Solar energy has found increasing applications in recent years, and the demand will continue to grow as society redirects to a more renewable development path. However, the required high-frequency solar irradiance data are not yet readily available everywhere. There have been endeavors to improve its forecasting in order to facilitate grid integration, such as with photovoltaic power planning. The objective of this study is to develop a hybrid approach to improve the accuracy of solar nowcasting with a lead time of up to one hour. The proposed method utilizes irradiance data from the Copernicus Atmospheric Monitoring Service for four European cities with various cloud conditions. The approach effectively improves the prediction accuracy in all four cities. In the prediction of global horizontal irradiance for Berlin, the reduction in the mean daily error amounts to 2.5 Wh m−2 over the period of a month, and the relative monthly improvement reaches nearly 5% compared with the traditiona... [more]

Many countries have adopted the addition of biodiesel to diesel as a way of inserting renewable content into mineral fuel and making a contribution to the environment. The addition of ethanol to the diesel/biodiesel blend to increase the renewable content of the added fuel blend and reduce the percentage of biodiesel could be a strategysince the demand for biodiesel production is high, and this fuel has a high production cost when compared to ethanol. Thus, this study evaluated the performance and the content of NOx, CO and CO2 exhaust gases from a diesel engine fueled with blends of diesel/biodiesel/ethanol: pure B7, B7E3 (B7 with 3% ethanol) and B7E10 (B7 with 10% ethanol). Emissions of fuel blends were evaluated using the engine speed variation and tested at a speed of 1500 rpm under constant load (185 Nm). Assays were performed at engine speeds of 1000, 1100, 1250, 1500 and 1750 rpm and with loads of 10, 25, 50, 75 and 100% of the maximum torque. Through the performance curves, the... [more]

The present study explores the impact of renewable energy usage, economic progress, urbanization, and trade on carbon emissions in Bhutan. The stationarity among the variables was tested by employing the two unit root tests by taking the annual data series variables from 1982−2020. A symmetric (ARDL) technique was utilized to analyze the associations among variables with short- and long-run estimations. In addition, the cointegration regression method using FMOLS and DOLS was used in this investigation to discover the robustness of the study variables. Findings showed that via long-run assessment the variables renewable energy consumption, urbanization, and trade have adverse connections with CO2 emission, while the variable economic progress shows a constructive linkage with carbon emission. However, the short-run assessment showed that the variable economic growth has a positive impact on carbon emissions. Further, the variables renewable energy consumption, urbanization, and trade h... [more]

Utilizing biological processes for hydrogen production via gasification is a promising alternative method to coal gasification. The present study proposes a dynamic simulation model that uses a one-dimensional heat-transfer analysis method to simulate a biohydrogen production system. The proposed model is based on an existing experimental design setup. It is used to simulate a biohydrogen production system driven by the waste heat from an integrated gasification combined cycle (IGCC) power plant equipped with carbon capture and storage technologies. The data from the simulated results are compared with the experimental measurement data to validate the developed model’s reliability. The results show good agreement between the experimental data and the developed model. The relative root-mean-square error for the heat storage, feed-mixing, and bioreactor tanks is 1.26%, 3.59%, and 1.78%, respectively. After the developed model’s reliability is confirmed, it is used to simulate and optimiz... [more]

The integration of power-electronics-based power plants is developing significantly due to the proliferation of renewable energy sources. Although this type of power plant could positively affect society in terms of clean and sustainable energy, it also brings adverse effects, especially with the stability of the power system. The lack of inertia and different dynamic characteristics are the main issues associated with power-electronics-based power plants that could affect the oscillatory behaviour of the power system. Hence, it is important to design a comprehensive damping controller to damp oscillations due to the integration of a power-electronics-based power plant. This paper proposes a damping method for enhancing the oscillatory stability performance of power systems with high penetration of renewable energy systems. A resilient wide-area multimodal controller is proposed and used in conjunction with a battery energy storage system (BESS) to enhance the damping of critical modes... [more]

Salinity gradient energy (SGE) plants generate power from the mixing of salt water and fresh water using advanced membrane systems. In the Strymon River, under low-flow conditions, a salt wedge is formed, developing a two-layer stratified system, which could be used to extract SGE. In this paper, a novel study was implemented by coupling a 3D hydrodynamic model simulating the salt wedge flow, with the SGE model which assesses the net energy produced by a 1 MW SGE plant. Two scenarios were followed: (a) the optimal scenario, operating throughout the year by mixing salt water from the sea (38.1 g/L) and fresh water (0.1 g/L) from the river to produce 4.15 GWh/yr, and (b) the seasonal scenario, utilizing the salinity difference of the salt wedge. Results show that the daily net SGE production varies between 0.30 and 10.90 MWh/day, in accordance with the salinity difference (ΔSsw ~15−30 g/L). Additionally, a retrospective assessment (from 1981 to 2010) of the annual and seasonal net energy... [more]

