Subjects -> ENERGY (Total: 414 journals)
    - ELECTRICAL ENERGY (12 journals)
    - ENERGY (252 journals)
    - ENERGY: GENERAL (7 journals)
    - NUCLEAR ENERGY (40 journals)
    - PETROLEUM AND GAS (58 journals)
    - RENEWABLE ENERGY (45 journals)

ENERGY: GENERAL (7 journals)

Showing 1 - 7 of 7 Journals sorted alphabetically
Energy Research Journal     Open Access   (Followers: 3)
Greenhouse Gases : Science and Technology     Hybrid Journal   (Followers: 4)
International Journal of Energy Optimization and Engineering     Hybrid Journal   (Followers: 3)
International Journal of Powertrains     Hybrid Journal   (Followers: 2)
International Journal of Renewable Energy Development     Open Access   (Followers: 6)
Journal of Power Technologies     Open Access   (Followers: 6)
Journal of Thermophysics and Heat Transfer     Hybrid Journal   (Followers: 94)
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International Journal of Renewable Energy Development
Number of Followers: 6  

  This is an Open Access Journal Open Access journal
ISSN (Print) 2252-4940 - ISSN (Online) 2252-4940
Published by Diponegoro University Homepage  [16 journals]
  • Optimal power flow solutions to power systems with wind energy using a
           highly effective meta-heuristic algorithm

    • Authors: Thi Minh Chau Le; Xuan Chau Le, Ngoc Nguyen Phuong Huynh, Anh Tuan Doan, Thanh Viet Dinh, Minh Quan Duong
      Abstract: This paper implements two novel meta-heuristic algorithms, including the Coati optimization algorithm (COA) and War strategy optimization (WSO) for determining the optimal solutions to the optimal power flow problem incorporating the use of wind turbines (WTs). Two objective functions are considered in this study, including minimizing the entire electricity generation expenditure (EEGE) with the value point effect and minimizing the voltage fluctuation index (VFI). IEEE 30-bus system is chosen to conduct the whole study and validate the efficiency of the two applied methods. Furthermore, DFIG WTs are used in grids with varying power output and power factor ranges. The comparison of the results obtained from the two methods in all case studies reveals that WSO is vastly superior to COA in almost all aspects. In addition, the positive contributions of WTs to the EEGE and VFI while they are properly placed in the grid are also clarified by using WSO. As a result, WSO is acknowledged as a highly effective search method for dealing with such optimal power flow (OPF) problems considering the presence of renewable energy sources.
      PubDate: Tue, 16 May 2023 00:00:00 +000
  • Co-firing of coal and woody biomass under conditions of reburning
           technology with natural gas

    • Authors: Nihad Hodžić; Kenan Kadic
      Abstract: It is a continuous imperative to establish the most efficient process of conversion of primary energy from fuel through combustion, which also has the least possible harmful effect on the environment. In this time of expressed demands for decarbonisation, it also means the affirmation of the use of renewable fuels and the indispensable application of appropriate primary measures in the combustion furnace. At the same time, the efficiency of the combustion process depends on several factors, from the type and properties of the fuel to the ambient and technological settings for the process. In this regard, with the aim of determining the static characteristics of combustion, experimental laboratory research was carried out on the combustion of mixtures of brown coal with low heating value and a high ash content with waste woody biomass and different process conditions: temperature, staged combustion air supply (air staging) and in conditions of application of a third or additional fuel (natural gas, reburning technology). Applied experimental methods included the analysis of the combustion process on the basis of input (reactants) - output (products), including the analysis of the composition of flue gases, i.e. the determination of the emission of the key components of flue gases CO2, CO, NOx and SO2, as well as the analysis of the composition of slag, ash and deposits ash, i.e. assessment and evaluation of the behaviour of ash from fuel in that process. Based on the obtained research results, this paper shows the significant positive effects of the application of primary measures in the furnace - compared to conventional combustion: air staging - reduction of net CO2 emissions during co-firing with biomass and reduction of NOx emissions by up to 30%; reburning technology - additional reduction of CO2 and NOx emissions in proportion to the share of natural gas, e.g. at a combustion process temperature of 1350 °C and at a 10% energy share of natural gas during the co-firing of a mixture of brown coal and waste woody biomass, compared to the emission without the use of natural gas, a reduction of NOx emissions by 185 mg/mn3 or by almost 30% was recorded. It was concluded, at the same time, the application of these primary measures in the furnace does not negatively affect the behaviour of ash from the fuel in the given settings of the combustion process.
      PubDate: Mon, 15 May 2023 00:00:00 +000
  • Design, optimization and economic viability of an industrial low
           temperature hot water production system in Algeria: A case study

