Paweł P. Włodarczyk, Barbara Włodarczyk

Catalysts • 2019

Microbial fuel cells (MFCs) are devices than can contribute to the development of new technologies using renewable energy sources or waste products for energy production. Moreover, MFCs can realize wastewater pre-treatment, e.g., reduction of the chemical oxygen demand (COD). This research covered preparation and analysis of a catalyst and measurements of changes in the concentration of COD in the MFC with a Ni–Co cathode. Analysis of the catalyst included measurements of the electroless potential of Ni–Co electrodes oxidized for 1–10 h, and the influence of anodic charge on the catalytic activity of the Ni–Co alloy (for four alloys: 15, 25, 50, and 75% concentration of Co). For the Ni–Co alloy containing 15% of Co oxidized for 8 h, after the third anodic charge the best catalytic parameters was obtained. During the MFC operation, it was noted that the COD reduction time (to 90% efficiency) was similar to the reduction time during wastewater aeration. However, the characteristic of the aeration curve was preferred to the curve obtained during the MFC operation. The electricity measurements during the MFC operation showed that power equal to 7.19 mW was obtained (at a current density of 0.47 mA·cm−2).

S. Latorrata, M. Sansotera, M. Gola et al.

Fuel Cells • 2020

Abstract In this work, perfluoropolyether (PFPE) functionalization was used as hydrophizing treatment for gas diffusion layers (GDLs) in polymer electrolyte membrane fuel cells (PEMFCs), instead of standard PTFE coatings, aiming to enhance the hydrophobicity of the gas diffusion media and to reduce the mass transfer limitations in the final device. Carbon cloth diffusion layers and carbon black were functionalized by decomposition of a PFPE peroxide. PFPE‐functionalized carbon black was employed in the preparation of an ink suitable for obtaining microporous layers (MPLs) by deposition onto macroporous backing layers. Dual‐layer gas diffusion media showing superhydrophobic behavior due to different hydrophobizing treatments were compared with conventional PTFE‐based materials, by testing in a single PEMFC working at two different temperatures and at low and high relative humidity conditions. Such tests demonstrated improved performances over conventional GDLs for pure PFPE‐based samples in terms of both overall electrical performance and reduced diffusive limitations in high current density conditions. The maximum output power achieved with the novel PFPE‐based compounds was 460 mW cm −2 at 80 °C and relative humidity (RH) 100% while the best improvement (10%) with respect to conventional GDLs was realized at 80 °C and RH 60%.

