The growing popularity of traveling with electric scooters in recent years is, on the one hand, a great opportunity to shift from the current forms of mobility to a new service among the public, but it is also a huge challenge for urban centers and operators. One of the main challenges related to electric scooters is the growing demand for high energy consumption, which is currently a big issue due to the growing interest in electromobility used in mobility as a service (MaaS) systems. However, in order to properly estimate the level of energy consumption of scooters, there is a real need for reliable scientific information on the actual electricity consumption of electric scooters used in shared mobility systems. An extensive literature analysis indicates the lack of research conducted in this area. Noting this research gap, studies were conducted to determine the factors influencing the energy consumption of an electric scooter. The study attempts to determine these values on the bas... [more]

This publication presents the impact of PM10, PM2.5, and cloudiness on the power that is generated by photovoltaic panels—the actual photovoltaic power was measured. Weather parameters that were recorded by a weather station were taken into account, and the dependencies between the weather parameters and the power that was generated by PV panels were determined. This study was based on actual data from a solar cell set and was designed to allow a certain size of a PV system to be able to supply power to a given load. For the entire measurement year, data on PM10, PM2.5, cloudiness, and generated power were collected; by using a genetic algorithm, the influence of the environmental parameters on the power that was generated by the PV panels was calculated. The research shows the influence of anthropogenic factors on the power that is generated by PV panels. It was observed that PM2.5 and PM10 air pollution decreased the power by about 16% among the analyzed factors as they were related... [more]

The development of the electric mobility market in cities is becoming more and more important every year. With this development, more and more electric scooters are appearing in cities. Currently, the restrictions that result from the upcoming trends are reducing the number of vehicles powered by combustion engines in favor of vehicles equipped with electric motors. Considering the number of electric vehicles, the dominant type is an electric scooter. The aim of this article is to determine the CO2 that is emitted into the atmosphere by using this type of vehicle. The main suppliers of this type of vehicle in cities are shared mobility systems. To recognize the research gap, consisting of the lack of CO2 emissions of an electric scooter type vehicle, studies were carried out on the energy consumption of an electric scooter and CO2 emissions, which were calculated based on the CO2 emission value needed to produce a given energy value kWh. The plan of the research performed was developed... [more]

In markets with strict emission legislations Selective Catalytic Reduction (SCR) has become the industry standard for NOx abatement in heavy-duty vehicles, and therefore modeling and control of these systems are vital. Many SCR catalyst models are available in the literature and in this paper different models are discussed and classified into groups. Two models, based on the two most popular classes for control-oriented models, are implemented and compared with each other, one based on the continuously stirred-tank reactor approximation, and the other on a quasi-static behavior of the gas phase. The results show that assuming a quasi-static behavior of the gas phase in the catalyst gives better results in terms of accuracy and simulation time, especially when it comes to predictions of ammonia slip.

In recent years, the energy market has seen an increase in small and medium enterprises (SMEs) participating in the sector and providing relevant services to customers. The energy sector SMEs need to acknowledge whether reengineering their marketing strategy by modeling customers’ website behavior could enhance their digital marketing efficiency. Web Analytics refers to the extracted data of customers’ behavior from firms’ websites, a subclass of big data (big masses of uncategorized data information). This study aims to provide insights regarding the impact that energy SMEs’ web analytics has on their digital marketing efficiency as a marketing reengineering process. The paper’s methodology begins with the retrieval of behavioral website data from SMEs in the energy sector, followed by regression and correlation analyses and the development of simulation models with Fuzzy Cognitive Mapping (FCM). Research results showed that customer behavioral data originating from SMEs’ websites can... [more]

Increasing energy efficiency in electric transportation systems is a topical issue, considering the worldwide concern for reducing CO2 emissions, and especially through the significant reduction in energy loss and energy consumption [...]

This study attempts to examine the existence of interdependencies between specific stock market indices, exchange rates and crude oil for the period January 2021 to July 2022 with daily data. In the period we have chosen, the post-vaccination phase against COVID-19, as well as the war in Ukraine, is covered. The variables selected for this study are RTSI, Eurostoxx, S&P 500, EUR/USD and RUB/USD exchange rates and crude oil prices. The selection of the specific variables was made because they are directly related to the pre-war period that coincides with the post-vaccine period of the pandemic, which allowed us to characterize it as the normal period and to characterize the period of the war in Ukraine that coincides with the energy crisis as the unstable period. In this way, the present study covers the markets of Russia and other developed economies. For empirical purposes, we applied a wavelet coherence approach in order to investigate the possible existence of simultaneous coherence... [more]

Massive hydraulic fracturing (MHF) is currently the most effective technology used to create fracture networks with sufficient conductivity and maximize the stimulated reservoir volume (SRV) in tight oil and gas reservoirs. The newly initiated fracture networks during MHF usually exhibit complex fracture morphology and contain intersected fractures and fracture branches. The conductivity of these fractures plays a pivotal role in determining long-term productivity. Due to the complex geometry, it is difficult to accurately evaluate intersected fracture conductivity through traditional conductivity measurement methods and devices which are designed for a single primary fracture. Unlike previous studies where fracture conductivity was measured using two rock slabs under single-direction (vertical) loading, we establish a novel conductivity measurement apparatus that can mimic different fracture intersection scenarios under both vertical and transverse loading to facilitate the evaluation... [more]

