Tuoyu Zhou, Rong Li, Shuting Zhang et al.

Biotechnology and Bioengineering • 2020

Abstract Copper pollution poses a serious threat to the aquatic environment; however, in situ analytical methods for copper monitoring are still scarce. In the current study, Escherichia coli Rosetta was genetically modified to express OprF and ribB with promoter P t7 and P cusC , respectively, which could synthesize porin and senses Cu 2+ to produce riboflavin. The cell membrane permeability of this engineered strain was increased and its riboflavin production (1.45–3.56 μM) was positively correlated to Cu 2+ (0–0.5 mM). The biosynthetic strain was then employed in microbial fuel cell (MFC) based biosensor. Under optimal operating parameters of pH 7.1 and 37°C, the maximum voltage (248, 295, 333, 352, and 407 mV) of the constructed MFC biosensor showed a linear correlation with Cu 2+ concentration (0.1, 0.2, 0.3, 0.4, 0.5 mM, respectively; R 2 = 0.977). The continuous mode testing demonstrated that the MFC biosensor specifically senses Cu 2+ with calculated detection limit of 28 μM, which conforms to the common Cu 2+ safety standard (32 μM). The results obtained with the developed biosensor system were consistent with the existing analytical methods such as colorimetry, flame atomic absorption spectrometry, and inductively coupled plasma optical emission spectrometry. In conclusion, this MFC‐based biosensor overcomes the signal conversion and transmission problems of conventional approaches, providing a fast and economic analytical alternative for in situ monitoring of Cu 2+ in water.

Jayanta Gogoi, Karan N, Abhishek Nalwad et al.

Water Practice & Technology • 2024

ABSTRACT This study developed a nature-based pilot-scale technology for simultaneous piggery WW treatment and resource recovery potential. The technology comprised a two-stage vertical flow constructed wetland (2-VFCW) integrated with a microbial fuel cell (MFC) and microalgal photobioreactor. The first and second stage was an unsaturated and saturated type, respectively. The bioelectricity generation was optimised by investigating the suitable electrode zonation, hydraulic retention time (HRT) and WW loading rate. The 2-VFCW-MFC-treated effluent was studied to grow microalgae for biomass production. The 2-VFCW-MFC showed better treatment efficiency than the 2-VFCW, possibly due to enhanced microbial activity on the electrode surface, leading to improved organic matter degradation and electron transfer to the cathode, enhancing NO3− and PO43− reduction. The 2-VFCW-MFC with electrode zonation of 20 cm (cathode) and 60 cm (anode) and HRT of 76 h, 48 min showed the highest open-circuit voltage of 291.83+13.53 mV and WW treatment efficiency. The highest algal biomass of 21,323.34+8,316.26 mg/L (wet weight) was produced at HRT of 96 h, then entered the death phase. Comparatively, the 2-VFCW-MFC showed higher WW treatment efficiency than 2-VFCW at 2 L/day by 23.24% COD, 27.43% TOC, 33.05% PO43−, 13.51% NO3−, 8.14% TN, except TAN (22.71%).

Rickelmi Agüero-Quiñones, Magaly De La Cruz-Noriega, Walter Rojas-Villacorta

Bioengineering • 2025

The projected global energy demand for 2050 drives the imperative search for alternative and environmentally friendly energy sources. An emerging and promising alternative is microbial fuel cells assisted with microalgae. This research evaluated the potential of Chlorella sp. biomass in electricity production using microbial fuel cells (MFCs) with a single chamber and activated carbon and zinc electrodes at the laboratory scale over 20 days of operation. Maximum values of voltage (1271 ± 2.52 mV), current (4.77 ± 0.02 mA), power density (247.514 mW/cm2), current density (0.551 mA/cm2), and internal resistance (200.83 ± 0.327 Ω) were obtained. The biomass-maintained pH values of 7.32 ± 0.03–7.74 ± 0.02 and peaks of electrical conductivity of 2450 ± 17.1 µS/cm and oxidation-reduction potential of 952 ± 20 mV were reached. Meanwhile, cell density and absorbance increased to average values of 2.2933 × 107 ± 1.15 × 106 cells/mL and 3.471 ± 0.195 absorbance units (AU), respectively. Scanning electron microscopy micrographs allowed the observation of filamentous structures of the formed biofilm attached to carbon particles, and energy-dispersive X-ray spectroscopy spectra of the anodes determined the predominance of oxygen, carbon, silicon, aluminum, and iron. Finally, this research demonstrates the great potential of Chlorella sp. biomass for sustainable bioelectricity generation in MFCs.

Salvatore Angelo Cancemi, Michela Angelucci, Rosa Lo Frano et al.

