bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical investigation of the effects of increased and mixed chord lengths for a 4-bladed darrieus vertical axis wind turbine
Authors: Wong K H , Lim C T J , Ng J H , Fazlizan A , Wang X H
Published: July 2024

Increasing amounts of study and research on vertical axis wind turbines (VAWTs) have shown that they are a competitive option in wind energy power generation. However, the VAWT’s primary drawback is low power efficiencies. Although there are several studies on the effects of solidity on Darrieus VAWT performances, few focus on the effect of the aerofoil chord length. Hence, in the present study, 2D numerical simulations are performed to explore the effects of different aerofoil chord lengths on the performance of a Darrieus VAWT. The simulation was first validated with the experimental data from the literature. The studied turbine is a 4-bladed VAWT fitted with NACA0021 blades with an original chord length, c of 85.8 mm and another with an increased chord length of 1.2 c (102.96 mm). Additionally, a modified rotor geometry with mixed chord lengths of c and 1.2 c to improve turbine performance is proposed and investigated. The coefficients of power (C
P) and torque (C
T) for tip speed ratios (TSRs) between 1.4 and 3.3 for each of the turbines are evaluated and comparatively analysed. All the data was obtained using the computational fluid dynamics (CFD) software ANSYS Fluent in conjunction with the shear stress transport (SST) k−ω turbulence model. The findings show that the turbine with 1.2 c chord length and hence larger solidity outperforms those with smaller chord lengths at low TSRs. However, their performances decrease significantly at TSRs above 2.5, resulting in up to 86.1% lower C
P values. The mixed chord lengths case was successful at achieving significantly higher C
P values at both TSR ranges with only a decrease of 3.03% in maximum C
P at its optimum TSR.
Experimental investigation into the effects of endplate designs for a Savonius turbine
Authors: Wong K H , Foo J S Y , Chong W T , Mat S , Ng J H
Published: July 2024

Wind energy is experiencing a trend of exponential growth in both literature and industrial employment, emphasizing its current pivotal role in achieving carbon neutrality by replacing fossil fuels. Vertical axis wind turbines (VAWTs) particularly Savonius rotors operate at a lower tip-speed-ratio (TSR) range compared to horizontal axis wind turbines (HAWTs). The Savonius rotor has good starting characteristics, making it suitable to be placed in urban areas with lower wind speeds. Due to its low efficiency, studies on augmentation and optimization have been conducted to improve its blade and deflector designs. Extensive research has established a common consensus that the use of endplates significantly improves the aerodynamic performance of the Savonius rotor. However, limited research has been undertaken to explore the endplate design further. In this study, wind tunnel tests were conducted on different endplate ratios, to investigate the effects of endplate design on the aerodynamic performance of a conventional Savonius turbine. Three different Savonius rotor with no endplate, semi-circular endplate and circular endplate were designed and manufactured. Experiments were conducted in an open-type suction wind tunnel at a constant measured wind velocity of 5.89 m/s. The turbine’s performance for different endplate ratios was evaluated across a TSR range of 0.2 to 1.0. The performance was assessed based on the maximum power generated and its self-starting ability. From the experimental results, the circular endplate ratio of 1.1 shows a significantly high coefficient of power compared to both semi-circular and without endplates. This is due to reduced spanwise spillage and enhanced airflow capture by the rotor. The endplates direct incoming air to the advancing blade and overlap region, resulting in the increased pressure difference between the concave and convex sides of both the advancing and returning blade, thereby improving the power efficiency of the turbine with 1.1D diameter endplate and semi-circular endplate by 296.6% and 6.9% compared to no endplates case.
Simulation on solidification process of molten salt-based phase change material as thermal energy storage medium for application in Stirling engine
Authors: Putra G J P , Putra N
Published: July 2024

Thermal energy storage technologies have been widely used to mitigate intermittency from renewable energy such as solar energy. Phase change material (PCM) is a certain material that can be used as a heat storage medium and is available in a wide range of operating temperatures. Molten salt is one of the PCMs that has the advantage of a very high operating temperature. The PCM solidification simulation based on HitecXL molten salt using COMSOL Multiphysics software will be carried out with variations in heat absorption of 1 - 5 kW/m2, assuming constant heat absorption. The results show that the PCM solidification process starts from the surface of the Stirling engine heat exchanger pipe. The part of the PCM that has been solidified will fall following the direction of gravity and cause a phenomenon such as a droplet. The flow that occurs is a natural flow caused by the buoyancy force due to changes in density due to temperature gradients in the solidification process. The time required for the PCM to completely solidify is closely related to the amount of heat absorption. The greater the heat absorption from the pipe, the faster the PCM to fully solidified.
Startup characteristics of a water loop heat pipe with dual heat sources for battery thermal management system in electric vehicle
Authors: Fathoni A M , Hendrayanto P A , Aliefiansyah M S , Putra N
Published: July 2024