Large induction motors can have a high inrush and run-up current during starting, often up to ten times the rated current. In weak supplies, this could be a problem, causing system stability issues and the voltage to dip below acceptable levels. In islanded systems, the capacity could be pulled below its maximum. There are several different starting methods possible, but they are often only suitable for smaller machines. One method not investigated is the use of parallel capacitor compensation during the starting because large induction motors are very inductive during the starting sequence, so that supplying reactive power may be more effective than supplying energy. This paper first investigates several different induction motors with increasing size and assesses their compensation requirements in terms of the reactive power requirement during starting. It is shown that they do generally become more inductive as they increase in size. It is illustrated, using simulations, that using... [more]

This paper presents a method for multi-period optimization of natural gas and electric power systems incorporating gas-fired power plants to analyze the impact of the interdependence between those commodities, in terms of cost and energy supply. The proposed method considers electricity network constraints, such as voltage profile, electrical losses, and limits of the transmission lines, as well as the technical restrictions on the gas network, such as the diameter, length, pressure, and limits for those variables. The proposed method was applied to a 12-bus electric network and a 7-node gas network, and several interdependencies between the electricity and the natural gas system network can be observed. The results show how the restrictions cause the behavior of the gas-fired power plants—in a low demand stage, it is restricted even when the gas-fired power generation prices are below the hydraulic generation prices, while in scenarios of higher demand, saturated cargo flows are obser... [more]

The photovoltaic array has gained popularity in the global electrical market. At the same time, battery storage, which is recently being placed by energy consumers alongside photovoltaics, continues to fall in price. Domestic and community loads may be combined utilizing central battery storage and shared solar power through an integrated grid or microgrid system. One of the main targets is maximum self-sustainability and independence of the microgrid system and implemented solution. This research study looks at the energy flows in a single household system that includes solar arrays and battery storage. The analysed household system is represented by a model which uses real load profiles from experimental measurements, local solar distribution, and onsite weather data. The results show that depending on the system configuration, two important parameters, self-consumption and self-sufficiency, can vary significantly. For a properly designed photovoltaic system, the energy self-consumpt... [more]

The renewable energy technologies attracted 70% global energy investment in 2021, but the global CO2 emission is increased by 1 [...]

This paper investigates the application of anisotropic low-coercive force (LCF) magnets to a novel variable-flux spoke-type permanent magnet synchronous motor (VFS-PMSM) for electrical vehicles with a wide speed range. In the VFS-PMSM, flux is regulated by swiveling the magnetization of the anisotropic LCF magnets instead of directly magnetizing or demagnetizing them. The previously proposed VFS-PMSM uses only isotropic LCF magnets for easily swiveling the magnetic pole direction, resulting in lower torque density. The challenge thus lies in the feasibility to swivel the magnetic pole direction of the anisotropic LCF magnet, and the impact of the different magnetization strengths of the anisotropic magnets on the motor performance. This paper first studies the feasibility to swivel the magnetization direction of anisotropic LCF magnets through experiments. It is confirmed that the magnetization direction can be successfully swiveled by 90 degrees with a reduced external magnetizing fie... [more]

This paper presents the design of a permanent magnet generator for a gearless backyard wind turbine. The magnetisation characteristics of the rotor steel and the stator at different field strength ranges were considered at the design stage and mathematically described using a model in Matlab. The detailed calculations and the design of the planar model were carried out using FEMM software. The high-quality results obtained from the calculations shown in the paper made it possible to make a real model of the generator. This paper presents views of the stator package, the rotor, the entire generator and selected test results. The parameter of this turbine that distinguishes it from a wide range of manufactured generators is its low, non-standard rotational speed and low breakaway torque, which allows the power plant to start in winds of approximately 2 m/s. Other advantages of this generator is its low weight resulting from the use of a light rotor and light alloys for the generator hous... [more]

Electrical models of battery cells are used in simulations to represent batteries’ behavior in various fields of research and development involving battery cells and systems. Electrical equivalent circuit models, either linear or nonlinear, are commonly used for this purpose and are presented in this article. Various commercially available cylindrical, state-of-the-art lithium-ion battery cells, both protected and unprotected, are considered. Their impedance properties, according to four different equivalent circuit models, are measured using electrochemical impedance spectroscopies. Furthermore, the pricing, impedance, specific energy, and C-rate of the chosen battery cells are compared. For example, it is shown that the energy density of modern 18650 cells can vary from a typical value of 200 to about 260 Wh kg−1, whereas the cell price can deviate by a factor of about 3 to 5. Therefore, as a result, this study presents a concise but comprehensive battery parameter library that shoul... [more]