Volume 11: Student Paper Competition • 2024

Abstract In nuclear reactor fuel engineering, the phenomena of Pellet-Cladding Interaction (PCI) and Pellet-Cladding Mechanical Interaction (PCMI) present significant challenges. These issues affect the design and safety of NPPs, mainly due to factors like fission gas release and fuel swelling. Accurately modeling these interactions is complex, as they are complexly linked with the fuel’s neutronic and thermal responses. Traditionally, the simulation of these interactions, essential for nuclear safety and risk assessment, has been complex and resource intensive. This study focuses on developing innovative surrogate models to enhance computational efficiency in nuclear fuel code analysis. A surrogate model based on a neural network approach is a data-driven computational model that approximates the behavior or output of complex, time-consuming, or resource-intensive simulations. This study specifically employs Artificial Neural Networks (ANNs) and statistical algorithms, aiming to reduce high computational cost of traditional approaches. A validated synthetic dataset, representing thermal analysis under steady-state conditions, is used to train the machine learning model. The dataset specifically focuses on Cladding Temperature. The study investigates eight different Test-Case. The surrogate model, trained on only 20% of the dataset, can predicts the entire time series of temperature using ARIMA, LSTM, and Prophet algorithms. The maximum error achieved by the surrogate model is 3.19°C compared to the validated temperature. The study demonstrates that surrogate models offer a time-efficient alternative for simulating complex physical phenomena, achieving a balance between accuracy and efficiency. This approach is particularly beneficial in scenarios where full-scale 2D and 3D simulations are excessively time-consuming, providing quicker results and significantly reducing computational resources.

Anil N. Ghadge, Dipak A. Jadhav, Makarand M. Ghangrekar

Environmental Progress & Sustainable Energy • 2016

Performance of 45 L pilot scale microbial fuel cell (MFC) made from glass fiber‐reinforced plastic and ceramic‐separators (CS) with multiple electrode assembly was evaluated. Study on effect of external resistance ( R ext ) varying from 100 to 3 Ω revealed that maximum power ( P max ) of 14.28 mW (37.8 mA current) with chemical oxygen demand (COD) removal of 84 ± 5.1% was observed at R ext of 10 Ω. While evaluating influence of organic loading rate (OLR) from 0.75 to 8 g COD L −1 d −1 , the MFC showed P max of 17.63 mW (42 mA current) and COD removal of 69 ± 5.1% at OLR of 4.5 g COD L −1 d −1 . Internal resistance ( R int ) of 12.4 Ω observed is among the least value reported in literature for larger MFCs. Simplicity in design, ease of fabrication, lower R int , longevity and low cost CS, which can withstand more hydraulic pressure than polymeric membranes, are the advantages that this MFC offers to make it suitable for field applications. © 2016 American Institute of Chemical Engineers Environ Prog, 35: 1809–1817, 2016

Aline Oliveira da Silva, Simone Perazzoli, Hugo Moreira Soares et al.

Engenharia Sanitaria e Ambiental • 2023

ABSTRACT The aim of this study was to assess the feasibility of using cassava wastewater as a substrate for dual-chamber microbial fuel cells (MFCs) operating with denitrifying biocathodes. Two configurations related to the ion exchange membrane used were evaluated: one with an anion exchange membrane (MFC-A) and the other with a cation exchange membrane (MFC-C). Both bioreactors were operated in sequential batch mode. Furthermore, a low-cost platform based on Arduino technology was also proposed to enable continuous measurement and recording of voltage data from the MFCs. The highest voltage values were observed in the first days of MFC operation, with readings reaching approximately 350 mV (0.41 W·m 3) and gradually decreasing after 100 days of operation to 243 mV (0.20 W·m 3) and 125 mV (0.05 W·m 3) for the MFC-A and MFC-C, respectively (mean values for the last 20 days of operation). In both MFCs, the chemical oxygen demand reduction and nitrogen removal were over 98% after reactor stabilization, with no noticeable nitrite accumulation. The experimental results indicated superior performance when MFC was equipped with an anion exchange membrane. The results presented here demonstrate the feasibility of using cassava wastewater as a viable substrate for MFCs equipped with a denitrifying biocathode, allowing for efficient wastewater treatment and simultaneous electricity generation.

, Erich J. Mace, Yossef A. Elabd

• 2011

Proton-exchange membrane fuel cells (PEMFCs) are promising as high-efficiency energy conversion devices, but the need for expensive noble metal catalysts such as Pt has hindered commercialization. An alternative is the alkaline membrane fuel cell (AMFC), which intrinsically possesses faster kinetics at the cathode, enabling noble metals to be replaced by Co, Ag, Fe, or Ni. In order to compete with PEMFCs (i.e. achieve 1.0 W/cm2 power density), AMFCs require improved membranes. In particular, membranes must achieve conductivities of ~0.1 S/cm and be thermally, chemically, and mechanically stable. The membrane mass transport phenomena governing conduction should be clearly understood in order to efficiently develop new materials. In particular, there is need for an improved, molecularlevel understanding of the relationship between membrane water content and membrane conductivity, as well as an elucidation of the kinetic mechanism causing membrane carbonation. The dependency of conductivity on membrane water content is explored using Fourier Transform Infrared Attenuated Total Reflectance (FTIR-ATR) spectroscopy with twodimensional correlation techniques, and Electrochemical Impedance Spectroscopy (EIS). The particular role that specific water cluster states play during transport is elucidated, and the transient behavior associated with membrane carbonation is explored.

