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Ambarella is one of the most popular tropical fruits in Southeast Asia. Since it has a high concentration of organic acids, the fruit has the potential to be employed as an electrolyte in biobatteries. In this work, Zn-Cu biobattery electrolytes are derived from the flesh and peel of ambarella fruit. The Open- and Closed-Circuit Voltage, Maximum Power Density, and Battery Capacity of Zn-Cu Biobatteries were investigated. The OCV of the fruit's flesh was 455 mV, while the OCV of its peel was 530 mV. Given the average CCV created by ambarella peel was 471.3 mV and the average CCV generated by ambarella flesh was 342.1 mV. The highest power of Zn-Cu biobatteries was 0.27 mW when fruit flesh was used as the electrolyte and 0.22 mW when fruit peel was used as the electrolyte, Indicating a difference of 18.5%. The peel of an ambarella fruit has a battery capacity of 540 mAh, while the flesh has a capacity of 328 mAh for the Zn-Cu biobattery. This indicates that Zn-Cu with an Ambarella peel has a greater capacity but less power, urging that it be investigated prior to any prospective use. [ABSTRACT FROM AUTHOR]

This paper describes the use of a commercial Fumasep® FAA3-50 membrane as an anion exchange membrane (AEM) in alkaline direct methanol fuel cells (ADMFCs). The membrane, supplied in bromide form, is first exchanged in chloride and successively in the hydroxide form. Anionic conductivity measurements are carried out in both a KOH aqueous solution and in a KOH/methanol mixture. AEM-DMFC tests are performed by feeding 1 M methanol, with or without 1 M KOH as a supporting electrolyte. A maximum power density of 5.2 mW cm−2 at 60 °C and 33.2 mW cm−2 at 80 °C is reached in KOH-free feeding and in the alkaline mixture, respectively. These values are in good agreement with some results in the literature obtained with similar experimental conditions but with different anion exchange membranes (AEMs). Finally, methanol crossover is investigated and corresponds to a maximum value of 1.45 × 10−8 mol s−1 cm−2 at 50 °C in a 1 M KOH methanol solution, thus indicating that the Fumasep® FAA3-50 membrane in OH form is a good candidate for ADMFC application. [ABSTRACT FROM AUTHOR]

This paper is devoted to the determination of the value of the maximum specific power of capacitive electrostatic micromotors based on nanometer working gaps. The motors under consideration were developed earlier. They have the following structure: a metal—thin crystalline ferroelectric layer with a high dielectric constant—a nanometer working gap—a movable electrode. The mechanism limiting the magnitude of the maximum field in the gap have also been determined in previous works. The mechanism is the stripping of atoms from the surface of the movable electrode under the action of electrostatic forces. It was shown that the maximum energy density in the working gap can be as high as 1.6 × 109 J/m3. In the presented paper, a maximum frequency of electromechanical energy conversion as high as 10 MHz is estimated for these motors, with a maximum specific power of 5 × 108 W/kg. The application of the proposed motors for micromachines is discussed. [ABSTRACT FROM AUTHOR]

Electricity access is an essential factor for any nation's fast-growing economic and technological development. Therefore, to meet the fast-growing world population, the adoption of a mix of energy sources, including renewable energy, is one of the ways to address the paucity supply of energy worldwide. In this paper, the performance yields of five solar photovoltaic (PV) modules, named PV1, PV2, PV3, PV4, and PV5, from different manufacturers were analyzed and compared to their respective cost benefits for profitable customer's choice. The study on the panels was conducted at the geographical locations of 25.7535° S latitude and 28.2079° E longitude, with an average perimeter of 525.6 m in Pretoria, South Africa. The panels were installed without shading under the same condition of solar irradiation. The power output of each module was collected three times a day for six months. The analysis showed that the power outputs or performances of the respective modules are majorly affected by their surface temperatures as indicated by the values of multiple regression correlation of 92.9%, 96.9%, 99.1%, 97.2%, and 77.5% between the respective modules' power outputs and temperature. The study also showed a techno-economic evaluation method that helps to economically alleviate the cost of solar PVs and balance the choice of the PV panels according to their short-term performances. [ABSTRACT FROM AUTHOR]