, Azhar Uddin

• 2019

With the issue of the rise of anthropogenic CO2, global warming and rise of the primary energy demand, strong measures for the energy transition and the diversification with renewables and existing fossil-based infrastructure are required. Also, carbon capture and utilization of CO2 would also be needed. In that sense, thermochemical redox cycles gain particular interest to produce synthetic fuels, which can be used for energy generation and production of chemicals. In a two-step redox cycles, metal oxides acts as oxygen carriers and undergo looping between two reactors. In the reduction reactor, metal oxide is reduced with release of oxygen (solar-thermal) or produces syngas (for fuel reduction) whereas, in oxidation, CO2/H2O splits for form syngas when in contact with the metal oxide. Ceria being readily available at large scale and due to its nature of undergoing reduction non-stoichiometrically at low temperature makes it a good candidate. In the present thesis, a detailed investigation of thermochemical dissociation of CO2 and H2O considering solar thermal and fuel reduction with a focus on non-structured reactors is carried out. For the solar-driven cycle, an assessment of counter-current flow moving bed reactors for reduction and oxidation is performed and a chemical looping (CL) unit is added to a 100 MW power plant. With an operating temperature of 1600oC and 10-7 bar pressure, a maximum power output of 12.9 MW with solar to electricity efficiency of 25.4% is calculated. This additional power would bring down the efficiency loss due to carbon capture from 11.3 to 6%. Even though a considerable efficiency is obtained on very optimistic operating conditions, it still requires a huge solar field. Economics revealed that with a carbon tax of $40/tone of CO2 the levelized cost of electricity (LCOE) achieved is 17.8 times higher than the existing market price (without carbon capture). If a higher carbon tax of 80$/MWh is considered that it would still be 6.28 times higher for a plant with a carbon tax. As an alternative, methane-driven CL unit is integrated into a power plant to access the overall system efficiency and amount of efficiency regain after carbon capture. Since there exists no solid-state kinetic model in the literature for methane driven CO2/H2O splitting cycle, an experimental investigation was performed which revealed that an Avrami-Erofe’ev (AE3) model fit best to both oxidation and reduction, with activation energies of 283 kJ/mol and 59.7 kJ/mol, respectively. A comparative assessment was performed to investigate the influence of kinetics. A CL unit based on thermodynamics and kinetics (with moving bed reactors) were tested in a power plant. A drop of 20% in the efficiency of the CL unit was observed when the kinetic-based CL unit is considered. However, due to thermal balance within the system, a similar thermal efficiency of the overall plant was achieved as 50.9%. However, when the thermodynamic-based CL unit layout is considered there exists an excess heat which predicts the possibility of improving the efficiency. An economic assessment revealed a specific overnight capital cost of 2455$/kW, a levelized cost of CO2 savings of 96.25 $/tonneCO2, and a LCOE of 128.01 $/MWh. However, with a carbon tax of 6 $/tonneCO2, the LCOE would drop below 50 $/MWh. The methane-driven CL unit is later integrated as an add-on unit to a polygeneration plant that produces electricity and dimethyl ether. The results showed that the plant can produce 103 MWe and 2.15 kg/s of DME with energy and exergy efficiency of 50% and 44%, respectively. The capital investment required for the plantis about $534 million. With the carbon tax of $40/tonne of CO2, a current DME price of $18/GJ and an electricity price of $50/MWh would be achieved. Overall, the integration of the CL unit as an add-on unit to the power plant is more suitable than polygeneration with respect to the existing market price. El aumento del CO2 antropogénico y el calentamiento global y el aumento de la demanda de energía primaria hace que se requieran medidas para la transición energética y la diversificación con energías renovables e infraestructuras existentes basadas en combustibles fósiles. Además de implementar medidas para la captura y el secuestro de carbono, también se necesita desarrollar métodos para la utilización de CO2. En ese sentido, los ciclos redox termoquímicos son particularmente interesantes para producir combustible sintético que, a su vez, pueden utilizarse para la producción de otras substancias químicas. La rotura de CO2 / H2O (CL) mediante una vía termoquímica de dos pasos está compuesta por dos reacciones redox con un óxido metálico. El primer paso es la reducción de los óxidos metálicos al perder oxígeno y crear vacantes en la red a una temperatura más alta y convertirse en óxido de metal de valencia más baja. Durante la etapa de oxidación, los gases reactivos CO2 / H2O reaccionan con el óxido metálico reducido formando CO y H2. Se ha investigado el uso de diferentes óxidos metálicos en función de su capacidad de transporte de oxígeno y sus propiedades para realizar ciclos redox continuos a distintos valores de temperatura y presión. Después de un examen cuidadoso, se ha seleccionado a la ceria para la división de CO2 / H2O a gran escala. En el presente trabajo, se investigan las divisiones termoquímicas de CO2 / H2O impulsadas por energía solar y la reducción de metano para la producción de gas de síntesis, con especial atención a su aplicación en reactores no estructurados. Se evalúa el uso de reactores de lecho móvil basado en flujo contracorriente y reactores de lecho fluidizado que funcionan en diferentes regímenes de fluidización. Es un reactor de lecho móvil tanto para la etapa de reducción como para la etapa de oxidación se obtienen altas selectividades de CO y H2 con volúmenes óptimos del reactor, mientras que en un reactor de lecho fluidizado el volumen requerido es mucho más alto, lo que lo hace inviable. Los modelos de reactor se han desarrollado en Aspen plus y se validan a partir de la literatura. Un análisis de sensibilidad ha revelado que la unidad CL depende en gran medida de la temperatura y la presión. El análisis se ha ampliado integrando la unidad desarrollada de CL como una unidad adicional a una central eléctrica de 100 MW con captura de carbono. La eficiencia de la planta se ha investigado considerando sólo la división de CO2, sólo la del H2O y la mezcla de CO2 y H2O como alimentación al reactor de oxidación de la unidad CL. El resultado es de una potencia máxima de 12.9 MW con una eficiencia de energía solar a eléctrica de 25.4%. Esta potencia adicional reduciría la pérdida de eficiencia debido a la captura de carbono de 11.3 a 6%. Para lograr esto, el reactor de reducción de la unidad CL debe funcionar a 1600 ° C y 10-7 bar de presión. Estas condiciones necesitarían un enorme campo solar y la operación, en ausencia de almacenamiento térmico, se limitaría a unas pocas horas durante el día. El análisis técnico-económico ha revelado que el coste nivelado de la electricidad es de 1321 $/MWh sin incluir incentivos ni impuestos sobre el carbono. Posteriormente, se ha considerado la reducción del metano como una alternativa a la reducción térmica. Al principio, se realizaron análisis termodinámicos de la unidad de CL impulsada por metano. A partir del análisis, se ha demostrado que la temperatura mínima requerida es de 900°C con 50% de exceso de metano para la reducción, lo que supone una eficiencia de la unidad CL de 62% con un rendimiento óptimo de CO y H2. La división de CO2/H2O en el reactor de oxidación a una mayor temperatura de salida beneficiaría considerablemente la eficiencia energética del ciclo redox CL completo. La variación de la relación H2/CO en la salida con respecto a los parámetros de entrada variables que incluyen la composición del gas al reactor de oxidación se ha estudiado con el fin de especificar las condiciones operativas idóneas. Posteriormente, la unidad CL impulsada por metano se ha integrado como una unidad adicional a una central eléctrica de 500 MW alimentada por oxígeno. Se ha investigado el rendimiento de un sistema con un ciclo combinado de gas natural convencional con o sin captura de carbono. Se ha obtenido una eficiencia de sistema y eficiencia energética de 50.7 y 47.4%, respectivamente. La eficiencia del sistema podría mejorarse a 61.5%, sujeto a la optimización del sistema. La evaluación tecno-económica ha revelado un coste de capital durante la noche de 2455 $/kW con un coste de ahorro de CO2 de 96.25 $/tonelada CO2 y un LCOE de 128.01 $/MWh. Sin embargo, con créditos de carbono de 6 $/tonelada CO2, el LCOE caería por debajo de 50 $/MWh. Con l'aumento delle emissioni di CO2 antropogenica che contribuiscono al riscaldamento globale e l'incremento della domanda mondiale di energia primaria, sono richieste significative misure per favorire la diversificazione delle fonti e la transizione energetica tramite fonti rinnovabili a partire dalle infrastrutture esistenti basate su combustibili fossili. Prima ancora degli interventi per la cattura e il sequestro dell’anidride carbonica, anche l’utilizzo della CO2 rappresenta una misura necessaria al raggiungimento degli obiettivi di decarbonizzazione. In questo senso, i cicli redox termochimici hanno acquisito particolare interesse per la produzione di combustibile sintetico da utilizzare come intermedio nella produzione di altri prodotti chimici. La separazione chimica di CO2/H2O attraverso un ciclo termochimico – chemical looping splitting (CL) – in due fasi è composta da due reazioni redox con un ossido di metallo. La prima fase del ciclo avviene alla temperatura più elevata e consiste nella riduzione dell’ossido di metallo, che cede ossigeno creando vacanze nel reticolo e diventando ossido di metallo a bassa valenza. Durante la fase di ossidazione, i gas reagenti CO2/H2O reagiscono con l'ossido di metallo ridotto che forma CO e H2. Una mappatura dettagliata dei diversi ossidi di metallo è stata effettuata in base alla loro capacità di trasporto dell’ossigeno e alle proprietà nei cicli di ossido-riduzione a funzionamento continuo in condizioni di variazione di temperatura e pressione. Dopo un attento esame, l’ossido di Cerio - ceria - è stato selezionato per l'applicazione che può essere disponibile per la scissione CO2 / H2O su larga scala. In questo lavoro, sia la separazione termochimica di CO2/H2O alimentata tramite energia solare, sia i cicli con riduzione tramite metano, entrambi finalizzati all produzione di syngas sono stati studiati con particolare attenzione ai reattori non strutturati. Per il ciclo termochimico basato su energia solare, è stata effettuata la valutazione dei reattori a letto mobile a flusso in controcorrente e a letto fluido che operano in diversi regimi di fluidizzazione. Il reattore a letto mobile è stato individuato come il più performante sia per la riduzione che l’ossidazione, con elevate selettività verso CO e H2 e volumi ottimali del reattore, mentre una resa analoga con reattori a letto fluidizzato potrebbe essere ottenuta solo con volumi di reattore molto alti, rendendo questa scelta irrealizzabile nella pratica. I modelli di reattore sono stati sviluppati in Aspen plus e sono stati validati dalla letteratura. Un'analisi di sensitività ha rivelato che la performance dell'unità CL è in larga misura dipendente dalla temperatura e dalla pressione di riduzione. L'analisi è stata estesa integrando l'unità CL sviluppata come unità aggiuntiva di una centrale elettrica a ossicombustione da 100 MW con cattura di carbonio. L'efficienza dell'impianto è stata studiata considerando di alimentare il reattore di ossidazione dell'unità CL sia con CO2, sia con H2O, sia con una miscela di CO2 e H2O. I risultati indicano una potenza massima di 12,9 MW con un rendimento da solare a elettricità del 25,4% generabile grazie all’unità di CL. Questa potenza aggiuntiva ridurrebbe la perdita di efficienza dovuta alla cattura di carbonio dall'11,3 al 6%. Per ottenere ciò, il reattore di riduzione dell'unità CL deve operare a 1600 ° C con una pressione di 10-7 bar. Queste condizioni avrebbero bisogno di un enorme campo solare e l'operazione sarebbe limitata a poche ore durante il giorno senza l’integrazione di un accumulo termico. L'analisi tecno-economica ha rivelato che il costo livellato (levelizad cost) dell'elettricità era di 1321 $ / MWh, senza includere incentivi o tassazione sul carbonio. Successivamente, è stata considerata la riduzione della ceria con metano come alternativa alla riduzione termica. Inizialmente, sono state condotte analisi termodinamiche dell'unità CL con riduzione a metano. Dall'analisi è emerso che la temperatura minima richiesta era 900 °C per la riduzione con un eccesso di metano del 50%, che ha prodotto un'efficienza dell'unità CL del 62% con una resa ottimale di CO e H2. In questo caso, la scissione di CO2/H2O nel reattore di ossidazione consisteva nell'ossidazione completa esotermica della ceria, per cui una temperatura di uscita più elevata avrebbe notevolmente migliorato l'efficienza energetica del ciclo CL redox completo. La variazione del rapporto H2 / CO all'uscita rispetto ai vari parametri di input, compresa la composizione del gas inviato al reattore di ossidazione, è stata studiata per specificare le condizioni operative necessarie. Successivamente, l'unità CL a metano è stata integrata come unità aggiuntiva in una centrale elettrica a ossicombustione da 500 MW. Sono state studiate le prestazioni del sistema in una valutazione comparativa con un ciclo combinato convenzionale a gas naturale, un ciclo a ossicombustione con cattura di carbonio e l'impianto proposto. Sono stati ottenuti per l’impianto rispettivamente un rendimento del sistema e un'efficienza energetica del 50,7% e del 47,4%. L'efficienza del sistema potrebbe essere migliorata fino al 61,5% tramite l'ottimizzazione del recupero termico del sistema, valutata attraverso la pinch analysis del sistema. Una dettagliata valutazione tecno-economica ha rivelato un costo specifico del capitale di 2455 $ / kW (overnight cost), un costo livellato delle emissioni di CO2 evitate 96,25 $ / tonnellata di CO2, e un costo dell’elettricità (LCOE) di 128,01 $ / MWh. Tuttavia, considerando un incentivo di 6 $ / tonnellata di CO2 evitata, il LCOE scenderebbe sotto i 50 $ / MWh. L'unità CL a metano viene successivamente integrata come unità aggiuntiva in un impianto di poligenerazione che produce elettricità e dimetil-etere. I risultati hanno mostrato che l'impianto può produrre 103 MWe e 2,15 kg/s di DME con un’efficienza energetica ed exergetica del 50% e del 44% rispettivamente. L'investimento di capitale richiesto per l'impianto ammonta a 534 M$. Con un valoré per la carbon tax di $ 40 / tonnellata di CO2, il DME e l’elettricità raggiungerebbero la parità con gli attuali prezzi di mercato, pari a $18/GJ per il DME e $50/MWh per l’elettricità. I costi risultanti sono dovuti all'unità di separazione dell'aria richiesta per la centrale elettrica a ossicombustione e può essere ridotta sostituendo l'unità di separazione dell'aria con una tecnologia a membrana per la separazione dell'ossigeno. Poiché in letteratura non esiste un modello completo per cinetica dello stato solido che descriva la riduzione con metano della ceria, esso è stato ricavato per via sperimentale. Sono stati condotti esperimenti in un reattore tubolare orizzontale a letto fisso in un intervallo di temperatura di 900-1100 °C. E’ stata studiata la cinetica della scissione della CO2, essendo una reazione più complessa rispetto alla scissione dell'acqua, la cui cinetica è stata invece ottenuta dalla letteratura. In base all’analisi sperimentale condotta, il modello cinetico Avrami-Erofe'ev (AE3) è risultato essere il migliore per entrambe le reazioni, con le rispettive energie di attivazione ottenute rispettivamente come 283 kJ/mol e 59,68 kJ/mol. L'ordine della reazione è stato ricavato come relazione tra temperatura e concertazione dei reagenti. L'analisi è stata effettuata seguendo un approccio termodinamico, ma la reazione eterogenea dell'ossido di metallo e dei gas reagenti limita il raggiungimento dell'equilibrio durante la reazione e dipende sempre dal tipo di reattore scelto per x l'applicazione. Pertanto, un modello di reattore a letto mobile è stato sviluppato considerando la riduzione del metano ottenuta sperimentalmente e la cinetica di splitting della CO2 è stata incorporata per valutare i due impianti proposti: la centrale elettrica e l'impianto di poligenerazione. È stata osservata una riduzione del 20% nell'efficienza dell'unità CL. Tuttavia, grazie all’integrazione termica interna al sistema, l’efficienza termica dell'impianto complessivo è molto simile a quella raggiunta nell’analisi termodinamica, con un valore del 50,9%. Tuttavia, a differenza del layout termodinamico, non è disponibile calore in eccesso per migliorare ulteriormente l'efficienza del sistema. Oltre al riciclo e all'utilizzo della CO2, come criteri di valutazione della sostenibilità per il layout proposto sono stati analizzati anche l’occupazione del suolo terreno e il fabbisogno idrico. Sia il fabbisogno di terra che di acqua aumentano di 2,5 volte rispetto ad una centrale convenzionale a ciclo combinato a gas naturale. Inoltre, anche l’impianto di poligenerazione con produzione di energia elettrica e dimetil etere (DME) è stato studiato considerando un modello dell’unità CL basato sulla cinetica e ha rilevato che la produzione di DME scenderebbe da 2,15 kg/s a 1,48 kg/s e la potenza elettrica prodotta da 103 a 72 MW. Pertanto, la cinetica ha una forte influenza sulla prestazione complessiva del sistema, e considerarla nell’analisi porta a ridurre la produzione di energia e DME di circa il 30% con un aumento di costo del 30%. Complessivamente, l'integrazione dell'unità CL come unità aggiuntiva ad una centrale elettrica a ossicombustione risulta più adatta rispetto alla poligenerazione, considerando il prezzo di mercato attuale per le commodities prodotte.

