 0.80 V) of the polarization curves, the cell performance of both set of MEAs are identical at both 100 and 50% RH. In the mass transport region at high current densities, the MEAs containing the SSC ionomer in their cathode CLs perform better than those containing the LSC ionomer in their cathode CLs under both moderate (50%) and high (100%) relative humidity. Our results appear to be unique because others have only seen improvement in PEMFCs with SSC LEW ionomers under low RH conditions, while we see performance improvements from the LEW SSC ionomers across the full range of RH. (1, 2) This presentation will discuss how the SSC ionomer affects the physical attributes of the MEA (porosity, impedance), resulting in higher performance at high current densities independent of the RH. Figure 1. Comparison of the average polarization curves measured for 5 Pt/VC MEAs employing the SSC ionomer (Aquivion® 830EW) in their cathode CLs to 5 Pt/VC MEAs employing the LSC ionomer (Nafion® 1100EW) in their cathode CLs at 80°C fed with ambient pressure air humidified at 50% and 100% RH. 1. C. Lei, D. Bessarabov, S. Y. Ye, Z. Xie, S. Holdcroft and T. Navessin, J Power Sources , 196 , 6168 (2011). 2. Y. C. Park, K. Kakinuma, H. Uchida, M. Watanabe and M. Uchida, J Power Sources , 275 , 384 (2015). Figure 1

Neerudi Bhoopal, Dokku Sivanaga Malleswara Rao, Nagineni Venkata Sireesha et al.

Journal of New Materials for Electrochemical Systems • 2022

The chemical energy of a hydrogen-oxygen reaction is converted directly into dc electrical energy by fuel cells (FC). PEMFCs (Proton Exchange Membrane Fuel Cells) are a feasible alternative for electrical transportation and stationary applications. This paper presented a PEMFC modelling approach using Artificial Intelligence. The main objective of this research is to build a model of an 18w Polymer Electrolyte Membrane (PEM) fuel cell and test its performance under different hydrogen pressure conditions. The physical model of the 18W hydrogen fueled PEM fuel cell is designed and tested at BHEL R&D. Additionally, a method for predicting a PEMFC's operating temperature using the voltage and current measures is suggested and successfully tested. However, the proposed technique is validated using experimental data from an 18W fuel cell. The analytical data and testing procedures required for determining the parameter values used in the proposed model are specified.

Somayeh Toghyani, Seyed Ali Atyabi, Xin Gao

Energies • 2021

One of the marketing challenges of unmanned aerial vehicles (UAVs) for various applications is enhancing flight durability. Due to the superior characteristics of proton exchange membrane fuel cells (PEMFCs), they have the potential to reach a longer flight time and higher payload. In this regard, a numerical assessment of a UAV air-cooled PEMFC is carried out using a three-dimensional (3-D), multiphase, and non-isothermal model on three flow fields, i.e., unblocked bean-shaped, blocked bean-shaped, and parallel. Then, the results of single-cell modeling are generalized to the PEMFC stack to provide the power of 2.5 kW for a UAV. The obtained results indicate that the strategy of rising air stoichiometry for cooling performs well in the unblocked bean-shaped design, and the maximum temperature along the channel length reaches 331.5 K at the air stoichiometric of 30. Further, it is found that the best performance of a 2.5 kW PEMFC stack is attained by the bean-shaped design without blockage, of which its volume and mass power density are 1.1 kW L−1 and 0.2 kW kg−1, respectively. It is 9.4% lighter and 6.9% more compact than the parallel flow field. Therefore, the unblocked bean-shaped design can be a good option for aerial applications.

M. Hou, P. Ming, D. Sun et al.

Fuel Cells • 2004

Abstract This paper describes a PEM Fuel Cell Engine (FCE) with 40 kW stacks designed for a car. This was developed by DICP and Sunrise Power and is funded by the Chinese “863” key project. The FCE system construction, stack performance, specifications, and operating characteristics are explained. The efficiency of the FCE is analyzed. The net power output for this FCE is 27 kW and the efficiency is 35–38%. The utilization of air and hydrogen are more than 50% and 97%, respectively.

Wang Jian Hui, Ewusi-Mensah David, Jingyu Huang

Journal of Water Reuse and Desalination • 2019

Abstract Algae biocathodes have become one of the most sustainable replacements for abiotic cathodes which were expensive and had toxic chemical oxidant by-products. In this study, a pure culture of Chlorella vulgaris from a photobioreactor was pumped into a photosynthetic microbial desalination cell to treat real landfill leachate (had undergone physical treatment) under varying ‘factor-conditions (FC)’ to embark on a factor-performance relation (FPR) study. This aimed at determining the relationship between operating factors and to depict the most favourable conditions (and range) in order to boost the overall performance of the reactor/cell. Three groups of FC (A, B and C) were adapted, in that, under FC A external resistance was varied, FC B varied pumping rate and FC C varied temperature, light intensity and dissolved oxygen under conditions flow and recirculation mode. Results showed 95% chemical oxygen demand (COD) removal, a maximum power density of 121.57 mWm−2 (anodic volume) and an average desalination rate of 3.93 mg/L/h. The varying results at different FC showed the significant impact of operating conditions on performance. Algae biocathodes also proved to be an essential benefit in boosting the sustainable application of microbial desalination cells (MDCs) in wastewater and landfill pre-treatment as well as the generation of bioenergy.

