Among the main components of a smart city, the energy system plays a vital and core role in the transition towards a sustainable urban life. Furthermore, the utilization of renewable energy sources ...has been demonstrated as a significant contribution to reducing pollutant emissions and enhancing the quality of the living environment. Therefore, designing the energy systems based on clean and renewable criteria is considered a sustainable solution for smart cities. Indeed, the deep and rapid penetration of renewable energy-based technologies have been believed to very well fit into a smart city under various scales, this could supply a secure basis for a modern society with a low-carbon economy. In this review paper, the main components and roles of renewable energy resources (such as solar, wind, geothermal, hydropower, ocean, and biofuels) for the smart city were fully introduced. Besides, integrating the renewable sources form into the energy systems of smart cities was thoroughly analyzed on the basis of technical and economic criteria. Finally, existing challenges and future scenarios were also discussed in detail to clarify the progress and perspective of smart renewable energy systems for the smart city. In general, the integration of renewables into energy systems of the smart city is a sagacious perspective and solution aiming to achieve cleaner process and more sustainable development. However, the optimization issues of the energy system for integrating of renewable components, ensuring good stability, maximizing the operating range, and minimizing the investment costs should be critically evaluated in the future works.
•Designing tools and key criteria for smart renewable energy systems.•Efficiency and prospect of integrating renewables into energy system for smart city.•Existing problems and challenges for renewable-based energy system in smart city.•Future scenarios for the sustainable development of energy system in smart city.
•Used fuels including preheated and unpreheated Jatropha oil, diesel fuel.•Impacts of triple-physical properties of fuel on atomization, breakup, and combustion.•Trilateral correlation of deposits, ...spray characteristics, and engine performance.•Thorough analysis on the relation of accumulated deposits and pollutant emissions.•Dependence of spray penetration and cone angle on formed deposits and fuel properties.
The benefits and advantages of bio-based fuels according to the research results of scientists and researchers related to the stable maintenance and sustainable development for the purpose of harmonizing the environment and life is an indisputable fact. Experimental studies on the use of bio-based fuels for engines in the long term should be thus thoroughly conducted to obtain the fullest results of economic-technical features and emissions, to name just a few. In this paper, a state-of-the-art analysis on the core correlation based on the trilateral relationship of spray characteristics, combustion, and emissions of a high-speed four-stroke diesel engine running on Jatropha oil (JO) in two cases of preheated and unpreheated in comparison to diesel fuel was investigated and carried out. Tests included two phases: (i)-tests of spray characteristics, analysis of combustion and emissions for engine fueled with preheated JO, unpreheated JO, and DF at the first hour and after 300 h of endurance test for engine, (ii)-analysis of formed deposits in the nozzle orifices and piston crown after 300 h of operation. As a result, huge deposits formed in the injector orifices and piston crown based on optical observation by SEM in case of using unpreheated JO as fuel were found, followed by preheated JO and DF. In addition, a sharp increase in spray penetration length and a significant decrease of cone angle for unpreheated JO compared to preheated JO and DF were also indicated, whereas thermal efficiency of the test engine for preheated JO, unpreheated JO, and DF was reduced by respectively 1.68%, 4.38%, and 0.98% after 300 h of operation. For emission data, negative changes such as a more reduction of NOx along with a higher augment of CO, HC, and smoke with unpreheated JO than those of preheated JO and DF were reported. In closing, core correlation as well as trilateral impacts of accumulated deposits, spray characteristics, and combustion were thoroughly demonstrated and deeply analyzed.