, Cristina Rotoni

• 2025

Agricultural efficiency, including in floriculture, requires sustainable methods to increase productivity while reducing the environmental impact of chemical fertilizers and pesticides. Overuse of fertilizers leads to soil degradation, water pollution, and biodiversity loss. One promising alternative is the use of plant-beneficial microorganisms as biofertilizers. However, optimizing the use of these microbial inoculants—either as single strains or complex microbial communities—remains challenging, especially in balancing nutrient inputs and maximizing plant-microbe interactions in commercial flower production. In this thesis, chrysanthemum (Chrysanthemum indicum L.) was used as a model plant for vegetative propagation to investigate the interactions between plant genetics, microbial inoculation, and nutrient availability during early root development. The study aims to understand how genotype-microbiome-environment interactions shape plant growth and nutrient use efficiency in chrysanthemum cultivation. In Chapter 2, the genetic variability among chrysanthemum cultivars and its influence on rhizosphere bacterial and fungal communities were investigated. Results showed that different cultivars select distinct rhizosphere microbiomes while maintaining a shared core of microbial species. Genetic differences among cultivars influenced the composition of these microbial communities. In Chapter 3, microbial inoculations with bacterial isolates and arbuscular mycorrhizal fungi (AMF), along with AMF-accompanying microbiomes (AMFc), were tested on chrysanthemum growth and rhizosphere microbiome composition. AMFc had a stronger effect on microbiome assembly and plant growth compared to single bacterial strains, highlighting the potential of complex microbial inoculations. In Chapter 4, AMF propagation was examined over 11 cycles of millet cultivation using trap propagation methods. The study evaluated traits such as indole-3-acetic acid (IAA) production and phosphate solubilization. AMFc consistently increased IAA production, particularly under low microbial activity, underscoring the importance of AMF in maintaining beneficial soil microbiomes and improving nutrient cycling. In Chapter 5, co-inoculation with AMFc and two bacterial strains (SMF006 and SMF018) was tested for its effects on chrysanthemum growth and root architecture. Co-inoculation with AMFc and SMF006 enhanced root dry biomass and enriched beneficial microbial taxa, including Sphingomonas, Taibaiella, Trichoderma, and Penicillium. In Chapter 6, the effects of nutrient availability on the interaction between AMFc and bacterial isolate SMF006 were explored. Genomic analysis of SMF006 revealed plant growth-promoting traits like nitrogen fixation, siderophore production, and IAA production. Increased nutrient input reduced microbial recruitment in the endophytic and epiphytic communities, indicating that nutrient limitation enhances microbial recruitment and plant growth promotion. Overall, this thesis highlights the potential of combining AMFc with beneficial bacterial strains to enhance plant growth, and reduce the need for chemical inputs. By optimizing microbial inoculation strategies and understanding plant-microbe interactions, this research provides a framework for more sustainable and efficient flower production systems.

Babita Tripathi, Soumya Pandit, Aparna Sharma et al.

Catalysts • 2022

The present study explores the use of carbon dots coated with Iron (II, III) oxide (Fe3O4) for its application as an anode in microbial fuel cells (MFC). Fe3O4@PSA-C was synthesized using a hydrothermal-assisted probe sonication method. Nanoparticles were characterized with XRD, SEM, FTIR, and RAMAN Spectroscopy. Different concentrations of Fe3O4- carbon dots (0.25, 0.5, 0.75, and 1 mg/cm2) were coated onto the graphite sheets (Fe3O4@PSA-C), and their performance in MFC was evaluated. Cyclic voltammetry (CV) of Fe3O4@PSA-C (1 mg/cm2) modified anode indicated oxidation peaks at −0.26 mV and +0.16 mV, respectively, with peak currents of 7.7 mA and 8.1 mA. The fluxes of these anodes were much higher than those of other low-concentration Fe3O4@PSA-C modified anodes and the bare graphite sheet anode. The maximum power density (Pmax) was observed in MFC with a 1 mg/cm2 concentration of Fe3O4@PSA-C was 440.01 mW/m2, 1.54 times higher than MFCs using bare graphite sheet anode (285.01 mW/m2). The elevated interaction area of carbon dots permits pervasive Fe3O4 crystallization providing enhanced cell attachment capability of the anode, boosting the biocompatibility of Fe3O4@PSA-C. This significantly improved the performance of the MFC, making Fe3O4@PSA-C modified graphite sheets a good choice as an anode for its application in MFC.

Junyeong An, Hyung‐Sool Lee

ChemSusChem • 2014

Abstract Voltage reversal in stacked microbial fuel cells (MFCs) is a significant challenge that must be addressed, and the information on its definite cause and occurrence process is still obscure. In this work, we first demonstrated that different anodic reaction rates caused voltage reversal in a stacked MFC. Sluggish reaction rates on the anode in unit 1 of the stacked MFC resulted in a significantly increased anode overpotential of up to 0.132 V, as compared to negligible anode overpotential (0.0247 V) in unit 2. This work clearly verified the process of voltage reversal in the stacked MFC. As the current was gradually increased in the stacked MFC, the voltage in the stacked unit 1 decreased to 0 V prior to that of the stacked unit 2. Then, when the voltage in unit 1 became 0 V, it was converted from a galvanic cell to an electrochemical cell powered by unit 2. We found that the stacked unit 2 provided electrical energy for the stacked unit 1 as a power supply. Finally, the anode potential of the stacked unit 1 significantly increased over cathode potential as current increased further, which caused voltage reversal in unit 1. Voltage reversal occurs in stacked MFCs as a result of non‐spontaneous anode overpotential in a unit MFC that has sluggish anode kinetics compared to the other unit MFCs.

Raisa C.P. Oliveira, Maria J. Jeremias, Maria Margarida Mateus et al.

Fuel Cells • 2022

Abstract This work reports preliminary studies to develop new direct liquid fuel cells that employ two by‐products from kraft and sulfite pulp mills as the fuel, namely kraft black liquor (BL) and spent sulfite liquor (SSL). The composition and properties of BL and SSL are characterized, being determined a conductivity 40 times higher for BL than for SSL. The performance of the BL fuel cell (BLFC) and the SSL fuel cell (SSLFC) is assessed employing 5 M hydrogen peroxide solution as the oxidant at different pH values. For the BLFC, an anion‐exchange membrane (AEM) is used, and for the SSLFC, both AEM and cation‐exchange membrane (CEM) are tested. Different parameters that characterize the fuel cell performance (e.g., peak power density) are determined and compared with similar wastewater‐based fuel cells described in the literature. To the best of the authors’ knowledge, it is the first time two pulp mill by‐products (BL and SSL) are reported as fuels for application in fuel cells.

Andrew Odorona Odeh, Peter Ogbemudia Osifo, Hein J. P. W. Neomagus

ECS Transactions • 2013

Development and characterization of polymer electrolyte membrane (PEM) using low cost Chitosan were carried out by blending with sulphonated zirconium oxide, and assessed for its potential to serve as possible polymer electrolyte membrane fuel cell (PEMFC) application. Synthesized membranes were thus characterized by scan electron microscope (SEM) to define the morphology of the membrane. Fourier Transform Infra-red (FT-IR) to confirm the presence of functional groups. Thermal Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) were used to verify the thermal stability of the membrane. Membrane water uptake was used to investigate the porosity and swelling ability of the membrane, while impedance spectroscopy was used to measure the proton conductivity of the membrane. The permeability of the membrane was determined using a diffusion cell that was developed at Vaal University of Technology. The results obtained revealed that the blending of the chitosan with sulphonated zirconium oxide improved the water uptake, thermal stability, proton conductivity and permeability of the composite membrane than Nafion 117, which is the commercially available membrane. The water uptake was in the range of 70-74% while that of Nafion 117 is in the bracket of 25-33%. The TGA and DSC analysis showed that the composite membrane developed is a glassy polymer with a glass transition temperature (T g ) of 184 o C. The proton conductivities were in the range of 10 -3 -10 -2 S/cm and tend to increase with increase in the composition of the sulphonated zirconium oxide use in synthesizing the composite membrane. The permeability obtained was in the range of 4 x 10 -6 – 7 x 10 -6 mol/m 2 .s.Pa. From the results of the proton conductivity and the permeability, the selectivity factor of the membrane, which is a measure of performance of the membrane were determined. This is in the range of 14 – 34.

Raymond Daniel Rodriguez Martinez, Maria Eugenia Alvarez Bermudez

Clean Energy • 2023

Abstract Growing energy demand is a current problem with greater incidence in the future. The research objective is to establish seed bases to give a leading role to plants used in anthropogenic production activities and consumption, and even plants belonging to wildlife in terms of energy production. The use of living plants to obtain electrical energy through a microbial-vegetable fuel cell is proposed as a mechanism to supply the energy demand with easy access worldwide, especially in areas far from urban centres. In this work, the voltage produced by microbial-vegetable fuel cells was measured using graphite electrodes and plants belonging to the species of aloe (Aloe vera), corn (Zea mays), black beans (Phaseolus vulgaris), tomato (Solanum lycopersicum) and moss (Dicranidae). They were selected for their presence in everyday life and their great commercial and agricultural value, reaching a maximum voltage of 884 mV from moss. There is evidence that all plants can be a source of energy to a greater or lesser extent and that their performance is given by the plant root interactions at the electrodes. However, an extensive root system can favour the accumulation of substrate after the hydrolysis of dead roots, provided that their presence does not interfere with microbial activity on the anodic surface. For this, using plants with low resistance to thermal stress can lead to a substrate richer in substances that can be decomposed. Therefore, it is recommended to use plants according to their life cycle and the morphology of their roots, and plants that can grow in waterlogged conditions or without direct contact with the Sun.