Ahmed O. Said, Ashwani K. Gupta

ASME 2016 Power Conference • 2016

Fuel injection at two locations in a combustor using premixed, partially pre-mixed and non-premixed schemes has been explored for improved distributed combustion. The effect of dual location fuel injection to the combustor is examined and the results compared from single fuel injection. Focus of dual and single injection scheme was on enhancing reaction zone uniformity in the combustor. A cylindrical combustor at a combustion intensity of 36MW/m3.atm and heat load of 6.25 kW was used. Three different schemes of dual location fuel injection with different proportions of fuel injected from each injector were investigated using methane as the fuel. The role of fuel distribution between the two injection ports using constant air flow rate to the combustor at room temperature was examined on reaction zone distribution and pollutants emission. Three different equivalence ratios of 0.6, 0.7 and 0.8 were examined with different fuel distributions between the two injectors to the combustor at a constant overall thermal load. The results showed lower emission with dual location fuel injection as compared to single location. Dual location fuel injection showed 48% NO reduction with 90% of the total fuel from injector 1 while only 13% reduction was achieved with 80% of the fuel injection from this location. . OH* Chemiluminescene intensity distribution within the combustor showed that under favorable fuel injection condition, the reaction zone shifted downstream to allow longer fuel mixture preparation time prior to ignition. The longer mixing time resulted in improved mixture preparation and lower emissions. The OH* Chemiluminescene intensity distribution with fuel introduced through two injectors showed improved OH* distribution in the combustor. Improved mixture preparation enhanced reaction distribution in the combustor and lower emission.

Miriam Schüttoff, Christian Wachtel, Robert Schlumberger et al.

Fuel Cells • 2024

ABSTRACT Polymer electrolyte membrane fuel cell durability is still a major challenge. To overcome time‐consuming durability tests, so‐called accelerated durability tests (ADTs) are of urgent need. This work presents our recent results in developing ADT protocols in the context of realistic operating conditions, especially voltage clipping at 0.85 V. A 5500 h long‐term test was carried out as a reference applying a realistic automotive drive cycle. Focusing on different stressors such as temperature, relative humidity (RH), and load profile four different ADT protocols of 1200 h duration were derived. Seven‐cell short stacks with 240 cm 2 active area were used. Comparing cell voltage as a key indicator, an acceleration factor of 3–7 could be achieved. In‐situ characterization techniques such as spatially resolved current measurement, cyclic voltammetry, and electrochemical impedance spectra were employed to investigate the influences of individual stressors on specific degradation mechanisms and components. The highest acceleration was observed in the mass transport region of ADTs addressing RH as a stressor, suggesting that RH cycling leads to increased degradation of hydrophobic surfaces. Increased temperature was found to accelerate primarily carbon support degradation. Accelerated catalyst aging seems to be low, demonstrating the effectiveness of voltage‐clipping conditions. Our most promising ADT shows quite a homogeneous acceleration of voltage degradation across all current regions.

Jingrong Yu, Ping Cheng, Zhiqi Ma et al.

1st International Fuel Cell Science, Engineering and Technology Conference • 2002

The fabrication of miniature silicon wafer fuel cells by micro-fabrication technologies and their performance evaluation are presented in this paper. Various thickness of Nafion membranes, such as Nafion 117, 115, and 112, were tested as electrolytes in a miniature single cell operating with dry H2/O2. Among these membranes, Nafion 112 (with the thinnest thickness) gave the best performance of 92.2 mW/cm2 at 250mA/cm2. In order to enhance the output voltage of the fuel cell, a miniature twin-fuel-cell was fabricated in series using two membrane-electrode-assemblies of Nafion 112 membrane sandwiched between two silicon substrates. The novel structure of the miniature twin-fuel-cell is that the electricity interconnect from the cathode of one cell to the anode of another cell is made on the same plane. The interconnect is fabricated by sputtering a layer of gold on the top of the silicon wafer. Silicon dioxide is deposited on the silicon wafer adjacent to the gold layer to prevent short-circuiting between the twin-cells. At ambient conditions, the measured peak power densities of the miniature twin-fuel-cell operating with H2/O2 and 1.5M methanol/O2, are 190.4mW/cm2 and 15.4mW/cm2, respectively.