In this review, recent achievements in the application of high-entropy alloys (HEAs) and high-entropy oxides (HEOs) in the technology of solid oxide fuel cells (SOFC) are discussed for the first time. The mechanisms of the stabilization of a high-entropy state in such materials, as well as the effect of structural and charge factors on the stability of the resulting homogeneous solid solution are performed. An introduction to the synthesis methods for HEAs and HEOs is given. The review highlights such advantages of high-entropy materials as high strength and the sluggish diffusion of components, which are promising for the use at the elevated temperatures, which are characteristic of SOFCs. Application of the medium- and high-entropy materials in the hydrocarbon-fueled SOFCs as protective layers for interconnectors and as anode components, caused by their high stability, are covered. High-entropy solid electrolytes are discussed in comparison with traditional electrolyte materials in terms of conductivity. High-entropy oxides are considered as prospective cathodes for SOFCs due to their superior electrochemical activity and long-term stability compared with the conventional perovskites. The present review also determines the prioritizing directions in the future development of high-entropy materials as electrolytes and electrodes for SOFCs operating in the intermediate and low temperature ranges. [ABSTRACT FROM AUTHOR]

Summary: Microbial fuel cell (MFC) is a promising technology since two important processes: wastewater treatment and electrical energy, can be obtained simultaneously. The performance of the MFC (maximum power density (MPD) and COD removal) depends mainly on substrate concentration, pH time, and initial COD. Therefore, the main target of this work is to simultaneously increase the MPD and COD removal by determining the optimal controlling parameters. The proposed methodology integrates fuzzy modelling and Harris Hawks optimization (HHO). Firstly, based on the experimental data set, an accurate fuzzy model is created to simulate the performance of MFC in terms of four controlling parameters. To prove the superiority of fuzzy model, the results are compared with response surface methodology (RSM) in terms of RMSE and coefficient of determination (R2). Secondly, using HHO, the optimal values of substrate concentration, co‐culture composition, pH, and time are determined. These four controlling parameters are used as decision variables during the optimization process, whereas the objective function is the simultaneous maximization of the MPD and COD removal. The obtained results proved that the optimal substrate concentration, pH, time, and initial COD values are 58.2%, 7, 14.4 days, and 32 × 10−3 (mg/L) respectively. Under this condition, the integration between fuzzy and HHO, the overall performance of MFC has been improved by 10.37% and 19.13%, respectively, compared with the experimental and RSM. [ABSTRACT FROM AUTHOR]

Ibuprofen degradation and energy generation in a single-chamber Microbial Fuel Cell (MFC) were evaluated using a bioanode fabricated from devil fish bone char (BCA) synthesized by calcination in air atmosphere. Its performance was compared with conventional carbon felt (CF). Bone char textural properties were determined by nitrogen adsorption. Before and after, the bacterial colonization on the materials was analyzed by environmental scanning electron microscopy. Energy generation was evaluated by electrochemical techniques as open-circuit potential, linear sweep voltammetry, and electrochemical impedance spectroscopy. Ibuprofen degradation was analyzed by High-Performance Liquid Chromatography-Ultraviolet, and the chemical oxygen demand (COD) removal was measured. Results showed a specific area of 136m²/g for BCA, having enough space to immobilize microorganisms. The micrographs confirmed the biofilm formation on the electrode materials. Over the 14 days, MFC with BCA reached a maximum power density of 4.26mW/m², 175% higher than CF, and an electron transfer resistance 2.1 times lower than it. This coincides with the COD removal and ibuprofen degradation efficiencies, which were 43.6% and 34% for BCA and 31.8% and 27% for CF. Hence, these findings confirmed that BCA in MFC could provide an alternative electrode material for ibuprofen degradation and energy generation. [ABSTRACT FROM AUTHOR]