, Albert García Tormo

• 2011

Aquesta tesi tracta sobre amplificació de potència d'alt rendiment de senyals variables en el temps; concretament, tracta sobre conversió de potència eficient (amb mínimes pèrdues) de tensions DC continues en senyals de tensió no constants. Aquest tipus de conversió de potència està present en la majoria de dispositius electrònics d'ús quotidià, com ara telèfons mòbils i reproductors de música portàtils, així com també en dispositius d'alta potència com amplificadors d'àudio i estacions base de telefonia mòbil. Generalment l'energia està disponible en forma de tensió DC contínua (d'una bateria o d'una font d'alimentació). D'acord amb la informació a transmetre, aquesta energia s'ha de processar o transformar en un senyal variable en el temps de manera que, per exemple, es pugui convertir en àudio per un altaveu . La tendència de mercat és a reduir la mida i el pes dels dispositius electrònics i a oferir noves funcionalitats, incloent una llarga autonomia en dispositius alimentats per bateries. Millorar l'eficiència dels amplificadors de potència no només n'estendria l'autonomia, sinó que també permetria utilitzar dissipadors més petits i lleugers. Altres aplicacions com les d'alta potència o integrades també es beneficiarien de millores en l'eficiència dels amplificadors de potència. Els dispositius electrònics de processament de potència més eficients són els amplificadors commutats. Aquests utilitzen components reactius (bàsicament bobines i condensadors) per dur a terme un processament de potència idealment sense pèrdues, així com dispositius actius (transistors) controlats com interruptors (o bé tancats o bé oberts), per tal de controlar aquest procés. Tot i que es poden assolir eficiències molt altes amb amplificadors commutats, la precisió de seguiment pot no ser gaire bona. Es pot millorar la precisió de seguiment senzillament incrementant la freqüència de commutació (la freqüència a la qual es fan commutar els interruptors), tot i que, com que es requereix una certa quantitat d'energia per fer commutar cada interruptor (pèrdues de commutació), aquesta tècnica també deteriora l'eficiència de l'amplificador. Existeix doncs un comprimís entre la freqüència de commutació i la precisió de seguiment en els amplificadors commutats (compromís eficiència-distorsió). Els amplificadors commutats habitualment es dissenyen per treballar a una freqüència de commutació alta comparada amb l'amplada de banda que han de seguir. Mentre que amb aquesta estratègia de disseny (i tecnologia actual) es poden dissenyar amplificadors per seguir senyals de l'ordre de kHz, si s'aplica per seguir senyals de l'ordre de MHz, els amplificadors haurien de treballar a freqüències de commutació massa altes, inviables des del punt de vista de les pèrdues de commutació. Amb l'objectiu d'abordar el compromís entre distorsió i eficiència dels amplificadors commutats, aquesta tesi explora diferents tècniques per estendre l'amplada de banda relativa dels amplificadors commutats, és a dir, tècniques per reduir la relació entre la freqüència de commutació de l'amplificador i la seva amplada de banda de seguiment. Basant-se en una interpretació alternativa dels amplificadors commutats, com a procés de codificació i reconstrucció, les diferents tècniques d'extensió de banda que aquí s'exploren contemplen utilitzar modulacions alternatives, amplificació de potència multi-nivell, filtrat d'ordre elevat i polítiques de commutació millorades en els convertidors commutats. La caracterització de les prestacions en termes de freqüència de commutació, error de seguiment i robustesa davant no idealitats (incloent compatibilitat electromagnètica i acoblament entre canals) apunta la idoneïtat de l'amplificació de potència multi-nivell basada en moduladors asíncrons per dissenys que treballin a freqüències de commutació relativament baixes, és a dir, a freqüències de commutació comparables a l'amplada de banda del senyal a seguir i amplificar. This thesis is about power amplification of time-varying signals; more precisely, it is about efficient power conversion, i.e. with minimum losses, of DC constant voltages into non-constant voltage signals. This kind of power conversion is quite common in power-management circuits and electronics in general. It is present in most everyday use electronic devices, including mobile phones, portable audio players and routers, as well as in high-power devices such as audio amplifiers and wireless base stations. In most electronic devices, whether portable or not, the energy is available as DC constant voltage (typically from a battery or a power supply). According to the information to transmit, this energy must be processed or transformed into a time-varying analogue signal so that, for instance, it can be directly converted into audio by a speaker or radiated by an antenna. The market trend is to reduce the size and weight of electronic devices whilst offering new or enhanced functionalities, including long autonomy in battery-powered devices (mainly portable). Improving the efficiency of power amplifiers not only extends the autonomy, but also allows using smaller and lighter heatsinks. Other applications such as high-power or embedded would also benefit from efficiency improvements of switching amplifiers. The most efficient power-processing electronic devices are switching amplifiers. Switching amplifiers use reactive components (mainly inductors and capacitors) to perform an ideally lossless power processing, and active devices (transistors) driven as switches, either ON or OFF, to control this process. Whilst very high efficiencies can be achieved with switching amplifiers, their tracking fidelity may not be very high. The tracking fidelity can be improved by simply increasing the switching frequency (i.e. the frequency at which the active devices are driven), although, provided that a certain amount of energy is required to switch the state of each active device (switching losses), this technique also degrades the efficiency of the amplifiers. Therefore, there exists a trade-off between switching frequency and tracking fidelity in switching amplifiers (efficiency-distortion trade-off). Switching amplifiers are typically designed using a high switching frequency compared to the amplifier's tracking bandwidth. Whilst this design strategy leads to feasible designs for kHz-bandwidth applications (using state-of-the-art technology), when applied to MHz-bandwidth applications, it leads to designs operating at very high switching frequencies, unfeasible with regard to switching losses. With the scope of addressing the efficiency-distortion trade-off of switching amplifiers, this thesis explores different techniques to extend the relative bandwidth of switching amplifiers, i.e. techniques to reduce the ratio of the amplifier's switching frequency to the amplifier's tracking bandwidth. Based on an alternative interpretation of switching amplifiers, as an encoding-reconstruction process, the different bandwidth extension techniques consider using alternative modulations, multi-level power amplification, high-order filtering and enhanced switching policies in the switching converter. The performance characterisations in terms of switching frequency, tracking error and robustness against non-idealities (including electromagnetic compatibility and crosstalk) points out the suitability of multi-level power amplification based on asynchronous modulators for designs operating at relatively low switching frequencies, i.e. at switching frequencies in the same range than the bandwidth of the signal to track and power amplify.

Taichi Ogawa, Shogo Nakamura, Ryo Miyamoto et al.

ECS Transactions • 2023

The durability of cathode catalysts in polymer electrolyte fuel cells remains a significant technical issue. Start-stop cycles cause carbon support corrosion and Pt catalyst particle detachment from the support leading to a significant cell degradation. SnO 2 -supported electrocatalysts using carbon materials as the conducting framework have the potential to achieve both high activity and high durability. However, cell performance in the high current density range needs to be improved to apply them to heavy-duty vehicles. This study selected mesoporous carbon (MC) as the conductive framework because the use of mesopores could also improve load-cycle durability. In this study, the microstructure of the electrocatalyst layers using Pt/Sn 0.98 Nb 0.02 O 2 /MC is controlled to improve the power generation of the cells. In addition, Pt/Sn 0.98 Nb 0.02 O 2 /MC electrocatalyst demonstrates durability improvement against the start-stop cycles.

Maher Al-Baghdadi

• 2020

Polymer electrolyte membrane (PEM) fuel cell system is an advanced power system for the future that is sustainable, clean and environmental friendly. PEM fuel cells are growing in importance as sources of sustainable energy and will doubtless form part of the changing program of energy resources in the future. PEM fuel cells are still undergoing intense development, and the combination of new and optimized materials, improved product development, novel architectures, more efficient transport processes, and design optimization and integration are expected to lead to major gains in performance, efficiency, reliability, manufacturability and cost-effectiveness. The difficult experimental environment of PEM fuel cell systems has stimulated efforts to develop models that could simulate and predict multi-dimensional coupled transport of reactants, heat and charged species using computational fluid dynamic (CFD) technology. The strength of the CFD numerical approach is in providing detailed insight into the various transport mechanisms and their interaction, and in the possibility of performing parameters sensitivity analyses. The results of CFD analyses are relevant in: conceptual studies of new designs, detailed product development, troubleshooting, and redesign. CFD analysis complements testing and experimentation, by reduces the total effort required in the experiment design and data acquisition. Relevant case studies and recent progress in CFD techniques used in PEM fuel cell development have been presented and analyzed. The CFD models are shown to be able to provide a computer-aided tool for design and optimize future PEM fuel cell with much higher power density, long cell life, and lower cost.

E. I. Vazquez-Oviedo, M. G. Ortiz-Lopez, L. H. Diaz-Saldierna et al.

Journal of Fuel Cell Science and Technology • 2013

A fuel-cell stack produces a low and unregulated dc voltage; therefore, a dc-dc converter is required to step up and regulate the output voltage. A major drawback is that the output voltage of the fuel-cell stack exhibits a nonlinear behavior since the output voltage drops when more current is drawn. This output voltage will be later connected to a switch-mode dc-dc converter to step up its value; therefore, it is very important to consider the dynamic behavior of fuel-cell stack as input to a switching converter. In this work, a model is proposed for a combined fuel-cell stack/boost converter system. The interest of this model is clearly motivated by the need to have a model compatible with the standard techniques for controller design as current-mode control. The model is tested using a power module and a boost converter delivering an output power of 740 W. The power module uses polymer electrolyte membrane fuel cells (PEMFCs) and delivers a variable output dc voltage between 24 V to 42 V. Experimental results verify the theoretical results given within.