M. Priya, N. Ramesh Raju, V Madhavi et al.

International Journal of Advanced Research in Science, Communication and Technology • 2025

The Modular-Multilevel Converter (M-MC) has substantially contributed to the integration of non-conventional energy sources into grid systems, particularly Proton Exchange Membrane Fuel Cells (PEMFC). This paper proposes an M-MC system to interface PEMFC with the grid, focusing on controlling circulating currents and ensuring stability. A Fuzzy Logic is employed to mitigate circulating current (CC) harmonics. Phase-Shifted Carrier (PSC) modulation is used to improve capacitor voltage balancing, thus maintaining a constant input voltage. The boost converter enhances the input voltage to a higher level, which is essential for maintaining the necessary voltage margin in MMC. The main contribution of this paper is (I)The PSC-PWM was implemented for MMC to maintain a quality +y of output voltage by the control of capacitor voltages.(II)The proposed fuzzy logic controlled circulating current must be achieved in order to regulate the dc ripple component, arm current, and circulating current of MMC.(III)It is essential to regulate the SM capacitor voltages in order to provide a balanced and equal output while maintaining the ratings and limits of the SMs, and this will be accomplished.

Ivonne L. Alonso-Lemus, Carlos Cobos-Reyes, Mayra Figueroa-Torres et al.

Journal of Chemistry • 2022

In this work, electroactive biofilms of Bacillus subtilis (B. subtilis) or Escherichia coli (E. coli) were supported on functionalized biocarbon (AB7-F), which was synthesized from waste leather and was used as catalysts to develop bioanodes for microbial fuel cells (MFCs). This way, bioanodes were fabricated and further evaluated in a three-electrode cell using pharmaceutical wastewater (PWW) as substrate. The electrochemical measurements showed a higher performance of the bioanode based on AB7-f+ B. subtilis to oxidize organic matter from PWW. The polarization curves in the dual-chamber MFC showed that AB7-f+ B. subtilis bioanode can generate an open circuit voltage of 602 mV and a power density of 77 mW m−2. During long-term tests of the MFC, a variation in performance was observed, with a maximum of 96.3 mW m−2 on day 7. Such variation was attributed to the development of more stable biofilm as well as consumption of some compounds metabolized by bacteria grown on the bioanode. The results showed that AB7-f+ B. subtilis can be used as bioanode for MFCs with PWW as substrate removing around 45% of the chemical oxygen demand (COD).

Zijie Wu, Zhengyang Ni, Mengmeng Qin et al.

SmartMat • 2024

Abstract Microbial fuel cells (MFCs) benefit from the introduction of iron in the anode, as its multiple valence states and high electron‐catalytic activity led to improved power densities in MFCs. However, the effect of long‐term Fe 3+ release into the electrolyte on the power density of MFCs is often overlooked. Herein, an anode consisting of a three‐dimensional iron foam uniformly coated by reduced graphene oxide (rGO/IF) with a suitable loading density (8 g/m 2 ) and a large specific surface area (0.05 m 2 /g) for high‐density bacterial loading was prepared. The hybrid cells based on the rGO/IF anode exhibit a maximum power density of 5330 ± 76 mW/m 2 contributed by MFCs and galvanic cells. The rGO/IF anode enables continuous Fe 3+ release for high electron‐catalytic activity in the electrolyte during the discharging of the galvanic cells. As a result, the hybrid cells showed a power density of 2107 ± 64 mW/m 2 after four cycles, facilitated through reversible conversion between Fe 3+ and Fe 2+ in the electrolyte to accelerate electron transfer efficiency. The results indicate that the rGO/IF anode can be used for designing and fabricating high‐power MFCs by optimizing the rate of release of Fe 3+ in the electrolyte.

Ayesha Kausar, Ishaq Ahmad, Tingkai Zhao et al.

Journal of Composites Science • 2023

Fuel cell efficiency can be improved by using progressive electrodes and electrolytes. Green nanomaterials and green technologies have been explored for the manufacturing of high-performance electrode and electrolyte materials for fuel cells. Platinum-based electrodes have been replaced with green materials and nanocomposites using green fabrication approaches to attain environmentally friendly fuel cells. In this regard, ecological and sustainable electrode- and electrolyte-based membrane electrode assemblies have also been designed. Moreover, green nanocomposites have been applied to form the fuel cell electrolyte membranes. Among fuel cells, microbial fuel cells have gained research attention for the incorporation of green and sustainable materials. Hence, this review essentially focuses on the potential of green nanocomposites as fuel cell electrode and electrolyte materials and application of green synthesis techniques to attain these materials. The design of and interactions with nanocomposites have led to synergistic effects on the morphology, impedance, resistance, power density, current density, electrochemical features, proton conductivity, and overall efficiency. Moreover, we deliberate the future significance and challenges of the application of green nanocomposites in electrodes and electrolytes to attain efficient fuel cells.