The usage of electric vehicles has significantly reduced emissions of greenhouse gases and other pollutants. However, the high heat release generated by the electric vehicle batteries poses a challenge. To solve this problem, scientists have created a passive cooling thermal management system specifically for electric vehicle based on heat pipes, particularly loop heat pipes. A battery pack often consists of several battery modules, which results in multiple heat sources being dispersed according to their power capacity. Startup behavior of loop heat pipe has been investigated extensively in the literature. However, most of the studies use only one heat source. This paper aims to fill the research gap, particularly when the system is implemented in dual heat sources managed by only one evaporator. To achieve the research objectives, a custom loop heat pipe was constructed. This cooling system’s design is briefly described. The evaporator is made of copper, deionized water was selected as the working fluid because of its high merit number, which indicates strong performance as a heat pipe working fluid and the stainless-steel wire mesh serves as the porous wick. Battery simulator was built using aluminum material and a cartridge heater to mimic the heat produced by the battery. Two case studies were done. First, only one battery simulator was used. Second, two battery simulators were placed on both sides of the evaporator. A type-K thermocouple attached to the NI DAQ 9214 module was used to measure the temperature while the electric heat load varied between 10 W and 50 W. The study investigated the interaction between the heat load distribution and the startup behavior of the loop heat pipe. Startup behavior is crucial for the performance of the loop heat pipe. Based on the experimental results, the loop heat pipe demonstrates outstanding startup performance. It can effectively initiate operation even at a minimal heat load as low as 30 W for the first and second case study. The findings of the study indicate that the dual heat source arrangement effectively mitigates overshoot temperatures and enhances heat transfer performance by increasing the contact area.
Effect of alkali metal cations in alkaline iron battery electrodes
Authors: Loresca D E D , Paraggua J A D R
Published: July 2024

Rechargeable alkaline iron batteries (e.g. Ni-Fe and Fe-air) have been extensively studied recently as viable energy storage systems for renewable energy sources. However, inherent issues such as passivation of the iron and parasitic hydrogen evolution reaction (HER) on the electrode surface limit their full capability. Multiple approaches to improving iron electrode performance have been conducted, few of which focused on electrolyte composition. While alkali metal (AM) cations on the electrolyte do not directly participate in the electrochemical reactions, their intrinsic characteristics can dictate the performance of the electrode. Investigating the interface interactions and electrical double layer (EDL) structure can provide a deeper insight into the operation of iron electrodes in an alkaline solution. In this work, we investigated the effect of alkali metal cations (Li+, Na+, K+, Cs+) in the electrolyte solution in inhibiting passivation and HER on electrodeposited iron on carbon paper (Fe/CP) electrodes. The electrochemical measurements show that the iron redox and HER activities of the electrode increased with increasing cation size in the electrolyte. The non-covalent interactions between hydrated alkali metal cations and adsorbed OH species resulted to the formation of quasi-adsorbed clusters which can block active sites on the electrode surface. Furthermore, the concentration of these clusters decreases with increasing cation size which resulted to higher EDL capacitance and ECSA values of the electrode. The results of this work provide a better understanding of the surface reactions on iron electrodes and can help in developing novel techniques for suppressing passivation and parasitic HER on rechargeable alkaline iron batteries.
Energy stacking efficiency of a novel low-frequency spring-like piezoelectric energy harvester
Authors: Wong G S , Lee K Q , Eileen Lee M S , Kang H S , Wong K Y
Published: July 2024

This study introduces a novel approach to energy harvesting through a spring-like piezoelectric harvester, termed SPEH, specifically designed for extremely low-frequency excitations. Through the integration of PVDF films and incorporating multiple thin plastic layers, the experimental setup underwent testing across various impact amplitudes and loads. Notably, the results revealed that the height of the impact significantly influenced peak voltage generation, with a remarkable 74% surge observed between a 3-inch and a 1-inch impact under a 90g load. Conversely, the impact load exhibited a comparatively lesser influence on peak voltage. The analysis of generated RMS voltage demonstrated a consistent trend, where higher impact height and load weight correlated with increased RMS voltage, emphasizing the significance of system mass. This innovative approach seeks to harness ambient vibration energy for sustainable power generation, marking a stride in advancing low-frequency piezoelectric energy harvesting systems.
Designing an absorber for solar photovoltaic thermal systems: a heat pipe approach and comparative evaluation
Authors: Kamble A D , Das D , Kalita P
Published: July 2024