Traditional biofuel cells (BFCs) are devices that use biological catalysts to catalyze the oxidation of organic materials and in the meantime convert chemical energy into electrical energy. In this work, a nonenzymatic catalyst that integrated copper oxide with multi-walled carbon nanotubes (CuO/MWCNTs) was synthesized by a simple solvothermal method, and the composites show an outstanding electrocatalytic activity for oxidation of phenol due to the synergistical contribution of CuO nanoparticles and MWCNTs. The effects of the pH, concentration of electrolyte and phenol and scan rate on the phenol oxidation are investigated. Benefitting from the excellent performance toward phenol oxidation, a H-type phenol fuel cell was fabricated with CuO/MWCNTs as anode material and electro-deposited platinum film as cathode material. The results show that the phenol fuel cell has an open-circuit potential (OCP) of 0.69 V and can produce a maximum power density of 0.25 mW cm − 2 at 0.44 V with 500 mg ⋅ L − 1 phenol and 0.1 mol ⋅ L − 1 PBS. The stability test revealed that the fuel cell could still deliver about 0.24 mW ⋅ cm − 2 after repeating the test for five times, indicating that the fuel cell has good stability. A nonenzymatic catalyst that integrated copper oxide with multi-walled carbon nanotubes was synthesized by a simple solvothermal method, and the composites show an outstanding electrocatalytic activity for oxidation of phenol. H-type phenol/O2 fuel cell was fabricated combining CuO/MWCNTs/GCE anode for directly oxidizing phenol and Pt/GCE cathode for reducing oxygen. Test results show that fuel cells have high power density and good stability. [ABSTRACT FROM AUTHOR]

A high-efficiency, stable, and flexible glucose/oxygen enzymatic biofuel cell is fabricated based on three-dimensional gold-coated nickel foam. The gold-coated layer makes the skeleton of nickel foam rougher, enhancing the relative apparent surface area of nickel foam and decreasing the electron transfer resistance. With the gold-coated nickel foam as substrate, the bioanode and biocathode exhibit good electrocatalysis activity and stability. By assembling the bioanode and biocathode with agarose gel electrolyte, cellulose acetate membrane, and silicone rubber layer-by-layer, the flexible biofuel cell is obtained. As per the results, the three-dimensional gold-coated nickel foam enlarges the enzymatic loading density to 5.68 × 10−7 mol cm−2, increasing the short circuit current density to 9.04 mA cm−2. The maximum power density of this flexible biofuel cell reaches 2.32 ± 0.07 mW cm−2 with excellent stability for retaining 84.6% of its performance after 60 days. Additionally, the flexible biofuel cell can be very stable in and after 1000 times of bending. [ABSTRACT FROM AUTHOR]

Microbial fuel cells (MFCs) and microbial electrolysis cells (MECs) are promising bioelectrochemical systems (BESs) for simultaneous wastewater treatment and energy/resource recovery. Unlike conventional fuel cells that are based on stable chemical reactions, these BESs are sensitive to environmental and operating conditions, such as temperature, pH, external resistance, etc. Substrate type, electrode material, and reactor configuration are also important factors affecting power generation in MFCs and hydrogen production in MECs. In order to discuss the influence of these above factors on the performance of MFCs and MECs, this study analyzes published data via data synthesis and meta-analysis. The results revealed that domestic wastewater would be more suitable for treatment using MFCs or MECs, due to their lower toxicity for anode biofilms compared to swine wastewater and landfill leachate. The optimal temperature was 25-35 °C, optimal pH was 6-7, and optimal external resistance was 100-1000 W. Although systems using carbon cloth as the electrodes demonstrated better performance (due to carbon cloth's large surface area for microbial growth), the high prices of this material and other existing carbonaceous materials make it inappropriate for practical applications. To scale up and commercialize MFCs and MECs in the future, enhanced system performance and stability are needed, and could be possibly achieved with improved system designs. [ABSTRACT FROM AUTHOR]

Microbial fuel Cell (MFC) has gained much attention in recent years due to its capability in simultaneous organic decomposition and electricity generation. Here, self-fabricated MFCs system were used to generate electricity and to reduce organic pollutant contained in slaughterhouse wastewater. In order to investigate the MFC configuration for process optimization, the experiments were conducted by employing different types of electrode materials, electrode size, and substrate-rumen microbe's ratio. Results shows that configuration of MFC with graphite-copper electrode 31.4 cm2 (active surface), and substraterumen microbes ratio 1:10 shows the best result by producing 318 m-2 of current density, potential of 2.4 V, and achieve maximum power density up to 700 mW m-2. In addition, self-fabricated MFC also shows its ability in reducing organic component by decreasing the chemical oxygen demand (COD) of the slaughterhouse wastewater to 67.9% and increasing the system pH from 5.9 to 7.5 which emphasize that MFC (operating at ambient condition 29°C) can be used as an alternative green-technology for slaughterhouse wastewater treatment. [ABSTRACT FROM AUTHOR]