Pavlina Theodosiou, Ioannis Ieropoulos, John Greenman et al.

ECS Meeting Abstracts • 2017

Introduction: Renewable energy production from waste using microbial fuel cell (MFC) technology is attracting increasing attention. MFCs are bio-electrical devices that use microorganisms as biocatalysts to convert chemical energy (stored in organic matter) into electrical energy. MFCs consist of a positive cathode and a negative anode, which are separated by a semi-permeable membrane. Microorganisms are inoculated in the anodic compartment and through substrate oxidation, release electrons to the anode electrode. The two electrodes are connected by an external circuit, which facilitates the flow of electrons from the anode to the cathode. One of the main contributors affecting the cost and performance of MFCs is the membrane, since these tend to be quite expensive, even though they are commercially available. To overcome this, alternative materials and configurations need to be identified. One design is the membrane electrode assembly (MEA) that improves power output by reducing the internal resistance. This study looks at 3D printing MFCs using novel extrude-able materials that can emerge from the Evobot platform (Figure 1). The focus is on the development of cost-effective MEA using extrude-able air-dry membranes painted with conductive paint. Materials and Methods: Twelve cubic analytical size MFCs were assembled with only one chamber forming the 25mL anode, so as to have an oxygen-diffusion cathode, whilst the membranes were glued to the anode chamber. For this experiment, three types of potentially extrude-able membranes were tested against a conventional CEM. These materials were two air-dry clays; Fimo and terracotta and standard terracotta clay (Figure 2A). The latter was kilned at a temperature of 1070 o C prior to use, to allow the structural bonding of the clay and ensure durability, whereas the rest were dried overnight at room temperature. The thickness of the tested membranes was consistent for all the custom made membranes (2.5mm). The control membrane required activation in 5% NaCl prior to use. A conductive graphite coating was applied to each membrane and formed the cathode electrode (Figure 2B). The coating was fabricated using polyurethane rubber coating (PlastiDip), white spirit and graphite powder. The membranes were coated with the conductive cathode mixture and the surface resistance was measured for each coating, until the lowest value was achieved (100-200 Ohms). After the membrane electrode assembly had dried, a cable was attached to the cathode using conductive wire glue, to form the cathodic current collector. The MFCs were then partially wrapped with Parafilm® to ensure moisture retention in the open-to-air cathode side (Figure 2C). All the cells were inoculated with activated sludge and fed with neat human urine collected anonymously from healthy individuals. Results and Discussion: Initially, the air-dry terracotta outperformed the other materials (70 µW), whereas the commercially available and most commonly used CEM was the least performing (30 µW). Air-dry Fimo and kilned terracotta were almost identical in terms of power output (50 µW). The experiment started with a 2.7 kΩ load, and although initially the air-dry clay was outperforming the rest, after fourteen days, both air-dry clay and fimo were identical. Following electrochemical analysis, the optimal external resistance was identified (1 kΩ). Once the MFCs were run at this resistance value the performance levels had clearly diverged and Fimo outperformed the other materials. The results from the polarisation experiment showed a difference with the real-time data, suggesting that the air-dry clay was the best performing with 123 μW, followed by Fimo with an output of 79 μW. However, in all cases, the soft materials were operating better than the conventional cation exchange membrane. The materials tested as alternative membranes come in the form of soft modelling clay, which makes these suitable for extrusion from the EVOBOT platform. As the original form of the electrode material is fluid, it can also be applied using EVOBOT by incorporating a brush/roller on the actuation layer of the robot. This will apply the conductive coating onto the dried extruded membranes, and help produce a uniform layer on the surface. Conclusions: The findings presented in this study demonstrate for the first time that soft materials cured in air can be used as membranes for MFCs, and in addition, even improve power output. This offers a great advantage over the conventional and expensive CEMs, and is a novelty in the MFC field. The EVOBOT robotic platform is flexible and can be modified to extrude such membranes. This is an exciting development and a step towards the overall goal of the EVOBLISS project, which is to monolithically 3D-print MFCs using EVOBOT. Figure 1