Vegetable oils are always considered as the potential sources since the renewable and alternative fuels have been being paid attention by all countries in the world based on the strategies of the ...environmental pollution reduction. The aim of this experimental study is to evaluate the effects of as-used fuels on emission characteristics, deposit formation, and lubricating oil (LO) degradation of a 4 stroke-4 cylinder diesel engine running on preheated vegetable oil and diesel oil. All tests were conducted under 2000 rpm of engine speed, and 80hp of power within different periods of time depending on the test purposes. The ICP-MS analyzer was used to measure the LO quality through the parameters of kinematic viscosity, density, and metal concentrations on the basis of ASTM D5185-09 standard after every 25 hours of the test duration. Meanwhile, the emission characteristics were tested by an exhaust analyzer after every 50 hours, and deposit formation on piston crown and piston groove was evaluated by the assistance of Scanning electron microscopy (SEM) after 300 hours of the test. Besides, the thorough analysis related to the relationship between deposit formation, the degradation of the engine LO and emission characteristics were presented.
Currently, the development of alternative and green energy sources has been being strongly pushed aiming to recoup the lack of fossil energy, to meet the ever-increasing demand of energy use in ...modern society, and to palliate concerns regarding environmental pollution and global climate change. Therefore, producing energy from biomass sources has recently been of great interest because biomass is considered as a reliable and ubiquitous source. Indeed, the conversion of biomass into furan derivatives through the catalytic production process is emerging as a fascinating and promising method. Being one of the furan-based compounds, 2-Methylfuran (MF) is known as a critical platform substance and an ideal green solution on the pathway of finding alternative fuels because the MF properties are similar to those of fossil fuels and MF could be generated from renewable biomass source. In this review paper, the process of MF synthesis from biomass through catalyst reactions was thoroughly analyzed. More importantly, the pyrolysis and oxidation progress of MF was also critically presented aiming to clarify the applicability of MF to internal combustion engines. Finally, the performance, the characteristics of combustion, and pollutant formation of internal combustion engines fueled with MF were discussed in detail. In general, MF could become a promising alternative fuel for internal combustion engines although studies on the engine durability, compatibility to materials, tribology behaviors should be further carried out in the future.
•Catalyst-based MF synthesis from biomass through furfural was critically presented.•Pyrolysis progress, combustion, and ignition behaviors were thoroughly analyzed.•Key characteristics of engines fueled with MF-based fuels were discussed in detail.•Economic aspect, existing challenges, and future perspective were mentioned.
In this paper, we propose a novel fuzzy inference system on picture fuzzy set called picture inference system (PIS) to enhance inference performance of the traditional fuzzy inference system. In PIS, ...the positive, neutral and negative degrees of the picture fuzzy set are computed using the membership graph that is the combination of three Gaussian functions with a common center and different widths expressing a visual view of degrees. Then, the positive and negative defuzzification values, synthesized from three degrees of the picture fuzzy set, are used to generate crisp outputs. Learning in PIS including training centers, widths, scales and defuzzification parameters is also discussed. The system is adapted for all architectures such as the Mamdani, the Sugeno and the Tsukamoto fuzzy inferences. Experimental results on benchmark UCI Machine Learning Repository datasets and an example in control theory - the Lorenz system are examined to verify the advantages of PIS.
The production of chemicals and fuels from renewable biomass with the primary aim of reducing carbon footprints has recently become one of the central points of interest. The use of lignocellulosic ...biomass for energy production is believed to meet the main criteria of maximizing the available global energy source and minimizing pollutant emissions. However, before usage in bioenergy production, lignocellulosic biomass needs to undergo several processes, among which biomass pretreatment plays an important role in the yield, productivity, and quality of the products. Acid-based pretreatment, one of the existing methods applied for lignocellulosic biomass pretreatment, has several advantages, such as short operating time and high efficiency. A thorough analysis of the characteristics of acid-based biomass pretreatment is presented in this review. The environmental concerns and future challenges involved in using acid pretreatment methods are discussed in detail to achieve clean and sustainable bioenergy production. The application of acid to biomass pretreatment is considered an effective process for biorefineries that aim to optimize the production of desired products while minimizing the by-products.
Display omitted
•Main composition of lignocellulosic biomass was presented.•Key variables in biomass pretreatment process using acid were reviewed.•Efficiency of various acid-based biomass pretreatment was evaluated in detail.•Application of acid-pretreatment is an effective method for the biorefineries.•The economic feasibility of acid pretreatment should be further investigated.