T. A. Greszler, T. E. Moylan, H. A. Gasteiger

Handbook of Fuel Cells • 2010

Abstract Starting from fundamental principles, we have developed an isothermal, one‐dimensional model for cation contamination of a proton exchange membrane (PEM) fuel cell. When current is drawn, the foreign cations migrate toward the cathode under the influence of the potential gradient while diffusion acts to balance this migration. The model provides the electrolyte potential along with the concentration of water, cation, and proton across the membrane electrode assembly (MEA) at steady‐state condition. The voltage loss associated with cation contamination is largely thermodynamic in nature owing to the proton concentration (pH) difference that develops between the anode and cathode. This potential loss is proportional to current density and inversely proportional to water content. If the cation fraction in the cathode approaches unity, the cell current becomes limited because of proton starvation. The model is validated with experimental hydrogen pump performance data using lithium‐doped MEAs. Hydrogen/oxygen operation is presented experimentally and discussed, but not explicitly modeled because of the added complications introduced by the sluggish oxygen reduction reaction kinetics. Experimental data for cobalt‐doped MEAs, which can react in the cathode when the local pH increases above five, is presented and explained with the aid of cobalt's Pourbaix diagram. Finally, the effect of cobalt ion contamination (e.g., from PtCo cathode catalysts degradation) on H 2 /air PEMFC performance under automotive conditions is shown.

C. Fink, S. Gößling, L. Karpenko‐Jereb et al.

Fuel Cells • 2020

Abstract The polymer electrolyte membrane (PEM) fuel cell model of a commercial software package is presented. The basic performance model is extended by two chemical degradation effects: ionomer degradation and carbon corrosion including platinum oxidation. The ionomer degradation model describes the ionomer mass loss due to hydrogen peroxide formation and subsequent attack of the ionomer by radicals. The carbon corrosion model calculates the carbon mass loss caused by carbon oxidation and the active area reduction due to platinum oxidation. The degradation models are coupled with an agglomerate model of the catalyst layer. The model is validated against measurements on an industrial cell. For these measurements, the cell is equipped with a segmented measuring board, which is used to measure the current density distribution and high frequency resistance of every segment. In order to test the predictability of the model under different operating conditions, measurements for stoichiometry and pressure variations are carried out. Calculated and measured current density distributions of the cell, aged by an accelerated stress test, are compared for the validation of the degradation model. Moreover, 3D simulation results of the fresh and aged cells are analyzed in detail and the influence of operating conditions on fuel cell aging is pointed out.

Yu Yang, Hen-Geul Yeh, Bryan Aguirre

• 2025

As California advances its ambitious goals for transportation electrification to combat climate change, hydrogen-powered fuel cells are emerging as a viable solution for overcoming the challenges of heavy-duty vehicles, offering an efficient alternative to lithium-ion batteries because they produce minimal chemical, thermal, and carbon emissions. One type of hydrogen fuel cell technology called proton exchange membrane fuel cells (PEMFCs) has garnered the most attention due to its distinct advantages, including relatively low operating temperatures (60–80 °C) and reliable performance at high current densities. However, despite their promise, PEMFCs face challenges, including in optimizing stack power output and safety concerns. To tackle these issues, accurate modeling and control strategies are essential. This study focuses on using data-driven modeling (specifically using a process known as “closed-loop system identification” under proportional controller and pseudo-random binary sequence excitation methods) to better understand and manage PEMFC systems. Various transfer functions models were analyzed, including first-order, first-order plus time delay, second-order, and second-order plus time delay models. The resulting closed-loop identification approach was applied on the humidifier, cooling, and oxygen supplier subsystems of simulated PEMFC to build their models under controlled operations. The results of this study highlight the potential of closed-loop system identification techniques to improve fuel cell vehicle performance in power supply, water, and heat management, without interrupting PEMFC operations. These findings demonstrate the significance of precise modeling as a cornerstone for advancing PEMFC control strategies and optimizing their application in renewable transportation and a more sustainable future.

, Pitch Sakwong

• 2008

This work aimed to study the effects of modified Montmorillonite clay (m-MMT) loading on the mechanical and thermal properties of the Nafion®/m-MMT composite membrane prepared by solution mixing method. Nafion® perfluorinated resin (5 wt% in lower aliphatic alcohol and water) was mixed with m-MMT (Bentone SD®1) at 0, 3, 6, and 10 phr. The structures of the composite membranes were studied by XRD. Their performances were determined in terms of water uptake, ion exchange capacity (IEC), thermal and mechanical properties. The XRD results showed that the interlayer spacing of m-MMT was decreased when incorporated into Nafion® matrix. Hence, the Nafion® matrix did not intercalate into interlayer spacing of m-MMT and the composite obtained was of a conventional composite type. The water uptake of Nafion®/m-MMT composite membrane increased with increasing amount of m-MMT in Nafion® matrix but the IEC values of Nafion®/m-MMT composite membranes decreased. These effects would balance each other out and the proton conductivity of Nafion®/m-MMT composite membranes would not differ from the pristine Nafion® membrane. The elastic moduli of soaked Nafion®/m-MMT composite membranes were about equal to the soaked pristine Nafion® membrane but the elongation at break of the soaked Nafion®/m-MMT composite membranes were lower. Therefore, the incorporation of this m-MMT into Nafion® matrix at least helped reduce the decay of these mechanical properties by counteracting the effects of increasing water uptake in the composite membranes.

Abu Danish Aiman Bin Abu Sofian, Vincent Lee, Henry Marn Jhun Leong et al.