I. Ieropoulos, J. Greenman, D. Lewis et al.

Journal of Water, Sanitation and Hygiene for Development • 2013

This study builds on the previous work of urine utilisation and uses small-scale microbial fuel cells (MFCs), working both as individual units in cascade or collectively as a stack, to utilise artificial urine. Artificial urine was prepared at concentrations typically found in real human urine with peptone employed as a surrogate proteinacious component. MFCs were constructed from Nanocure® polymer using rapid prototype technology. The anode and cathode electrodes were made of 15 cm2 carbon veil, folded down to fit in the 1 mL chambers. Eight MFCs were inoculated using activated anaerobic sludge; after 17 days of fed batch mode they were switched to continuous flow, initially at 0.09 mL/h and subsequently at 0.43 mL/h, resulting in HRT of 12.69 minutes/MFC. MFCs showed stable performance following the maturing period and produced, under polarisation experiments, peak power levels of 117 μW, corresponding to 962.94 W/m3. Continuous flow experiments data showed higher power production, increasing with the concentration of the carbon/energy source within artificial urine. The work demonstrates that artificial urine of varying composition can be successfully utilised for the production of energy and concomitant cleanup of organic waste. Finally, in line with the practical implementation and robotics work in our group, the small-scale MFCs were configured into a stack and directly energised electronic devices.

Kumar Sonu, Monika Sogani, Zainab Syed et al.

Environmental Progress & Sustainable Energy • 2021

Abstract The key operational constraints of the microbial fuel cell (MFC) technology in achieving its due potential are the high cost of electrodes and the difficulties in scaling up. To address these issues, carbonized corncob anodes were prepared and modified with the hydrogen peroxide (H 2 O 2 ) to increase the oxygenated functional groups favoring the extracellular electron transfer between the microbes and electrodes. Compared to the MFC with anode without any modification, that is, bare anode, the single chambered MFC with 20% H 2 O 2 modified anode exhibited excellent electro‐catalytic activity and a 91% decrease in the internal resistance (decreased from 35 ± 0.5 to 3.0 ± 0.6 kΩ) along with 89% increase in the maximum power density (increased from 8.8 ± 0.7 to 89.7 ± 0.6 mW/m 2 ). MFCs with 20% H 2 O 2 modified anode resulted in high decolorization efficiency of real dye wastewater (RDW) up to 92% which is 18% higher than that of the MFC with the bare anode. In order to boost the power output, the system was designed and studied by electrically stacking the 24 individual units of the MFC with the modified anode into parallel and series configurations. In parallel stacking and series stacking, the power output was 18.9 and 13.5 times higher than the single MFC unit, respectively. The RDW degradation rate was in the order of parallel stack > series stack > single MFC unit.

Qibin Li, Hong Liu

International Journal of Engineering and Technology • 2023

In southern China, where there is no district heating in residential buildings, the thermal comfort of indoor occupants cannot be guaranteed in winter due to the high energy consumption of whole-space heating. Foot Heating Pad (FHP), as a Personal Comfort System (PCS) device, enables occupants to improve thermal comfort with less cost. In this study, the effects of local heating by FHP on foot skin temperatures and thermal comfort were investigated, and the energy-efficiency performance of FHP was analyzed. A heat transfer model of human foot, which consists of four layers of body tissues, was established to simulate the foot temperatures under continuous and intermittent heating, and the numerical simulation of the model was accomplished using ANSYS. Besides, an FHP (36 W) based on Peltier heater was proposed and developed to heat the foot, and a climate chamber experiment involving 16 subjects was performed to collect subjects’ thermal comfort votes at three ambient temperature conditions of 8 °C, 11 °C, and 14 °C. The simulation results show that the foot skin temperature was significantly enhanced, and the plantar skin temperature increased by seven Temperature (K). Besides, there was no significant difference in foot temperature distribution between intermittent heating and continuous heating. However, the experimental results indicated that continuous heating was more effective in enhancing subjects’ thermal comfort and was able to ensure a neutral overall thermal sensation in a 14 °C environment. The Corrective Power (CP) of FHP was 7K and the Corrective Energy & Power (CEP) was 5.1W/K. This study is expected to provide guidance for the optimization design of PCS devices.

Keith Scott, Cassandro Murano

Journal of Chemical Technology & Biotechnology • 2006

Abstract The paper reports results of a mediatorless microbial fuel cell (MFC), utilising waste carbohydrate (manure) as a fuel, which did not use a catalyst or a proton exchange membrane and is thus environmentally friendly (by using no toxic substances) in treating waste. The cell used a manure sludge in the anode compartment and an aqueous salt solution (seawater) containing dissolved oxygen. The influence of the geometric position of the anode and cathode, both made of carbon cloth, had a major effect on the fuel cell power performance. The maximum power density obtained with the cell was 4.21 mW m −2 . The paper also reports results of a mediated MFC using a yogurt bacteria and methylene blue as mediator. This cell produced a maximum power density of over 13 mW m −2 . This power output compares quite favourably with that achieved with the same cell using glucose as fuel with E. coli (peak power density of 180 mW m −2 ). Copyright © 2007 Society of Chemical Industry

Neng Wu Zhu, Xi Chen, Li Xing Tu et al.