    • Authors: Karim Kaci; Mustapha Merzouk, Nachida Kasbadji Merzouk, Mohammed Missoum, Mohammed El Ganaoui, Omar Behar, Rabah Djedjig
      Abstract: Solar energy has a great potential in many areas of industrial activity in Algeria. This is because most of Algeria has high levels of sustainable solar insulation. Unfortunately, few industries use solar energy for hot water generation, but some industrial processes require hot water at temperatures that can be easily obtained from solar thermal panels. This paper presents a case study to investigate the technical and financial feasibility of a solar-powered industrial agro-processing system in Algiers. Based on  the solar collectors connection type for which the economic feasibility study was carried out, an appropriate design of the system was determined. The latter was actually done by analyzing the levelized cost of energy savings. The design of the thermo-solar process is carried out based on F-chart method with a new approach by integrating the incidence angle modifier and of using real and experimental data requirements to determine realistic achievable performance of the solar process. The results showed that, in comparison to the currently used electrical system, the electrical energy savings achieved by the solar-powered system make it an economically viable option with a solar coverage rate of 80%. The investment depreciation balance shows that the use of such a thermal solar energy system will be more competitive than fossil fuels system if the price of electricity in the country increases from 0.048 to 0.075 €/kWh.
      PubDate: Mon, 15 May 2023 00:00:00 +000
  • Utilization of the spent catalyst as a raw material for rechargeable
           battery production: The effect of leaching time, type, and concentration
           of organic acids

    • Authors: Tabita Kristina Mora Ayu Panggabean; Ratna Frida Susanti, Widi Astuti, Himawan Tri Bayu Murti Petrus, Anastasia Prima Kristijarti, Kevin Cleary Wanta
      Abstract: This study examines the potential use of the spent catalyst as a raw material for rechargeable batteries. The spent catalyst Ni/γ-Al2O3 still contains relatively high amounts of nickel. This indicates the potential use of the spent catalyst to be leached and purified for synthesizing nickel-based compounds so that it can be applied to rechargeable battery cathodes. In this study, the spent catalyst leaching process employed four types of organic acids: citric acid, lactic acid, oxalic acid, and acetic acid. The spent catalyst was leached under atmospheric conditions and room temperature. Organic acid concentrations were also varied at 0.1, 0.5, 1, and 2 M. The leaching process took place for 240 minutes, where sampling was conducted periodically at 30, 60, 120, 180, and 240 minutes. Experimental results showed that Ni (II) and Al (III) ions were successfully leached to the maximum when using 2M citric acids at a leaching time of 240 minutes. The conditions succeeded in leaching Ni (II) and Al (III) ions of 357.8 and 1,975.4 ppm, respectively. Organic acid, notably citric acid, has excellent potential for further development. Citric acid, as a solvent, has the ability to leach metal ions with high recovery. In addition, this acid is categorized as an eco-friendly and green solvent compared to inorganic acid. Thus, the leaching process can take place without harming the environment.
      PubDate: Mon, 15 May 2023 00:00:00 +000
  • Prediction of the output power of photovoltaic module using artificial
           neural networks model with optimizing the neurons number

    • Authors: Abdulrahman Th. Mohammad; Hasanen M. Hussen, Hussein J. Akeiber
      Abstract: Artificial neural networks (ANNs) is an adaptive system that has the ability to predict the relationship between the input and output parameters without defining the physical and operation conditions. In this study, some queries about using ANN methodology are simply clarified especially about the neurons number and their relationship with input and output parameters. In addition, two ANN models are developed using MATLAB code to predict the power production of a polycrystalline PV module in the real weather conditions of Iraq. The ANN models are then used to optimize the neurons number in the hidden layers. The capability of ANN models has been tested under the impact of several weather and operational parameters. In this regard, six variables are used as input parameters including ambient temperature, solar irradiance and wind speed (the weather conditions), and module temperature, short circuit current and open circuit voltage (the characteristics of PV module). According to the performance analysis of ANN models, the optimal neurons number is 15 neurons in single hidden layer with minimum Root Mean Squared Error (RMSE) of 2.76% and 10 neurons in double hidden layers with RMSE of 1.97%.  Accordingly, it can be concluded that the double hidden layers introduce a higher accuracy than the single hidden layer. Moreover, the ANN model has proven its accuracy in predicting the current and voltage of PV module. 
      PubDate: Mon, 15 May 2023 00:00:00 +000
  • A four-line active shunt filter to enhance the power quality in a