Food Technology and Biotechnology • 2025

Research background. The increasing environmental concerns due to fossil fuel consumption and industrial wastewater pollution necessitate sustainable solutions for bioenergy production and wastewater treatment. Palm Oil Mill Effluent (POME), a high-strength industrial wastewater, poses significant environmental challenges. Microbial Electrolysis Cells (MEC) and Microbial Fuel Cells (MFC) offer promising avenues for bioenergy recovery from such wastewaters. Experimental approach. Dual-chamber H-type reactors equipped with proton exchange membranes were employed to separately assess MEC and MFC performance in bioenergy production from POME. Hydrogen generation and COD removal in MECs were evaluated at varying applied voltages and influent COD concentrations, while the impact of external resistance on power output and COD reduction was investigated in MFCs. Response Surface Methodology (RSM) was used to optimise these operational parameters for maximal bioenergy recovery and efficient wastewater treatment. Results and conclusions. The findings revealed that hydrogen production and COD removal efficiency in MECs were maximised at low influent COD levels and low voltage supply. The MEC demonstrated effective hydrogen production and wastewater treatment, while the MFC achieved significant electricity generation and COD reduction. Field emission scanning electron microscopy confirmed the formation of biofilms on the electrodes, indicating active microbial communities involved in bioenergy generation. A trade-off between power density and COD removal efficiency in MFCs was observed, with medium resistance levels yielding maximum power output. The integration of MEC and MFC showed potential for treating high-strength industrial wastewater like POME, offering a greener and more energy-efficient approach. Novelty and scientific contribution. This study demonstrates the potential feasibility of integrating MEC and MFC technologies for simultaneous bioenergy production and wastewater treatment from POME. It advances knowledge in biochemical engineering by optimising operational conditions for enhanced bioenergy recovery and highlights the role of microbial communities in bioelectrochemical systems. The findings provide a foundation for future research on sustainable bioenergy production and contribute to environmental sustainability efforts.

A.L. Vázquez-Larios, O. Solorza-Feria, R. de G. González-Huerta et al.

Journal of New Materials for Electrochemical Systems • 2013

The objectives of this work were to evaluate (i) the application of a bimetallic chalcogenide, RuxMoySez, as an oxygen reduction reaction (ORR) catalyst and (ii) the effect of the type of two anodic materials on the performance of two microbial fuel cells (MFCs). A single chamber MFC-T was built with a plexiglass cylinder, the two extreme circular faces were fitted with PEM-cathode assemblage, i.e., left and right faces. The anode consisted of 65 small triangular pieces of graphite filling the anodic chamber. A second MFC-C had a ‘sandwich’ arrangement anode-PEM-cathode. The cathodes were made of ?exible carbon-cloth containing catalysts loading of 1mg/cm2 RuxMoySez or 0.5mg/cm2 Pt. Power derived by cell T with cathode chalcogenide catalyst was 43% inferior to that of a similar cell with Pt although the cost of the first catalyst is significantly lower than that of Pt, i.e., 73% lower. Finally, application of graphite anode made of small triangular pieces significantly improved the performance of a MFC-T that used RuxMoySez as a cathodic catalyst for ORR.