The inherent capability and increased efficiency of microalgae to convert sunlight into solar chemical energy are further enhanced by the higher amount of oils stored in microalgae compared to other ...land-based plant species. Therefore, the widespread interest in producing biofuels from microalgae has gained considerable interest among leading energy experts and researchers due to the burgeoning global issues stemming from the depletion of fossil fuel reserves, future energy security, increasing greenhouse gas emissions, and the competition for limited resources between food crops and conventional biomass feedstock. This paper aims to present the recent advances in biofuel production from microalgae and the potential benefits of microalgae in the energy and environmental sectors, as well as sustainable development. Besides, bottlenecks and challenges mainly relating to techniques of cultivation and harvesting, as well as downstream processes are completely presented. Promising solutions and novel trends for realizing strategies of producing biofuels from microalgae on an industrial and commercial scale are also discussed in detail. Alternatively, the role of microalgae in the circular economy is thoroughly analyzed, indicating that the potential of scaling up current microalgae-based production could benefit from the waste-to-energy strategy with microalgae as a key intermediate. In the future, further research into combining different microalgae biomass pretreatment techniques, separating the microalgae feedstock from the cultured media, developing new species, and optimizing the biofuel production process should be carried out to reduce the prices of microalgae biofuels.
Using vegetable oils as fuel for diesel engines in the long term may cause some extremely serious problems, such as an increase in toxic emission and pollutants, reduction in engine power, and ...degradation of lubricating oil (LO) due to deposit formation, abrasion, and wear, as well as damaged engines. In this study, the 4 stroke-4 cylinder-Yanmar TF120M diesel engine was tested the endurance during 300 h on diesel fuel (DF) and preheated straight jatropha oil to evaluate the effects of these two fuel types on the degree of deposit formation, LO, brake-specific fuel consumption (BSFC), and emission characteristics. The results showed that, although the properties of straight jatropha oil were improved by preheating at 90°C (SJO90), the degree of deposit formation for SJO90 was observed higher in comparison with DF. Furthermore, scanning electron microscopy (SEM) was used to analyze the deposits. Related to engine performance and emission characteristics, higher BSFC, unburnt hydrocarbons and carbon monoxide emissions, and lower nitrogen oxide emissions for SJO90 compared to DF were presented. About the results of LO analysis, the excessive metal concentrations in LO of test engine for SJO90 were much higher than the case of using DF. Besides, an increase in LO density and a reduction in LO viscosity also showed the degradation of LO for SJO90 in comparison with DF after test time.
Currently, the considerable decline in fossil fuel resources and the high rise in vehicle emissions have prompted researchers and governments to formulate strategies for sustainable energy ...development. In addition to imposing strict laws, promoting sustainable energy sources such as the development of new types of non-fossil fuels has been considered a suitable direction for the roadmap to healing the Earth’s environment. Biomass sources have affirmed huge potentials in the production of biofuels. In the pathway of searching renewable biofuels, it is found that that 2,5-dimethylfuran (DMF) can become a promising fuel because it is synthesized from lignocellulose biomass, which is an available feedstock for the production of prospective fuels. Indeed, recent review studies have focused in great detail on engine performance evaluation using DMF but seemed to have gaps in emission characteristics. In this work, the controversial issues of emissions from spark and compression ignition engines during the DMF combustion were completely assessed. Indeed, the mechanism of formation and oxidation of DMF compounds during combustion was clearly described to serve as the basis for analyzing and comparing the pollution emission behavior of different fuels. More importantly, gaseous emissions, PM characteristics, and soot tendency from spark and compression ignition engines were thoroughly evaluated on the basis of the experimental and numerical data. In general, DMF has shown outstanding advantages upon emissions compared to fossil fuels; however, the impacts of DMF on the engine durability and fuel system should be further investigated to have a comprehensive analysis of this biofuel class.