Electrode materials are critical for microbial fuel cells (MFC) since they influence the construction and operational costs. This study introduces a simple and efficient electrode material in the form of palm kernel shell activated carbon (AC) obtained in tropical regions. The novel introduction of this material is also targeted at introducing an inexpensive and durable electrode material, which can be produced in rural communities to improve the viability of MFCs. The maximum voltage and power density obtained (under 1000 W load) using an H-shaped MFC with AC as both anode and cathode electrode material was 0.66 V and 1.74 W/m³, respectively. The power generated by AC was as high as 86% of the value obtained with the extensively used carbon paper. Scanning electron microscopy and Denaturing Gradient Gel Electrophoresis (DGGE) analysis of AC anode biofilms confirmed that electrogenic bacteria were present on the electrode surface for substrate oxidation and the formation of nanowires. [ABSTRACT FROM AUTHOR]

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This study presents the design and performance analysis of a prototype axial‐flux permanent‐magnet (AFPM) synchronous machine. First, the design of AFPM machine is optimised by genetic algorithm based sizing equation and finite element analysis. The design objectives of this machine are maximum power density, minimum total harmonic distortion (THD) of the sinusoidal back‐electromotive force (back‐EMF) waveform and low cogging torque. Based on the optimised design of the machine a prototype 1 kW, three‐phase, 50 Hz, four‐pole AFPM synchronous machine is built. Then, the performance of the prototype machine is tested to see the cogging torque, torque–speed characteristic, efficiency and the THD of the induced voltage. It is found that the prototype machine validates the design in terms of high‐power density, lowest possible THD of the back‐EMF, low cogging torque while maintaining high efficiency. [ABSTRACT FROM AUTHOR]

This work shows the power of the variational approach for studying the efficiency of thermal engines in the context of the Finite Time Thermodynamics (FTT). Using an endoreversible Curzon-Ahlborn (CA) heat engine as a model for actual thermal engines, three different criteria for thermal efficiency were analyzed: maximum power output, ecological function, and maximum power density. By means of this procedure, the performance of the CA heat engine with a nonlinear heat transfer law (the Stefan-Boltzmann law) was studied to describe the heat exchanges between the working substance and its thermal reservoirs. The specific case of the Muser engine for all the criteria was analyzed. The results confirmed some previous findings using other procedures and additionally new results for the Muser engine performance were obtained. [ABSTRACT FROM AUTHOR]

The efficient power, defined as the product of power output and efficiency of the engine, is taken as the objective for performance analysis and optimization of an endoreversible combined Carnot heat engine model in the viewpoint of finite time thermodynamics (FTT) or entropy generation minimization (EGM). The effects of finite-rate heat transfer, cycle temperature ratio and thermal-conduction parameters are considered in the analysis. The obtained results are compared with those obtained using maximum power (MP) and maximum power density (MPD) criterion. The design parameters for the optimal performances were derived analytically, and the effects of cycle temperature ratio and thermal conductance on it are investigated. The engines designed at MEP approach are more efficient and smaller than those designed at MP and MPD conditions. [ABSTRACT FROM AUTHOR]

To evaluate the shielding performance of an equipment-level enclosure, a new measure termed shielding power ratio is proposed, which includes the average shielding power ratio (AS) and a statistically based enhancement factor. Two measurement environments, the anechoic chamber and the reverberation chamber, are considered and compared. To achieve a quick estimate of such measure, the reverberation chamber is proposed to measure the AS. The enhancement factor can be derived from the statistical analysis on both measurement results and simulation results. Based on the enhancement factor and the total radiated power, the maximum power density radiated from the enclosure can be estimated accurately. The paper is informing new developments in IEEE Standard 299. [ABSTRACT FROM AUTHOR]