Battery state of charge as an effective operational indicator is expected to play a crucial role in the advancement of electric vehicles, improving the battery capacity and energy utilization, avoiding battery overcharging and over-discharging, extending the battery’s useful lifespan, and extending the autonomy of electric vehicles. In context, this article presents a computationally efficient battery state-of-charge estimator based on the Coulomb counting technique with constant and variable discharging current profiles for an actual battery pack in real time. A dedicated experimental bench is developed for validation purposes, where pivotal measurements such as current, voltage, and temperature are initially measured during the charging/discharging cycle. The state of charge thus obtained via these measurements is then compared with the value estimated through the battery generic model. Detailed analysis with conclusive outcomes is finally presented to exhibit the flexible nature of... [more]

By coordinating the operation of regionally interconnected virtual power plants (VPPs), the growing penetration problem of renewable energy sources (RESs) into the power system can be addressed. This study presents an interactive trading cooperation model of regionally interconnected VPPs using bilateral contracts. The proposed model maximizes overall electricity market social welfare (SW) (i.e., maximization of consumer benefits while minimizing energy costs). The focus of the proposed approach is to design and develop a parallel energy exchange cooperation model of interconnected VPPs, ensuring the operational efficiency and reliability of interconnected power systems over the planning horizon. Given that adjacent VPPs may have differences in their energy generation and usage patterns, a scenario tree method is used to model the uncertainties associated with solar irradiation and load demand. A case study of two interconnected VPPs is used, the operational scenario is designed, and t... [more]

Much attention in the wind energy literature is devoted to condition monitoring [...]

Because of the problem of gangue discharge and surface subsidence during coal mining, the current research on underground filling mainly focuses on the paste filling, solid filling, and grouting filling of the overburden separation layer after scaffolding. We proposed the technology of fluidization gangue grouting for filling the collapse area based on our previous research. The prediction method of residual space in the collapse area and the diffusion law of gangue fluidization filling slurry are two essential points for successfully implementing the technology and maximizing the use of goaf for gangue backfilling and reducing overburden settlement. To further explore the remaining space distribution law of the collapsed goaf in thick seam fully mechanized top coal caving mining and the effect of coal gangue fluidization filling, the caving goaf of the 3307 fully mechanized top coal caving face in Sangshuping No. 2 coal mine in the Weibei mining area was detected by the transient elec... [more]

This study demonstrates that a drone flying above photovoltaic (PV) panels can clean the dust and enhance the panels’ efficiency. If operated regularly, the drone’s downward thrust generated during its cruise at a certain height above the panels can remove most of the accumulated dust. Sandstorms are frequent in Saudi Arabia, creating dust deposition on PV panels, which acts as a shield against solar radiation. As a result, the energy absorption from solar radiation is reduced and subsequently, the panels’ energy output is reduced. This experimental investigation was conducted at KFUPM University’s beach, Dhahran, Saudi Arabia, to prove the effectiveness of drone-based cleaning of PV panels. Volumes of 20, 50, and 100 CC of dust were spread on the panel during different experiments. These experimental results showed that the back thrust of the drone could remove most of the dust and improve the solar panels’ energy output performance. For example, for 50 CC dust spread on the panel, th... [more]

The article presents a comparison of exhaust emission test results from a passenger car with a spark-ignition engine examined with the WLTC (Worldwide Harmonized Light-Duty Vehicles Test Cycle) test, which was carried out on a chassis dynamometer, and examined with a RDE (Real Driving Emissions) test, which was conducted in real vehicle operating conditions. The exhaust emissions and the emitted particle number in the individual phases of both tests were determined. Large disparities were found in the results of the two tests. The cold start-up had a particularly significant impact on the test results in the case of the WLTC test. This impact is much greater than in the RDE test, mainly due to the fact that the RDE test is much longer than the WLTC test. Moreover, the engine load in the RDE test was greater than in the WLTC test. As a result of the conducted analyses, it was postulated that the research should be continued in stochastic conditions for the vehicle speed function, e.g.,... [more]

This study explores the effects of hydrothermal carbonization (HTC) on the fuel properties of empty fruit bunches (EFB) by varying the reaction temperatures between the range of 180−300 °C. The improved properties of hydrochars following HTC were achieved by analyzing the changes in the physical and chemical properties of EFB. Moreover, it can save energy during treatment processes, in addition to evaluating the improvement of the biofuel stability based on the equilibrium moisture content and agglomeration. The results showed that the chemical structure of EFB decomposed owing to dehydration and decarboxylation reactions, leading to increased carbon and fixed carbon concentrations in the obtained hydrochar; and thus, an increased calorific value. Hydrochar generated during HTC exhibited chemical properties similar to those of conventional coal fuel. The optimal HTC reaction temperature range was ~230−250 °C. Based on the X-ray fluorescence results, hydrochar produced during HTC had sm... [more]