Renewable energy power generation is extensively promoting for the global objective of mitigating greenhouse gas emissions. Solar energy leads all renewables due to its ubiquitous nature which can be harvested by solar thermal and solar photovoltaic devices. Solar PV is used widely because of its flexibility in working with both direct and diffuse radiation. However, PV systems experience efficiency loss for every degree rise of solar cell temperature above room temperature. Solar photovoltaic-thermal (PVT) collectors are proposed for co-generation of electrical and thermal energy by utilizing excess heat generated in the PV layer. The low heat transfer rate, energy-intensive nature, and freezing of working fluid in colder regions are some problems that persist in water- and air-based PV/Ts, leading us to consider alternatives. Thus, the present study addresses the current opportunities by utilizing heat pipes as PV/T absorbers. Heat pipe PVT is a passive system which operates in phase transition facilitating a tremendous amount of heat transfer enhancement. To enhance the efficiency of PV/T systems, the integration of advanced technologies, like heat pipe thermal absorbers, becomes imperative. Incorporating cutting-edge solutions, such as heat pipe thermal absorbers, is essential to optimize the performance of PV/T systems. Hence, the current study provides insight into heat pipe design through a case study on the application of heat pipes as thermal absorbers for photovoltaic systems. The existing absorbers with fluid flow configurations like Raster, Spiral or Rectangular spiral, etc. used in PV/T are considered as reference. Copper as tube material and water as working fluid are found to be compatible with each other for the proposed heat pipe. The maximum heat input of 0.55kW is computed by the inadequacy of the mentioned existing PVTs to extract the maximum available heat from the PV surface. Additionally, an analytical approach used to define the optimum size of the system and calculation of minimum requirement of tubes. The optimized design of copper heat pipes was found to be ½ inch in diameter and at least ten heat pipes were required to transfer a computed heat flux of 466kW/m
2 per pipe to outperform the existing PV/Ts.
Solar-assisted biogas system with air-source heat pump for the energy-saving of indoor heating in north China
Authors: Sun T M , Khairuddin A S M , Soon T K , Pang L L , Wang X R , Wu J S , Zheng Z J , Novikovs A
Published: July 2024

To address the challenges associated with winter heating in high-latitude regions of China, solar-assisted biogas heating systems have emerged as the predominant focus of research due to their cost-effectiveness, accessibility, and environmentally friendly attributes. However, traditional solar-assisted biogas heating systems encounter issues of low efficiency and limited practicality resulting from unstable solar radiation and extreme ambient temperatures during the heating season. To improve the economy and stability of the system, this study proposed a novel operational control method for a small-scale energy station system in rural regions of North China, named Solar-Biomass-Air Source Heat Pump Hybrid Heating System (SBHP-HHS). The integration of solar energy, biogas energy, and air-source heat pump (ASHP) systems in this proposed work has shown to create effective complementarity and enhances the production efficiency of the existing system. Test and simulation studies have been carried out for this system. The layout of buildings and equipment within a university campus in Beijing is reconfigured and redesigned, incorporating an ASHP into the existing heat source configuration. To begin with, a mathematical model is established for the complementary heating system that incorporates solar energy, a biogas digester, and an ASHP. Subsequently, a dynamic simulation model is developed using the TRNSYS platform, and a corresponding operational control strategy for the multi-energy complementary heating system is proposed. Dynamic simulation and analysis of the newly implemented system are performed using the TRNSYS platform, focusing on energy flow and thermodynamic performance. Throughout the heating season, the solar-biogas integrated system achieves a remarkable assurance rate of up to 79%. Additionally, ASHP maintains a relatively high heating efficiency, coefficient of performance (COP) reaches 3.02. Finally, an economic evaluation of the multi-energy complementary system was conducted based on the annual cost method. This was compared with the clean approach of using only an ASHP unit. The results indicate that the SBHP-HHS is more economical when the anticipated useful life is 6 years or longer. The results indicate that the proposed can achieve significant energy-saving and carbon-reduction benefits in rural areas, catering to their heating needs.
A comprehensive review of hybrid wind-solar energy systems
Authors: Nair Kartik Anil , Garlapati Nagababu
Published: July 2024

In the face of escalating global energy demands and growing environmental concerns associated with conventional energy sources, integrating renewable energy systems has become imperative. Solar and wind have become key contributors to a cleaner and more sustainable energy future among these renewable energy sources. However, their intermittent nature, unpredictability, and infrastructural demands present significant challenges. Hybrid renewable energy systems (HRES) have emerged as a transformative solution to address these challenges. This paper conducts a comprehensive review of HRES, explicitly focusing on integrating wind and solar energy sources to address the limitations of individual systems. The review encompasses a systematic analysis, commencing with identifying optimal deployment areas for hybrid systems, considering geographic and climatic factors that maximize energy yield. Also, reviewed the in-depth exploration of the pivotal components. Additionally, the paper critically examines the crucial aspect of sizing HRES systems, shedding light on recent methodologies applied to HRES. Furthermore, the paper investigates modern advanced technologies used in HRES, particularly the latest analytical software, its methodologies, and the incorporation of effective designs for hybrid wind and solar systems. In addition to evaluating the current state of HRES technology, this article also discusses the scope of future research prospects and emerging trends in the field. It also contemplates integrating other renewable energy sources, such as biomass, with wind and solar energy according to the availability and advantages of these sources and other associated aspects. This paper will help understand the current developments in the field of HRES.
Performance research on multi-energy complementary heating systems in rural areas of China: A mini review
Authors: Pang L L , Wang C Q , Wang X R , Sun T M , Wu J S , Novikovs A
Published: July 2024