Sabrina Marie Schuler

• 2021

Within the sagebrush steppe, fire has been shown to affect biogeochemical properties and the microbial community composition in soils. However, there is uncertainty about the magnitude and direction of these effects, since they vary by sites that differ in abiotic and biotic conditions. Moreover, differences in post-fire management strategies are likely to mediate the effect of fire on soil properties, thus further compounding this uncertainty. Any changes in soil biogeochemical properties following fire can prevent successful restoration of Artemisia tridentata sp. wyomingensis (sagebrush), leading to variable outcomes of restoration success in the sagebrush steppe. Previous research has shown that addition of native soil microbes and biochar can improve ecosystem restoration efforts, but the effects of these soil amendments on post-fire soil properties and sagebrush performance across sites are uncertain. With this study, I investigated how fire impacts soil properties (i.e., soil organic matter (SOM), soil structure, carbon (C) and nitrogen (N) concentrations, soil pH, net mineral N, microbial richness and composition) at a variety of sites that differ in time since exposure to fire, post-fire plant communities, and post-fire site management. I then implemented a greenhouse study to evaluate how amending soils with native microbial community inocula and biochar impact soil properties of the post-burn sites and sagebrush germination and growth. Taken together, these findings capture the influences of multiple fires and separate management strategies on soil properties, and how certain soil amendments may redirect soil recovery to aid in sagebrush restoration. In my first chapter, I asked two questions: (1) how does fire affect soil biochemical properties across sites that differ in fire history, post-fire plant communities, and post-fire site management, and (2) how does fire affect soil microbial richness and community composition across sites that differ in post-fire plant communities, and post-fire site management. To assess these questions, soils were collected from three south of Boise, Idaho within the Orchard Combat Training Center (OCTC) that contrasted in fire history, plant community, and post-fire management. The northern part of the Union Fire (180 acres; hereafter: UFN2011) burned in 2011, and was treated with a mix of imazapic and glyphosate during the spring of 2019, after which sagebrush was handplanted 8 months later that yea. The southern part of the Union Fire (160 acres; hereafter: UFS2011) burned in 2011 and seeded with native grass species and planted with sagebrush. The Christmas Fire (hereafter: CF2018) burned in 2018, and was subjected to the same seeding and handplanting treatments as UFS2011. At each site, I selected five locations within the perimeter of the burn, and five locations outside the burn, representing the unburned control plots. In these unburned control plots, the five locations were stratified by sagebrush canopy and interspace microsites separately. At each one of the five locations, I collected four soil cores (10cm depth, 2.5cm diameter). I evaluated differences in soil pH, soil organic matter (SOM), soil carbon (C) and nitrogen (N) contents, soil structure, N cycling, and soil microbial communities between burned and unburned sites. Fire reduced SOM and soil C contents, and these losses were greater in burned areas that received an herbicide treatment. This suggests that suppression of plant growth using herbicides may limit the recovery of soil properties that are foundational to sagebrush steppe ecosystem functioning. Furthermore, I found a loss of arbuscular mycorrhizal fungi (AMF) richness with fire and significant changes in soil microbial community structure when herbicide had been used. Finally, increased soil mineral N concentrations across all burned sites indicate that fire may significantly reduce ecosystem stability and increase the risk of invasion. These changes in soil properties are likely to lead to a persistent ecosystem state-changes in the sagebrush steppe, and future studies should evaluate which management approaches could be used to restore both soils and plant communities. In my second chapter, I investigated two management approaches that may be used to restore the soils and plant communities impacted by fire. I asked (1) How does a live native soil microbial inoculum impact sagebrush performance and soil properties, (2) how do biochar additions impact sagebrush performance and soil properties, and (3) how does prior management (e.g., herbicide) mediate the impact of soil microbial inoculation and biochar amendment on sagebrush performance? A full factorial greenhouse experiment was conducted for three months with soils collected from the three post-burn sites described in Chapter 1. In the greenhouse experiment I incorporated the following treatments: (1) sterile native inoculum [-Inoculum] and no biochar [-Biochar], (2) live native inoculum [+Inoculum] and no biochar [-Biochar], (3) sterile native inoculum [-Inoculum] and biochar [+Biochar], and (4) live native inoculum [+Inoculum] and biochar [+Biochar]. Inocula was derived from sagebrush canopies at unburned sites and either added as live native inocula or autoclaved to sterilize the microbial community. Biochar was crushed into planted, watered daily until cotyledons showed, and continually monitored throughout the growing period. Germination, soil moisture content and pH, above- and below-ground measurements, total mineral N, fungal root colonization proportional abundances, and microbial richness and composition were assessed. I found that inoculations did not significantly benefit sagebrush performance, most likely due to the ratio of inocula administered. In contrast, biochar consistently enhanced soil moisture, pH, sagebrush germination and other performance variables while its effects on total mineral N and fungal root colonization varied by site location. Lastly, presence of herbicide in post-burn soils significantly altered soil bacterial and fungal community composition, and its effects persisted enough to inhibit sagebrush performance. Together, my data show that addition of biochar has a greater positive impact on sagebrush germination and performance than addition of soil microbial inocula, and that herbicide addition has persistent negative impacts on sagebrush performance. My study captured the varying levels at which fire impacts ecosystem structure and function, and how different soil amendments affected sagebrush performance at these post-fire soils. My findings support the notion that soil properties will remain degraded without appropriate management strategies supporting restoration, and herbicide may actually suppress successful restoration, residing longer in the soil than previously documented. When growing sagebrush in post-burn soils within the greenhouse, biochar enabled soil recovery, and this benefited sagebrush performance. However, herbicide impacts persisted and decreased sagebrush biomass even when soil amendments were incorporated. Fire can have profound, yet vastly different, influences on soil properties, and soil amendments may be able to augment soil recovery. Future studies should investigate various soil amendments and their impacts on sagebrush performance in the midst of changing fire regimes, post-fire vegetation shifts, and current post-fire management.

Da Liu, Ruiwen Wang, Wen Chang et al.

Journal of Materials Chemistry A • 2017

Ti 3 C 2 MXene as the MFC anode facilitates bacterial adhesion and extracellular electron transfer, thus resulting in a power density of 3.74 W m −2 .

Hamed Dashtaki, Davood Ghadiri Moghaddam, Mohammad Jafar Kermani et al.

ASME 2010 8th International Fuel Cell Science, Engineering and Technology Conference: Volume 1 • 2009

In this paper, a simplified model partial pressure of Polymer Electrolyte Membrane Fuel Cell (PEMFC) is introduced. A Multi-Input–Multi-Output (MIMO) dynamic model with two inputs and two outputs is considered, where the inputs are control variable of anode and cathode, and the outputs are partial pressures of hydrogen and oxygen. Initially, the H∞ robust control strategies were applied to stabilize the system. The results show that the amplitude of alternative disturbances is decreased from 10 atm to 0.25 atm. Also, the pressure of each electrode tracks various input pressure profiles with negligible steady-state errors. On the other hand, the electrode pressure does not depend on the variations of constrained electrical current profiles by consumer in the PEM fuel cells. According to unsuitable percent overshoot (P.O.) and settling time of transient model response, system identification techniques are adopted to estimate the system’s transfer functions. After that a PID controller acting as a supervisory controller is properly developed to adjust the transient state behavior of the overall system. This makes the amplitude of alternative disturbances decrease from 10 atm to 0.003 atm. With this controller, the percent overshoot also decreases from 46% to 2% and the settling time (for 2% error) decreases from 0.26 to 0.03 seconds.

