Computational And Experimental Research In Materials And Renewable Energy

Utilization of Banana Peel Waste as a Sustainable Substrate in Microbial Fuel Cell Systems for Renewable Energy Development

Anantita Febrinia Arifani — 2025-11-28

Most power plants in Indonesia (66%) still rely on fossil fuels, which have adverse environmental impacts. Microbial Fuel Cells (MFCs) offer a promising alternative as a clean energy source. This study investigates a dual-chamber ceramic membrane MFC that utilizes rice paddy sludge as a microbial inoculum and banana peel waste as the organic substrate. The objective is to determine the system’s optimal performance in terms of power density under seven substrate concentration variations (0–3971 ppm) and different incubation durations. The MFC system comprises 21 chambers with three replicates for each concentration. Voltage and current were measured periodically. The results show that power density increases with substrate concentration, indicating that higher substrate levels provide more nutrients for electroactive microorganisms to grow and transfer electrons efficiently to the anode. The maximum power density of 910 mW/m² was achieved on the 7th day at the highest substrate concentration (3971 ppm). These findings demonstrate that both substrate concentration and incubation duration significantly influence MFC efficiency and highlight the potential of banana peel waste as an effective bio-substrate for enhancing MFC performance and supporting sustainable energy development.

Performance Analysis and Modeling of the Combustion Characteristics of Carbonized Rice Husk Briquettes: Effects of Clay-Binder Ratio and Compaction Level

Mersha Alebachew Fetene — 2025-11-28

This study investigates the combined effects of clay binder ratio and compaction level on the combustion performance of carbonized rice husk briquettes, focusing on ignition time, burning rate, flame duration, peak temperature, and thermal efficiency. Experimental results revealed that moderate clay contents (5–15%) and compaction levels (6–18 mm) significantly enhanced ignition stability, peak combustion temperature (up to ~970 ºC), and burn duration (up to 130 minutes). Moderate clay addition improved briquette strength but slightly reduced thermal efficiency, as the inert clay fraction diluted fuel energy. Low compaction (6 mm) increased porosity and airflow, resulting in rapid ignition and higher peak temperatures suited for quick, intense heating, whereas moderate compaction (12 mm) ensured balanced ignition, stable combustion, and prolonged flame duration. Excessive clay content (>15%) and high compaction (18 mm) reduced combustion efficiency due to increased ash formation and restricted airflow, leading to lower peak temperatures and incomplete combustion. Water boiling tests confirmed that briquettes with 5–10% clay and moderate compaction achieved optimal heat output for household cooking. A third-order polynomial regression model incorporating interaction terms accurately predicted ignition time, peak temperature, and burn duration (R2 = 0.900–0.997), effectively capturing nonlinear combustion behavior. The findings provide practical insights for tailoring briquette formulations to diverse cooking requirements—from quick, high-heat applications to long-duration simmering—thereby supporting the development of efficient, sustainable biomass fuels for rural and low-income communities.

Energy Recovery from Corn Straw via Batch Anaerobic Digestion: Experimental and Simulation Study Using Rumen Inoculum

Kabama Kasombo — 2025-11-28

This study examines the experimental and simulation-based performance of batch anaerobic bioreactors used for the biomethanization of corn straw inoculated with rumen juice from the Masina slaughterhouse. The objective was to evaluate the substrate inoculum interaction under discontinuous operating conditions. Volumetric, gravimetric, and electrometric methods, along with the principle of communicating vessels, were used to monitor the bioconversion process. A two-phase anaerobic digestion model was developed to simulate the evolution of key parameters such as substrate concentration, microbial activity, and methane production over time. Model outputs were compared with experimental results to validate its accuracy and gain insight into degradation dynamics. Two inoculum conditioning strategies were tested to assess their effect on enzymatic activity and methane yield. Preconditioned (non-fresh) rumen juice, combined with a high organic loading rate, significantly improved the hydrolysis of lignocellulosic biomass, leading to faster degradation and enhanced methane productivity. The approach relied on simple, low-cost techniques and delivered promising results. A significant volume of methane was generated after 28 days of digestion, confirming the efficiency of the selected process conditions. These findings highlight the potential of anaerobic digestion for valorizing agricultural waste into bioenergy, particularly in decentralized, resource constrained contexts.The cumulative methane productions for the experimental digesters I, II, III, and IV were 330 mL, 412 mL, 153 mL, and 197 mL respectively, while the simulation predicted a maximum methane production rate of 0.375 L/day at an initial dissolved glucose concentration of 5 g•L-1. These results emphasize the importance of developing local and sustainable biogas production processes from organic waste, thereby contributing to energy transition, greenhouse gas reduction, and the promotion of a circular economy within the renewable energy sector.