Micropower generators, which have applications in distributed sensing, have previously been classified into architectures and analyzed for sinusoidal driving motions. However, under many practical operating conditions, the driving motion will not be sinusoidal. In this paper, we present a comparison of the simulated performance of optimized configurations of the different architectures using measured acceleration data from walking motion gathered from human subjects. The sensitivity of generator performance to variations in generator parameters is investigated, with a 20% change in generator parameters causing between a 3% and 80% drop in generator power output, depending upon generator architecture and operating condition. Based on the results of this investigation, microgenerator design guidelines are provided. The Coulomb-force parametric generator is the recommended architecture for generators with internal displacement amplitude limits of less than ∼0.5 mm and the velocity-damped resonant generator is the recommended architecture when the internal displacement amplitude can exceed ∼0.5 mm, depending upon the exact operating conditions. Maximum power densities for human powered motion vary between 8.7 and 2100 μW/cm3, depending upon generator size and the location of the body on which it is mounted. [ABSTRACT FROM PUBLISHER]

Carbon materials such as carbon graphitic structures, carbon nanotubes, and graphene nanosheets are extensively used as supports for electrocatalysts in fuel cells. Alternatively, conducting polymers displayed ultrahigh electrical conductivity and high chemical stability havegenerated an intense research interest as catalysts support for polymer electrolyte membrane fuel cells (PEMFCs) as well as microbial fuel cells (MFCs). Moreover, metal or metal oxides catalysts can be immobilized on the pure polymer or the functionalized polymer surface to generate conducting polymer-based nanohybrids (CPNHs) with improved catalytic performance and stability. Metal oxides generally have large surface area and/or porous structures and showed unique synergistic effects with CPs. Therefore, a stable, environmentally friendly bio/electro-catalyst can be obtained with CPNHs along with better catalytic activity and enhanced electron-transfer rate. The mass activity of Pd/polypyrrole (PPy) CPNHs as an anode material for ethanol oxidation is 7.5 and 78 times higher than that of commercial Pd/C and bulk Pd/PPy. The Pd rich multimetallic alloys incorporated on PPy nanofibers exhibited an excellent electrocatalytic activity which is approximately 5.5 times higher than monometallic counter parts. Similarly, binary and ternary Pt-rich electrocatalysts demonstrated superior catalytic activity for the methanol oxidation, and the catalytic activity of Pt24Pd26Au50/PPy significantly improved up to 12.5 A per mg Pt, which is approximately15 times higher than commercial Pt/C (0.85 A per mg Pt). The recent progress on CPNH materials as anode/cathode and membranes for fuel cell has been systematically reviewed, with detailed understandings into the characteristics, modifications, and performances of the electrode materials. [ABSTRACT FROM AUTHOR]

Microbial fuel cells (MFCs) are a promising technology for bioenergy generation and wastewater treatment. Various parameters affect the performance of dual-chamber MFCs, such as substrate flow rate and concentration. Performance can be assessed by power density ( PD ), current density ( CD ) production, or substrate removal efficiency ( SRE ). In this study, a mathematical model-based optimization was used to optimize the performance of an MFC using single- and multi-objective optimization (MOO) methods. Matlab's fmincon and fminimax functions were used to solve the nonlinear constrained equations for the single- and multi-objective optimization, respectively. The fminimax method minimizes the worst-case of the two conflicting objective functions. The single-objective optimization revealed that the maximum PD ,   CD , and SRE were 2.04 W/m2, 11.08 A/m2, and 73.6%, respectively. The substrate concentration and flow rate significantly impacted the performance of the MFC. Pareto-optimal solutions were generated using the weighted sum method for maximizing the two conflicting objectives of PD and CD in addition to PD and SRE   simultaneously. The fminimax method for maximizing PD and CD showed that the compromise solution was to operate the MFC at maximum PD conditions. The model-based optimization proved to be a fast and low-cost optimization method for MFCs and it provided a better understanding of the factors affecting an MFC's performance. The MOO provided Pareto-optimal solutions with multiple choices for practical applications depending on the purpose of using the MFCs. [ABSTRACT FROM AUTHOR]