Winter heating in rural areas has always been an issue of great concern to the State. In China, traditional heating methods mainly use coal-fired boilers or heating stoves, however, coal burning has caused serious environmental pollution and air quality problems. In order to improve heating conditions and reduce environmental pollution, some rural areas have begun to try multi-energy complementary heating (MECH) system, which improves heating efficiency by comprehensively utilizing solar energy, biomass energy, ground source heat pump, air source heat pump (ASHP). However, due to poor economic conditions, the actual operation faces various factors and challenges. In order to solve these problems, this paper provides a systematic review of the research on MECH systems in rural areas in China in recent years. First, it summarizes the existing MECH systems, including various technologies such as solar-ASHP heating, solar-biogas heating, and ground source heat pump-solar heating, and lists their advantages and disadvantages in detail. Secondly, the effects of MECH systems in practical applications are discussed through case studies. Finally, recommendations for promoting MECH technologies are presented to facilitate the development of MECH systems in rural areas. The study contributes to the development of MECH system, which helps to improve rural heating conditions and reduce environmental pollution.
Evaluation of pyrolysis characteristics and kinetic parameters from several prospected biomass residues by thermogravimetric analysis
Authors: Pambudi S , Jongyingcharoen J S , Saechua W
Published: July 2024

With fossil fuel supplies dwindling and persistent environmental concerns surrounding their consumption, biomass has emerged as a highly promising renewable energy source. Understanding the characteristics of biomass pyrolysis is crucial as it provides valuable insights and guidance for designing and optimizing the pyrolysis process. In this regard, a thermogravimetric assessment was conducted to evaluate the pyrolysis characteristics and kinetic parameters of four prospective biomass sources: Yang Na wood (Dipterocarpus alatus), palmyra palm shell, cotton stalk, and spent coffee grounds with a condition temperature range of 33 °C to 700 °C and a heating rate of 10 °C·min-1 in a nitrogen atmosphere. The kinetic parameters were evaluated using the Coats and Redfern methods, employing various reaction order models. The activation energy and pre-exponential factor were determined for the active pyrolysis stage. The results revealed that the high heating values for all samples ranged from 18.20 to 23.00 MJ·kg-1. Additionally, the onset temperature fell within the range of 243 to 254 °C, while the offset temperature ranged from 365 to 452 °C for all samples. The conversion rate at the offset temperature was 0.67 for Yang Na wood, 0.62 for palmyra palm shell, 0.65 for cotton stalk, and 0.74 for spent coffee grounds. Moreover, the activation energies were measured as 46.47 kJ·mol-1 for Yang Na wood, 52.46 kJ·mol-1 for palmyra palm shell, 64.20 kJ·mol-1 for cotton stalk, and 69.01 kJ·mol-1 for spent coffee grounds. The higher activation energy corresponded to a higher pre-exponential factor. In conclusion, the pyrolysis characteristics and kinetic parameters of the four types of biomasses have been found to be favourable, indicating their potential for promotion and application as a raw material for the pyrolysis process.
Assessing the Effect of Aluminium Oxide Nanoparticle Additives on Biodiesel Combustion in Marine Diesel Engines
Authors: Mohd Noor Che Wan , Ismail Amir Azfar , Fhatihah Amirah Nur , Ahmad Mohammad Fadhli , Khasbi Jarkoni Mohammad Nor , Briggs Horizon Gitano
Published: July 2024

The increases in annual ship exhaust emissions have prompted the shift towards adopting alternative energy sources. Biodiesel is a suitable substitute fuel for marine engines that does not necessitate engine alterations. Biodiesel is renewable, environmentally friendly, and plant-based with biodegradable properties. The fuel is also non-toxic and oxygenated and shares similar characteristics with diesel fuel. Nonetheless, biodiesel fuel exhibits slightly reduced performance compared to diesel primarily due to its lower energy content. This study aims to evaluate the combustion attributes of a marine diesel engine employing palm biodiesel fuel incorporated with aluminium oxide (Al2O3) nanoparticle additives. A B20 biodiesel fuel was blended with 50, 100, and 150 ppm Al2O3 nano additives. The engine combustion parameters, in-cylinder pressure, heat release rate (HRR), mass fraction burned, and ignition delay were analysed and compared to the B20 fuel without additives. Adding Al2O3 nano additives to the B20 biodiesel blend improved the engine combustion characteristics. The optimal performance was recorded by the blend incorporating 150 ppm nanoparticles. The in-cylinder pressure and HRR peaks also improved by 5.41 to 15.1% and 4.69 to 16.9%, respectively, compared to the other B20 fuel blends. Furthermore, the B20 mixed with Al2O3 documented a more rapid mass fraction burned rate, resulting in a shorter ignition delay of approximately 5 CA°. In addition, the amount of oxygen in biodiesel blended with Al2O3 nano additives has improved engine combustion compared to B20 fuel. The present study demonstrated that adding Al2O3 nano additives to palm biodiesel fuel significantly enhanced engine combustion attributes, thus highlighting its potential to reduce reliance on petroleum-based fuels and provide sustainable fuel alternatives for marine diesel engines.
Trihalomethane formation potentials from the effluent of different wastewater treatment sources
Authors: Phlaengsattra K , Kanokkantapong V , Sangsanont J
Published: July 2024