Rahimi Parsa

Annals of Civil and Environmental Engineering • 2025

Polymer Electrolyte Membrane Fuel Cells (PEMFCs) operating in Dead-Ended Anode (DEA) mode present a promising alternative to traditional flow-through systems by simplifying design and reducing costs. However, their efficiency and durability are challenged by transient phenomena such as water accumulation, nitrogen buildup, and carbon corrosion throughout operation. This review investigates the dynamic behavior of DEA PEMFCs under dynamic operating states, aiming to improve their efficiency. By analyzing purge cycle optimization and transient response characteristics, we identify strategies to mitigate hydrogen loss, maintain voltage stability, and extend stack lifetime. The key findings indicate that precise purge scheduling and effective water management are critical for optimizing performance, with dynamic models providing insights into time-dependent processes. This study underscores the potential of DEA PEMFCs for high-efficiency applications provided transient effects are effectively managed.

Nisa Nur Atak, Battal Dogan, Murat Kadir Yesilyurt

Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy • 2024

In the present study, the performance parameters for a single-cell PEM fuel cell with 50 cm 2 active surface area and 0.0178 cm polymer membrane thickness at 4 different operating temperatures (303, 323, 343, and 363 K) and 4 different operating pressures (3, 6, 9, and 12 atm) was investigated by theoretical analysis. Hydrogen and oxygen partial pressures, membrane resistivity, internal resistance, activation, ohmic and concentration losses, cell voltage, power density, and thermal efficiency were calculated using this analysis. It has been observed that the augmentation of temperature and pressure in the fuel cell leads to a favorable increase in cell voltage, power density, and thermal efficiency. The thermal efficiency values were found to be 23% and 39%, respectively at the following conditions: temperatures of 303 K and 363 K, current density of 1 A/cm 2 , and constant pressure. At the same current density, the thermal efficiency is 29% and 32% at 3 atm and 12 atm operating pressures at a constant temperature. When operated under constant current density and temperature conditions, an increase in the operating pressure of the PEMFC from 3 atm to 12 atm results in a corresponding increase in cell voltage, from 0.4422 V to 0.4755 V, respectively. It was observed that the influence of temperature on the thermal efficiency of the PEM fuel cell was led to be higher than the influence of pressure.

Petia Mijaylova Nacheva, Danilo Gamboa-Santana, Edson B. Estrada-Arriaga

Sewage - Recent Advances, New Perspectives and Applications • 2022

The looking for sustainable sewage sludge management technology in the wastewater treatment plants, has brought to light the biocathode microbial fuel cells (bMFCs) which allow simultaneous biological stabilization and direct energy generation, avoiding the production of biogas. In the present study, the performance of bMFCs for the treatment of secondary sludge as anodic substrate was evaluated by analyzing the removal of organic matter, destruction of volatile solids and the generation of electrical energy under different operating conditions and applying two types of cathode chambers. The results indicated that VSS and tCOD removals up to 92% and 87% respectively can be achieved in the anodic chamber generating simultaneously energy. Current and power densities of 1.80 ± 0.09 A∙m−3 and 0.43 ± 0.02 W∙m−3 respectively were reached, showing that bMFCs are a reliable alternative to generate electricity during the sewage sludge stabilization process. It was revealed that the pH value and the type of cathodic zone are statistically significant factors that influenced the performance of the bMFCs. The obtained results demonstrated that the electrochemical performance of the bMFCs was better at pH value of 6 in the anodic chamber and when aerobic cathode zone was used.

V. V. Belousov, S. V. Fedorov

Fuel Cells • 2016

Abstract We suggest a novel molten oxide fuel cell (MOFC) concept. The MOFC is based on the oxygen‐ion‐conducting solid/molten oxide electrolyte (so‐called liquid‐channel‐grain‐boundary‐structure, LGBS, material) consisting of TeO 2 solid grains and chemically compatible TeO 2 +Te 4 Bi 2 O 11 liquid electrolyte at the grain boundaries. The intergranular liquid channels provide the LGBS mechanical plasticity (ductility), which makes it easy to shape and alleviates problems due to thermal incompatibility with electrodes (CTE), and high ionic conductivity. The volume fraction of liquid varied from 0.15 to 0.17 at 600–640 °C. The cell performance has been examined by standard electrochemical methods. With air used as a cathode gas, the single cell showed the power 11.5 mW cm −2 at the current density 90 mA cm −2 , electrolyte thickness 2.5 mm, and temperature 640 °C.

Radoslav R. Adzic, Junliag Zhang, Minhua Shao et al.

ECS Transactions • 2006

We have synthesized a new class of electrocatalysts for the oxygen reduction reaction, consisting of a monolayer of Pt or mixed monolayer of Pt and another late transition metal (Au, Pd, Ir, Ru, Rh, Re or Os) deposited on a Pd(111) single crystal or on carbon-supported Pd nanoparticles. Several of these electrocatalysts exhibited very high activity, amounting to 20-fold increase in a Pt mass activity, compared with conventional carbon supported-Pt electrocatalysts. The origin of this effect was identified through a combination of experimental methods, employing electrochemical techniques, x- ray absorption spectroscopy. In addition, we found that gold submonolayer clusters modified Pt or Pt/Pd catalysts have high activity and an exceptional stability against Pt dissolution under potential (0.6-1.1V) cycling regimes. These new electrocatalysts promise to alleviate some major problems of existing fuel cell technology by simultaneously decreasing materials cost and enhancing performance.

Nguyen Ha Hiep, Vu Duong

Engineering, Technology & Applied Science Research • 2024

This work presents the results of manufacturing a single Proton Exchange Membrane Fuel Cell (PEMFC) with Micro-Porous Layers (MPLs) and an active area of 25 cm2, and the experimental study required to build its polarization curve. Based on the physical model data, a numerical model of this PEMFC is created in the ANSYS PEM Fuel Cell module. Numerical simulations were performed with boundary conditions consistent with the experimental conditions on the test station. The calculation and experimental result comparison of the polarization curves for voltages ranging from 0.29 V to 0.94 V proved that the utilized numerical model is highly reliable. The simulation of PEMFC without MPLs was conducted according to other stable input parameters and boundary conditions. The results show that the PEMFC performance decreases significantly due to the flooding phenomenon inside PEMFC without MPLs compared to PEMFC with MPLs. Such phenomena are challenging to observe experimentally. Numerical modeling can be further used to optimize the fuel cell components.

Gema Montaner Ríos, Florian Becker, Anna Vorndran et al.

E3S Web of Conferences • 2021

Durability of proton exchange membrane fuel cell systems under cold weather conditions is essential and a critical challenge for transportation applications. During cold storage the water remaining in the cells can freeze causing damage to the cell components. In order to avoid this degradation, fuel cells are commonly purged with dried gases during shutdown prior to its storage at subzero temperatures. This work investigates cold storage of PEMFC systems at temperatures down to -40°C with the aim of developing a shutdown procedure that leads to minimal degradation due to cold storage, while meets energy efficient and time requirements of aeronautical applications. To that end, several experiments were carried out with two different stacks (a 4 kW liquid cooled and a 100 W air cooled) under a wide range of operating parameters: cathode gas, purge temperature, anode and cathode gas purge flow rates, purge time and cold storage temperature. The fuel cell performance degradation due to ice formation was measured by the polarization curves conducted prior and after every F/T cycle. The effects of these operating parameters on the durability of the PEMFC systems under cold storage are evaluated. The obtained experimental results showed that very long purge process lead to further performance degradation at -10°C than shorter process at -40°C, which indicates that eliminating all remained water in the cells is not only inefficient, but also lead to degradation due to the drying process. Moreover, guidelines to improve shutdown procedure for cold storage of proton exchange membrane fuel cell systems for aeronautical applications are discussed.

S S Daud, M A Norrdin, J Jaafar et al.

IOP Conference Series: Materials Science and Engineering • 2019

Abstract Bipolar membrane fuel cell (BPMFC) was firstly discovered in 2000 that composed of two-layered ionic conducting membranes. The importance of BPMC development is its ability to humidify the cell when operating at a high current density that eliminates the use of the external humidification system. It is able to self-humidify the cell because of water formation at the intermediate layer from the reaction of hydrogen ion (H + ) with hydroxide ion (OH − ). Up to now, there is no commercial bipolar membrane (BPM) in water formation configuration for the fuel cell humidifying purpose. Thus, the researcher had come out with a composition of proton exchange membrane with anion exchange membrane by the hotpressing method that allows them to carry the proton and anion simultaneously in a single cell. There are a few of polymeric-based PEM and AEM material had been selected for developing BPM such as Nafion, FumaPEM FAA3, quaternary ammonium polysulfone (QAPSF), and quaternary ammonium poly(phenylene)oxide (QAPPO). This review aims to determine the effect of material selection and design for developing BPM toward its performance in fuel cell based on published works. Besides, the potentialities of polymeric-based material are discussed, pointing out the main positive and negative effect of this BPM for fuel cell applications. As a case study, the use of different types of PEM and AEM material for BPM is particularly stressed, pointing out the main properties for its applications in BPMFC.

Hong Ki Lee, Sung Wan Hong, Sung Won Yang et al.