The thermal evolution process of organic matter is associated with the complete hydrocarbon generation and expulsion process in shale, however, the thermal evolution of organic matter is a long process and cannot be realized without experimental simulations. Although several scholars have substantially studied the thermal evolution of organic matter, it remains a challenging and much debated issue in the studies of organic geochemistry. Volcanic events are crucial in the enrichment of organic matter, and appropriate heating accelerates the thermal evolution of organic matter. However, how strong-rock baking restricts the evolution of organic matter in shale has not been specifically studied. The South Qilian Basin in China is a typical superimposed basin where complex tectonic movements have induced multiple volcanic events, which makes it a favorable location to perform the aforementioned research. This study used the Galedesi Formation shale in the Hala Lake Depression of the South Q... [more]

In this paper, the model of a proton exchange membrane fuel cell (PEMFC) with single straight channel is established to investigate the effect of dimensionless size factor of baffles on PEMFC performance. The influence of dimensionless length and height of baffles is discussed. Results show that adding baffles could dramatically optimize the mass transfer in PEMFC. The dimensionless length and height of the baffle have much influence on PEMFC performance.

The captured particulate matter (PM) in diesel particulate filters (DPF) must be periodically burned to maintain the performance and durability of the engine. The amount of PM in the filter must be monitored to determine a suitable regeneration period. In this study, the modeling parameters of the DPF were optimized using experimental data to determine a suitable regeneration period for the DPF for marine diesel engines. The differential pressure over the exhaust gas mass flow rate and temperature were measured using a fresh DPF. The modeling parameters of Darcy’s law were optimized using the experimental data. Finally, the model parameters were validated using differential pressure data obtained from a DPF containing PM. The proposed model, which is a function of the gas flow rate, temperature, and amount of collected PM, was developed to simulate the differential pressure of DPFs and shows potential for application in the development of regeneration logic for marine DPFs.

This paper answers the question: what is the path of the GDP elasticity of economy-wide energy consumption for OECD countries over the period 1960−2019? To do so, this study first considers the arguments as to why this elasticity might change over time, and then reviews the previous evidence on whether this elasticity has changed over time. Lastly, the paper compiles and uses a new dataset to analyze whether the GDP elasticity of energy demand in OECD countries (i) has changed between the periods before and after the major energy crises (e.g., 1974−1985); and (ii) has been stable since 1986. Elasticity stability is analyzed via rolling window regressions using dynamic mean group cross-correlated errors. We argue that (i) the GDP elasticity for economy-wide energy consumption was around unity for OECD countries prior to the first energy crisis; and (ii) the reactions to the extreme oil price experiences that occurred over 1974−1985 led to a substantially lower GDP elasticity for economy... [more]

Reducing the carbon emissions from hotels on non-interconnected islands (NII) is essential in the context of a low carbon future for the Mediterranean region. Maritime tourism is the major source of income for Greece and many other countries in the region, as well as hot-temperate and tropical regions worldwide. Like many NIIs, Rhodes attracts a high influx of tourists every summer, doubling the island’s energy demand and, given the high proportion of fossil fuels in the Rhodian energy supply, increasing carbon emissions. Using the theoretical framework ‘FINE’, this paper presents the optimisation of a medium-sized hotel’s energy system with the aim of reducing both cost and carbon emissions. By introducing a Photovoltaic (PV) net metering system, it was found that the carbon emissions associated with an NII hotel’s energy system could be reduced by 31% at an optimised cost. It is suggested that large-scale deployment of PV or alternative renewable energy sources (RES) in NII hotels co... [more]

This paper presents the various ways that lithium-ion batteries are being counterfeited, the problems that counterfeit batteries present, how they enter the consumer market, and the difficulties of detection. Simple external visual inspection of the battery is unreliable. As shown in the presented case study, even for the same brand batteries, their internal structures are different. The current counterfeit prevention methods focus on the manufacturing step. To reduce the risk of counterfeit batteries, device manufacturers and retail stores should characterize the batteries they receive. In addition, related authorities or organizations should set standards to enable a universal battery tracking method along the supply chain to prevent counterfeit lithium-ion batteries from entering the market.