    • Authors: Abdelkader Mostefa; Karim Belalia, Tayeb Lantri, Houari Merabet Boulouiha, Ahmed Allali
      Abstract: In recent years, power quality has become a major concern for electric network managers. Active filtering control schemes ensure improved power quality of the electric network and are able to maintain a desired voltage level at the point of connection, regardless of the current absorbed by nonlinear loads. Harmonics can cause vibrations, equipment distortion, losses and sweatiness in transformers. The main objective of this work is to enhance the quality of energy in a microgrid consisting of 100 kW photovoltaic (PV) system and a 50 kW battery storage connected to nonlinear and unbalanced loads. This paper proposes a the four-arm parallel active filter with a on Proportional-Integral (PI) controller to mitigate the harmonic problems in a microgrid. In addition, an algorithm has been designed to eliminate the neutral current. The identification function is one of the most particular approach for extracting harmonics, it involves providing a current reference imposed by the active filter in order to carry out the filtering operation. Both the performance and the quality of the current harmonic compensation's depend strongly on the strategy adopted for the generating the current reference. In this work, the instantaneous power strategy p-q is chosen outstanding the simplicity and effectiveness in implementation. The proposed control strategy has been tested under simulations and the results have shown good tracking of the references and a significant reduction in the Total Harmonic Distorsion (THD) level under highly unbalanced conditions of the nonlinear loads. The current THD is reduced from 43.64 before filtering to 3.74% after the application of the four-arm filter, following the recommendations of IEEE-519 standard (THD less than 5%).
      PubDate: Mon, 15 May 2023 00:00:00 +000
  • Agricultural waste-based magnetic biochar produced via hydrothermal route
           for petroleum spills adsorption

    • Authors: Dessy Ariyanti; I Nyoman Widiasa, Marissa Widiyanti, Dina Lesdantina, Wei Gao
      Abstract: Oil spills are one of the marine pollution events triggered by the results of tanker operations (air ballast), ship repairs and maintenance (docking), mid-ocean loading and unloading terminals, air bilge (drainage of water, oil, and engine-processed lubricants), ship scrapping, and the most common accidents/collisions of tankers. The impacts vary from the death of marine organisms, especially fish, changes in reproduction and behavior of organisms, plankton contamination, fish migration, as well as ecosystem damage, and economic loss. Bio-based absorbents such as biochar can be an environmentally friendly alternative to chemical sorbents that works to adsorb oil spills faster. In this study, the effectiveness of magnetic biochar in oil spill removal was investigated. It also includes the synthesisation of magnetic biochar from agricultural waste (bagasse, rice husks, and sawdust) using the hydrothermal method at a temperature of 200°C. Hydrothermal carbonization is considered a cost-effective method for biochar production because the process can be carried out at low temperatures around 180°- 250°C. Biochar characterization was carried out with a Scanning Electron Microscope and Energy Dispersive X-Ray (SEM-EDX), Fourier Transform Infrared Spectroscopy (FTIR), and X-Ray Diffraction (XRD). The Brunauer, Emmett, and Teller (BET) and Barrett–Joyner–Halenda (BJH) were used to analyse the surface area and pore size distribution. Based on the results of the SEM-EDX analysis, only biochar was made from rice husk and sugarcane bagasse which contained Fe elements, as a result of the FeCl3.6H2O reaction. This condition is also proven by the presence of the FeO on both samples based on FTIR. The three synthesized biochar are amorphous and categorized as mesopores due to pore size around 15 to 16 nm, which can absorb petroleum spills with a percentage of 81% for sugarcane bagasse-based biochar, 84% for rice husk-based biochar, and 70% for sawdust-based biochar. Biochar from rice husk has excellent adsorption effectiveness with an adsorption capacity of 0.21 g/g in 60 min due to its large functional group area and the excellent attachment of magnetic compound into the biochar surface to form magnetic biochar.
      PubDate: Mon, 15 May 2023 00:00:00 +000
  • Removal efficiency and reaction kinetics of phenolic compounds in refinery
           wastewater by nano catalytic wet oxidation