Advanced Materials Research • 2007

For the regenerative fuel cell (RFC), water electrolysis cell performance using membrane electrode assembly (MEA) in polymer electrolyte fuel cell (PEMFC) were investigated. A part of Nafion had been secondary sprayed on the surface of catalytic layer and variation of cell performance was diminished. The conformation of stability, improvement of mechanical and electrical properties was accomplished by addition of PVDF, graphite and RuO2. With the addition of graphite power and RuO2, the voltage was decreased from 3.6V to 2.5V and 2.2V. The improvement of the mechanical properties was obtained by addition of PVDF. The electrolysis cell manufactured with MEA electrode was showed less decomposition voltage of 1.3V than with Nafion electrode at 10A of applied current. The stability of MEA was confirmed from 30 days of cell operation

Venko N. Beschkov, Elena N. Razkazova-Velkova, Martin S. Martinov et al.

Catalysts • 2021

Hydrogen sulfide is frequently met in natural waters, like mineral springs, but mostly it is found in marine water with low renewal rate. The Black Sea has extremely high hydrogen sulfide content. It can be utilized in different ways, but the most promising one is direct conversion into electricity. This result can be attained by a sulfide-driven fuel cell (SDFC), converting sulfide to sulfate thus releasing electric energy up to 24 GJ/t. One of the most important problems is the mass transfer limitation on oxygen transfer in the cathode space of the fuel cell. This problem can be solved using a gas diffusion electrode or highly efficient saturation by oxygen in an ejector of the Venturi tube type. This work presents experimental data in laboratory-scale SDFC for sulfide conversion into sulfate, sulfite and polysulfide releasing different amounts of electric energy. Two types of aeration are tested: direct air blow and Venturi-tube ejector. Besides pure graphite, two catalysts, i.e., cobalt spinel and zirconia-doped graphite were tested as anodes. Experiments were carried out at initial sulfide concentrations from 50 to 300 mg/L. Sulfate, sulfite and thiosulfate ions were detected in the outlet solutions from the fuel cell. The electrochemical results show good agreement with the chemical analyses. Most of the results show attained high efficiencies of the fuel cell, i.e., up to 80%. The practical applications of this method can be extended for other purposes, like treatment of polluted water together with utilization as energy.

P. Agrawal, S. Ebrahim, D. Ponnamma

International Journal of Energy and Water Resources • 2024

Abstract Fuel cells hold great promise as a clean energy technology, yet challenges such as material compatibility, manufacturing costs, and durability issues, particularly with noble metal-based electrocatalysts like platinum (Pt), hinder their widespread adoption. This review explores strategies to enhance fuel cell performance while minimizing costs, focusing on developing efficient and cost-effective catalysts supported by nanocarbon materials, such as carbon nanotubes, graphene, carbon films, and their composites. The investigation delves into how these catalysts supports improve activity and stability, leading to superior fuel cell performance characterized by higher current density and enhanced durability compared to conventional Pt/C catalysts, with a specific focus on proton-exchange membrane fuel cells. Key topics covered include the role of nanocarbon in fuel cells, various nanocarbon-based catalyst supports, Pt-containing alloys, non-Pt catalysts, and nanocarbon composites for electrolyte membranes and corrosion protection. Notable findings include the importance of heteroatom doping in enhancing reactivity, the effectiveness of organic–inorganic composite proton exchange membranes in improving proton conductivity, and the potential of amorphous carbon film coatings and conductive polymer-nanocarbon composites in enhancing corrosion resistance. These advancements underscore the potential of nanocarbon-based catalysts and coatings in ensuring the reliability and longevity of fuel cell components, thus contributing to the widespread commercialization of fuel cell technology.

Yewondwosen Gzate

Research Square • 2024

Abstract The aim of this work is to improve and compare the performance of pure gasoline ethanol blend and hydrous ethanol blend fuels for spark ignition engine without major fuel system component modification. The comparative experiments were conduct on mechanical gasoline engine fueled with pure gosine, E10 and HE10.The effects of the engine loads and the additions of ethanol and water on combustion and emission characteristics were analyzed deeply. The modified engine was tested with gasoline-ethanol-water blend emulsion as a fuel, and the effect of data were recorded on brake torque, brake power, brake specific fuel consumption, thermal efficiency, exhaust emission (CO, CO 2 , HC, O 2 ) and smoke emission. In addition to performance test, the study on the miscibility of water, ethanol and gasoline blend was conducted mainly to know what extent water can be added to ethanol gasoline blend without phase separation. The amount of water it can be tolerate in the hydrous alcohol when used as a blending component with gasoline is up to 5% of ethanol. Higher water solubility in ethanol gasoline blends may be obviously useful and suitable nevertheless, temperature continuous ability of water to remain soluble in the blend is significantly affected by temperature and improvement in combustion characteristics. According to the experimental results, compared with pure gasoline and E10 blend, HE10 showed higher peak brake torque at high load. Increases in brake power were observes for HE10 fuel at all the operating conditions. The usage of HE10 fuel at optimum load conditions reduces HC, CO and CO 2 emissions significantly. In addition, decreases in NO X emissions were observed for HE10 from 0 Nm to 80 Nm. From the results, it can be concluded that HE10 fuel can be regard as a potential alternative fuel for gasoline engine applications.

Syarifah Noor Syakiylla Sayed Daud, Muhamad Noorul Anam Mohd Norddin, Juhana Jaafar et al.

Journal of Applied Membrane Science & Technology • 2022

The membrane in a fuel cell plays an essential role in permeating the ionic charges of positive and negative ions without passing the fuels and electrons through it. The membrane's common materials are perfluorinated polymer, non-fluorinated or hydrocarbon polymer, and natural polymer. The physicochemical properties of the membrane have the most significant influence on the performance of fuel cells in terms of mechanical stability, ionic conductivity, power output, and cell operation longevity. The incorporation of nanoparticles into polymeric-based materials improved the membrane's properties by suppressing fuel crossover, improving water retention, and increasing ionic mobility across the membrane. The effect of incorporating nanoparticles is determined by their type, size, shape, surface acidity, and relationship to the polymer matrix. The blending, sol-gel, and infiltration methods are used to develop the nanocomposite membrane. Compared to a commercial membrane in a fuel cell application, most of these membranes demonstrated superior cell performance. Based on published literature, this review briefly described the design and influence of specific advanced nanomaterials incorporated in polymer matrix toward membrane performance.

Chen Li, Xiaoming Xu, Hao Hu et al.

Journal of Electrochemical Energy Conversion and Storage • 2021

Abstract The electrochemical reaction inside a high-power fuel cell generates a lot of heat. Excessive heat affects the performance of the membrane, so it is necessary to introduce coolant. The main objective of coolant is regulating the temperature of relatively high-power proton exchange membrane fuel cell (PEMFC) stacks efficiently. The coolant channel has a great influence on the performance of PEMFC. In this work, a multiphase, 3D PEMFC model with serpentine flow channel is developed. In order to rank structural parameters according to the degree of influence on fuel cell performance, this study analyzed the current density, O2 mass fraction, and the distributions of temperature based on an orthogonal test scheme with three factors and three levels. The results show that rib width between the reactant flow channel and the cooling channel has the greatest influence on the current density, and gas flow channel width has the least influence.

F. A. de Bruijn, V. A. T. Dam, G. J. M. Janssen

Fuel Cells • 2008

Abstract Besides cost reduction, durability is the most important issue to be solved before commercialisation of PEM Fuel Cells can be successful. For a fuel cell operating under constant load conditions, at a relative humidity close to 100% and at a temperature of maximum 75 °C, using optimal stack and flow design, the voltage degradation can be as low as 1–2 μV·h. However, the degradation rates can increase by orders of magnitude when conditions include some of the following, i.e. load cycling, start–stop cycles, low humidification or humidification cycling, temperatures of 90 °C or higher and fuel starvation. This review paper aims at assessing the degradation mechanisms of membranes, electrodes, bipolar plates and seals. By collecting long‐term experiments as well, the relative importance of these degradation mechanisms and the operating conditions become apparent.

I G Bratu, R F Ene, M Vulpe et al.

IOP Conference Series: Earth and Environmental Science • 2021

Abstract The performance of PEM fuel cells is influenced by several factors such as: the operating temperature of the cell, the reactant gas flow, work pressures, the reaction gas humidity. In the present work we aimed to identify the optimal values of these parameters for operation of a PEM cell to achieve maximum power in conditions of high efficiency; the technological possibilities of its use in a portable energy application have been evaluated. Experimental measurements regarding the integrating polymeric membrane in three different fuel cell construction designed were performed. The influence of the mechanical compression of the GDL diffusion layer on the total internal resistance of the cell was achieved by comparative analysis of the polarization curves. It was found that as the deformation level of the MEA increases, the power generated by the battery increases progressively. The resulting experimental data subsequently allowed the design and implementation of a PEM fuel cell assembly, fully functional at power level, corresponding to the number of constituent elements.

Elif Eker Kahveci, Imdat Taymaz

E3S Web of Conferences • 2019

In this study, the effects of operating parameters on power density of a 3-cell PEMFC (Polymer Electrolyte Membrane Fuel Cell) stack with serpentine flow channels having 150 cm 2 total active layer have been examined experimentally. Desing Expert, which is the experimental design program (trial version) was used, and the data obtained as a result of the experiments were analyzed by entering this program. A total of 25 experiments were carried out according to the design created with the data entered into the program within the specified operating conditions range. The independent variables were entered which are cell temperature, humidification temperature, H 2 flow rate and O 2 flow rate, and the response is the power density. In this study, the hydrophobic cell stack which has the highest cell performance of which was previous studies results was used. In the optimization study, keeping the power density and maximum H 2 flow to a minimum, the most suitable values are cell temperature 57.826°C, humidification temperature 56.151°C, O 2 flow 1.587 L/min. Finally 432.398 mW/cm 2 power density value was obtained under these operating conditions.