Design and Deployment of an Uninterruptable Power Supply Utilizing a Solar PV System for Tilapia Aquaculture Farm in Sabah, Malaysia

Abdul Rahman — 2025-12-19

Continuous power supply is essential for maintaining operational stability of indoor aquaculture farms to protect their mortality. This paper examines the feasibility and performance of a 0.83 kWp stand-alone solar PV system for providing an uninterrupted power supply to a 185.8 m2 indoor tilapia farm located in Sabah, Malaysia (latitude: 6.03º N, longitude: 116.30ºE). Concerning these aspects, the system was designed specifically to operate critical equipment aerators and water pump within about five hours every week during grid power interruptions. The site was evaluated through the Global Solar Atlas showing an average global horizontal irradiation of 4.74 kWh/m2/day. Using on-site load analysis, the demand was found to be 1,750 Wh/week. The system consists of two 415 Wp PV modules connected in series, a 2.4 kWh lithium-ion battery, and a 2.4 kW inverter/charger scaled up to meet the demand while considering system losses. In addition, the virtual simulation of the system confirmed the average daily energy production to be about 2.95 kWh, which exceeds the demand by approximately 69%, hence allowing operation within the scheduled grid power outage. This research work highlights the technical feasibility along operational benefits resulting from small-scale PV deployment at aquaculture in tropical region, offering a scalable framework for improving energy reliability and sustainability in rural environments.

An Innovative Priority Control System for Electrical Device Usage in Smart Homes to Enhance Energy Efficiency: Integration of Decision Tree Algorithms, Sensors, and IoT

Gurum Ahmad Pauzi — 2025-11-28

This research was conducted to design a priority control system for efficient electricity usage by detecting current and voltage using ZMCT103C current sensor and ZMPT101B voltage sensor, then determining the priority sequence of household appliances using the C4.5 Algorithm. The designed tool utilizes ZMCT103C, ZMPT101B, NodeMCU8266, relay, and Arduino Uno. Monitoring and control can be performed in real-time using a website. Testing has shown that the priority control system tool has been successfully implemented and can measure current and voltage with high accuracy, as indicated by test data showing relatively small errors in current and voltage values not exceeding ± 5%. The prioritization sequence of household appliances includes the washing machine as the primary priority, followed by the refrigerator and water pump as the second priority, and the iron as the third priority. However, the rice cooker can be turned on simultaneously due to its low gain and entropy, thus not causing thermal shutdown.

Multi-Band Gap Transitions and Sub-Band Gap in rGO/MgF2 Films for Optoelectronic Application

Faridawati — 2025-11-28

We report the temperature-dependent optical properties of reduced graphene oxide (rGO)/MgF₂ films, emphasizing the emergence of multi-band gap transitions and sub-band gap states for optoelectronic applications. rGO films were thermally annealed at varying temperatures (400°C and 800°C), and their optical response was analyzed using UV-VIS spectroscopy. As deposited rGO film with an annealed temperature of 400°C exhibited a single dominant band gap transition at 2.07 eV, characteristic of π–π* transitions. Upon annealing at 800°C, additional transitions appeared at 2.34 eV until 2.40 eV, indicating the development of multi-band gap behavior due to structural ordering, oxygen functional group removal, and the formation of localized defect states. The calculated Urbach energy (E_(u )) increased from 0.279 eV to 0.288 eV at 800°C, signifying increased disorder and sharper optical absorption edges. The synergistic effects of rGO’s tunable band structure and MgF₂’s dielectric properties offer a versatile platform for optoelectronic devices application, such as broadband photodetectors, multi-junction solar cells and plasmon-enhanced sensors.

Model Predictive Control for Nonideal Positive Output Superlift Luo DC-DC Converter

Dhani Nur Indra Syamputra — 2025-11-28

Photovoltaic application as a renewable energy source demands stable and efficient power conversion techniques, especially under fluctuating input conditions due to solar power generation. Positive Output Superlift Luo Converter has a high voltage gain but has a nonlinear characteristic from its parasitic components. Nevertheless, common control method is not effective to overcome the nonideality of the converter. In this study, we propose a Model Predictive Control (MPC) strategy for a nonideal POSLLC, with a model derived from a discrete-time state-space model using the state-space averaging method. Simulation results showed that the MPC strategy improves the performance of the nonideal converter compared to an open-loop operation. The output voltage overshoot was reduced from 8.03% to 4.55%, and the settling time was shortened from 7.55 to 6.9 ms. As a result, the MPC strategy provides better damping and faster response to abrupt change in input voltage. The results demonstrate that MPC provides precise voltage regulation and adaptability for nonideal high-gain converters in PV-based power systems.

Sustainable Methylene Blue Removal using NaOH-Activated Rice Husk Charcoal

Naily Ulya — 2025-11-28

Water pollution from synthetic dyes such as methylene blue (MB) remains a serious environmental issue, particularly from textile and paper industries. This study explores rice husks as a low-cost bioadsorbent through four treatments: raw husks (SM), NaOH-activated husks (SA), rice husk charcoal (A), and NaOH-activated charcoal (AA). For the activated materials, the rice husks were immersed in a 6 M NaOH solution for 4 hours with intermittent manual stirring, followed by washing until neutral pH was reached and drying. Adsorption efficiency was evaluated using UV-Vis spectroscopy, while FTIR identified functional groups. AA demonstrated the best performance, reaching 95.28% efficiency at 6 hours and 96.96% at 18 hours, with equilibrium achieved at 6 hours. This enhanced adsorption is attributed to π–π stacking between aromatic structures and MB molecules, as well as electrostatic interactions from negatively charged –OH groups introduced by alkaline activation. In addition to its excellent adsorption capability, the application of rice husks as a renewable bioresource offers clear environmental and economic benefits through waste conversion and reduced dependence on conventional activated carbon. These results confirm the potential of NaOH-activated rice husk charcoal as an efficient, sustainable, and environmentally friendly adsorbent for dye wastewater treatment.