    • Authors: Yousif S. Issa; Khaleel I. Hamad, Rafi J. Algawi, Jasim Humadi, Sara Al-Salihi, Mustafa A. Ahmed, Ahmed A. Hassan, Abdul-Kareem Abd Jasim
      Abstract: A novel nano-catalyst based on iron oxide (MnO2/Fe2O3) was developed to promote wet oxidation of phenol. MnO2 was doped in Fe2O3 matrix to prepare composite nano-catalyst with different doping percentage (0, 2 and 5%). The catalytic phenol oxidation was conducted under different reaction temperatures and residence times. To evaluate the optimal kinetic parameters aiming to maximize phenol removal under the optimal conditions for the catalytic wet phenol oxidation process, modeling was applied on the batch reactor using the novel synthesis nano-catalyst (MnO2/Fe2O3) and the model developed was fed with the experimental data. gPROMS package was used to model the process of phenol oxidation and to optimize the experimental data. The error predicted between the simulated and experimental data was less than 5%. The optimal operating conditions were 294 min residence time, 70oC reaction temperature, and 764 ppm initial concentration of phenol over the prepared 5% MnO2/Fe2O3. Running of wet oxidation of phenol under the optimal operating conditions resulted in 98% removal of phenol from refinery wastewater.
      PubDate: Mon, 15 May 2023 00:00:00 +000
  • Experimental thermal and electrical performances of a PVT-air collector
           coupled to a humidification-dehumidification (HDH) cycle

    • Authors: Ahmed Ghazy
      Abstract: Despite their low electrical efficiencies, PVs are widely used to generate electricity from abundant solar energy. In order to maximize the utilization of incident solar energy, PVT collectors have been used to simultaneously generate electricity and thermal energy. Furthermore, combining PVTs with humidification-dehumidification (HDH) cycles can provide electricity and potable water in remote, arid rural areas that are not connected to the grid. In this paper, a PVT-air collector was coupled to an air-heated closed HDH cycle. Air was heated within the PVT collector and humidified by saline water spray inside the humidifier. Fresh water was produced by cooling humid air inside a dehumidifier that is cooled by saline water. The thermal and electrical performances of the PVT-HDH system were experimentally studied and compared to the electrical performance of a PV module with similar characteristics. The results demonstrated a significant decrease in PV temperature within the PVT-HDH system, which resulted in a 20% increase in the output power of the PVT-HDH system at midday compared to the identical PV module. In addition, the PVT-HDH system produced about 3.8 liters of water distillate for a PV module surface area of 1.48 m × 0.68 m, which contributed about 38% to the overall efficiency of the PVT-HDH system.
      PubDate: Mon, 15 May 2023 00:00:00 +000
  • Willingness to pay for green energy sources in the United Arab Emirates

    • Authors: Haileslasie Tadele; Baliira Kalyebara
      Abstract: This study investigates the willingness of customers in the UAE to pay a premium for green energy (GE) sources. Given the huge initial investment required for GE projects, raising capital is often achieved by increasing energy bills or taxes. To explore this issue, the study surveyed 192 small and medium-sized businesses using the contingent valuation method. The results indicate that while most businesses are aware of solar and wind energy sources and the importance of combating climate change, half of them are not willing to compromise their current energy use and do not support an increase in utility bills or taxes to finance GE projects. However, older businesses tend to be more willing to pay a premium for GE compared to younger businesses. Overall, majority of the businesses support a voluntary increase in electricity bills. The findings highlight the crucial role of current electricity bills and knowledge about GE sources in shaping customers' willingness to pay. This study contributes to the literature on energy finance and the contingent valuation method in the context of green energy in the UAE.
      PubDate: Mon, 15 May 2023 00:00:00 +000
  • Preparation of MgO-CaO/SiO2 catalyst from dolomite and geothermal solid
           waste for biodiesel production