Stuart Holmes, Maria Perez Page, Madhumita Sahoo et al.

ECS Meeting Abstracts • 2018

Fuel Cells have attracted great attention in recent times since can offer numerous benefits such a high power density, compactness, lightweight and zero emissions. One of the most attractive and effective regarding transportation applications is low temperature fuel cell or Proton Exchange Membrane Fuel Cells (PEMFC). Great efforts have been made to research of different materials to improve this Fuel Cell performance. Graphene materials have been attracted great interest in their electrical and barrier properties. CVD Graphene monolayer is an excellent electronic conductor in-plane and impermeable to all species except the protons through the plane. Graphene oxide has been demonstrated to be an ionic conductor but impermeable to dry gases and electrons. Graphene oxide is an organophobic material, property which makes this material as a good barrier. Different studies have been carried out for The University of Manchester to prove that incorporate CVD Graphene, Reduced Graphene Oxide (rGO) and Graphene oxide (GO) into the different layer of the PEM fuel cell Membrane Electrode Assemblies (MEAs) [1,2]. GO has been added as a barrier layer in Direct Methanol Fuel Cells providing additional tortuosity and decreasing the methanol crossover, one of the most important inconvenient in this type of PEM fuel cells. rGO has been incorporated as a catalyst support obtaining an important improvement in the methanol oxidation reaction. Several graphene preparation methods have been developed, such as chemical vapour deposition (CVD), arc discharge, segregation growth or Hummers method. However, the requirements of expensive equipment used, extreme reaction conditions and the usage of highly toxic chemicals are some of the inconvenient that these techniques present. Then, the synthesis of graphene in both high quality and quantity via economic ways is one of the most important challenges nowadays for practical applications. Electrochemical exfoliation of graphite has been presented as a green and cost-effective approach for producing high quality of graphene in high yield using simple equipment [3-5]. This work presents an alternative to Hummer’s method to produce GO and rGO by Electrochemical Exfoliation of Graphite. A simple two electrodes configuration, counter electrode and working electrode in different electrolyte solutions, NH 4 NO 3 , (NH 4 ) 2 SO 4 , has been carried out to produce this GO. Figure1 shows preliminary characterization results of GO produced by electrochemical exfoliation (EGO) using NH 4 NO 3 as electrolyte. Single flakes of GO can be observed in the TEM image. Raman spectra and their I D /I G ratio show that EGO presents a good quality compared with Hummer’s method. GO produced by Electrochemical Exfoliation will be incorporated into different MEAs layer to obtain an enhanced performance of low temperature fuel cell. GO. Effect of GO on the fuel cell was studied by electrochemical characterization. References: [1] Stuart M. Holmes, Orabhuraj Balakrishnan, Vasu. S. Kalangi, Xiang Zhang, Marcelo Lozada-Hidalgo, Pulickel M Ajayan, Rahul R. Nair. 2D Crystals Significantly Enhance the Performance of a Working Fuel Cell. Advance Energy Materials , 7, (2017). [2] S. Al-Batty, C. Dawson, S. P. Shanmukham, E. P. L. Roberts and S. M. Holmes. Improvement of direct methanol fuel cell performance using a novel mordenite barrier layer . J Mater. Chem . A, 2016, 4, pp. 10850-10857. [3] Richard Gondosiswanto, Xunyu Lu, and Chuan Zhao. Preparation of Metal-Free Nitrogen-Doped Graphene via direct electrochemical exfoliation of graphite in ammonium nitrate. Australian Journal of Chemistry , 68 (2015) 830-835. [4] Xunyu Lu and Zhao. Controlled electrochemical intercalation, exfoliation and in-situ nitrogen doping of graphite in nitrate-based proton ionic liquids . Physical Chemistry Chemical Physics, 15 (2013), 30005-200009. [5] Khaled Parvez, Ahong-shuai Wu, Tongjin Li, Xianjie Liu, Robert Graft, Xinliang Feng, and Klaus Mullen. Exfoliation of Graphite into Graphene in Aqueous solution of Inorganic Salts. Journal of the American Chemical Society, 136, (2014), 6038-6091. Figure 1

Vinaykumar Konduru, Ezequiel Medici, Jeffrey S. Allen

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

Water transport in the Porous Transport Layer (PTL) plays an important role in the efficient operation of polymer electrolyte membrane fuel cells (PEMFC). Excessive water content as well as dry operating conditions are unfavorable for efficient and reliable operation of the fuel cell. The effect of thermal conductivity and porosity on water management are investigated by simulating two-phase flow in the PTL of the fuel cell using a network model. In the model, the PTL consists of a pore-phase and a solid-phase. Different models of the PTLs are generated using independent Weibull distributions for the pore-phase and the solid-phase. The specific arrangement of the pores and solid elements is varied to obtain different PTL realizations for the same Weibull parameters. The properties of PTL are varied by changing the porosity and thermal conductivity. The parameters affecting operating conditions include the temperature, relative humidity in the flow channel and voltage and current density. A parametric study of different solid-phase distributions of the PTL and its effect on thermal, vapor and liquid transport in the PTL under different operating conditions are discussed.

Zachary R. Williamson, Daejoong Kim, Dae-Keun Chun et al.

ASME 2011 9th International Conference on Fuel Cell Science, Engineering and Technology • 2010

An experimental analysis of cell temperature effects on an air-breathing, PEM fuel cell is presented. The cell was tested in three active area sizes of 5 cm2, 10 cm2, and 25 cm2. The cell’s design minimized the influence of self-heating by using a large thermal body in its construction which conducted heat away from the active area. This allowed for the use of a heater and controller to test a constant cell temperature uninfluenced by current density. Polarization and electrochemical impedance spectroscopy testing showed that at higher current density, elevated temperature increased the buoyancy of the air around the cell which improved open cell performance. However, the opposite is true for lower current density as membrane dehydration becomes more prevalent at higher temperatures. Schlieren imaging, in conjunction with the polarization and EIS data, shows how heated and more buoyant air boosts cell performance. Infrared imaging identifies temperature gradients on the active surface which may hinder cell performance slightly.

Yavuz Yagizatli, Irfan Ar

Journal of Polymers and the Environment • 2024

Abstract This study focuses on developing an alternative membrane for PEMFC due to the disadvantages of using Nafion. Fluoroboric acid (FBA) was used as an additive material to SPEEK-PVA blend membranes at different weight ratios (1%, 5%, 7.5%, 10%, and 12.5%), and a synthesis procedure was carried out with the solution-casting. Thermal crosslinking was performed with all membranes. Utilizing FBA, with its highly electronegative fluorine groups, is a novel approach expected to enhance proton conductivity. The structural, morphological, and thermal properties of the synthesized membranes were determined by FTIR, XRD, SEM, TGA-DTG, and DSC. Water uptake capacity (WUC), swelling property, area change, dynamic mechanical analysis, ion exchange capacity (IEC), AC impedance analysis, hydrolytic stability, and oxidative stability analyses were performed for fuel cell applications. Although FBA does not have a crystal structure, the synergy it created with the SPEEK-PVA membrane increased the crystallinity of the membrane and, accordingly, glass transition temperature. SEM images of membranes at a ratio above 7.5% show that agglomerations occur in the structure and this is supported by other analyses. It was determined that the membrane composition with the highest WUC (16.44%), IEC (1.55 meq/g), and proton conductivity (0.57 S/cm) values contained 7.5% FBA from the characterization studies, and a single-cell performance test was actualized with this. 418 mA/cm 2 current density and 250.8 mW/cm 2 power density were obtained at 0.6 V cell potential, with the membrane containing 7.5% FBA. This study shows that the synthesized membrane, especially the FBA, is a promising option for PEMFC application. Graphical Abstract

K. Krishna Pandi, K. Ramesh, D. Kulandaivel et al.

international journal of engineering technology and management sciences • 2022

Over the past ten years, proton exchange membrane (PEM) fuel cells have gained popularity as a potential energy source. PEM fuel cells are a high efficiency, environmentally friendly power source that are not constrained by Carnot efficiency. Due to its characteristics of zero emissions, high power density, rapid start-up, and low operating temperature, they are seen as one of the attractive options to be utilized for electric cars. In this project work, a fuel cell uses that a low cost bipolar plate material with a high fuel cell performance are important for the establishment of PEM fuel cells into the competitive market world are taken in consideration. The analysis is carried out for the selected materials like Aluminium, Copper and Stainless steel on considering the design and operational parametric conditions of the PEM fuel cell. The aluminium bipolar plate exhibits improved uniformity in the dispersion of hydrogen, oxygen, and water vapour, which will improve the ionic conductivity in the membrane. After analysing the data, we found that the aluminium bipolar plate material had the best temperature distribution in the fuel cell and the lowest pressure loss when compared to the copper and stainless steel materials. Therefore, due to its light weight and reasonably low price of material, aluminium serpentine bipolar plate material may be thought of as the ideal bipolar plate material, especially for portable applications.

, Farah Syakinah Md Sokor, Ryan Yow Zhong Yeo et al.