Advanced Materials Research • 2011

Stacking microbial fuel cells (MFCs) in series can provide higher voltage; however, voltage reversal (VR) adversely affects performance of the stacked MFCs. In this paper, diodes are introduced into three stacked MFCs so as to investigate the VR behavior and offer a diodes-based explanation of the VR. The results show that VR occurs in the different stacked MFCs systems. VR of the stacked MFCs connected with forward diodes (～0.37 V) happens in a similar pattern as that without diodes (～0.80 V). However, it only happens at the end of a cycle. This can be analyzed that the resistance of the diodes consume a part of the flowing electrons and the speed of potential changes of the electrodes slows down. Differently, in the stacked MFCs connected with reverse diodes, the voltages of each unit MFC approximately equal their open circuit voltages (～0.75 V), and VR happens in the unit MFC with reverse diodes at the cathode end only. It implies that the imbalanced consumption of electrons in unit MFCs and the potential changes of specific electrode directly result in VR.

, Mark Dondi Arboleda

Journal of Environmental Science and Management • 2017

The current Philippine energy crisis reminds us of the importance of finding alternative energy sources. Microbial fuel cells (MFC) may contribute to the solution. MFCs utilizing marine sediments, rice straw, domestic sewage, and agricultural water have a large potential as an alternative energy source. The objectives of the project were to isolate the biological agent, determine the optimum waste substrates, and to develop a working microbial fuel cell using locally available materials as fuel source. Soil, sediment, and corn stover were collected. An improvised MFC was constructed with two compartments for the anode and cathode sections separated by an agar plug (5% w/v). Each compartment had 750 ml capacities. Several combinations of materials were determined. Triplicates of each material-isolate combination were used to determine voltage, amperage, and Columbic output. Thirty percent fish farm sediments produced the highest voltage and amperage. This treatment was able to produce power for 7 to 25 days after MFC setup. Addition of ammonium sulfate in this setup reduced electrical output. Other treatments also produced power but were not as comparable. This study showed that utilizing wastes as substrate for MFCs is feasible and may have practical use.

Maria G. Savvidou, Pavlos K. Pandis, Diomi Mamma et al.

Energies • 2022

High-energy consumption globally has raised questions about the low environmentally friendly and high-cost processes used until now for energy production. Microbial fuel cells (MFCs) may support alternative more economically and environmentally favorable ways of bioenergy production based on their advantage of using waste. MFCs work as bio-electrochemical devices that consume organic substrates in order for the electrogenic bacteria and/or enzyme cultures to produce electricity and simultaneously lower the environmental hazardous value of waste such as COD. The utilization of organic waste as fuels in MFCs has opened a new research path for testing a variety of by-products from several industry sectors. This review presents several organic waste substrates that can be employed as fuels in MFCs for bioenergy generation and the effect of their usage on power density, COD (chemical oxygen demand) removal, and Coulombic efficiency enhancement. Moreover, a demonstration and comparison of the different types of mixed waste regarding their efficiency for energy generation via MFCs are presented. Future perspectives for manufacturing and cost analysis plans can support scale-up processes fulfilling waste-treatment efficiency and energy-output densities.

Osamu Ichihashi, Kayako Hirooka, Tatsuya Takeguchi et al.

ECS Meeting Abstracts • 2016

Microbial fuel cell is a device that can achieve wastewater treatment and power generation simultaneously. For the practical application of microbial fuel cell, development of alternative cathode catalyst for platinum is necessary. In this study, a kind of sodium cobalt oxide, NaCo 2 O 4 was investigated, because estimated cobalt reserve is 100 times higher than platinum, and its price is about one thousandth. Catalyst ink was prepared by mixing NaCo 2 O 4 powder with carbon black powder and Nafion dispersion. Then cathode was fabricated by applying the ink to PTFE treated carbon paper. Cathode with Pt catalyst and that with activated carbon (NORIT SX PLUS) were also prepared for comparison.ORR activity of the cathodes was measured by linear sweep voltammetry (LSV). Oxygen reduction reaction (ORR) activity of NaCo 2 O 4 cathode increased 15-25 times by the addition of carbon black as conductive assistant material in catalyst ink. Two kinds of carbon black were tested, and a cathode with Ketjen black showed better ORR activity than that with Vulcan XC-72. By increasing coating amount of catalyst ink from 2mg/cm 2 (NaCo 2 O 4 ) to 4mg/cm 2 , ORR activity increased 1.6 - 1.7 times, which was equivalent to 50-60% of Pt catalyst (Fig) . Gram based ORR activity of this catalyst was higher than that of activated carbon (NORIT SX PLUS) catalyst (Fig). The NaCo 2 O 4 cathode having highest ORR activity was built into a pre-acclimated MFC, and then used for the treatment of synthetic wastewater. The current density was about 3A/m 2 , which was a little lower than the value during the operation equipped with a Pt cathode (about 4A/m 2 ). However, any problems such as a decrease in electricity generation were not observed in several days of operation. Power density curve of the MFC equipped with the NaCo 2 O 4 cathode was obtained by the LSV measurement , and the maximum current density was 0.58 W/m 2 , which is about a half of the density achieved by a Pt cathode. Further research on the preparation condition of the cathode, such as the amount of conductive assistant material, the amount of binder, and the coating amounts of the catalyst ink, would probably contribute to further improve the cathode ORR activity, which would improve electricity generation performance of a MFC. Figure 1

