Santosh Krishnakant Rai, Chandrahas Sahu

International Journal of Innovative Science and Research Technology (IJISRT) • 2024

In order to lower power consumption and leakage currents during active operation, the suggested SRAM architecture with power gating design trims the source voltage across the SRAM cell, ranging from 50 to 150 mV. Power gating based on sectors is utilized, using a self-biasing approach where the gate terminal and source of a PMOS transistor act as a diode, controlling the virtual ground. However, three challenges arise with this method in nanometer technology: the additional self- biasing transistor (SBT) occupies 5% more space, the source voltage adjustment mechanisms are not effectively implemented, and the increase in virtual ground voltage leads to bias temperature instability. To implement this design, a 4x4 SRAM cell array is constructed, consisting of 4 rows and 4 columns of 10T SRAM cells. A decoder addresses these cells, and each row represents half a byte, with control circuitry managing input and output data. Additionally, the outputs of individual cells in each column are combined using a 4-bit OR, producing a single data output point. This architecture effectively reduces power consumption while maintaining operational efficiency, making it suitable for nanometer-scale SRAM designs.

Mike L. Perry

ECS Meeting Abstracts • 2015

A systematic methodology to determine what is limiting the performance of a fuel cell will be presented. The basis of this methodology is to utilize in-situ cell data combined with simple analytical techniques. The key analytical techniques are based on theoretically-predicted limiting cases for the different types of overpotential that can limit the performance of a polymer-electrolyte fuel cell (PEFC). These limiting cases are compared to PEFC performance data utilizing simple graphical techniques in order to provide semi-quantitative insight into the mechanisms primarily responsible for the cell polarization observed operating under the operating conditions of interest. This diagnostic methodology is ideally suited to investigate changes in the performance of a fuel cell. For example, the use of this methodology to investigate durability losses in PEFCs has been described [1]. However, the same techniques can be used to determine why the performance of one type of cell is different than a cell of a different configuration, or why the performance of a given cell varies with different operating conditions. Examples of each of these types of cell-performance investigations will be used to illustrate the methodology. The diagnostic method recommended here is a systematic, step-by-step method. The first step is to determine what major type(s) of overpotential are responsible for the changes in performance, namely: kinetic, ohmic, or mass transport. Polarization-change curves, such as those depicted in Figure 1, are a simple and useful tool to assist in apportioning performance changes to the different types of overpotential. The limiting cases depicted in Figure 1 were constructed with a relatively simple model of cell polarization [1]. These simple limiting cases, as well as some actual polarization-change curves examples, will be presented. Once the major types of overpotential have been identified, additional cell diagnostics can be selected to establish the sources ( i.e ., cell components and/or locations) of these changes. In-cell diagnostics for each of the major types of polarization are also recommended. For example, to determine whether mass-transport resistance is increasing within or external to the catalyst layer (or catalyst agglomerate) one can utilize an oxygen-gain analysis, which is based on a relatively simple model of the cathode potential and the two limiting cases predicted by this model [2]. To determine whether mass-transport losses are primarily due to oxygen transport and/or proton transport ( i.e ., ohmic losses in the catalyst layer), one can utilize an oxygen-dependence analysis, which is also based on limiting cases predicted by a simple model of the cathode [3]. The examples used to illustrate these diagnostic techniques will be on state-of-the-art PEFCs, so that the actual performance limitations being investigated should also be of interest to PEFC research community, such as mass-transport losses in PEFCs with ultra-low catalyst loadings. Acknowledgements Thanks to the organizers of this Symposia for the invitation to present. The author would also like to thank his many fuel-cell collaborators at United Technologies Corporation (both past and present). Funding from U.S. Department of Energy, EERE’s Fuel Cell Technologies Office under contract numbers DE-AC02-05CH11231 and DE-AC02-06CH11357 has enabled much of the recent work at UTRC on PEFCs that will be used as examples here, and is also gratefully acknowledged. References: 1. M. Perry, R. Balliet, and R. Darling, “Experimental Diagnostics and Durability Testing Protocols,” in Modern Topics in Polymer Electrolyte Fuel Cell Degradation , M. Mench, E. Kumbur, and T. Veziroglu (Editors); Elsevier, Denmark, 2011. 2. K. O’Neil, J. Meyers, R. Darling, and M. Perry, “Oxygen Gain Analysis in Proton Exchange Fuel Cells,” International Journal of Hydrogen Energy , 37 (2012) 1, 373. 3. M. Perry, J. Newman, and E. Cairns “Mass transport in gas-diffusion electrodes: A diagnostic tool for fuel-cell cathodes,” Journal of the Electrochemical Society , 145 (1998) 1, 5. Figure Caption: Figure 1. Four limiting cases of Polarization-Change Curves (PCC), which are constructed from experimental cell data by taking the difference between two different polarization curves ( e.g ., from two different cells or the same cell under different operating conditions). Four theoretically-predicted limiting cases are shown here, which were derived using a simple model: 1) Kinetic (solid line), 2) Ohmic (dashed line), 3) Transport (dotted curved line), and 4) Leak (dash and dot curve). Figure 1

Maurizio Santini, Manfredo Guilizzoni, Massimo Lorenzi et al.

Biointerphases • 2015

Power output limitation is one of the main concerns that need to be addressed for full-scale applications of the microbial fuel cell technology. Fouling and biofilm growth on the cathode of single chamber microbial fuel cells (SCMFC) affects their performance in long-term operation with wastewater. In this study, the authors report the power output and cathode polarization curves of a membraneless SCMFC, fed with raw primary wastewater and sodium acetate for over 6 months. At the end of the experiment, the whole cathode surface is analyzed through X-ray microcomputed tomography (microCT), scanning electron microscopy, and energy-dispersive X-ray spectroscopy (EDX) to characterize the fouling layer and the biofilm. EDX shows the distribution of Ca, Na, K, P, S, and other elements on the two faces of the cathode. Na-carbonates and Ca-carbonates are predominant on the air (outer) side and the water (inner) side, respectively. The three-dimensional reconstruction by X-ray microCT shows biofilm spots unevenly distributed above the Ca-carbonate layer on the inner (water) side of the cathode. These results indicate that carbonates layer, rather than biofilm, might lower the oxygen reduction reaction rate at the cathode during long-term SCMFC operation.

Carlo Santoro, Alexey Serov, Santiago Rojas-Carbonell et al.

