Biomass-based briquettes offer a renewable energy alternative that can help reduce CO₂ emissions. Coconut shells and coffee grounds are promising waste materials due to their high calorific value. This study aimed to optimize the composition and carbonization time in producing briquettes from these two materials. The briquettes were prepared following SNI 01-6235-2000 and export briquette standards. The process included drying, carbonization at 300 °C for 60, 90, 120, 150, and 180 minutes, sieving, mixing, molding, and drying. Coconut shells and coffee grounds were mixed at weight ratios of 9:1, 8:2, 7:3, 6:4, and 5:5 with a total of 46.5 grams and 8.5 grams of adhesive. Briquette quality was evaluated based on moisture content, ash content, volatile matter, density, calorific value, and fixed carbon. The 9:1 composition yielded the highest calorific value of 6,472 cal/g, while a carbonization time of 90 minutes produced the best calorific value of 6,504 cal/g. The results show that a high proportion of coconut shells with limited coffee grounds and optimal carbonization time can produce briquettes with high energy potential, suitable for use as an alternative fuel.

Pollution caused by dye waste from the textile industry, specifically Rhodamine B, poses significant risks to human health. Furthermore, large-scale discharge of Rhodamine B into aquatic environments can alter water pH, thereby adversely affecting aquatic ecosystems. Environmental pollution caused by this dye can be prevented through adsorption using activated carbon. In this study aims to evaluate the efficiency of Rhodamine B dye removal from synthetic wastewater by varying the mass of activated carbon from coconut shell carbon and to determine the appropriate adsorption isotherm model based on the adsorption capacity of Rhodamine B on the adsorbent. The experiment was conducted by activating coconut shell carbon physically using a furnace at a temperature of 700℃ for 2 hours and chemically using 2.5 M KOH and soaked for 20 hours with a ratio of 1: 3 (m/v). The results of the study based on variations in adsorbent mass showed the best mass of 3 g with the smallest final concentration of 2.1717 ppm, an equilibrium time of 120 minutes, and an adsorption effectiveness of 86.13%. The appropriate adsorption isotherm model is the Langmuir isotherm.

Biofuel is a promising renewable energy alternative to reduce dependence on fossil fuels and lower greenhouse gas emissions. This article presents a comprehensive overview of biofuel classification (generation I–IV and physical forms), production technologies (fermentation, transesterification, gasification, pyrolysis), and the applications of bioethanol, biodiesel, and biogas in the transportation, industrial, and power generation sectors. Energy efficiency and environmental impact analyses are conducted using a life cycle assessment (LCA) approach, while national energy policies are examined in the Indonesian context, including the mandatory blending program (B30–B50) and sustainability strategies. While biofuels have significant potential, challenges such as production efficiency, land conflicts, and regulatory consistency need to be addressed for biofuels to truly contribute to the national energy transition

This experimental study investigates the performance of a Horizontal Axis Wind Turbine (HAWT) with a flat taper 4:5 blade design and a 25° exit angle, focusing on the effect of varying the number of blades (6, 9, and 12). The turbine, with a diameter of 1.1 m and blade dimensions of 470 mm length, 110 mm top width, and 137 mm bottom width, was tested at wind speeds of 3 m/s, 5 m/s, 7 m/s, and 9 m/s in a laboratory setting. Parameters such as wind speed, turbine rotation, voltage, and current were measured to analyze system efficiency. The results indicate that blade count and wind speed significantly influence efficiency. The highest efficiency of 12.51% was achieved at 3 m/s with 9 blades, while at 5 m/s, the efficiency peaked at 3.95% with 9 blades. For higher wind speeds (7 m/s and 9 m/s), the optimal efficiency decreased to 2.03% and 0.95%, respectively, both achieved with 6 blades. The study concludes that this turbine design is most effective at low wind speeds (≤5 m/s), making it suitable for regions with similar wind conditions, such as Indonesia. The findings contribute to optimizing blade configurations for small-scale wind energy applications.

This study aims to investigate how changing the roundness of the back edge of blades affects a 4:5 flat taper wind turbine. Tests used blades with 5 mm, 10 mm, and 15 mm rounded edges, compared to a 5 mm notched blade, across wind speeds from 3 to 9 m/s. The results show the 5 mm rounded edge works best at low wind speeds, with an efficiency of 11.12% at 3 m/s. At higher wind velocities, the 15 mm rounded blade demonstrated superior aerodynamic performance, attaining an efficiency of 1.63% at 7 m/s. The rounded trailing edge improved aerodynamic behavior by minimizing turbulence and enhancing flow stability. Therefore, the optimal edge radius should be determined based on regional wind characteristics, especially for low-speed wind zones typical of Indonesia