    • Authors: Widayat Widayat; Nadia Taradissa Maheswari, Wahyu Fitriani, Luqman Buchori, Hantoro Satriadi, K Kusmiyati, Norzita Ngadi
      Abstract: Energy demand will increase along with the increase in population. The current energy demand is dominated by non-renewable energy as it could reduce dependence on fossil energy sources; hence, it is imperative to be developed. Biodiesel with waste cooking oil as its raw material is one of the renewable energies currently being developed. Catalyst can be utilized to improve the quality of biodiesel product and process. The major content in solid waste of geothermal power plant is silica oxide, while dolomite contains magnesium oxide and calcium oxide. This study aims to test the MgO-CaO/SiO2 catalyst performance from geothermal waste and dolomite in biodiesel production. The results of catalyst characterization based on FTIR, SEM, and BET tests indicates a successful impregnation method in MgO-CaO/SiO2 catalyst production. The result shows that the best variable to produce biodiesel is at the ratio of MgO-CaO: SiO2 is 15:85. The conversion of biodiesel using this variable is 92.63%. The overall results of biodiesel obtained in this study have a good quality and is in accordance with SNI 7182-2015.
      PubDate: Mon, 15 May 2023 00:00:00 +000
  • An investigation of a 3D printed micro-wind turbine for residential power

    • Authors: Mohammad Shalby; Ahmad A Salah, Ghayda’ A Matarneh, Abdullah Marashli, Mohamed R. Gommaa
      Abstract: The wind energy sector is rapidly growing and has become one of the most important sources of renewable power production. New technologies are being developed to increase energy production. This study focuses on developing and evaluating a 3-D printed micro-wind turbine system for residential electricity production. The effectiveness of using Poly Lactic Acid material for model production was assessed using the SolidWorks environment. Then, three–dimensional CFD model was developed to simulate a micro-wind turbine. The CFD model was validated in good agreement against scale physical model experiments performed in a wind tunnel. The results demonstrated that the 5-blade micro-wind turbine design was the most effective under the tested conditions, with a low cut-in speed and the ability to operate under torque up to 70 N.m. Finally, the currently available manufacturing processes for micro-wind turbines have been evaluated. Future work should evaluate the performance of the MWT system under realistic conditions in a site test to determine energy production and total efficiency
      PubDate: Mon, 15 May 2023 00:00:00 +000
  • Three-dimensional CFD-solid mechanics analysis of the hydrogen internal
           combustion engine piston subjected to thermomechanical loads

    • Authors: Maher A.R. Sadiq Al-Baghdadi; Sahib Shihab Ahmed, Nabeel Abdulhadi Ghyadh
      Abstract: Fueling internal combustion engines with hydrogen is one of the most recommended alternative fuels today in order to combat the energy crisis, pollution problems, and climate change. Despite all the advantages of hydrogen fuel, it produces a higher combustion temperature than gasoline. In an internal combustion engine, the piston is among the numerous complex and highly loaded components. Piston surfaces are directly affected by combustion flames, making them critical components of engines. To examine the stress distribution and specify the critical fracture zones in the piston for hydrogen fuel engines, a three-dimensional CFD-solid-mechanics model of the internal combustion engine piston subjected to real thermomechanical loads was analyzed numerically to investigate the distribution of the temperature on the piston body, the interrelated thermomechanical deformations map, and the pattern of the stresses when fueling the engine with hydrogen fuel. With the aid of multiphysics COMSOL software, the CFD-solid-mechanics equations were solved with high accuracy. Despite the increase in pressure on the piston and its temperature when the engine is running on hydrogen fuel, the results show that the hydrogen fuel engine piston can withstand, safely, the thermomechanical loads. In comparison to gasoline fuel, hydrogen fuel caused a deformation of 0.34 mm, an increase of 17%. This deformation is within safe limits, with an average clearance of 0.867 mm between the cylinder liner and piston.
      PubDate: Mon, 15 May 2023 00:00:00 +000
  • Mediating role of stock market volatility to evaluate asymmetries in the
           growth-degradation nexus in Nigeria

