Ee Sann Tan

Anaerobic Digestion (AD) is a renewable energy technology that converts organic wastes into a sustainable energy source, such as biogas. This paper presents the formulation of a Machine Learning (ML) forecasting model to predict emissions from the AD process. Five distinctive ML algorithms, including Artificial Neural Networks (ANN), Random Forest (RF), Decision Tree (DT), Support Vector Machine (SVM), and Genetic Algorithm (GA)-optimized have been developed to evaluate their predictive performance and formulated using key operational parameters as input variables. Model performance of each ML algorithm was evaluated using statistical analysis such as the coefficient of determination (R2), root mean square error (RMSE), and mean absolute error (MAE). The results demonstrated that the RF model achieved the highest accuracy in predicting emissions, while the SVM model had the lowest. The RF model yielded the best prediction, with an R2 value of 0.9733, followed by GA-optimized, DT, ANN, and SVM (with R2 values of 0.9714, 0.9527, 0.9475, and 0.9389, respectively). The findings of this study emphasized the potential of ML forecasting models to support the development of efficient and sustainable biogas systems, with particular relevance to agricultural waste management in Malaysia.

The high cost and food competition associated with conventional biodiesel feedstocks limit its widespread adoption. This research investigates using palm fatty acid distillate (PFAD), a low-cost industrial by-product which is high in free fatty acids (FFAs), as a sustainable feedstock. A novel glycerol-free esterification route was developed employing ethyl acetate as acyl acceptor and sulfuric acid as catalyst, producing fatty acid ethyl esters (FAEEs) and valuable acetic acid as by-product. The characterization of PFAD confirmed its high FFA content of 91.78 ± 0.62%, then the Taguchi method was employed to systematically optimize key reaction parameters: reaction time (2–4 h), temperature (55–75 °C), catalyst amount (3–9 wt%), and ethyl acetate to PFAD molar ratio (5:1–15:1). Taguchi orthogonal design revealed that the ethyl acetate to PFAD molar ratio had the most significant impact on FFA conversion and time had the lowest impact. Optimal conditions were identified as 4 h, 65 °C, 6 wt%, and 15:1 molar ratio, yielding a predicted maximum FFA conversion of 87.74%. Experimental validation under these conditions achieved an average conversion of 86.28, confirming excellent agreement with the prediction. This research presents one of the first systematic Taguchi optimizations of PFAD esterification using ethyl acetate, offering a greener, glycerol-free pathway compared to conventional methanol-based processes. The proposed route contributes to sustainable biodiesel production from waste products, aligning with global renewable energy goals and economic viability.

Rice husk gasification offers a sustainable route to produce hydrogen-rich biogas, addressing global energy security and environmental challenges. This study investigates the gasification of rice husk biomass in a horizontal tube furnace at 800°C under controlled nitrogen flow to optimize hydrogen production. The rice husk feedstock had a moisture content of 11.7%, ash content of 16.3%, volatile matter of 58.0%, fixed carbon of 13.9%, and a gross calorific value of 3411 kcal/kg. Biogas composition was analysed using gas chromatography with a thermal conductivity detector (GC-TCD), and it revealed a maximum hydrogen content of 50.99%. Compared to subsequent samples, it represents a 1.5 time increase in hydrogen yield. The study highlights rice husk as a viable biomass feedstock for renewable hydrogen production. Therefore, future work needs to focus on catalytic gasification through the use of nickel-based catalysts and biological pre-treatments like white-rot fungi degradation to enhance hydrogen yield and process efficiency. Conclusively, the research contributes to the advancement of renewable energy technologies with potential environmental benefits over fossil fuels and other biomass sources.

The article presents a thorough analysis of climate change education, highlighting its challenges and the need for a holistic approach. It delves into the inadequacies of current education models in addressing the complex nature of climate change and...

This study explores the pyrolysis of disposable face masks to produce chemicals suitable for use as fuel, addressing the environmental concern posed by single-use face masks. Co-pyrolysis of biomass with face mask plastic waste offers a promising solution. The research focuses on the co-pyrolysis of biomass and face masks, aiming to characterise the properties for analysis and optimisation. Selected agricultural biomass and face mask plastic waste were subjected to temperatures from 250 °C to 400 °C for co-pyrolysis. Slow pyrolysis was chosen because face masks cannot be converted into useful bioproducts at temperatures exceeding 400 °C. The samples were tested in four different ratios and the study was conducted under inert conditions to ensure analysis accuracy and reliability. The results indicate that face masks exhibit a remarkable calorific value of 9310 kcal/kg. Face masks show a two-fold increase in calorific value compared with biomass alone. Additionally, the low moisture content of face masks (0.10%) reduces the heating value needed to remove moisture, enhancing their combustion efficiency. This study demonstrates the potential of co-pyrolysis with face masks as a means of generating valuable chemicals for fuel production, contributing to environmental sustainability.