Reused wastewater is commonly treated with disinfection to remove pathogenic microorganisms; however, this process generates disinfection byproducts (DBPs), such as trihalomethanes (THMs). This study aimed to investigate the levels of THMs and THM formation potential (THMFP) in treated wastewater originating from different sources i.e., domestic, food-processing industry and hospital. The samples from each source were collected three times between June and August 2023. Dissolved organic carbon (DOC) was evaluated from the samples prior to and after disinfection with chlorine over a period of 7 days. The results found that the concentration of DOC was highest in hospital effluent, with an average value of 5.60±0.16 mg/L followed by effluent from the food-processing industry and domestic, which had average DOC concentrations of 4.60±1.39 mg/L and 4.46±0.37 mg/L, respectively. The concentration of THMs in hospital effluent was found the highest at 6.91±0.88 µg/L followed by effluent from the domestic and food-processing industries, which exhibited amounts of 6.74±0.77 µg/L and 5.25±0.77 µg/L, respectively. In contrast, the food-processing factory had the highest concentration of THMFP at 299.39±26.54 µg/L, while the domestic and hospital effluent displayed a lower concentration of 133.64±36.86 µg/L and 51.48±9.01 µg/L, respectively.
Hydrochar production through co-hydrothermal carbonization of water hyacinth and plastic waste
Authors: Ong M Y , Nomanbhay S , Rosman C U A A C , Yusaf T , Silitonga A S
Published: July 2024

The global expansion of the economy and concerns about greenhouse gas emissions and climate change necessitate the exploration of sustainable alternatives to fossil fuels. Water hyacinth (WH) is globally recognized as one of the most problematic aquatic weeds, posing significant challenges to urban management by clogging waterways, polluting water sources, and causing harm to ecosystems. However, water hyacinth is enriched with hemicellulose, cellulose, and lignin, making it a noteworthy and superior biomass resource. Hence, this study focuses on the hydrothermal carbonization of water hyacinth into a renewable fuel source, the hydrochar. Hydrothermal treatment was implemented in this work as it can treat wet biomass, in this case, the water hyacinth, without the need of energy-extensive drying process. Plastic waste (PW), or more specifically low-density polyethylene (LDPE), was added as the co-feedstock during the HTC process with the purpose to boost the higher heating value (HHV) of the end product. The co-hydrothermal carbonization (co-HTC) process of the mixture of WH and PW at various ratios and temperatures were conducted to investigate the optimal HTC condition for high hydrochar yields. As the result, the highest hydrochar yield of 29.23 wt% was obtained with 12.5% LDPE substitution percentage, at 200 °C after a holding time of 90 min. However, in term of energy recovery efficiency (ER), the highest efficiency (27.28%) was achieved with 12.5% LDPE substitution percentage at 260 °C. The HHV value of the hydrochar produced in this work is in the range of 17.71-24.69 MJ/kg. In summary, the co-HTC of WH and LDPE could definitely be a promising alternative to bridge the gap from solid waste to renewable fuels.
Optimization of bio-oil production from macroalgae, caulerpa lentillifera via hydrothermal liquefaction
Authors: Ong M Y , Azmi N L , Nomanbhay S
Published: July 2024

An environmentally friendly method of producing bio-oil through the hydrothermal liquefaction (HTL) of algae has emerged, providing a path toward renewable energy and reducing greenhouse gas emissions. Algae is currently received a lot of interest as biomass feedstock due to its long growing season in warm climate area, does not require arable land, and relatively rapid growing rate. This study aims to optimize the HTL process of macroalgae (Caulerpa lentillifera) for bio-oil production, focusing on optimizing the bio-oil yield based on three parameters (operating temperature, the loading size of catalyst sodium hydroxide (NaOH), and algae-to-water ratio) using Box Behnken Design (also generally known as Response Surface Methodology). The results showed that an ideal reaction temperature of 277 °C, a 1:10 algae-to-water ratio, and 0.88 wt% catalyst loading led to an optimal experimental bio-oil yield of 11.65 wt%. Sensitivity study also revealed that the temperature is the second most important component, after the algae-to-water ratio. The difference in the catalyst loading showed low impact on the HTL of algae. Slight improvement to the bio-oil yield under the presence of NaOH is mainly due to the alkali environment provided by NaOH. The FTIR spectrum revealed the existence of various functional groups in the bio-oil. In summary, HTL has been effective in turning Caulerpa lentillifera into useful bio-oil. Overall, this study contributes to the growing body of research on algae-based bio-oil production. The results highlighted the potential of HTL as a promising technology for sustainable biofuel production, offering a pathway towards a greener and more energy-efficient future.
Emerging pollutants in waste water: Challenges and advancements in treatment technology
Authors: Corpus R M B , Bayani M S , Aguilar J L , Aguilar J C B , Aguilar H B
Published: July 2024