Ganesh Chinnaraj, Gomathi Priya Ponnaiah

Chemical Engineering & Technology • 2021

Abstract The microbial fuel cell (MFC) is a device for wastewater treatment with simultaneous power generation. As batch‐mode MFCs are common, the present research work reports on two trials of continuous mode operation of MFCs using domestic wastewater as substrate and sludge as bacterial source. Trial‐2 was carried out with low substrate flow rate. The maximum chemical oxygen demand (COD) reduction during substrate treatment in trial‐1 and 2 was determined. Though the average power output was high in trial‐1, it had a drastically changing trend. Trial‐2 provided better water treatment and non‐fluctuating power output. Thus, it is favorable considering sustainable electricity generation.

Jinzhu Tan, Y. J. Chao, Woo-Kum Lee et al.

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

A Polymer Electrolyte Membrane (PEM) fuel cell stack requires elastomeric gaskets in each cell to keep the reactant gases within their respective regions. If any gasket degrades or fails, the reactant gases (O2 and H2) can leak overboard or mix with each other directly during operation or during standby, and affect the overall operation and performance of the fuel cell. The degradation of four commercial gasket materials was investigated in a simulated fuel cell environment in this study. In an effort towards predicting lifetime of fuel cells, two solutions and two temperatures were used in the short-term, accelerated aging tests. Bend-strip environment crack resistance tests were performed on samples with various bend angles. Weight loss was monitored and surface structure changes were examined using optical microscopy on the samples exposed to the simulated fuel cell environment for selected periods of time. Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectroscopy was employed to study surface chemistry of the gasket materials before and after exposure to the simulated fuel cell environment over time. Stress and strain analysis was conducted using finite element method (FEM) to quantify the stress/state in test samples. The test results reveal that two silicone materials were degraded significantly while the other two did not show much degradation up to 42 weeks exposure to the simulated fuel cell environment. Optical microscopy and ATR-FTIR spectroscopy analysis indicate that the surface chemistry altered gradually via mechanisms involving de-cross linking and chain scission in the backbone. From experimental and numerical results, it is concluded that there is an interaction between chemistry and stress that appears to accelerate the degradation of the gasket materials in fuel cell environment.

Chetan Laddha

SPE Offshore Europe Conference & Exhibition • 2023

Abstract Ammonia is a dense energy carrier with high energy density and established supply chain for transport, and storage of green energy. 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. 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 the last 7 years 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.

Masakazu Yoneda, Masato Takimoto

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

It is very important to understand the transport phenomena under various operating and structural conditions to achieve the high performance of Polymer Electrolyte Fuel Cell (PEFC). In this study, the effect of liquid water removal inside flow channel on the performance of a large-sized cell was investigated. To calculate the performance of a cell or stack, we developed a simulation tool with macroscopic models of MEA characteristics such as electrochemical kinetics, catalyst utilization, limiting current density, and two-phase transport inside the gas diffusion layer (GDL) and the flow channel. At first, we investigated the effect of wall contact angle and cross-section of flow channel on the liquid water removal by the Moving Particle Semi-implicit method and calculated the velocity ratio (liquid water velocity for gas velocity) inside the flow channel including the effect of mesoscopic structure of GDL. Applying this correlation to the two-phase model of the macroscopic PEFC simulation, we confirmed that the performance in the case of hydrophilic and shallow-shaped channel is much better in other case under low utilization operation.

Paolo Bombelli, Ross J. Dennis, Fabienne Felder et al.

Royal Society Open Science • 2016

Plant microbial fuel cells are a recently developed technology that exploits photosynthesis in vascular plants by harnessing solar energy and generating electrical power. In this study, the model moss species Physcomitrella patens , and other environmental samples of mosses, have been used to develop a non-vascular bryophyte microbial fuel cell (bryoMFC). A novel three-dimensional anodic matrix was successfully created and characterized and was further tested in a bryoMFC to determine the capacity of mosses to generate electrical power. The importance of anodophilic microorganisms in the bryoMFC was also determined. It was found that the non-sterile bryoMFCs operated with P. patens delivered over an order of magnitude higher peak power output (2.6 ± 0.6 µW m −2 ) than bryoMFCs kept in near-sterile conditions (0.2 ± 0.1 µW m −2 ). These results confirm the importance of the microbial populations for delivering electrons to the anode in a bryoMFC. When the bryoMFCs were operated with environmental samples of moss (non-sterile) the peak power output reached 6.7 ± 0.6 mW m −2 . The bryoMFCs operated with environmental samples of moss were able to power a commercial radio receiver or an environmental sensor (LCD desktop weather station).