Research in the field of Internal Combustion (IC) engines focuses on the drastic reduction of both pollutant and greenhouse gas emissions. A promising alternative to gasoline and diesel fuel is represented by the use of gaseous fuels, above all green hydrogen but also Natural Gas (NG). In previous works, the authors investigated the performance, efficiency, and emissions of a supercharged Spark Ignition (SI) engine fueled with mixtures of gasoline and natural gas; a detailed research involving the combustion process of this kind of fuel mixture has been previously performed and a lot of experimental data have been collected. Combustion modeling is a fundamental tool in the design and optimization process of an IC engine. A simple way to simulate the combustion evolution is to implement a mathematical function that reproduces the mass fraction burned (MFB) profile; the most used for this purpose is the Wiebe function. In a previous work, the authors proposed an innovative mathematical m... [more]

Gas disasters, such as coal and gas outburst and gas overflow, always occur during the mining of the steep and extra-thick coal seam in the horizontal, fully mechanized, top coal slice caving (HFMTCSC) method. To solve these issues and guarantee the safe and efficient mining in the Yaojie No. 3 coal mine, 3DEC software was used in this work to investigate the overburden movement and collapse law as well as the stress redistribution and coal-seam deformation characteristics below the goaf. The results show that a pressure arch structure and a hinge structure are formed in succession in the overburden rock, which induces stress redistribution in the coal below the goaf. During the mining of the upper slice, more than 75% of the coal in the lower slice is located at the effective pressure relief zone; therefore, the steep and extra-thick coal seam can then be protected slice by slice. Meanwhile, with the increase of mining depth, the efficient pressure relief range expands. Based on this... [more]

Jet scale affects the mixing and combustion of fuel and inflow. With the increase in the scale of scramjet combustors, the study of large-scale jets is particularly significant. The effects of jet scale on flame stability in scramjet combustors were studied by direct-connect combustion experiments. In this paper, the flame distribution characteristics of different jet scales were compared by using similar jet/inflow momentum ratios. The inflow Mach numbers were 2.4 and 3.0, and the total temperature was 1265 K and 1600 K, respectively. The results show that, when the equivalence ratio increases, the combustion intensity increases. Under the condition of same momentum ratio, the increase of jet scale is conducive to fuel injection into the core mainstream, increasing heat release, and the flame stabilization mode will change from cavity stabilization mode to jet-wake stabilization mode. Increasing the distance between jet orifices is not beneficial to combustion, and may even lead to bl... [more]

Presence of a transformer in a grid connected photovoltaic system provides galvanic isolation between the photovoltaic panels and the grid. However, it increases the overall cost, makes the circuit bulky and reduces the efficiency of the system. Hence, transformerless inverters have gained significant importance owing to its low cost, light weight and increased efficiency. However, due to the absence of the transformer, there is no galvanic isolation between photovoltaic panels and the grid and there is always a threat of flow of leakage current. In this research paper, an elaborate analysis of H4, H5 and H6 transformerless inverter is carried out. DC side decoupled circuits are studied to eliminate the leakage current. Their performances are compared based on the simulations carried out in MATLAB/SIMULINK software. A novel H6 inverter is proposed by introducing an additional switch in H5 topology. A direct current path is provided in H5 topology during one of the active modes, so that... [more]

A battery−supercapacitor hybrid energy storage system is investigated as a solution to reduce the high-power delivery stress on the battery. An optimally-sized system can further enhance the storage and cost efficiency. This paper discusses several possible problems in the sizing of a battery−supercapacitor hybrid energy storage system for practical applications. A sizing method that utilises data collected from a fully active embedded control hybrid energy system is proposed. The feasibility of the method is then tested on three load profiles that represent the load demand of inter- and intra-applications with a battery−supercapacitor hybrid energy storage system. The result is compared to a battery-only single energy storage system. The results verified that the number of batteries required in the hybrid energy storage system is reduced by at least 50% compared to the battery-only single energy storage system.

This study focuses on the problem of the efficient energy management of an independent fleet of freight electric vehicles (EVs) providing service to a city multi-floor manufacturing cluster (CMFMC) within a metropolis while considering the requirements of smart sustainable electromobility and the limitations of the power system. The energy efficiency monitoring system is considered an information support tool for the management process. An object-oriented formalization of monitoring information technology is proposed which has a block structure and contains three categories of classes (information acquisition, calculation algorithms, and control procedures). An example of the implementation of the class “Operation with the electrical grid” of information technology is presented. The planning of the freight EVs charging under power limits of the charging station (CS) was carried out using a situational algorithm based on a Fuzzy expert system. The situational algorithm provides for moni... [more]