Microplastics, per- and polyfluoroalkyl substances (PFAS), pharmaceuticals and personal care products (PPCPs), and other emerging contaminants in wastewater have all caused serious environmental and public health issues. The effectiveness of conventional wastewater treatment techniques to remove these pollutants, such as activated sludge, membrane bioreactors, and coagulation-flocculation, is often insufficient. The difficulties and improvements in treatment technology for eliminating developing contaminants from wastewater are examined in this thorough review study. The review gives a general overview of the most important subcategories of emerging pollutants, the shortcomings of traditional wastewater treatment techniques, and the developments in treatment technologies, including advanced oxidation processes (AOPs), adsorption-based methods, and novel biological treatment approaches. The obstacles mentioned include the need for sustainable and energy-efficient solutions, regulatory and monitoring concerns, and technological and economic hurdles. A number of suggestions are made as a response to these difficulties, such as boosting oversight and regulating procedures, fostering cooperation and information sharing, encouraging industry participation, and supporting research and development. These suggestions may be put into practice in order to reduce the hazards posed by developing contaminants in wastewater and safeguard our water resources and the ecosystem over the long run. The article emphasizes the value of using a multidisciplinary and cooperative approach to solving the problems caused by new contaminants. In order to create original solutions, advance best practices, and build suitable regulatory frameworks, it underlines the necessity for ongoing research, policy development, and stakeholder collaboration. The ultimate goal of this analysis is to provide academics, decision-makers, industry stakeholders, and the general public with a useful resource in their quest to comprehend and resolve the complicated problem of developing contaminants in wastewater.
Hydrogen sulphide removal from raw biogas using novel coconut husk and sugarcane bagasse composite biochar adsorbent
Authors: Das B , Basumatary S , Kalita P
Published: July 2024

The presence of water, hydrogen sulfide (H2S), ammonia, oxygen, nitrogen, and siloxanes in biogas is not desirable for thermal and electrical applications through the engine route. H2S adversely affects engines and fuel cells by causing corrosion on metal components, poisoning catalytic converters, and accelerating wear and tear, compromising performance and longevity. To meet specific quality requirements for diverse applications such as heating, combined heat and power generation, vehicle fuel, and fuel cells, biogas must undergo cleaning and upgrading processes. Using biochar to remove H2S in biogas is a comparatively new technique and can be a promising option for small-scale, decentralized units. Current research primarily investigates the potential of biochar derived from coconut husk (CH) and sugarcane bagasse (SB) for effectively removing H2S from raw biogas within an experimental framework. The selection of a composite material consisting of equal parts CH and SB was based on available literature and material accessibility. The integrated methodology provided comprehensive insights into the performance of biochars in biogas purification. Morphological analysis elucidated the role of pore structure in facilitating H2S removal, while CHNS analysis highlighted the influence of elemental composition on biochar reactivity. Additionally, pH studies underscored the potential for biochar application to mitigate biogas acidity. According to the findings, the biochar from the combination of CH and SB exhibited a removal efficiency of 77.60% for H2S in raw biogas.
Waste separation intention of households in Sri Lanka
Authors: Shukri S , Jayasena D M
Published: July 2024

The effective practice of waste separation at the source is crucial for achieving sustainable development and promoting the reduce, reuse, and recycle concept. This practice should be adopted by both households and business organisations. The primary objective of this study is to investigate the factors that influence the intention of waste separation at the household level in Sri Lanka. For this purpose, a random selection of 388 households representing the entire country was undertaken. Independent variables, including attitude, perceived cost benefits, moral norms, inconvenience, and rules and regulations, were examined in relation to their impact on the dependent variable, which was the intention of waste separation. A 5-point Likert scale questiommaire was utilised to assess each of these variables. The methodology employed in this study included principal component analysis, factor analysis, and Structural Equation Model (SEM) to establish the underlying model. The results of the analysis revealed the significance of attitude, perceived cost benefits, and moral norms at a 5% significance level. Interestingly, although inconvenience exhibited a negative influence on intention, its significance was not established. Furthermore, while existing literature commonly attributed local government rules and regulations as a significant factor, the model indicated a positive and insignificant relationship. In conclusion, this study underscores the importance of positive attitudes, perceived benefits in terms of cost, and adherence to moral norms in fostering the intention for waste separation. Despite the negative impact of inconvenience not reaching statistical significance, it remains a noteworthy consideration. Additionally, the unexpected positive and insignificant relationship with local government rules and regulations prompts further exploration.
Prediction of nitrate, phosphate and ammonia removal in wastewater by phytoremediation-vortex system using artificial neural network
Authors: Cuevas D G , Pescos C J , Carrillo L , Sibal A , Guevarra N G
Published: July 2024

Clean water is an essential component for human survival. However, the growing global population and the relentless pace of industrial development have resulted in an alarming increase in water contamination. This renders many bodies of water as unfit for consumption or usage. In order to safeguard our natural resources, it is imperative that wastewater should be treated to follow a standard set by environmental specialists. In the Philippines, the enactment of the DAO 2021-19 has updated the requirements for release to more stringent standards. Because of this, a tertiary treatment, such as a phytoremediation bed, can be employed as an additional step in a wastewater treatment process. This study involves a comprehensive approach that consists of a phytoremediation setup, which includes the use of three plant species and specialized soil matrices, and a vortex system. The three plant species, Phragmites australis, Vetiveria zizanioides, and Canna indica are known for their capability for removal of the three pollutants, nitrates, phosphates and ammonia. The phytoremediation-vortex system was able to remove the pollutants and effectively reduce the pollutant concentration that the treated wastewater passes the standards for release. The predictive model, artificial neural network (ANN), was employed to assess the results. By using this technique, the study aimed to not only understand the intricate workings of the vortex system but also to optimise its performance for the effective reduction of pollutants, such as, nitrates, phosphates and ammonia, in wastewater. This research represents a critical step towards developing sustainable and efficient solutions for addressing the pressing challenges posed by water pollution, thereby fostering the availability of clean and potable water for human consumption and various industrial purposes.
Production of biodiesel from non-edible waste palm oil and sterculia foetida using microwave irradiation
Authors: Milano J , Tiong S K , Chia S R , Ong M Y , Sebayang A H , Kalam M A
Published: July 2024