    • Authors: Abdullah AlGhazali; Nana Ize Musa, Saifullahi Sani Ibrahim, Ahmed Samour
      Abstract: This study explores the mediating role of stock market volatility in the economic growth and environmental degradation nexus in Nigeria using data covering period from 1984 until 2020. The study uses Nonlinear Autoregressive Distributed Lag (NARDL) and a nonparametric asymmetric causality model. While the Wald test in model 1 reveals evidence of weak long-run asymmetric nexus between CO2 and economic growth however, findings in model 2 indicates that stock market volatility (SMV) exerts a strong asymmetric effect in growth-CO2 relation in the long-run. The result of nonlinear model validates the inverted U-shaped growth-degradation nexus consistent with EKC hypothesis. The finding in model 1 reveals that investment exerts a strong impact on CO2 in both the short-run and long-run. On the other hand, the results in model 2 show that the positive component of economic growth has a positive and significant impact on CO2 in Nigeria. However, the negative component of economic growth has a negative impact on CO2. Moreover, the dynamic causality model reveals: (i) a feedback causality between CO2 and the negative component of GDP; and (ii) a unidirectional causality flowing from CO2 to the positive component of GDP. Similarly, result of nonlinear causality test reveals a feedback causality between CO2 and GDP. The implication of the finding suggests that while asymmetric properties of economic growth must be controlled in efforts of promoting environmental sustainability, the stock market has a dedicated role to play in widening access to funds for green investment in Nigeria and other developing economies.
      PubDate: Mon, 15 May 2023 00:00:00 +000
  • Response surface optimization and social impact evaluation of Houttuynia
           cordata Thunb solar drying technology for community enterprise in
           Chiangrai, Thailand

    • Authors: Torpong Kreetachat; Saksit Imman, Kowit Suwannahong, Surachai Wongcharee, Nopparat Suriyachai
      Abstract: Drying has emerged as one of the most important ways of preserving high-quality and quantity food goods. A force convection solar drying is considered an ecologically and environmentally friendly alternative. This research presents parameter optimization of greenhouse tunnel dryer  of  Houttuynia cordata Thunb (H. cordata) using response surface methodology with the assessment of economic feasibility and social return on invesment. The influence parameters of the drying process were evaluated to obtain maximum efficiency. The individual parameters were temperature (40 – 60 °C), material length (10 – 30 cm), and relative humidity (30 – 50%). The individual parameters of drying temperature showed an extreme effect on the response of moisture content and color value change, while the relative humidity had only an influence on moisture content. On the other hand, the parameter of material length was not significance in both responses. When compared to open-air drying, solar drying reduced the drying time of H. cordata by 57.14%. The payback period of the dryer was found to be 2.5 years. Furthermore, the results reveal that the social return on investment ratio in 2021 was 2.18, then increasing to 2.52 in 2022 and 2.91 in 2023. According to the findings, solar drying technology has the potential to be an adequate product quality improvement technology for H. cordata. It is a feasible drying technology in terms of economic evaluation.
      PubDate: Mon, 15 May 2023 00:00:00 +000
  • The application of equilibrium optimizer for solving modern economic load
           dispatch problem considering renewable energies and multiple-fuel thermal

    • Authors: Hung Duc Nguyen; Khoa Hoang Truong, Nhuan An Le
      Abstract: This study presents a modern version of the economic load dispatch (MELD) problem with the contribution of renewable energies and conventional energy, including wind, solar and thermal power plants. In the study, reduction of electricity generation cost is the first priority, while the use of multiple fuels in the thermal power plant is considered in addition to the consideration of all constraints of power plants. Two meta-heuristic algorithms, one conventional and one recently published, including Particle swarm optimization (PSO) and Equilibrium optimizer (EO), are applied to determine the optimal solutions for MELD. A power system with ten thermal power plants using multiple fossil fuels, one wind power plant, and three solar power plants is utilized to evaluate the performance of both PSO and EO. Unlike other previous studies, this paper considers the MELD problem with the change of load demands over one day with 24 periods as a real power system. In addition, the power generated by both wind and solar power plants varies at each period. The results obtained by applying the two algorithms indicate that EO is completely superior to PSO, and the solutions found by EO can satisfy all constraints. Particularly in Case 1 with different load demand values, EO achieves better total electricity production cost (TEGC) than PSO by 0.75%, 0.87%, 0.13%, and 0.45% for the loads of 2400 MW, 2500 MW, 2600 MW and 2700 MW. Moreover, EO also provides a faster response capability over PSO through the four subcases although EO and PSO are run by the same selection of control parameters. In Case 2, the high efficiency provided by EO is still maintained, though the scale of the considered problem has been substantially enlarged. Specifically, EO can save $51.2 compared to PSO for the minimum TEGC. The savings cost is equal to 0.33% for the whole schedule of 24 hours. With these results, EO is acknowledged as a favourable search method for dealing with the MELD problem. Besides, this study also points out the difference in performance between a modern meta-heuristic algorithm (EO) and the classical one (PSO). The modern metaheuristic algorithm with special structure is highly valuable for complicated problem as MELD.
      PubDate: Mon, 15 May 2023 00:00:00 +000
  • Simulation and experimental study of refuse-derived fuel gasification in
           an updraft gasifier