Jiyeon Kim, Hongsuck Kim, Byunggoon Kim et al.

Water Science and Technology • 2014

A key criterion in microbial fuel cell (MFC) design is that the bio-electrochemical reaction between bacteria and the bulk solution should occur evenly on the electrode surface in order to improve electricity generation. However, experimental optimization of MFC design over a wide range of conditions is limited. Computational fluid dynamics (CFD) technology makes it possible to evaluate physicochemical phenomena such as fluid flows, mass transfer and chemical reaction, which can assist in system optimization. Twelve MFCs (M1–M12) with different internal structures were subjected to CFD analysis. The dead (DS) and working spaces (WS) of the anode compartment were calculated. The flow patterns of the anodic fluid varied according to the internal structures. The WS where the bio-electrochemical reaction can actually occur varied over the range of 0.14–0.57 m2. Based on the above results, the power densities were estimated under the assumption that a monolayer biofilm was formed on the electrode. M11, with 18 rectangular-type internal structures, showed the largest WS of 0.57 m2 and a theoretical maximum power density of 0.54 W/m2. Although the optimization of the MFC configuration with only CFD analysis remains limited, the present study results are expected to provide fundamental data for MFC optimization.

Wei Yang, Jun Li, Linghan Lan et al.

ChemCatChem • 2019

Abstract As a renewable energy technology, microbial fuel cell (MFC) has been attracting increasing attention in recent decades. However, practical applications of MFCs has been hampered by the unsatisfactory electrode performance, in particular, at the cathode. Herein, Fe/N/S‐doped carbon hollow tubes were prepared by a facile two‐stage procedure involving hydrothermal treatment and pyrolysis at controlled temperatures. Electrochemical studies showed that the obtained samples exhibited an apparent electrocatalytic activity towards oxygen reduction reaction in both alkaline and acidic media, a performance comparable to that of commercial Pt/C, and the sample prepared at 800 °C stood out as the best among the series with a half‐wave potential of +0.81 V vs. RHE and an electron transfer number of 3.98 at +0.6 V vs. RHE. The Fe/N/S‐doped carbon tubes also exhibited a remarkable performance as an MFC anode by facilitating bacterial growth and electron transfer between the biofilm and electrode. In fact, an MFC based on the carbon tubes as both cathode and anode showed a markedly higher performance (maximum power density 479 W m −3 ) than the control MFC based on a graphene aerogel anode and Pt/C cathode (359 W m −3 ). These results suggest that Fe/N/S‐doped carbon composites can be used for the fabrication of high‐efficiency MFC electrodes.

Huidong Li, Lu Zhang, Ruiwen Wang et al.

EcoMat • 2022

Abstract Microbial fuel cells (MFCs) that can directly convert chemical energy of organic matter into electrical energy are expected to continuously obtain energy from wastewater. However, the practical application of MFCs is still limited by unsatisfactorily low power output due to low bacterial loading capacity and relatively poor extracellular electron transport (EET) efficiency between anode and electrochemically active biofilm. Herein, hierarchical porous carbon foams (HPCFs) prepared by pyrolyzing nanoscale Fe‐MIL‐88B‐NH 2 modified seitan composite were developed as 3D free‐standing MFC anodes. Its marcoporous structure and good biocompatibility favor the bacterial adhesion, while the N‐doped carbon skeleton, abundant mesopores and iron ions boost the bacteria‐electrode charge transfer efficiency. As a result, the HPCF anodes equipped MFCs deliver a maximum power density of 11.21 W m −3 and a current density of 23.11 A m −3 , outperforming the most previously reported 3D porous anodes. This study provides a new idea for the design of anodes for high‐performance MFCs. image

Ziwei Zhong, Lingkai Zhu, Wei Zheng et al.

E3S Web of Conferences • 2021

With the establishment of the goal of “carbon peaking and carbon neutralization”, a new power system based on new energy is proposed. With the rapid development of ultra-high voltage external power and new energy in Shandong power grid, the difficulty of system peak regulation is increasing. At present, the peak regulation is mainly based on direct regulating thermal power units. The capacity of pumped storage power stations is limited and there are no gas-fired generating units, which also leads to serious shortage of other flexible regulation resources that Shandong power grid can call. In 2022, Shandong Province plans to implement the renewable energy multiplication plan, and it is expected that the installed capacity of new energy will account for 38%. With the large-scale access of new energy, the “double high” characteristics of the power system are highlighted, and the technical characteristics and stability mechanism of the power grid will undergo profound changes. In the new power system with new energy as the main body, the role of thermal power generation has gradually changed from the electric power source to the regulating power source. Under the variable load conditions, find the optimal efficiency conditions and provide necessary data for the optimal denitration efficiency operation.

Antonio Martín-Alcántara, Laura González-Morán, Javier Pino et al.