ECS Meeting Abstracts • 2016

Bioelectrochemical systems (BESs) are novel systems that utilize biological reactions coupled with electrochemical reactions for organics removal [1], electricity production [1,2] or product/nutrients recovery [2]. Specific attention was dedicated to the electrodes materials improvements. The anode material selected is usually based on three-dimensional conductive carbonaceous materials in order to respond to the necessary features that the anode needs for the optimum oxidation reaction. Particularly, the anode has to be: i) electrically conductive, ii) biologically friendly to accommodate bacteria, iii) mechanically durable and corrosion-free, iv) low cost. The main problem is instead related with the cathode. In fact, at neutral working pH, the cathode suffers of tremendous losses mainly due to activation overpotentials and low kinetics. Enzymatic based cathode have been showed to have the lowest overpotentials [3] but it has also been showed the enzyme are not very durable under “clean” or “polluted” conditions. Metal-free catalysts based on carbonaceous materials have been also used for the oxygen reduction reaction (ORR) in neutral media. Those carbonaceous materials possess high surface area, electronic conductivity, mechanical strength and durability over time and consequently can be considered suitable for microbial fuel cell (MFC) application. We have showed previously that the addition of an iron-based catalyst in an air-breathing gas diffusional electrode increased significantly the performance compare to activated carbon (AC) cathode [4]. In that study, iron-aminoantipyrine (Fe-AAPyr) was used as cathode catalyst and the catalyst was prepared using sacrificial support method with FeNO 3 as a metal source and aminoantipyrine as a nitrogen-rich precursor. The advantage of Fe-AAPyr compared to AC cathode was 50% [4]. We have also successfully tried Fe-AAPyr in double chamber MFC [5] and in ceramic-based MFC [6]. In this work, eight novel catalysts have been synthesized, characterized chemically and morphologically and the electrochemical performances have been studied in clean condition and in a working MFC. The novelty of the catalysts was in the low-cost organic precursors utilized during the preparation. The organic precursors used were named: niclosamide, ricobendazole, guanosine, succinylsulfathiazole, sulfacetamide, quinine, sulfadiazine and pyrazinamide. SEM images showed clear 3-D structure typical from the sacrificial support method utilized. XPS showed 2- 3% of atomic nitrogen with the distribution of different types of nitrogen species typical for M-N-C obtained by SSM. Pyridinic nitrogen and nitrogen coordinated to the metal, which have been shown to be important species for ORR [7] are detected in significant amounts. The catalysts have been embedded into a mixture of AC, carbon black (CB) and PTFE and pressed on a stainless steel mesh. The cathode configuration was an air breathing gas diffusion electrode. The new catalysts have been compared with Pt and AC used as a control. The cathode was inserted on a lateral hole of a single chamber MFC. Cathode polarization curves were run in phosphate buffer. Results showed that six catalysts (Fe-Ricobenzadole, Fe-Niclosamide, Fe-Pyrazinamide, Fe-Guanosine Fe-Succinylsulfathiazole and Fe-Sulfacetamide) outperformed compared to Pt and all outperformed compared to AC. Similar trend was achieved when the cathodes were inserted in working MFCs (Figure 1). Actually three catalysts (Fe-Ricobenzadole, Fe-Niclosamide and Fe-Pyrazinamide) had the highest power density output that was measured between 202 and 209 μWcm -2 (Figure 1). Correlations between surface properties and performance showed a linear relationship between the power achieved and the amount of pyridinic nitrogen, nitrogen coordinated to metal and pyrrolic nitrogen. The positive role of N x -Fe and pyridinic nitrogen for ORR in acidic and alkaline conditions has been shown before [7]. In contrast to the observations in this report, in an acidic environment, pyrrolic N causes partial reduction of oxygen to hydrogen peroxide thereby reducing an overall activity. References [1] X. Wang, C. Santoro, P. Cristiani, G. Squadrito, Y. Lei, A. G. Agrios, U. Pasaogullari, B. Li. J. Electrochem. Soc. 160 (7) , G117 (2013). [2] I. Gajda, J. Greenman, C. Melhuish, C. Santoro, B. Li, P. Cristiani, I. Ieropoulos. Sustainable Energies Technologies and Assessments 7, 187 (2014). [3] C. Santoro, F. Soavi, A. Serov, C. Arbizzani, P. Atanassov. Biosens. Bioelectron. 78 , 229 (2016). [4] C. Santoro, A. Serov, C.W. Narvaez Villarrubia, S. Stariha, S. Babanova, K. Artyushkova, A.J. Schuler, P. Atanassov. Sci. Rep. 5 , 16596 (2015). [5] C. Santoro, A. Serov, C.W. Narvaez Villarrubia, S. Stariha, S. Babanova, A.J. Schuler, K. Artyushkova, P. Atanassov. ChemSusChem 8(5) , 828 (2015). [6] C. Santoro, K. Artyushkova, I. Gajda, S. Babanova, A. Serov, P. Atanassov, J. Greenman, I. Ieropoulos, A. Colombo, S. Trasatti, P. Cristiani. Int. J. Hydrogen Energy 40(42) , 14706 (2015) [7]. K. Artyushkova, A. Serov, S. Rojas-Carbonell, P. Atanassov, J. Phys. Chem. C 119 (46) , 25917 (2015). Figure 1

Alisa Kongthong, Pimprapa Chaijak

Journal of Degraded and Mining Lands Management • 2024

This study investigated the application of a microbial fuel cell (MFC) system integrated with freshwater microalgae Chlorella sp. TSU-FF67for wastewater treatment, electricity generation, and bio-oil production. The MFC with Chlorella sp. TSU-FF67achieved a significantly higher open-circuit voltage (OCV) of 413.67 ± 15.67 mV compared to the control (13.33 ± 6.38 mV), indicating enhanced bioelectrocatalytic activity. The system also demonstrated efficient organic matter removal from palm oil mill effluent (POME) with a maximum color removal of 95.12 ± 3.50%. Furthermore, Chlorella sp. TSU-FF67 recovered from the PMFC exhibited a remarkable docosahexaenoic acid (DHA) yield of 1,932.28 ± 88.69 µg/mL (1.93 ± 0.08 mg/mL), highlighting its potential as a feedstock for bio-oil production. This work presents a promising approach for sustainable wastewater treatment while simultaneously generating bioelectricity and bio-oil using microalgae-MFC integration.

Junyeong An, Taeyoung Kim, In Seop Chang

Energy Technology • 2016

Abstract One in four microbial fuel cell (MFC) units suffers from power overshoot. Series connection of the unit to a high‐current‐producing unit showed significant current loss (57 %) due to power overshoot and the resultant voltage reversal. To concurrently control the power overshoot and voltage reversal, the two MFC units in series were converted to parallel connection, and this was then connected in series with another parallel‐connected MFC group. The current loss for series connection of the two parallel‐connected MFCs was as small as 3 % compared to the sum of the maximum current of the four individual MFC units, without power overshoot; the anode potentials in the units were kept low between −0.24 V and −0.10 V at which electrochemically active bacteria can be easily grown. These results show that series connection of parallel‐connected MFCs could be a readily applicable way for concurrently controlling the power overshoot and voltage reversal in MFC systems.

Fengjiang Wu, Boyang Li, Jiandong Duan

IET Power Electronics • 2016

Efficiency improvement has become a hot topic in grid‐connected inverters (GCI). In single‐phase single‐stage cascaded multilevel GCIs (CM‐GCI), the level number of the inverter output voltage will change with the variation of the DC supply source generation power. This results in significant changes of switching losses and changes in the total harmonics distortion (THD) of the grid current. In this study, the switching losses and the current THD of CM‐GCI are derived under variable DC voltage. The theoretical analysis indicates that switching losses will increase with increasing DC voltage while the current THD will be reduced. Furthermore, on the basis of the derived expression of the current THD and taking the special grid current THD standards as design criteria conditions, an European efficiency enhancement scheme with adjusting carrier frequency in real time is proposed. Detailed experimental results including the constant and variable carrier frequency schemes are given and compared with each other to verify the accuracy of the theoretical analysis results and the validity of the proposed efficiency enhancement scheme.