    • Authors: Thanh Xuan Nguyen-Thi; Thi Minh Tu Bui, Van Ga Bui
      Abstract: Refuse-derived fuel (RDF) made from the mixture of wood and loose rice husk increases the porosity of the fuel in the furnace to facilitate the gasification process. Simulation results show that CO is concentrated in the incomplete combustion zone and CO2 forms mainly in the fully burned area; CH4 forms in the reduction region, while H2 forms in the region of high temperature of the furnace. When the mixture composition was f=0.3, the CO concentration in the syngas reached about 21%, the H2 concentration reached about 2% and the CH4 concentration was too low to be ignored. When the mixture composition increased to f = 0.5, the CO concentration reached about 26%, the H2 concentration remained almost unchanged and the CH4 content increased to 6%. The calorific value of the syngas reached a maximum when f = 0.5 and the temperature of the reduction zone is in the range of 900K to 1200K. Air humidity affects CO concentration but not much on CH4 and H2 concentration as well as the syngas calorific value. The difference between simulation and experimental results is not more than 10% for CH4 concentration and not more than 14% for CO2 concentration. The power of the spark ignition engine is reduced by 30% when running on syngas compared to when running on gasoline.
      PubDate: Mon, 15 May 2023 00:00:00 +000
  • Techno-economic analysis of fixed versus sun-tracking solar panels

    • Authors: Akram Elahi Gol; Milan Ščasný
      Abstract: The potential output of photovoltaic (PV) panels is influenced by several factors, including the direction of solar radiation from the sun toward the panel’s surface. The maximum output of the panels is obtained when the panels are vertical to the sun's rays. In this study, a techno-economic analysis is conducted to examine whether an automatic one-axis sun tracker system is an economically feasible option for installing a large-scale PV park in the Nicosia district in the central part of Cyprus. The performance of a one-axis sun tracker with an installed capacity of 781 kWp is compared to a PV system with a fixed flat structure having the same capacity and larger capacity at 1034 kWp. Output generated by the three PV system options is simulated by three alternative simulation software (SolarGIS, PVSyst, and PVGIS). Financial analysis is performed utilizing simulated PV power output, accounting for electricity feed-in tariff and overall cost of the project. The cash-flow model is run for several scenarios defined by different leverage ratios, including no leverage. Considering the technical parameters of a PV system and solar panel characteristics, such as the degradation effect on solar panel efficiency and solar radiation, we estimate the solar tracking system produces about 20%–30% more energy compared to a fixed structure. We find both technologies are economically viable options, however, a one-axis tracker system performs better financially. LCOE in all scenarios is below the highest acceptable level for solar PV projects in Cyprus which is 103 EUR per MWh. LCOE for a solar tracker PV is 39 EUR per MWh with a 30% leverage ratio and up to 79 EUR per MWh with 85% leverage. LCOE for a sun-tracker is ~20% lower than LCOE for a PV with a fixed axis of comparable size. Despite higher investment costs, the solar tracking PV system performs with a 12% higher equity internal rate of return, and a 9% shorter loan payback period compared to the same installed power of a fixed structure. The Financial analysis is complemented by quantified benefits due to avoided carbon emissions. Accounting for carbon benefits makes a sun-tracker PV system economically a better option over the fixed tracker PV system, resulting in 228,000 EUR more benefits. Overall, the present value of net benefits of a solar-tracker PV amounts to 1.39 mil. EUR and due to high irradiation in Cyprus, the carbon footprint of PV power output represents only 6% of the footprint of generating electricity in thermal power plants. When these benefits are accounted for the sum of NPV and social benefits will turn out to be higher for a one-axis tracker compared to the total social benefits of a fixed tracker of the same size.
      PubDate: Mon, 15 May 2023 00:00:00 +000
  • Modeling anaerobic co-digestion of water hyacinth with ruminal
           slaughterhouse waste for first order, modiļ¬ed gompertz and logistic
           kinetic models