Processes • 2022

The influence of the different properties of the gas diffusion layer (GDL) on the operation of a liquid-cooled, proton-exchange polymer electrolyte fuel cell (PEMFC) has been studied in this work. Three-dimensional numerical simulations (CFD) have been conducted to compare several commercial GDLs with different properties, analyzing their influence on the cell performance. Specifically, four GDLs (AvCarb P-75, SIGRACET 34BC, SIGRACET 34BA and Toray TGP-H-090) have been studied, two of them including a microporous layer (MPL). The effect of the MPL has been inspected by contrast of the results obtained with the same GDL, with or without MPL. Potentiostatic boundary conditions have been applied, varying the electric potential between 1.05 and 0.35 V to obtain a representative i−V curve with enough resolution. Detailed postprocessing tasks were carried out to gain a deeper understanding on the phenomena occurring within the cell for each GDL. It can be concluded from this work that a high electrical conductivity and a high permeability lead to a better fuel cell performance. On the other hand, although the presence of MPL provides lower permeability leading to a worse overall performance, it has been shown that the lack of it may result in membrane dehydration and cell degradation issues.

Atul Verma, Ranga Pitchumani

ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology • 2013

Understanding the performance of proton exchange membrane (PEM) fuel cells is critical to the water management in the fuel cell system. Low-humidity operating conditions present a complex interaction between dynamic behavior and water transport owing to different time scales of water transport mechanisms in the transient process. Toward understanding the effects of membrane properties on the dynamic behavior, this paper presents numerical simulations for a single channel PEM fuel cell undergoing changes in load, by subjecting the unit cell to step change in current. The objective is to elucidate the complex interaction between cell voltage response and water transport dynamics for various membrane properties, where the performance is critically related water content of the membrane. Detailed computational fluid dynamics (CFD) simulations are carried out to show that step increase in current density leads to anode dryout due to electro-osmotic drag, and investigate its dependence on variations in membrane properties.

Sébastien Wasterlain, Denis Candusso, Fabien Harel et al.

Journal of Fuel Cell Science and Technology • 2010

A three-cell polymer electrolyte membrane fuel cell stack equipped with perfluorinated ionomer membranes is tested for 1000 h in severe operating conditions. The fuel cell (FC) is fed by dry hydrogen/low humidified air and it is simultaneously operated at overnominal temperature. During the long term experiment, some polarization curves and electrochemical impedance spectra are recorded at regular time-spaced intervals for various stoichiometry rates. The objective is to characterize the degradation of FC performances with the aim to better understand the FC aging mechanisms. Some response surfaces are plotted to display and analyze the stack voltage variations as a function of aging time, static load current, and gas utilization rates. Different points of the FC impedance spectra are also considered. The evolutions of their coordinates in the Nyquist plot can be monitored versus aging time and for different gas utilization rates.

V. Venkatramanan, Shachi Shah, Ram Prasad

The Open Biotechnology Journal • 2021

Increasing demand for renewable energy in the backdrop of global change calls for waste valorization and circular economy strategies. Public health concerns and demand for clean energy provide impetus to the development of wastewater based MFC. Wastewater treatment and simultaneous generation of bioelectricity offer a myriad of environmental benefits. Nevertheless, it is pertinent to know the challenges with the microbial fuel cell (MFC) technology to upscale the wastewater based MFC. This paper attempts to critically analyse the processes, application, challenges and opportunities of wastewater based MFCs. A literature survey was conducted to find out the advances in the field of wastewater based MFCs and the focus was to decipher the challenges to the implementation of wastewater based MFCs. Recent developments in MFC technology have improved the power output and studies show that a diverse group of organic-rich wastewater can be treated with MFCs. The developments include improvements in MFC configuration, development of biocatalysts and biocathode, anodic biofilm formation, microbial community interactions, and progress in the organic and pollutant removal. Nevertheless, the MFC technology is replete with challenges about the organic removal rate, power density, electrode performance limiting factors, economic viability, high initial and maintenance cost and difficulty to maintain the exoelectrogens activity in a complex wastewater environment. Opportunities exist in scaling up of MFCs, integration with other wastewater treatment methods and measures to minimise the operating costs. MFCs have the potential to increase the resilience capacity of the sustainable wastewater treatment plant.

Shaoduan Ou, Luke E. K. Achenie

Journal of Fuel Cell Science and Technology • 2005

Artificial neural network (ANN) approaches for modeling of proton exchange membrane (PEM) fuel cells have been investigated in this study. This type of data-driven approach is capable of inferring functional relationships among process variables (i.e., cell voltage, current density, feed concentration, airflow rate, etc.) in fuel cell systems. In our simulations, ANN models have shown to be accurate for modeling of fuel cell systems. Specifically, different approaches for ANN, including back-propagation feed-forward networks, and radial basis function networks, were considered. The back-propagation approach with the momentum term gave the best results. A study on the effect of Pt loading on the performance of a PEM fuel cell was conducted, and the simulated results show good agreement with the experimental data. Using the ANN model, an optimization model for determining optimal operating points of a PEM fuel cell has been developed. Results show the ability of the optimizer to capture the optimal operating point. The overall goal is to improve fuel cell system performance through numerical simulations and minimize the trial and error associated with laboratory experiments.