Maruf A. Aminu, Garba U. Kangiwa

Archives of Current Research International • 2019

This paper evaluates performance indices based on industry-wide practice and suggests possible approach for improving the operational efficiencies of Jebba, Kainji and Shiroro hydro power generating stations. To actualize that, data including average daily gross operating head, daily flow rate and daily energy generated were obtained from Jebba, Kainji and Shiroro power stations and the National Control Center (N.C.C.) Osogbo. From the energy (MWh) generated the average daily power generated (MW) was computed. Consequently, the average operational efficiencies of Jebba, Kainji and Shiroro hydro schemes were evaluated and found to be 89.43%, 88.45% and 94.03% respectively. Similarly, performance indicators including deemed generation, auxiliary energy consumption, availability factor, capacity index, workforce deployment, forced outage factor and scheduled outage factor were evaluated and technical inferences made. The study was limited to the year 2010 due to non-availability of data for other years.

Nikolay Rogalev, Andrey Rogalev, Vladimir Kindra et al.

Energies • 2022

Today, with the increases in organic fuel prices and growing legislative restrictions aimed at increasing environmental safety and reducing our carbon footprint, the task of increasing thermal power plant efficiency is becoming more and more topical. Transforming combusting fuel thermal energy into electric power more efficiently will allow the reduction of the fuel cost fraction in the cost structure and decrease harmful emissions, especially greenhouse gases, as less fuel will be consumed. There are traditional ways of improving thermal power plant energy efficiency: increasing turbine inlet temperature and utilizing exhaust heat. An alternative way to improve energy efficiency is the use of supercritical CO2 power cycles, which have a number of advantages over traditional ones due to carbon dioxide’s thermophysical properties. In particular, the use of carbon dioxide allows increasing efficiency by reducing compression and friction losses in the wheel spaces of the turbines; in addition, it is known that CO2 turbomachinery has smaller dimensions compared to traditional steam and gas turbines of similar capacity. Furthermore, semi-closed oxy–fuel combustion power cycles can reduce greenhouse gases emissions by many times; at the same time, they have characteristics of efficiency and specific capital costs comparable with traditional cycles. Given the high volatility of fuel prices, as well as the rising prices of carbon dioxide emission allowances, changes in efficiency, capital costs and specific greenhouse gas emissions can lead to a change in the cost of electricity generation. In this paper, key closed and semi-closed supercritical CO2 combustion power cycles and their promising modifications are considered from the point of view of energy, economic and environmental efficiency; the cycles that are optimal in terms of technical and economic characteristics are identified among those considered.

Vinh Nguyen Duy, Jung Koo Lee, Ki Won Park et al.

Materials Science Forum • 2014

Flow-field design affects directly to the PEM fuel cell performance. This study aims to stimulate the under-rib convection by adding sub-channels and by-passes to the conventional-advanced serpentine flow-field to improve the PEM fuel cell performance. The experimental results show that if reacting gases flow in the same direction as the neighboring main channels, the under-rib convection shows a flow from the main channels to the sub-channels makes progress in reducing pressure drop and enhancing uniform gas supply and water diffusion. Alternatively, if in the direction opposite to that of the neighboring main channels, the under-rib convection shows a flow from the inlet side towards the outlet side across the sub-channel as in the conventional serpentine channels. Analyses of the local transport phenomena in the cell suggest that the inlet by-pass supplies the reacting gases uniformly from the entrance into the sub-channels and the outlet by-pass enhances water removal. Novel serpentine flow-field pattern employing sub-channels and by-passes shows uniform current density and temperature distribution by uniformly supplying the reacting gas. Furthermore, performance improvement of around 20% is observed from the experimental performance evaluation. As a result, longer battery life is expected by reducing the mechanical stress of membrane electrode assembly.

Huan Niu, Xia Luo, Peihan Li et al.

• 2024

Abstract. Microbial fuel cell (MFC) is an efficient in-situ approach to combat pollutants and generate electricity. This study constructed a soil MFC (SMFC) to reduce Cr(VI) in paddy soil and investigate its influence on microbial community and microbial resistance characteristics. Fe3O4 nanoparticle as the cathodic catalyst effectively boosted power generation (0.97 V, 102.0 mW/m2), whose porous structure and reducibility also contributed to Cr reduction and immobilization. After 30 days, 93.67 % of Cr(VI) was eliminated. The bioavailable Cr decreased by 97.44 % while the residual form increased by 88.89 %. SMFC operation greatly changed soil enzymatic activity and microbial structure, with exoelectrogens like Desulfotomaculum (3.32 % in anode) and Cr(VI)-reducing bacteria like Hydrogenophaga (2.07 % in cathode) more than 1000 folds of soil. In particular, SMFC operation significantly enhanced the abundance of heavy metal resistance genes (HRGs). Among them, chrA, chrB, and chrR increased by 99.54~3314.34 % in SMFC anode than control, probably attributed to the enrichment of potential tolerators like Acinetobacter, Limnohabitans, and Desulfotomaculum. These key taxa were positively correlated with HRGs but negatively correlated with pH, EC, and Cr(VI), which could have driven Cr(VI) reduction. This study provided novel evidence for bioelectrochemical system application in contaminated paddy soil, which could be a potential approach for environmental remediation and detoxification.

Xiang Fei

Applied and Computational Engineering • 2025

In modern computer systems, the Arithmetic Logic Unit (ALU) is the core component of the central processing Unit (CPU) and performs basic tasks such as arithmetic operations, logic operations, and data transmission. With the development of information technology, the demand for computing is growing, the requirements for computing accuracy, speed and energy consumption are becoming more stringent. The design and optimization of ALU is directly related to the overall performance and energy efficiency of the system, so it becomes the focus of research and the key to technological breakthroughs. This paper focuses on summarizing and exploring the application scenarios, development, and optimization prospects of ALUs. This study reviews various application contexts, including embedded systems, quantum computing, and high-performance processors, highlighting how tailored ALU designs can meet the demands of each. In the field of optimization strategies, Gate Diffusion Input (GDI) technology, reversible logic, and Single Electron Transistor (SET) technology were discussed as a way to reducing power consumption and improving processing speeds.