    • Authors: Erick Auma Omondi; Peter Kuria Ndiba, Gloria Koech Chepkoech, Arnold Aluda Kegode
      Abstract: Water hyacinth (Eichhornia crassipes), an invasive aquatic weed with large biomass production is of socio-economic and environmental concern in fresh water bodies such as the Lake Victoria in East Africa. Efforts towards its control and removal can be complemented by biogas production for use as energy source. The co-digestion of water hyacinth (WH) with ruminal slaughterhouse waste (RSW) has the potential to improve biogas production from WH through collation of processes parameters such as the C/N and C/P ratios, potassium concentration and buffering capacity. Knowledge of optimum proportion of the RSW as the minor substrate is of both process and operational importance. Moreover, efficient operation of the process requires an understanding of the relationship between the biogas production and the process parameters. Kinetic models can be useful tools for describing the biogas production process in batch reactors. While the first order kinetics models assume that the rate of biogas production is proportional to the concentration of the remaining substrates, other models such as the modified Gompertz and the Logistic models incorporate the lag phase, a key feature of the anaerobic digestion process. This study aimed to establish the optimum proportion of RSW in co-digestion with WH under mesophilic conditions, and apply kinetics models to describe the biogas production. The study conducted batch co-digestion of WH with 0, 10, 20 and 30% RSW proportions at mesophilic temperature of 32ºC. Co-digestion of WH with 30% RSW proportion improved biogas yield by 113% from 19.15 to 40.85 CH4 ml/(gVS) at 50 days of co-digestion. It also exhibited the most stable daily biogas production and the largest biogas yield. The biomethanation data were fitted with the first order kinetics, modified Gompertz and the Logistic models. Biogas production for co-digestion of WH with 30% RSW proportion was best described by the modified Gompertz model with a biogas yield potential, Mo, of 43.2 ml (gVS)-1d-1; maximum biogas production rate, Rm, of 1.50 ml (gVS)-1d-1; and duration of lag, λ, of 3.89 d.
      PubDate: Mon, 15 May 2023 00:00:00 +000
  • Performance enhancement and emissions reduction in a diesel engine using
           oleander and croton biodiesel doped with graphene nanoparticles

    • Authors: Treza Wambui; Meshack Hawi, Francis Njoka, Joseph Kamau
      Abstract: Biodiesel is considered a suitable substitute for petroleum diesel because it is renewable, environment-friendly, and has a low carbon footprint. However, its high density, high viscosity and low heating value prevents it from replacing petroleum diesel completely. This study investigates the performance and emission characteristics of a compression ignition engine operating on oleander and croton biodiesel doped with graphene nanoparticles. Five fuel samples are used, including diesel (D100), diesel - 80% blended with oleander and croton biodiesel - 20% (OCB20) and OCB20 dosed with graphene nanoparticles at mass fractions of 50 ppm (mg/L), 75 ppm (mg/L) and 100 ppm (mg/L), respectively. The chemical composition of biodiesel and graphene nanoparticles is analyzed using Fourier Transform Infrared (FTIR) spectroscopy while the morphology of the nanoparticles is analyzed using Scanning Electron Microscope (SEM). Engine tests reveal a significant improvement in brake thermal efficiency, especially at 75 ppm concentration which is 2.76%  and 18.93% higher than diesel and OCB20, respectively, and a reduction in brake specific fuel consumption by 2.44% and 16.67% compared to diesel and OCB20, respectively. Carbon monoxide (CO) and unburnt hydrocarbon emissions (UHC) decreases for the 50 ppm sample, recording 8.58% and 21.65% reduction in CO and 52.2% and 50% in UHC compared to the diesel and OCB20, respectively. However, Oxides of Nitrogen (NOx) emissions increase. The results indicate that graphene nanoparticle-enhanced biodiesel can adequately substitute petroleum diesel, albeit with NOx reduction techniques. 
      PubDate: Mon, 15 May 2023 00:00:00 +000
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Tel: +00 44 (0)131 4513762

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