Tiancai Cheng, Qiang Liu, Guangjun Jiang et al.

Fuel Cells • 2024

Abstract The performance and durability of proton‐exchange membrane fuel cells (PEMFCs) are constrained by fuel delivery and water management. Based on parallel and serpentine flow fields, the effects of triangular baffles (30°, 45°, and 60°) and conical runners (1°, 2°, and 3°) on the performance output of PEMFC at different angles are studied. The three‐dimensional and multi‐phase models are established by using the simulation software package (ANSYS FLUENT). The findings demonstrate that the battery's output performance reaches its peak when the baffle angle is set at 45°. When the output current density is 0.7 A/cm 2 , the power density of the 45° baffle increases by 18.87%. The pressure loss is not only lower than that of the 60° baffle but also exhibits no significant difference when compared to the 30° baffle. In addition, the introduction of conical channels has enhanced the output performance of PEMFCs in comparison to the traditional serpentine flow field. The power density of the 2°tapered channel exhibits a 12.65% increase when the output current density reaches 0.8 A/cm 2 . However, the performance output of the 3°tapered channel is inferior to that of the conventional serpentine flow field.

Li Wang, Qiao Lin, Jie Zhang et al.

Advanced Materials Research • 2013

Electrodes, catalysts, membranes, if present, are three main components in constructing a MFC for harvesting desired maximum power density and achieving higher coulombic efficiency (CE). Great improvements have been made, based on previous researches, in developing and diversifying materials, aside from architectures. Electrodes most familiar to us are widely used carbon materials. For anodes, carbon matrix composites (e.g., acombination of polyaniline (PANI) with TiO2 using carbon as substrate) have gained special attention, though carbon material itself can exhibit excellent performance by diversifying molecular structures such as carbon nanotubes (CNTs). In the meanwhile, the evolution of MFC architectures, heading to the direction of improving power generation, contributes to the combination of membranes and cathodes from separate modes to diverse assemblies, on which all sorts of catalysts, such as from commonly used Pt to iron phthalocyanine (Pc), metal tetramethoxyphenylporphyrin (TMPP), MnOx, or pyrolyzed iron (ll) phthalocyanine (pyr-FePc), can immobilize through synthesis of these catalysts with polymer such as Nafion 117 (Dupont Co., USA) or tetrafluoroethylene (Teflon) containing functional groups or Polypyrrole (PPy). This paper is mainly aimed at reviewing the development of materials in recent years and making several proposals.

Riya Bhattacharya, Debajyoti Bose, Pranathi Ganti et al.

Research Square • 2023

Abstract In plant microbial fuel cells or p-MFCs living plants photosynthesize between two electrodes. The plant exudes organic waste material from the roots. In the rhizosphere, bacteria consume these wastes by oxidizing them in contrast to the atmosphere that reduces it. This redox reaction along with photosynthesis can be harnessed as an energy source in the form of bioelectricity. In this work, the plant Withania somnifera (L.) Dunal was used for generating bioelectricity from the root exudates and organic matter available in the soil. An open circuit voltage of 930 ± 21 mV was achieved between multiple cycles of operation. The cell voltage further increased to 1260 ± 140 mV with enrichment in the form of discards from vegetable matter. The peak recorded voltage was 1400 mV. Graphite fibre felt electrodes ensured uniform microbial growth with power densities that were achieved at 57 mW/m 2 and 84 mW/m 2 with and without enrichment respectively. ATR-FTIR demonstrated complete degradation of specific compounds attached to the carbon matrix in the soil along with the polysaccharide content from the enrichments. Additionally, this work also monitored the changes in soil pH and its homogeneity, the impact of photosynthetically active radiation, humidity, and the presence of CO 2 in the air, and how it affects plant growth and ultimately the microbes at the rhizosphere which accounted for the bioremediation and the resultant bioelectricity production. SEM imaging further confirmed the importance of anaerobic environment and electrode properties that allow the growth of conductive biofilms from the electrochemically active microbes present in the soil.

Nicolas Chabert, Violaine Bonnefoy, Wafa Achouak

Microbial Biotechnology • 2017

Summary Acidithiobacillus ferrooxidans is a strict acidophilic chemolithoautotrophic bacterium that obtains its energy from reduced inorganic sulfur species or ferrous iron oxidation under aerobic conditions. Carbon felt electrodes were pre‐colonized by A. ferrooxidans ATCC 23270 T using ferrous iron or sulfur as electron donors, via the addition (or not) of a mixture of C14 acyl‐homoserine lactones (C14‐ AHL s). Electrode coverage during pre‐colonization was sparse regardless of the electron donor source, whereas activation of quorum sensing significantly enhanced it. Microbial fuel cells ( MFC s) inoculated with pre‐colonized electrodes (which behaved as biocathodes) were more efficient in terms of current production when iron was used as an electron donor. Biocathode coverage and current output were remarkably increased to −0.56 A m −2 by concomitantly using iron‐based metabolism and C14‐ AHL s. Cyclic voltammetry displayed different electrochemical reactions in relation to the nature of the electron donor, underlying the implication of different electron transfer mechanisms.