Jurnal Kejuruteraan • 2024

Microbial Electrochemical Sensor (MES) is classified as a self-powered electrochemical biosensor and utilising biofilm electrode used as a sensor. Conventional techniques such as ion chromatography (IC), highperformance liquid chromatography (HPLC), and chemical oxygen demand (COD) require large, expensive, and non-portable equipment. Therefore, MES has gained significant attention due to its advantages, including low cost, easy operation, and portability. Stainless steel (SS404L) is widely used in various applications but exhibits lower biocompatibility compared to carbon-based materials when used as an anode. This MES is constructed using modified electrodes through techniques such as carbon coating, electrochemical reduction, flame oxidation, and graphene coating. A nutrient medium stock is periodically supplied daily to enrich the electroactive microbes and maintain the biosensor’s performance at a stable level. Samples are collected and analyzed during pollutant testing to determine pH, conductivity, IC, and COD values. These parameter values are correlated with MES signal data to assess each biosensor’s performance in terms of reaction rate. FESEM-EDX and RAMAN analysis indicated an increase in O content from 2.4% to 19.9% for flame oxidation. For carbon and graphene coatings, carbon content increased from 4.1-9.1% to 48.4-78.6%. The carbon coating exhibited an R² value of 0.7023 for tests using 4-nitrophenol. Meanwhile, for potassium nitrate, the graphene coating demonstrated the highest R² value of 0.8785. A higher R² value indicates a stronger correlation and suggests better performance in electrode modification within MES. This highlights the significance of MES results in water quality monitoring, which can be understood and applied more effectively.

Jalal Tavalaei, Zulkurnain Abdul-Malek, Amir Hesam Khavari et al.

Applied Mechanics and Materials • 2015

Non linear resonance usually resonates in network which is consisting of ferromagneticcore. When distributed capacitance calculated form circuit breaker; mainly circuit breaker and cablecapacitance; after switching and opening the network feed apparatus, magnetization current on ferromagnetic core jump to saturation. Duration of ferroresonance is deeply relying on capacitance, and itwill be decaying by disembarking total store energy. Although, ferroresonance commence by switching circuit breaker off; protecting relay and other protecting schemes have no reaction, because thelast protection step for saving a device is a circuit breaker. There is no reported method to mitigatedisruptive phenomenon; which elder publication focus on the explosion of capacitive transformer,melting of power transformer core lamination and arresters problem. This work is tried to dampingferroresonance and reducing devastation effect on the apparatus. While, protecting devices is useless,fault point topology mutating by FACTS to control and decrease this phenomenon. FACTS deviceis settled at the upstream of apparatus to improve power quality, is switched on at initiating momentresonating. Modeling and simulating of ferroresonance are done by the actual value of transformerand other power system related devices extracted by UTM-TNB.

Konstantin A. Weber, Marta Zaton, Mark Muggli et al.

ECS Meeting Abstracts • 2023

Within the past years, proton exchange membrane (PEM) fuel cells have become more and more attractive due to their potential for the transition towards an environmentally friendly hydrogen economy. Especially by reducing the platinum catalyst loading, significant system cost reductions could be achieved, but low Pt loadings still lead to unassigned voltage losses during operation. [1,2] In order to overcome those losses, well-designed catalyst layers with optimized ionomer content and distribution are indispensable. The used perfluorosulfonic acid (PFSA) ionomers for PEM fuel cells are commonly characterized by the chemical structure of the ionomer and the equivalent weight (EW), which strongly affects the proton conductivity. [3,4] Current research focusses on the synthesis of modified ionomers with higher oxygen permeability to reduce mass transport losses, but also investigates the influence of the ionomer’s molecular weight (MW). [1,5,6] A high MW minimizes the water uptake of the ionomer/membrane in liquid water, which is desired for the use in PEM fuel cells to reduce mechanical stress during relative humidity (RH) cycling. [5] The exact MW of an ionomer is not easily accessible, but can be estimated by measuring the melt flow index (MFI), whereas a high MW is commonly reflected by a lower MFI if the ionomer chemistry and EW are the same. Within this study, a 3M ionomer modified to have a high MFI of 156 g/10 min (measured at 265 °C with a mass of 5 kg) is investigated and compared to a 3M standard ionomer with a low MFI of 6 g/10 min. Both PFSA ionomers have the same chemical structure and a similar EW of ~800. The significantly higher MFI of the modified ionomer (i.e., comprising a lower MW) is clearly reflected by a ~2 times higher water uptake compared to the 3M standard ionomer (measured for solution-cast membranes in liquid water at 80 °C). To evaluate the impact of the MFI within the cathode electrode, 5 cm² active area membrane electrode assemblies (MEAs) with these two ionomers at various ionomer/carbon (I/C) mass ratios in the cathode electrode (based on a 40 wt.% Pt/Vulcan catalyst at loadings of 0.11 mg Pt /cm²) are manufactured and electrochemically characterized. At sufficiently high I/C ratios and under humid operation (i.e., I/C = 0.90 and 90 % RH), differential flow H 2 /air polarization curves of the MEAs reveal that the higher liquid water uptake of the 3M high-MFI ionomer can be correlated with a lower cell voltage (see Figure 1). Contrary to the MEAs with the 3M low-MFI standard ionomer, the larger ionomer swelling in MEAs with the 3M high-MFI ionomer reduces the void volume fraction in the electrode structure during operation. Most pronounced at high current densities, where oxygen mass transport plays an important role, the MEAs containing the 3M high-MFI ionomer show a significant voltage loss of ~50 mV at 2.5 A/cm² compared to the MEAs with the 3M low-MFI ionomer. This study demonstrates that the effect of ionomer volume expansion upon changes in the MFI and thus the MW might not be crucial for the MEA performance when using electrodes with a low I/C ratio, but is critical when aiming for electrode compositions with a high ionomer content, in which case a low-MFI (i.e., a high MW) ionomer should be favorable. References [1] A. Kongkanand and M. F. Mathias, J. Phys. Chem. Lett., 7 (7), 1127–1137 (2016). [2] A. Z. Weber and A. Kusoglu, J. Mater. Chem. A, 2 (41), 17207–17211 (2014). [3] M. Doyle and G. Rajendran. in Handbook of Fuel Cells: Fundamentals, Technology, Applications , W. Vielstich, A. Lamm, H. A. Gasteiger, Editor, p. 538, Chichester, John Wiley & Sons Ltd. (2003). [4] N. Ramaswamy, S. Kumaraguru, R. Koestner, T. Fuller, W. Gu, N. Kariuki, D. Myers, P. J. Dudenas and A. Kusoglu, J. Electrochem. Soc., 168 (2), 24518 (2021). [5] Y. Li, R. Jiang and C. Gittleman, J. Power Sources, 478, 228734 (2020). [6] A. Katzenberg, A. Chowdhury, M. Fang, A. Z. Weber, Y. Okamoto, A. Kusoglu and M. A. Modestino, J. Am. Chem. Soc., 142 (8), 3742–3752 (2020). Acknowledgements This project has received funding from the Fuel Cells and Hydrogen 2 Joint Undertaking (now Clean Hydrogen Partnership) under grant agreement No 826097. This Joint Undertaking receives support from the European Union’s Horizon 2020 research and innovation program, Hydrogen Europe and Hydrogen Europe Research. Figure 1

John F. Cooper

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

A direct carbon fuel cell (DCFC) using a carbon-rich derivative of coal would maximize the conversion efficiency of this vast energy resource by avoiding the efficiency limitations of heat engines. A total conversion efficiency of 80% (based on heat of combustion of carbon) has been achieved at 30–120 mA/cm2 using carbon materials extracted from coal and other fossil resources. High experimental efficiency is grounded in two favorable aspects of the reaction thermodynamics. The net fuel cell reaction (C + O2 = CO2) has a nearly zero entropy change and therefore a theoretical efficiency of 100%. The fixed chemical potentials of carbon reactant and CO2 product make possible the full utilization of fuel in a single pass through the cell. The pure CO2 product can be used directly in enhanced oil and gas recovery, or sequestered. Historically, the development of carbon fuel cells have been limited by low anode rates, accumulation of impurities in the electrolyte, logistics of refueling, and lack of suitable cathodes. These problems are being addressed by recent developments of highly reactive carbon materials, low-cost techniques for separation of coal from ash, the possibility of pneumatic distribution of solid particulate fuel to the cells, and availability of cathodes from the molten carbonate fuel cell technology. Rate depends on atomic scale disorder and accessibility of reactive sites, but not on purity. Sources of suitable anode fuel include thermally decomposed products of (1) mechanical and chemical coal/ash separation or (2) solvent extraction. With current understanding of the cell basics, the next steps are demonstration of an engineering scale fuel cell stack (∼1 kW), supported by development of coal-to-carbon processes and techniques of electrolyte management. Successful development of a direct conversion fuel cell for coal (or coal-derived carbon) has extraordinary implications in extending the energy reserves of coal-producing nations, easing the control of regulated emissions at the plant, and expanding the use the earth’s greatest fossil resource while decreasing emissions of greenhouse gas.

Liping Fan, Yaobin Xi

Energies • 2021

Anode modification is a useful method to increase the performance of microbial fuel cells (MFCs). By using the electrochemical deposition method, Fe3O4 and polypyrrole (PPy) were polymerized on a carbon felt anode to prepare Fe3O4-PPy composite modified anodes. In order to ascertain the effect of electrodeposition time on characteristics of the modified electrode, the preparation time of the modified electrode was adjusted. The modified anodes were used in MFCs, and their performances were evaluated by analyzing the electricity generation performance and sewage treatment capacity of MFCs. Experimental results indicated that the Fe3O4-PPy composite modified anodes could enhance the power production capacity and sewage treatment efficiency of MFC effectively. In particular, when the deposition time was 50 min, the modified anode could significantly improve the MFC performance. In this case, the steady-state current density of MFC increased by 59.5% in comparison with that of the MFC with an unmodified carbon felt anode, and the chemical oxygen demand (COD) removal rate was 95.3% higher than that of the unmodified anode. Therefore, the Fe3O4-PPy composite is an effective material for electrode modification, and a good anode modification effect can be obtained by selecting the appropriate electrodeposition time.