Mehdi Tahoori, Mohammad Saber Golanbari

Journal of Low Power Electronics and Applications • 2020

Modern electronic devices are an indispensable part of our everyday life. A major enabler for such integration is the exponential increase of the computation capabilities as well as the drastic improvement in the energy efficiency over the last 50 years, commonly known as Moore’s law. In this regard, the demand for energy-efficient digital circuits, especially for application domains such as the Internet of Things (IoT), has faced an enormous growth. Since the power consumption of a circuit highly depends on the supply voltage, aggressive supply voltage scaling to the near-threshold voltage region, also known as Near-Threshold Computing (NTC), is an effective way of increasing the energy efficiency of a circuit by an order of magnitude. However, NTC comes with specific challenges with respect to performance and reliability, which mandates new sets of design techniques to fully harness its potential. While techniques merely focused at one abstraction level, in particular circuit-level design, can have limited benefits, cross-layer approaches result in far better optimizations. This paper presents instruction multi-cycling and functional unit partitioning methods to improve energy efficiency and resiliency of functional units. The proposed methods significantly improve the circuit timing, and at the same time considerably limit leakage energy, by employing a combination of cross-layer techniques based on circuit redesign and code replacement techniques. Simulation results show that the proposed methods improve performance and energy efficiency of an Arithmetic Logic Unit by 19% and 43%, respectively. Furthermore, the improved performance of the optimized circuits can be traded to improving the reliability.

Haiping Wang, Liguo Zheng, Changyin Tan et al.

Clean Energy • 2024

Abstract A two-chamber microbial fuel cell (MFC) with algal-film cathode was constructed. It showed good electric-generating performance with three electric-generating stages: start-up, development, and stable. An average output voltage reached ~0.412 V during the stable period. A maximum power density during continuous operation was 19.76 mW/m2. Bacterial samples were collected from the anode in the three stages (A1, A2, and A3), and their community structure and diversity were analyzed using Illumina MiSeq high-throughput sequencing technology. A total of 4238 operational taxonomic units were identified based on the number of taxa. At the phylum level, Proteobacteria and Bacteroidetes played a dominant role in the three stages and increased significantly during electricity generation. Compared with A1, the relative abundances of Proteobacteria in A2 and A3 increased by 23.30% and 32.06%, respectively, whereas those of Bacteroidetes in A2 and A3 increased by 5.56% and 14.50%, respectively. At the genus level, there were differences in the composition of bacterial communities among the three stages. Acinetobacter and Chlorobium became the dominant genera in A2, replacing Nitrospira and norank_f__Saprospiraceae in A1, and Sphingobacterium and Ochrobactrum became the dominant genera in A3. According to the sample cluster and principal component analyses, A1 was clustered into one class, and A2 and A3 were clustered into a second class. This work revealed bacterial community succession at the anode of an algal-film cathode MFC during the electricity generation process, which provides a theoretical basis for the subsequent promotion of electricity generation by algal-film cathode MFCs.

Hadi Moradisizkoohi, Jafar Milimonfared, Meghdad Taheri et al.

International Journal of Circuit Theory and Applications • 2015

Summary This paper presents a high step‐up soft switched dc–dc converter having the feature of current ripple cancelation in the input stage that is specialized for power conditioning of fuel cell systems. The converter comprises a special half‐bridge converter and a rectifier stage based upon the voltage‐doubler circuit, in which the coupled‐inductor technology is amalgamated with switched‐capacitor circuit. The input current with no ripple is the principal characteristics of this topology that is achieved by utilizing a small coupled inductor. In addition, the low clamped voltage stress across both power switches and output diodes is another advantage of the proposed converter, which allows employing the metal–oxide–semiconductor field‐effect transistors with minuscule on‐state resistance and diodes with lower forward voltage‐drop, and thereby, the semiconductors' conduction losses diminish considerably. The inherent nature of this topology handles the switching scheme based on the asymmetrical pulse width modulation in order for switches to establish the zero voltage switching, leading to lower switching losses. Besides, because of the absence of the reverse‐recovery phenomenon, all diodes turn off with zero current switching. At last, a 250‐W laboratory prototype with the input voltage 24 V and output voltage 380 V is implemented to verify the especial features of the proposed converter. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

Pınar Celen, Hasan Hüseyin Erdem

Bitlis Eren Üniversitesi Fen Bilimleri Dergisi • 2024

The performance of power plants is very critical since it is directly related with operating and electricity production costs. Among the other different type of power plants, coal-fired ones have advantages such as reliability and low cost fuel. In this paper, a coal (lignite) fired thermal power plant having capacity of 160 MW is taken into consideration and the impact of condenser pressure, moisture content of lignite, excess air coefficient, efficiency of turbine pressure and heater numbers on power plant thermal efficiency is investigated. It is aimed to determine performance losses of each equipment by means of the thermodynamics and economic analysis. In this scope, it is expected that the power plant operator will be able to evaluate the reduction potential of equipment performance losses and ensure more effective use of the power plants by correctly planning the maintenance and rehabilitation needs and times. In the calculations, the boiler efficiency was determined with EN 12952-15 standard (indirect method) since this method has higher accuracy in coal fired boilers. It is seen that the condenser pressure and excess air coefficient increments have not significant impact on power plant efficiency compared to moisture content of lignite, excess air coefficient, efficiency of turbine pressure and heater numbers. The significant effect is observed for fuel moisture content which rises from 22% to 47% and the power plant efficiency falls from 40% to 28%. The variation of the power plant thermal efficiency in case of failure of heaters is investigated and the power plant efficiency has decreased from 40.17% to 36.09% when the pre-heaters are no longer in to be in use because of any reason. In addition, revenue losses are estimated for each main equipment efficiency reduction for better use of power plant capacities and electricity lowering production costs.

C.-W. Lin, S.-H. Liu, A.-S. Chang et al.

Journal of Insects as Food and Feed • 2024

Abstract Insects are a suitable raw material for refinement into biodiesel owing to their high fat content, but the refining process produces large amounts of insect waste and glycerol as a byproduct. Biochar electrodes were produced from insect waste for application in microbial fuel cells (MFCs), and experiments were performed to evaluate the electrochemical performance and glycerol conversion efficiency. The biochar was characterized by rich functional groups (O–H, O=C=O, C=C, C=O) and high microporosity, which favored the colonization of microbes. Among the electrode configurations considered, the optimal configuration was a biochar anode and carbon cloth cathode (B-MFC), showing the highest glycerol conversion efficiency (>95%). The B-MFC also exhibited the highest power density (122.3 mA/m 3 ), 1.46-2.34 times that of the other MFCs tested. Adding Nitrogen-rich insect frass to the anode tank further stimulated microbial growth and increased power production, with the highest voltage output of 443.2 mV at 10 mg/L nitrogen concentration, 1.18 times higher than without addition. This study is the first to utilize insect exuviae as biochar electrodes in an MFC to solve the problems of excessive insect waste from biodiesel refinement and converting glycerol into a renewable energy source.

Cynthia J. Castro, Joseph E. Goodwill, Brad Rogers et al.

Journal of Water, Sanitation and Hygiene for Development • 2014

A microbial fuel cell (MFC) latrine that treats human waste and produces compost and electricity was deployed in Agona Nyakrom, Ghana. After solid wastes were composted, the MFC treated organic matter and nitrogen from the remaining liquid stream. Organic matter was oxidized in the anode by anode-respiring bacteria that transfer electrons to an external circuit, producing electricity, which was observed to be 268 nW/m2 after two years of operation. A separate nitrification stage transformed ammonium present in urine, to nitrate. Nitrate was reduced to nitrogen gas by cathode-oxidizing bacteria in the cathode completing nitrogen removal. The MFC Latrine was constructed on-site using local labor and materials. Evidence of total nitrogen removal and power production was observed while the MFC Latrine was in operation. Multiple user challenges and maintenance affected the performance, yielding low power output. The initial findings suggest that the viability of the system is directly correlated with its use. Incorporating the MFC Latrine system into the user community's typical social practices is key to a successful deployment of the MFC Latrine as a sanitation technology.