So̸ren Juhl Andreasen, Rasmus Mosbæk, Jakob Rabjerg Vang et al.

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

This paper presents test results regarding the poisoning effects of CO and CO2 on H3PO4/Polybenzimidazole (PBI) membrane based high temperature proton exchange membrane fuel cell (HT-PEMFC). Electrochemical impedance spectroscopy (EIS), which is a non intrusive diagnostic tool for electrochemical systems, has been used to investigate these effects. A single cell test setup consisting of an electrically heated single cell assembly with a PEMEAS CELTEC P membrane electrode assembly (MEA) of an active area of 45cm2 and mass flow controllers for Air, H2, CO and CO2 was constructed in the laboratory. All operational parameters as well as data acquisition are controlled by two LabView programs, running on two separate computers. The impedance spectrum of the fuel cell is recorded at different operating points and then an Equivalent Circuit (EC), proposed for modelling the cell impedance, is fitted to the spectrum in order to analyze and quantify the impact of the individual factors on HT-PEMFC performance. Results showed that CO poisoning has an effect on all the losses monitored. Intermediate frequency resistances showed higher increase with increasing contamination and decreasing temperature than high frequency resistances, which is attributable to the adsorption of CO on Pt catalyst.

Najla Grioui, Amal Elleuch, Kamel Halouani et al.

C • 2023

In this study, exhausted olive pomace (EOP) biochar prepared by carbonization at 400 °C is investigated as a fuel in a direct carbon fuel cell (DCFC) with an electrolyte-supported configuration. The feasibility of using the EOP biochar in the DCFC is confirmed, showing a maximum power density of 10 mW·cm−2 at 700 °C. This limited DCFC performance is compared with other biochars prepared under similar conditions and interrelated with various biochar physico-chemical characteristics, as well as their impact on the DCFC’s chemical and electrochemical reaction mechanisms. A high ash content (21.55%) and a low volatile matter (40.62%) content of the EOP biochar are among the main causes of the DCFC’s limited output. Silica is the major impurity in the EOP biochar ash, which explains the limited cell performance as it causes low reactivity and limited electrical conductivity because of its non-crystal structure. The relatively poor DCFC performance when fueled by the EOP biochar can be overcome by further pre- and post-treatment of this renewable fuel.

Feng Ji, Linlin Yang, Yinhua Li et al.

Energy Science & Engineering • 2019

Abstract Internal reforming methanol fuel cell (IRMFC) has potential applications in portable or stationary power supply system, but currently performance of the IRMFC is limited by the low hydrogen production of its reformer. In order to produce more hydrogen with less volume, in this paper a single channel serpentine packed bed reformer was designed, and its bed size was optimized by experiment and numerical simulation to enhance heat transfer and increase catalyst utilization. It was found that with the bed diameter from 5.8 mm down to 3.8 mm, the reformer temperature distribution was more uniform but the bed pressure drop increased a lot. Considering performance and pressure drop, the reformer of 5 mm was optimal, per milliliters of which could supply 9.8 mL/min hydrogen at 453 K, almost twice as much as that by A. Mendes et al with one‐third of their catalyst loading. The reformer was quite stable, and less than 10% decline in methanol conversion was observed during the 100 hours period at 473 K. When incorporated into an IRMFC single cell, power density of the single cell reached 0.45‐0.55 W/cm 2 at 453‐473 K under CH 3 OH solution and air feed, the highest in existing reports. The main drawback has to do with low stability of the IRMFC single cell at high current density.

Hengyuan Liu, Qili Hu

Journal of Water Reuse and Desalination • 2022

Abstract Nitrate widely exists in water pollution and is the most stable form of nitrogen pollution. This study investigated the effect of the current density (CD) and the wheat-rice stone powder (WP) on denitrification performance, microbial diversity and enzyme activity in a bio-electrochemical reactor (BER). It was found that an optimum CD of 200 mA/m2 and the addition of WP significantly improved the nitrate removal rate constant compared with the control group (12.28 d−1 versus 9.75 d−1) and remarkably reduced the intermediate accumulation of nitrite. The application of both optimum CD and WP enhanced the microbial diversity and catalytic activity of nitrate reductase (Nar) and nitrite reductase (Nir). The most dominant microbial taxa in our reactor were Methyloversatilis, Methylotenera, and an unclassified genus of the family Methylophilaceae. Moreover, WP allowed the denitrifiers to better withstand the stress of high CD. This study presented results supporting the use of an optimum CD and natural mineral addition to improving the performance of the denitrification process within a BER.

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