Organic and plastic waste (OPW) is diverted from landfills in order to lower carbon emissions. Nevertheless, modern pyrolysis techniques are frequently utilized in laboratories (using feedstocks that weigh less than 1 kg), which employ costly pure nitrogen gas (N₂). This study developed a fast pyrolysis system to produce pyrolysis oil or liquid (PyOL) from OPW using flue gas as the pyrolysis agent. The added benefits included the efficient value-added chemical extractions and the non-thermal plasma reactor upgraded PyOL. OPW was also pyrolyzed at a pilot scale using flue gas fast pyrolysis in this study. In addition to lowering operational expenses associated with pure N₂, flue gas reduced the lifecycle carbon emissions to create PyOL. The results indicated that considerable material agglomeration occurred during the OPW pyrolysis with an organic-to-plastic-waste (O/P) ratio of 30/70. Furthermore, the liquid yields were 5.2% and 5.5% when O/P was 100/0 (305 °C) and 99.5/0.5 (354 °C), respectively. The liquid yields also increased when polymers (polypropylene) were added, enhancing the aromatics. Two cases were employed to study their techno-economic feasibility: PyOL-based production and chemical-extraction plants. The mitigated CO₂ from the redirected OPW and flue gas produced the highest revenue in terms of carbon credits. Moreover, the carbon price (from RM 100 to 150 per ton of CO₂) was the most important factor impacting the economic viability in both cases. Plant capacities higher than 10,000 kg/h were economically viable for the PyOL-based plants, whereas capacities greater than 1000 kg/h were financially feasible for chemical-extraction plants. Overall, the study found that the pyrolysis of OPW in flue gas is a viable waste-to-energy technology. The low liquid yield is offset by the carbon credits that can be earned, making the process economically feasible.

Sulfur hexafluoride (SF₆) gas is one of the high global warming potential (GWP) gases regulated under the Kyoto Protocol. In Malaysia’s Biennial Update Report 3, the Revised 1996 Intergovernmental Panel on Climate Change Guidelines were followed to estimate the SF₆ emissions in the country, including the time series from 1990 to 2016. The majority of SF₆ emissions originate from the use of this gas in electrical equipment, where it is predominantly used in transmission switch gears, which have increased rapidly because of increasing electricity demand. SF₆ gas plays a significant role in greenhouse gas emissions in Malaysia because this gas has a higher GWP than carbon dioxide. Hence, this SF₆ gas needs to be estimated using newer guidelines such as the 2006 IPCC Guidelines. Detailed activity data in the new methodology require stakeholders’ engagement with utility providers and government agencies. This paper describes the GHG inventory improvement plan, focusing on SF₆ emissions for Industrial Processes and Product Use for Malaysia through this transition of methodology.

Small-scale vertical-axis wind power generation technologies such as Savonius wind turbines are gaining popularity in suburban and urban settings. Although vertical-axis wind turbines (VAWTs) may not be as efficient as their horizontal-axis counterparts, they often present better opportunities for integration within building structures. The main issue stems from the suboptimal aerodynamic design of Savonius turbine blades, resulting in lower efficiency and power output. To address this, modern turbine designs focus on optimizing various geometric aspects of the turbine to improve aerodynamic performance, efficiency, and overall effectiveness. This study developed a unique optimization method, incorporating a new blade geometry with guide gap flow for Savonius wind turbine blade design. The aerodynamic characteristics of the Savonius wind turbine blade were extensively analyzed using 3D ANSYS CFX software. The optimization process emphasized the power coefficient as the objective function while considering blade profiles, overlap ratio, and blade number as crucial design parameters. This objective was accomplished using the design of experiments (DOE) method with the Minitab statistical software. The research findings revealed that the novel turbine design “OR0.109BS2BN2” outperformed the reference turbine with a 22.8% higher power coefficient. Furthermore, the results indicated a trade-off between the flow (swirling flow) through the gap guide flow and the impact blockage ratio, which resulted from the reduced channel width caused by the extended blade tip length.

Renewable energy sources are preferred for many power generation applications. Energy from the wind is one of the fastest-expanding kinds of sustainable energy, and it is essential in preventing potential energy issues in the foreseeable future. One pertinent issue is the many geometrical alterations that the scientific community has suggested to enhance rotor performance features. Hence, to address the challenge of developing a model that resolves these problems, the purpose of this investigation was to determine how well a scaled-down version of a Savonius turbine performed in terms of power output using a wind tunnel. Subsequently, the effect of the blockage ratio produced in the wind tunnel during the chamber test on the scaled model was evaluated. This study discusses the influences of various modified configurations on the turbine blades’ torque and power coefficients (Cp) at various tip speed ratios (TSRs) using three-dimensional (3D) unsteady computational fluid dynamics. The findings showed that the scaled model successfully achieved tunnel blockage corrections, and the experimental results obtained can be used in order to estimate how the same turbine would perform in real conditions. Furthermore, numerically, the new models achieved improvements in Cp of 19.5%, 16.8%, and 12.2%, respectively, for the flow-guiding channel (FGC at Ⴔ = 30°), wavy area at tip and end (WTE), and wavy area on the convex blade (WCB) models in comparison to the benchmark S-ORM model and under identical wind speed conditions. This investigation can provide guidance for improvements of the aerodynamic characteristics of Savonius wind turbines.