This research undertakes an operational performance analysis of a high-frequency inverter (HFI) within a Solar Power Plant (SPP) system configuration. The investigation prioritizes assessing the effects of pure resistive and mixed resistive-inductive load profiles on its efficiency stability. Experimental findings definitively demonstrate that the HFI inherently maintains superior efficiency stability when operating under purely resistive loads. Conversely, the introduction of varying inductive loads tends to compromise this efficiency stability, inducing significant fluctuations. These results yield crucial recommendations, establishing that HFIs are optimally suited for systems with predominantly resistive loads, thereby contributing to the overall system power efficiency enhancement

The continuous accumulation of used tires has raised serious environmental concerns due to their non-biodegradable nature. Pyrolysis offers a promising thermal conversion method to transform used tires into alternative energy sources. This study investigates the pyrolysis of used motorcycle tires, cut into 1 x 1 cm pieces, under atmospheric pressure at various temperatures ranging from 400°C to 750°C, using 500 grams of tire material for each run. The tar and char yields were collected, and the calorific values of the liquid product were analyzed. The optimum operating condition was found at 700°C, yielding 276.56 g of tar and 184.55 g of char after 2 hours and 35 minutes of reaction. The highest calorific value obtained was 39.98 MJ/kg. Although the liquid fuel produced exhibits significant energy content, its calorific value remains lower than that of conventional fuels used in vehicles. This indicates the potential of tire-derived oil as a supplementary fuel, with further improvement needed in quality and performance.

Batik is one of the cultural heritages in Indonesia that must be maintained and preserved. The batik industry process itself produces liquid waste that comes from the coloring processing, washing, wax removing, also rinsing. Batik waste, if not treated properly, can harm the environment. Various studies have shown that effluent treatment using the Rotary Algae Biofilm Reactor (RABR) method is promising. This research focuses on improving the RABR design and optimal conditions for treating batik wastewater, as well as utilizing the synergy between batik production and Ulva sp. The variables used in this research are the rotation speed of 20, 30, and 40 rpm, the lightning time for 0, 6, and 12 hours, and the disk diameter size of 9, 11, and 13 cm. The parameters that analyzed are BOD, COD, and pH levels. Waste treatment optimization in this research uses the RSM with a combination of Design Expert 13 software. Based on the results, the most optimal batik wastewater treatment variable is when the disk diameter is 10.306 mm, the rotation speed is 20 rpm, and the lightning time is 7.805 hours, yielding response values of 55.673 mg/L for BOD, 25.538 mg/L for COD, and 10.406 for pH.

The development of edible films using natural polysaccharides presents a sustainable alternative to synthetic packaging materials. This study aimed to enhance the barrier properties of edible films composed of carboxymethyl cellulose (CMC), konjac glucomannan (KGM), and κ-carrageenan (κCarr) by incorporating stearic acid (SA). Films were prepared by blending the biopolymers with SA at varying concentrations (0.1–0.5% w/w) and characterized for their structural, physical, and mechanical properties. Fourier-transform infrared (FTIR) spectroscopy confirmed molecular interactions between SA and the polysaccharide matrix, evidenced by reduced O–H absorption bands and intensified –CH₂– peaks. SA incorporation increased film thickness and moisture content but reduced tensile strength, elongation at break, solubility, and water vapor permeability (WVP). Although the WVP of SA-modified films did not meet the Japanese Industrial Standard at the tested concentrations, the observed trend suggests that higher SA levels could further improve barrier performance. The optimal formulation (0.5% SA) demonstrated enhanced hydrophobicity, acceptable water activity, and moderate tensile strength and opacity. These findings indicate that stearic acid can effectively modify the functional properties of polysaccharide-based edible films, advancing their potential as eco-friendly food packaging materials. Further optimization of SA concentration is recommended to achieve industrial moisture barrier standards.

One of the primary objectives in decarbonization is the separation of CO₂ from industrial gas mixtures, particularly in application such as biogas purification and flue gas treatment. A dual-layer crossflow membrane module was utilized under both circulation and batch operating modes with a 30% DEA solution. This study investigates the influence of solvent flow velocity on CO₂ separation performance using a hollow fiber membrane contactor with a 30% DEA solvent. the process was evaluated under two operating modes: batch and solvent circulation. Key variables measured include the solvent flow rate (40–160 mL/min), operating temperature (30–50°C), and sweep gas flow rate (100–300 mL/min). The results indicate that under continuous operation with a solvent flow rate of 160 mL/min, a temperature of 30°C, and a sweep gas flow rate of 100 mL/min, 50.42% of the CO₂ was successfully removed. In contrast, the batch system, under identical conditions achieved only a 27.8% removal rate. The superior performance in circulation mode is attributed to the continuous renewal of the solvent, which sustains a stable concentration gradient and minimizes mass transfer resistance. These findings underscore the potential of membrane-based systems with optimized solvent circulation for efficient and stable CO₂ capture in industrial applications.