Leila M. Khaksar, Ali Ghayoumi, Amir H. Hasani et al.

Linnaeus Eco-Tech • 2017

Microbial fuel cells (MFCs) represent a new method for treating wastewaters and simultaneously producing electricity (renewable energy (bioelectricity)) as innovative technologies. Feasibility of using synthetic wastewater as a substrate for electricity generation using anaerobic sludge as a source of microorganisms was investigated after a short acclimatization period of less than 10 days. among two different kind substrate (methanol and acetic acid) Significant reduction in COD of synthetic wastewater by 63% and 75% was observed at initial COD=2743 mg/l and 2560 mg/l respectively in Methanol and Acetic Acid indicated effective wastewater treatment in batch experiments. The present article deals with the studies of a two chambered salt bridge (membrane-less) MFC anode chamber [(with mediator; plain graphite electrode; acidified by ortho-posphoric acid (pH≈6)]; cathode chamber (50mM potassium ferricyanide [K3Fe(CN)6] in phosphate buffer; pH ≈7.5; plain graphite electrode) in the presence of mediators. The effect of Methylene Blue (MB) and Neutral Red (NR) as electron mediators and microelements inoculated to anolyte chamber on the power generation in MFCs are reported. The best performance was obtained in the case of Acetic Acid. Using methylene blue (MB) (0.2mM) as the electron mediator, the maximum power density and current density of 61.718 mW/m2 and 92.530 mA/m2 were obtained respectively with CE of 3.94%, which are found to be very promising. The maximum power density and current density of 58.820 mW/m2 and 89.940 mA/m2 were obtained respectively with CE of 8.05%. In the most cases, results show that MB has more effective role than NR. Efforts are being made to improve the performance and reduce the construction and operating costs of MFCs.

Szymon Potrykus, Sara Mateo, Janusz Nieznański et al.

Energies • 2020

The energy contained in wastewaters has been identified as a promising sustainable energy resource that could be harvested by using microbial fuel cells (MFC). When dealing with real wastewaters, the MFCs should be able to manage high flow rates and flow rates fluctuations. In this work, the short-term effects of the influent flow rate variations on the performance of a microbial fuel cell has been studied. With this aim, the influent flow rate was stepwise increased from 0.72 to 7.2 L/d and then stepwise decreased. The obtained results indicate that, on the one hand, an increase in the influent flow rate leads to higher chemical oxygen demand removal rates up to 396 g/(L/d) and higher electric power generation almost 18 mW/m2, but to lower coulombic efficiencies. On the other hand, the reduction of the flow rate increases the coulombic efficiencies, as well as the percentage of chemical oxygen demand removed, but decreases electric power generation. In the short-term, the exposition to higher influent flow rates causes the growth of the microbial population of the MFC, the growth of the non-electrogenic microorganisms being higher than that of the electrogenic ones. The higher growth of non-electrogenic microorganisms may lead to lower coulombic efficiencies.

Jian Xie

ECS Meeting Abstracts • 2023

The biggest challenge of the widespread implantation of the polymer electrolyte membrane fuel cells (PEMFCs) is the cost, primarily due to the use of platinum catalysts. The high intrinsic catalyst activity exhibited using a rotating disc electrode (RDE) is rarely realized in the membrane electrode assembly (MEA), which is the core of PEMFC, due to the difference on the electrolyte(ionomer)/catalyst interfaces. To translate the catalyst RDE performance into MEA, the design of an ideal ionomer/catalyst interface is proposed: a thin, conformal ionomer film covers the maximum surface of a Pt nanoparticle that simultaneously maximizes catalyst utilization, (i.e. high mass activity and electrochemical active surface area) and O 2 diffusion (i.e. high current density performance) without compromising proton conduction. Building such an interface is a long-standing challenge due to no control of ionomer distribution over catalyst particle, resulting in large ionomer agglomerates and inhomogeneous ionomer coverage over the catalyst nanoparticle, consequently, poor fuel cell performance. In this work, this ionomer/catalyst interface has been constructed utilizing the electrostatic charge attraction between positively charged catalyst and negatively charged ionomer particles in a liquid and preserved into a solid catalyst layer. Consequently, this interface leads to the previously unachieved fuel cell performance on both the catalyst utilization (75% vs. 45%) and the rated/peak power density (Pt/C, 0.910/1.430 W/cm 2 for H 2 /Air, Pt loading: 0.1 mg Pt /cm 2 ), matching that of Pt alloy catalysts. This work demonstrated the formation of the interface in the liquid phase (using ultra-small angle x-ray scattering in combination with cryo-TEM, isothermal‐titration‐calorimetry) and the preserved interface in the solid catalyst layer (using TEM) and estimated the effective coverage and thickness of the ionomer film (using the limiting current density, RDE and fuel cell performance).

Li-Fen Huang, Ji-Yu Lin, Kui-You Pan et al.

International Journal of Molecular Sciences • 2015

Ferredoxins (FDX) are final electron carrier proteins in the plant photosynthetic pathway, and function as major electron donors in diverse redox-driven metabolic pathways. We previously showed that overexpression of a major constitutively expressed ferredoxin gene PETF in Chlamydomonas decreased the reactive oxygen species (ROS) level and enhanced tolerance to heat stress. In addition to PETF, an endogenous anaerobic induced FDX5 was overexpressed in transgenic Chlamydomonas lines here to address the possible functions of FDX5. All the independent FDX transgenic lines showed decreased cellular ROS levels and enhanced tolerance to heat and salt stresses. The transgenic Chlamydomonas lines accumulated more starch than the wild-type line and this effect increased almost three-fold in conditions of nitrogen depletion. Furthermore, the lipid content was higher in the transgenic lines than in the wild-type line, both with and without nitrogen depletion. Two FDX-overexpressing Chlamydomonas lines were assessed in a photo microbial fuel cell (PMFC); power density production by the transgenic lines was higher than that of the wild-type cells. These findings suggest that overexpression of either PETF or FDX5 can confer tolerance against heat and salt stresses, increase starch and oil production, and raise electric power density in a PMFC.

Qian Qian Yuan

Advanced Materials Research • 2012

By particular theoretical analyzing on detection error of the traditional current loop proportion-integral (PI) controller, this paper points out the limitations of detection harmonic current at load side and proposes a current feedforward compensation controller. It can track harmonic instructions with zero static error and good compensation performance. Meanwhile, it overcomes the deficiencies of traditional load side detection harmonic current PI controller, with the traditional controller’s flexibility. Even if the load harmonic current is higher than the capacity of active power filter, it can basically maintain zero static error output and has certain theoretical significance and engineering value.

Tobias Tiedemann, Michael Kroener, Martin Vehse et al.