The environmental damage stemming from traditional diesel begins during crude oil extraction and persists throughout its usage. The burning of fossil fuels has further deteriorate the environmental effect and added to global warming by emitting harmful substances. Moreover, the reduction of finite fossil fuel reserves due to widespread extraction has made the adoption of renewable resources essential. Given these considerations, biodiesel emerges as a highly promising alternative to conventional diesel due to its environmentally beneficial nature, renewable source, and economic feasibility. In this study, biodiesel was prepared by a microwave reactor in the presence of potassium methoxide using blended waste palm oil and sterculia foetida. The effects of raw materials characteristics on transesterification products were studied. The studied process parameters were methanol/oil ratio, microwave temperature, catalyst concentration, reaction time, and stirring speed. The optimal yield with 98.5% FAME content was obtained at a methanol/oil ratio of 60 vol. %, microwave temperature of 120 °C, catalyst concentration of 0.3 wt.%, and 3 min reaction time, and stirring speed of 500 rpm. The potassium methoxide was used to catalyse the transesterification process. The physicochemical properties and the fatty acid methyl ester composition were discussed thoroughly. The flash point of biodiesel, at 157.5°C, exceeds that of diesel fuel by more than two times. The cetane index is 59.5 which is higher than diesel (49.6). The biodiesel’s fuel properties conformed to the requirements of both ASTM D6751 and EN 14214. High biodiesel conversion and low sulphur content show that waste palm oil and sterculia foetida are sustainable and economical feedstocks that produce clean fuel to aid the feasibility of the energy transition of the global energy sector. In addition, the selection of synthesis approaches can be further explored for potential catalysts to ensure eco-green biodiesel’s sustainability with minimised.
Production of green diesel from waste cooking oil via catalytic deoxygenation reaction using metal doped eggshell catalyst
Authors: Lee Z S , Seah C C , Habib S H , Hafriz R S R M , Razali N M
Published: July 2024

Green diesel production via catalytic deoxygenation of waste cooking oil (WCO) over metal doped eggshell catalyst was investigated in this work. The catalyst was prepared through liquid-liquid precipitation of 5 transition metal solutions and ground eggshell (ES) as the catalyst support. The prepared catalyst, Fe-ES, Cu-ES, Co-ES, Zn-ES, and Ni-ES were characterized using BET surface area and Scanning Electron Microscopy (SEM) analysis. BET surface area data and SEM images of the catalyst shows a promising catalyst physical properties that tailor to the deoxygenation reaction. Gas Chromatography Mass Spectrometry (GCMS) was used to determine the hydrocarbon composition of the oil yield product from the reaction. The reaction also produces gas, soap and liquid acid phase while the remaining unreacted WCO becomes coke. The percentage of all products and coke were calculated using mass balance. Deoxygenation of WCO with Ni-ES catalyst produced highest oil yield at 61.6% with the hydrocarbon content of 56.11%. Ni-ES also produced 22.9% coke; the least percentage compared to other catalyst. The findings proved that Ni-ES catalyst exhibited the highest conversion of WCO into gas and liquid product with a greater yield of oil and minimal coke formation. These findings demonstrate the feasibility and practicality of using eggshell catalysts as substitutes for commercial catalysts in green diesel production.
Sensitivity analysis on heat pump - mechanical vapor recompression desalination system by recovering waste heat of offshore power converter station
Authors: Shi C Y , Hu X W , Dong S M , Fu X Y , Liu T , Jin M S
Published: July 2024

Offshore wind power converter stations produce massive low-temperature waste heat, which can hardly be used constrained by their offshore location. Therefore, the recovery of the waste heat has been raising widespread concern. Meanwhile, a large amount of fresh water is needed for its cooling system. So, a novel system combining high temperature heat pump and a mechanical vapor recompression system (HP-MVR) was proposed, and sensitivity analysis was performed to optimize it. The heat pump was used to absorb the waste heat and to produce high temperature water. The mechanical vapor recompression system was adopted to produce fresh water and to recover the condensation heat from the steam. In order to determine the impact parameters on the two crucial performance indicators of freshwater production and unit energy consumption, this article introduces a sensitivity analysis method, focusing on analyzing the sensitivity of the three operating parameters of heat pump condensation temperature, saturated water vapor inlet temperature entering the compressor, and freshwater condensation temperature to these two performance indicators. The results show that the sensitivity coefficients of heat pump condensation temperature, saturated water vapor inlet temperature entering the compressor, and freshwater condensation temperature are 1.13, -0.26, and 1.56. So, the freshwater condensation temperature has the most significant effect on freshwater output. Their sensitivity coefficients to unit energy consumption are 1.02, 1.41, and -0.64. The saturated water vapor inlet temperature entering the compressor has the most significant impact on the required power consumption per unit of freshwater. It will give some guidance for the application of low-temperature waste heat in seawater desalination and the reduction of operating costs.
On application of molecular dynamics simulation for studying the effect of temperature and heating rate on HTL of biomass
Authors: Trinh Thuat T , Tran Khanh-Quang
Published: July 2024