A Microleakage Study of Various Dental Fillers (Nanohydroxyapatite, Bioactive Glass and Nanohydroxyapatite/Bioactive Glass) for Dental Restoration

Nur Aisyah Nuzulia — 2025-11-28

Microleakage has been considered a common issue in dental restorations, leading to secondary or recurrent caries. One approach to addressing microleakage in dental cements focuses on enhancing the material's mechanical properties and chemical adhesion to the tooth, thereby sealing microscopic gaps. This study aims to evaluate the mechanical properties and microleakage of various dental fillers comprising nanohydroxyapatite (HA), bioactive glass (BG), and HA/BG composite. Before microleakage evaluation, all dental cement samples were mixed with Fuji FX resin and applied to the cavity of premolar teeth. The results showed that all teeth restored with specific dental fillers had higher compressive strength than those restored with the commercial product (GIC Fuji IX), with the HA/BG composite exhibiting the highest compressive strength at 16.47 kPa. Moreover, all teeth restored with specific dental fillers demonstrated lower microleakage than those restored with commercial fillers, suggesting better sealing. However, there was a shrinkage of the HA cement, leading to microleakage as demonstrated by methylene blue penetration into dentin. Similar microleakage into dentin was obtained in the HA/BG composite, but there was no shrinkage as occurred in HA cement. Overall, bioactive glass cement exhibited superior sealing ability, with the least microleakage, as evidenced by methylene blue penetration limited to the surface (enamel layer). This microleakage evaluation indicates the potential of HA/BG composites as dental cements with superior mechanical performance, with further optimization to enhance chemical adhesion to teeth and minimize microleakage.

Modeling and Simulation of a Hybrid Renewable Mini-Grid System for Electrification of Jaliadwip Island, Teknaf

Sabab Zaman — 2025-11-28

Affordable and reliable energy is essential for economic development, yet many remote islands in Bangladesh remain without electricity due to high grid extension costs and geographical constraints. Jaliadwip, an off-grid island in Teknaf, faces such challenges despite its selection by the Bangladesh Economic Zones Authority (BEZA) for the NAF Tourism Park, which is expected to require approximately 16 MW of power. This study proposes a hybrid renewable energy–based mini-grid system to meet the projected demand using an optimal configuration determined through HOMER software. The proposed system integrates solar photovoltaic (PV), wind turbines, biogas, and diesel generators. Simulation results show that the optimized PV–Wind–Diesel–Biomass hybrid system achieves the lowest Levelized Cost of Energy (LCOE) of 7.91 Tk/kWh with zero emissions, outperforming other standalone and hybrid options. Furthermore, the inclusion of net-metering PV and feed-in tariff (FIT) mechanisms further reduces the LCOE to 4.25 Tk/kWh and 3.33 Tk/kWh, respectively. The proposed approach provides a cost-effective and environmentally sustainable solution for electrifying Jaliadwip and offers a replicable model for similar island regions in Bangladesh.

DFT-Based Optimization of Morse Potential Parameters for Selected Metallic and Non-Metallic Materials

M. Husein Shodiq — 2025-11-28

The accurate description of interatomic interactions is essential for understanding the structural, mechanical, and thermal properties of metals at the atomic scale. The Morse potential is a widely used empirical model due to its simple analytical form and ability to capture basic bonding characteristics. However, its accuracy strongly depends on the choice of potential parameters, which are often obtained from experimental data or semi-empirical approaches and may not reliably represent non-ideal conditions such as defects, high stress, or phase transitions. In this work, we develop, optimize, and validate Morse potential parameters for several materials, including C, B, Ti, Al, Ni, and Fe, using reference data from DFT calculations. DFT simulations are performed using the open-source Quantum ESPRESSO package to obtain total energy data for isolated atomic pairs at various interatomic separation distances. The Morse potential parameters, namely the potential well depth (D), equilibrium distance (rₑ), and stiffness parameter (α), are determined by fitting the DFT total energy curves over a wide range of interatomic distances, including regions below and above the equilibrium separation up to the asymptotic limit. The fitted parameters are validated by comparing the resulting Morse potential energy profiles with the corresponding DFT reference data. This approach ensures that the optimized parameters accurately reproduce the underlying ab initio energy landscape while retaining the computational efficiency of empirical potentials. The resulting Morse parameters are intended for use in large-scale molecular dynamics simulations, particularly for modeling ballistic impact and armor systems involving materials such as B₄C, Ti-based alloys, and polymer–metal composites. This study provides a systematic framework for deriving DFT-consistent Morse potential parameters, enabling more reliable atomistic simulations of metallic and composite materials under extreme loading conditions.

Cover and Table of Contents

2025-11-28

Editorial Team

2025-11-28