Energies • 2022

Fuel cell electric vehicles (FCEVs) can be used during idle times to convert hydrogen into electricity in a decentralised manner, thus ensuring a completely renewable energy supply. In addition to the electric power, waste heat is generated in the fuel cell stack that can also be used. This paper investigates how the energy demand of a compiled German neighbourhood can be met by FCEVs and identifies potential technical problems. For this purpose, energy scenarios are modelled in the Open Energy System Modelling Framework (oemof). An optimisation simulation finds the most energetically favourable solution for the 10-day period under consideration. Up to 49% of the heat demand for heating and hot water can be covered directly by the waste heat of the FCEVs. As the number of battery electric vehicles (BEVs) to be charged increases, so does this share. 5 of the 252 residents must permanently provide an FCEV to supply the neighbourhood. The amount of hydrogen required was identified as a problem. If the vehicles cannot be supplied with hydrogen in a stationary way, 15 times more vehicles are needed than required in terms of performance due to the energy demand.

Kit Sum Cho, Guanying Li, Nicholas Bardell

Aviation • 2020

The purpose of this paper is to see if airlines in general, and U.S. air-carriers in particular, are meeting their IATA-agreed 1.5% average annual fuel efficiency improvements between 2010 and 2020. To assess the fuel efficiency performance, a quantitative analysis was performed using data provided by ICAO, IATA and the U.S. Bureau of Transportation Statistics (BTS) Form 41 Schedules P 12(a) and T-2. The metric used to assess fuel efficiency is the one advanced by ICAO, namely Litres per Revenue Tonne Kilometre performed. Trends are examined over an extended timeframe to establish annual fuel efficiency improvements. The findings show that the overall performance of U.S. air-carriers from 2010 to 2018 has just met IATA’s 1.5% target with a 1.52% year-upon-year annual fuel efficiency improvement, with domestic operations showing a greater level of improvement than international operations. Such performance suggests that the U.S.A, and by inference, the rest of the world, are just likely to meet their IATA target by 2020. This achievement has largely been made possible through industry’s tremendous efforts to enhance aircraft engine technologies, implement operational improvements, and reduce airframe weight through the extensive application of composite materials.

S. E. Cotterill, J. Dolfing, C. Jones et al.

Fuel Cells • 2017

Abstract The potential benefits of applying microbial electrolysis cell (MEC) technology to wastewater treatment are clear and profound. Previous pilot studies have demonstrated a ‘proof of concept' with domestic waste at ambient temperatures, but have not yet treated waste to required discharge standards, and have not reached energy neutrality. In addition, these reactors have been many orders of magnitude smaller than would be needed for full scale wastewater treatment plants. Scale‐up affects many of the parameters that underpin performance; understanding its impact will be vital to further progress. Modifying a previously tested cassette‐style design, we reduced the internal resistance, and increased the module size by a factor of 16, constructing an MEC with six 1 m 2 anodes. This created an anodic surface area to volume ratio of 34 m 2 m −3 . The system was operated at a hydraulic retention time of 5 hours on settled domestic wastewater for 217 days, producing more current than a scaled‐down reactor, which was run in parallel. The large MEC produced 0.8 L of 93% pure H 2 d −1 at ambient winter temperatures (11.4 ± 2.5 °C). Chemical oxygen demand (COD) removal averaged 63.5% with an average effluent quality of 124.7 mg COD L −1 , achieving the European Urban Wastewater Treatment Directive (1991) consent.

Kuichang Zuo, Han Liu, Qiaoying Zhang et al.

ChemSusChem • 2015

Abstract The traditional chamber‐based microbial fuel cell (MFC) often has the disadvantages of high ohmic resistance, large volume requirements, and delayed start‐up. In this study, paper‐shaped MFCs utilizing a porous carbon anode, a solid Ag 2 O‐coated carbon cathode, and a micrometer‐thin porous polyvinylidene fluoride (PVDF) separator are investigated to address the classical MFC issues. The Ag 2 O‐coated cathode has a low overpotential of 0.06 V at a reducing current of 1 mA compared to a Pt–air cathode. Rapid inoculation by filtration results in an instantaneous power density of 92 mW m −2 with an internal resistance of 162 Ω. Integrated current over the first 30 min of operation has a linear relation with microbial concentration.

Enas Taha Kasem, Takuya Tsujiguchi, Nobuyoshi Nakagawa

Key Engineering Materials • 2012

Effect of modification of carbon paper with a thin layer of cobalt or gold on the performance of yeast-based microbial fuel cells was investigated. The modification was conducted by depositing Co or Au thin layer with different thickness, 5 nm and 30 nm, using a sputtering technique. The electrode performance was evaluated by measuring the electrode potentials and the fuel cell power output. The Co modification significantly increased the performance of the fuel cell, while the Au modification inhibited the performance. SEM observation indicated that the adhesion density of the yeast cells on the electrode surface was affected by the metals. It was confirmed that the electron transfer took place through the surface confined species at the mediatorless anode.

Kexun Li, Ziqi Liu

ECS Meeting Abstracts • 2016

Three kinds of three-dimensional (3D) Cu x O catalysts were prepared to modify activated carbon air-cathode using a facile electrochemical method with addition of surfactants. The maximum power density of MFC using SC-Cu air cathode (added sodium citrate into the electrolyte solution in eletrodeposition process) was 1550±47 mW m -2 , almost 77% higher than AC cathode. Specifically, the charge transfer resistance significantly decreased by 89% from 9.3980 Ω to 1.0640 Ω compared to the control. Lumphy and mutually embedded filmy sheet structure were observed in SEM, which provided sufficient active sites for oxygen adsorption and diffusion. In XRD and TEM result, Cu x O with mixed facets showed special structure which had a better performance. Crystallization condition of electrodeposited materials played a significant role in their nature electrochemical properties, morphology controlled by surfactant of CuxO exhibited high properties on the air-cathode MFC.

A.O. Sirajudeen, S. Ibrahim, A.S. Adediji et al.

Nigerian Journal of Biotechnology • 2024

The ability of exoelectrogenic bacteria to directly transfer electrons without any mediators to extracellular electron acceptors is vital in microbial fuel cell technology. The current study evaluates the exoelectrogenic potential of bacteria isolated from Palm Oil Mill Effluent (POME) in microbial fuel cell. The POME samples were obtained from Palm Oil mill factory in Iwo, Osun State, Nigeria. The isolates were analysed on Chromogenic (differential) medium for colour change from black to whitish. The isolates were identified phenotypically and molecularly. The potential of the isolates to generate efficient electricity were investigated in a doublechambered Microbial Fuel Cell (MFC). Overall, ten isolates were obtained from POME sample, with only three isolates showing the exoelectrogenic potential by turning the agar colour from black to whitish. The molecular analysis revealed three novel strains as Bacillus velezensis strain AAS001 (OQ690764), Bacillus amyloliquefaciens strain AAS002 (OQ690765) and Priestia aryabhattai strain AAS003 (OQ690766). Strain AAS003 showed the highest voltage potential of 1407mV compared to strain AAS001 with 229mV and strain AAS002 with 191mV. Similarly, the power and current densities (345 mW/m2 and 437 mA/m2 respectively) recorded by strain AAS003 were far superior to that of strain AAS001 (10 mW/m2 and 64 mA/m2 ) and strain AAS002 (15 mW/m2 and 92 mA/m2 ). This study suggests that strain AAS003 is an excellent biocatalyst for bioelectricity generation.