Hydrothermal liquefaction (HTL) of biomass has garnered increasing attention as a promising pathway for converting solid biomass to liquid biofuels and valuable chemical products. HTL involves processing of biomass in water at high-temperature and high-pressure conditions. The heating rate during this process plays a critical role in determining the yield and composition of the liquefied products. To probe the impact of heating rate, we develop a detailed atomistic model biomass by using cellulose as model compound and place it in a simulated HTL reactor. Our Reactive molecular dynamics simulations are capable of capturing the dynamic chemical reactions and structural changes during HTL. The effect of reaction temperature and heating rates on reaction pathways, product distributions, and reaction kinetics is rigorously analyzed. Our findings reveal that the reaction temperature and heating rate significantly influences the extent of cellulose degradation and the composition of bio-oil product.
Performance evaluation of pilot phyto-vortex integrated system in the reduction of wastewater pollutants
Authors: Guevarra NG , Cuevas DG , Pescos CJ , Sibal A , Carrillo L
Published: July 2024

Wastewater pollution remediation connects to goal 6 of the United Nations 17 Sustainable Development Goals (SDG) ensuring availability and sustainable management of water and sanitation for all. Conventional and advanced wastewater treatment are quite expensive to operate to fully comply with regulatory standards in the country. Phyto-vortex integrated system is an alternative tertiary wastewater treatment system that interfaces with an oil and grease skimmer and vortex technology, relying on green plants and a variety of soil substrates to remediate wastewater. The research evaluated the potential of the Phyto-vortex system and its performance in the reduction of domestic wastewater pollutants. Plants and soil substrates were selected via Analytic Hierarchy Process (AHP) using one-way sensitivity analysis. Common reed, Vetiver grass, and Canna Lily were planted in constructed reed beds with various soil matrices using substrates laid at different levels. The beds operate continuously as a horizontal subsurface flow treating 5 m3 of a sewage treatment effluent per day with 1-3 days hydraulic retention time (HRT). The vortex unit aerates the water for further removal of gaseous pollutants. Samples were taken at designated points for 18 weeks. Analysis of the results shows a maximum reduction of 92% for biochemical oxygen demand (BOD), 60 % for chemical oxygen demand(COD), and 70 % for total suspended solids (TSS). Concentration of identified heavy metals in the influent are within the regulatory standards except for a rise in zinc concentration which was 97% reduced in the system. The percentage reduction of pollutants varies each week with nitrates decreasing in the range of 50% to 99%, phosphates from 8% to 39.5%, and ammonia from 45.65% to 99%. Varying environmental conditions such as monsoon rains and extreme heat caused algal blooms and plant disease affecting the results. Lower temperatures and lower humidity favor a decrease in the levels of the pollutants while higher temperature, higher humidity favor an increase in the levels of Nitrates, Phosphates, and Ammonia. The overall results show an effective integrated system of phytoremediation coupled with a vortex unit in the reduction of wastewater pollutants.
Life Cycle Assessment of Large-Scale Solar Photovoltaic Plant based in Malaysia
Authors: Quek A , Abbas A R , Zaman N Z I S , Ata W N S W , Zainal M F , Yapandi F K M , Ibrahim Z F , Suhardi A
Published: July 2024

A cradle-to-grave life cycle assessment (LCA) has been performed on a Large Scale Solar Photovoltaic (LSSPV) plant based in Peninsular Malaysia to study the detailed environmental impact of its life cycle. The LSSPV, with a capacity of 78 MWdc, is currently one of Malaysia’s largest solar power plants. The different life cycle phases of the LSSPV, starting from resource manufacturing and transportation, through plant construction and electricity generation, and to decommissioning of the plant, were assessed using the SimaPro software with the Ecoinvent v3.8 database. Results show that the overall emission rate for the LSSPV is 0.0309 kgCO2eq/kWh. It is estimated that the construction phase of the power plant, which includes activities such as infrastructure works and production of PV modules and Balance of System, yields the largest amount of kgCO2eq/kWh emission at 85.7% and imposes the highest environmental impact as compared to the other phases. The second biggest contributor is attributed to the transportation phase, contributing to 14.0% of the total kgCO2eq/kWh emission, of which most of the emission is emitted during the sea freight transportation of PV components from China port to Malaysia port (12.4%). A sensitivity analysis was performed to compare the environmental impact between open ground installation and the slanted roof installation mounting system of LSSPV. The findings from LCA proposed that open-ground installation has a greater negative impact on the environment because it involves additional land clearing and infrastructure transformation. The findings from this study serve as a benchmark for the LSSPV system in Malaysia and present technical perspectives for the future development of PV projects considering environmental impacts across the project lifetime.