Barbara Mecheri, Alessandro Iannaci, Alessandra D'Epifanio et al.

ChemPlusChem • 2015

Abstract Cost‐effective electrode materials to be used as cathodes in lab‐scale prototype microbial fuel cells (MFCs) were prepared from mixtures of carbon black (C) and zirconium oxide (ZrO 2 ) of different composition. The catalytic activity of these cathodes in the oxygen reduction reaction (ORR) and their stability toward poisoning in typical MFC operative conditions were assessed by using electrochemical techniques. Scanning electron microscopy and Brunauer–Emmett–Teller measurements gave insights into sample morphology and surface area. The results indicated that the C/ZrO 2 sample with a ZrO 2 loading of 25 wt % (C/ZrO 2 _25) represents the best compromise in terms of ORR activity and stability. C/ZrO 2 _25 was assembled into cathodes of a prototype single‐chamber MFC, which produced a maximum power density of 600 mW m −2 . A comparative cost analysis of energy production indicated that the cost of energy delivered by MFCs assembled with a C/ZrO 2 cathode was more than 15 times lower than that of MFCs assembled with a reference Pt/C cathode.

Xavier Alexis Walter, Iwona Gajda, Samuel Forbes et al.

ECS Meeting Abstracts • 2016

The microbial fuel cell (MFC) is a technology in which microorganisms employ an electrode (anode) as a solid electron acceptor for anaerobic respiration. This result in direct transformation of chemical energy into electrical energy, which in turn means that organic wastewater can be used as fuel. Amongst the various organic wastes that are employed as fuel for MFCs, urine is of interest since it represents 75% of the nitrogen present in domestic wastewaters and yet only 1% of the total volume. However, here is a persistent problem for the scaling up of MFCs. The smaller the surface of electrode to volume ratio of an MFC is, the higher its power density is. Hence, to reach usable power levels, a plurality of units needs to be assembled in stack, which implies configuring both the hydraulic circuitry and the serial/parallel electrical connection patterns. Because of this plurality, the units need to have a simple design for the whole system to be cost-effective. The goal of this work is to address how to build these multiple MFCs in stack. We report a novel membrane-less stack design using manifold ceramic plates semi-submerged with anodes and cathodes sharing urine solution. The top half of each plate were semi-submerged were covered in cathodes while the anodes, on the lower half of each plate, were fully submerged. The MFCs in each box were connected in parallel and multiple modules were configured in series and placed. This allowed self-stratification of the collective environment (urine column) under the natural activity of the microbial consortia thriving in the system. For size comparisons, the module footprints were enlarged from 900 mL to 5000 mL and, importantly, this scaling-up did not negatively affect power density (» 19 W/m^3), a factor that has proven an obstacle in previous studies. However, we should note that this observation is limited for the dimensions we tested. This was achieved by maintaining a plurality of microenvironments within the collective system and resulted in a simple, robust system fuelled by urine. The developed system was then used to treat urine of single individual (» 2.5L per 24h), in order to serve as the energy source charging mobile phones. Six boxes, each comprising 20 MFCs connected in parallel, were hydraulically cascaded and connected in series. Best performances were obtained in pulse-feed batch mode. At equilibrium, the stack of six boxes was feed with 600 mL every 6h at a flow rate of 2 L/min and was producing between 110 and 125 mW. Under these conditions, a smart phone (Samsung Galaxy S, battery of 1600 mAh) was fully charged in 68 h and 80 h, when turned off or on respectively. It has to be noted that these performances were stable for a period of 8 months. We concluded that our scaling-up approach within the tested range was successful to convert chemical energy in urine to electricity and this was demonstrated by charging cell phones.

Mimi Hani Abu Bakar, Neil F Pasco, Ravi Gooneratne et al.

Jurnal Teknologi • 2017

Properties such as electrical conductivity, low resistivity, chemicals and corrosion resistance are mostly found in carbon based materials. Epoxy resin is excellent for electrical insulation and can be used as a conductor with the addition of conductive filler. Combinations of carbon and epoxy show qualities of a conductive electrode, mechanically strong with design flexibility and thus makes them suitable as electrodes in microbial fuel cell (MFC). In this study, graphite-epoxy composites were fabricated with multi-walled carbon nanotube (MWCNT) embedded in the matrix surface. 9,10-Anthraquinone-2,6-disulfonic acid disodium salt/polypyrrole (PPy/AQDS) was used as mediator, covalently electrografted on electrode’s surface. Electrochemical stability of anodes during continuous operation were measured in air-cathode MFCs. It appears that maximum power in MFC could be increased up to 42% with surface modification using PPy/AQDS. Internal resistance (Rint) could be reduced up to 66% with the inclusion of MWCNT. These findings show that a one-day fabrication of a-ready-to-use conductive electrode is possible for graphite content between 70-80% (w/w).

Anders Olof Lundblad, Camila Chavez Varela

ECS Meeting Abstracts • 2015

Micro fuel cells can be used for autonomous energy systems are used for surveillance, wireless communication nodes and other power needs where there is no access to grid electricity. For small power levels (e.g. 10 W) a battery or supercapacitor pack is often used. For long runtimes there is, however, a need for a large battery. The idea of this autonomous system is to reduce the battery/supercap package and instead use a photovoltaic during the day to charge up the batteries. The fuel cell contributes in the event of bad weather conditions when the photovoltaic is unable to deliver enough energy for several days. The energy system comprises a battery package for storage of electrical energy, a photovoltaic module which delivers electricity to the battery pack, a fuel cell for backup delivery of electricity, and a power control electronics unit which transfers the power to the load. The simplified fuel cell system consists of a hydrogen storage tank (pressurized hydrogen or metal hydride), a pressure regulation valve, a control valve, and a fuel cell stack. Thanks to that the battery pack can handle load variations the fuel cell system can be adapted to run at a constant gas flow level. Thereby, the control valve can be reduced to an on-off valve, which means that simplified the fuel cell system can compete with the cost for batteries. This work will analyse how the voltage from an external fuel cell (short circuited over a resitor and fed by the hydrogen exhaust) can be used to control the power draw of the stack. The sensitivity to hydrogen flow variation, start-up and shut-down procedures will be investigated.

Isaac B. Sprague, Prashanta Dutta

Applied Physics Letters • 2012

A fuel cell device is presented based on a counter-flow microfluidic fuel cell (CFMFC) with nano-porous electrodes by developing an advection flux of ions within the electric double layer (EDL). Typically, in a microfluidic fuel cell, advection in the EDL is negligible because the near wall electrolyte velocity is zero. However, by using nano-pores, a non-negligible ion flux due to advection can be developed in the charged regions of the EDL which affects the structure of the EDL. In this article, we use a mathematical model to study how advection in the EDL affects the kinetic performance of fuel cells. Our model predicts that the peak power density can be increased by more than 2 fold in a CFMFC using this approach to kinetic enhancement.

Gang Chen, Shaohui Zhang, Meng Li et al.

Water Science and Technology • 2015

A double-chamber denitrifying microbial fuel cell (MFC), using boric acid-borate buffer solution as an alternative to phosphate buffer solution, was set up to investigate the influence of buffer solution concentration, temperature and external resistance on electricity generation and pollutant removal efficiency. The result revealed that the denitrifying MFC with boric acid-borate buffer solution was successfully started up in 51 days, with a stable cell voltage of 205.1 ± 1.96 mV at an external resistance of 50 Ω. Higher concentration of buffer solution favored nitrogen removal and electricity generation. The maximum power density of 8.27 W/m3 net cathodic chamber was obtained at a buffer solution concentration of 100 mmol/L. An increase in temperature benefitted electricity generation and nitrogen removal. A suitable temperature for this denitrifying MFC was suggested to be 25 °C. Decreasing the external resistance favored nitrogen removal and organic matter consumption by exoelectrogens.

Marjolein Helder, David PBTB Strik, Hubertus VM Hamelers et al.

Biotechnology for Biofuels • 2012

Abstract Due to a growing world population and increasing welfare, energy demand worldwide is increasing. To meet the increasing energy demand in a sustainable way, new technologies are needed. The Plant-Microbial Fuel Cell (P-MFC) is a technology that could produce sustainable bio-electricity and help meeting the increasing energy demand. Power output of the P-MFC, however, needs to be increased to make it attractive as a renewable and sustainable energy source. To increase power output of the P-MFC internal resistances need to be reduced. With a flat-plate P-MFC design we tried to minimize internal resistances compared to the previously used tubular P-MFC design. With the flat-plate design current and power density per geometric planting area were increased (from 0.15 A/m 2 to 1.6 A/m 2 and from 0.22 W/m 2 to and 0.44 W/m 2 )as were current and power output per volume (from 7.5 A/m 3 to 122 A/m 3 and from 1.3 W/m 3 to 5.8 W/m 3 ). Internal resistances times volume were decreased, even though internal resistances times membrane surface area were not. Since the membrane in the flat-plate design is placed vertically, membrane surface area per geometric planting area is increased, which allows for lower internal resistances times volume while not decreasing internal resistances times membrane surface area. Anode was split into three different sections on different depths of the system, allowing to calculate internal resistances on different depths. Most electricity was produced where internal resistances were lowest and where most roots were present; in the top section of the system. By measuring electricity production on different depths in the system, electricity production could be linked to root growth. This link offers opportunities for material-reduction in new designs. Concurrent reduction in material use and increase in power output brings the P-MFC a step closer to usable energy density and economic feasibility.

Zainab Ziad Ismail, Ali Awaid Habeeb

Journal of Engineering • 2015

In this study, a novel application of lab-scale dual chambered air-cathode microbial fuel cell (MFC) has been developed for simultaneous bio-treatment of real pharmaceutical wastewater and renewable electricity generation. The microbial fuel cell (MFC) was provided with zeolite-packed anodic compartment and a cation exchange membrane (CEM) to separate the anode and cathode. The performance of the proposed MFC was evaluated in terms of COD removal and power generation based on the activity of the bacterial consortium in the biofilm mobilized on zeolite bearer. The MFC was fueled with real pharmaceutical wastewater having an initial COD concentration equal to 800 mg/L and inoculated with anaerobic aged sludge. Results demonstrated that the COD removal efficiency, power density and current density were 66%, 2.4 mW/m2 and 10 mA/m2, respectively.

Htoo Nay Wunn, Shinichi Motoda, Motoaki Morita

ECS Meeting Abstracts • 2017

We have been studied the performance of TiO 2 electrode which is assembled in Marine Microbial Fuel Cell (MMFC). To increase the performance of TiO 2 electrode and to improve conversion efficiency from solar energy, dye sensitizing was introduced to TiO 2 electrode. The dye used for this experiment is a Ruthenizer complex, Di-tetrabutylammonium cis- bis (isothiocyanato) bis (2, 2-bipyridyl-4, 4’-dicarboxylato) ruthenium (II), well known as N719 dye, which shows high reproducibility and stability performance in dye-sensitized solar cells (DSSC). We also tried forming of Hydroxyapatite (HAp) layer on TiO 2 surface before dye sensitizing for the purpose of anchorage effect of dye on TiO 2 surface. The measurement of photopotential and polarization property were carried out in the artificial seawater as an electrolyte which does not include the redox couple as a mediator. Photopotential and polarization was measured with a standard calomel electrode (SCE) as a reference electrode under the irradiation of a 150 W Xenon Lamp, and a platinum electrode was used as a counter electrode for polarization curve. In the measurement of photopotential, the potential dropped to active direction when the light was turned on. Once it reached to the most active potential value, it went back to noble direction slightly for 5 to 15 minutes after the light was on. The change in photopotential after that duration became small and it tended to be stable for 2 hours. This behaviour of photopotential was similar in all measurement of test electrodes. The amount of Ruthenizer after 2-hour measurement of photopotential became relatively smaller compared to that before measuring. This is because dye recombination with TiO 2 electrons took place with artificial seawater electrolyte in the absence of a redox couple for dye regeneration. But, the photopotential of dye-sensitized TiO 2 electrode with HAp layer showed more active than that without HAp. This showed good compatibility of HAp since it did not disturb the performance of photo-catalytic reaction of TiO 2 and it may show the ion or electron selectivity between Ruthenizer and TiO 2 phases. The polarization measurement showed no distinct effectiveness of Ruthenizer sensitizing on TiO 2 surface other than suppressing the TiO 2 photo-catalytic reaction. As the results, Ruthenizer sensitizing on TiO 2 electrode showed lower photo-catalytic effect by the recombination of oxidized Ruthenizer electron due to absence of a redox mediator. On the other hand, using HAp on TiO 2 electrode for Ruthenizer sensitizing showed improvement in photopotential characteristics of TiO 2 electrode.

Emilio Steven C. Navarro, Melissa May M. Boado

Nature Environment and Pollution Technology • 2024

The rapid consumption of fossil fuels has led to calls to switch from non-renewable to renewable energy sources. Microbial fuel cells are a promising technology that simultaneously treats wastewater and produces power. This study used the Taguchi Experimental method to optimize anode thickness and pH to obtain the maximum power density of an air-cathode microbial fuel cell (ACMFC). The graphene-sponge (G-S) anode thickness and chamber pH were selected as operating parameters, with their corresponding levels. The L9 orthogonal array was chosen for the experimental design. According to the Taguchi Method, the optimum G-S anode thickness and chamber pH were determined to be 1.0 cm and 8.0, respectively. A confirmatory run was performed under these optimum conditions, and the maximum power density observed was 707.75 mW·m−3. Analysis of variance (ANOVA) was conducted to identify the percentage contributions of the operating parameters to the process, which were found to be 30.66% for pH and 69.34% for anode thickness.