One of the emerging problems in modern computational fluid dynamics is the simulation of flow over rough surfaces. A good example of these rough surfaces is wind turbine blades with ice formation on its leading edge. Instead of resolving the airflow field using a fine computational grid near the wall, rough wall functions (RWFs) can be used to model the flow behavior in case of the presence of roughness. This work aims to investigate the performance of state-of-the-art RWFs to show which of these models can provide the most accurate results with the lowest computational cost possible. This aim is achieved by comparing coefficients of lift and pressure resulting from CFD simulations with wind tunnel results of an airfoil with actual ice profiles collected from the site. The RWFs are used to simulate airflow field over the airfoil profiles with ice profile attached to its leading edge using OpenFOAM CFD framework. The comparison of the numerical simulations and the wind tunnel measuremen... [more]

This research aims to maximize the resilience of an electrical power system after an N−1 contingency, and this objective is achieved by switching the transmission lines connection using a heuristic that integrates optimal dc power flows (DCOPF), optimal transmission switching (OTS) and contingencies analysis. This paper’s methodology proposes to identify the order of re-entry of the elements that go out of the operation of an electrical power system after a contingency, for which DCOPF is used to determine the operating conditions accompanied by OTS that seeks to identify the maximum number of lines that can be disconnected seeking the most negligible impact on the contingency index J. The model allows each possible line-switching scenario to be analyzed and the one with the lowest value of J is chosen as the option to reconnect, this process is repeated until the entire power system is fully operational. As study cases, the IEEE 14, 30 and 39 bus bars were selected, in which the propo... [more]

The uniform and smaller-sized (~3 μm) LiNi0.8Co0.1Mn0.1O2 (SNCM) particles are prepared via a fast nucleation process of oxalate co-precipitation, followed by a two-step calcination procedure. It is found that the fast nucleation by vigorous agitation enables us to produce oxalate nuclei having a uniform size which then grow into micron-particles in less than a few minutes. The impacts of solution pH, precipitation time, calcination temperature, and surface modification with ZrO2 on the structural, morphological, and electrochemical properties of SNCM are systematically examined to identify the optimal synthetic conditions. A novel bimodal cathode design has been highlighted by using the combination of the SNCM particles and the conventional large (~10 μm) LiNi0.83Co0.12Mn0.05O2 (LNCM) particles to achieve the high volumetric energy density of cathode. The volumetric discharge capacity is found to be 526.6 mAh/cm3 for the bimodal cathode L80% + S20%, whereas the volumetric discharge ca... [more]

This paper presents a detailed review of the streaming electrification phenomena of different insulating fluids for power transformers. The comparison of different techniques used to assess the charging tendency of fluids is discussed depending on the flow type (planar or centrifugal), volume of oil, and interface material. The charge separation between the insulating fluid and metallic/pressboard interfaces is explained in terms of the electrical double layer formation involving a fixed layer and diffuse layer. Based on the experimental results, the streaming electrification is observed to be a function of various factors such as speed, temperature, electric field, and surface roughness. Depending on the molecular structure of insulating liquids that come into contact with solid insulation at the interface, the streaming current can increase; hence, a suitable additive (benzotriazole, fullerene, Irgamet 39) is selected based on the type of fluid and charge polarity. The degradation of... [more]

The thermal performance of fin-and-tube heat exchangers (HX) is a crucial aspect in a multitude of applications and fields; several design and operational parameters influence this performance. This study focuses on the issue of flow maldistribution and its effect on the HX thermal performance. For this purpose, an experimental setup is designed and implemented to emulate the conditions under which an automotive heat exchanger operates in regard to the non-uniform upstream airflow velocity distribution over the HX surface. The setup allows obtaining various configurations of airflow velocity non-uniformity of some desired mean velocity and standard deviation. The experimental results reveal that a higher degree of non-uniformity (higher standard deviation of the velocity distribution) causes an increased deterioration of the HX thermal performance. For example, at a water flowrate of 200 L/h and a mean airflow velocity of 2 m/s, increasing the standard deviation from 0 to 2 m/s (i.e.,... [more]

This study is a systematic analysis of selected research articles about power-to-X (P2X)-related processes. The relevance of this resides in the fact that most of the world’s energy is produced using fossil fuels, which has led to a huge amount of greenhouse gas emissions that are the source of global warming. One of the most supported actions against such a phenomenon is to employ renewable energy resources, some of which are intermittent, such as solar and wind. This brings the need for large-scale, longer-period energy storage solutions. In this sense, the P2X process chain could play this role: renewable energy can be converted into storable hydrogen, chemicals, and fuels via electrolysis and subsequent synthesis with CO2. The main contribution of this study is to provide a systematic articulation of advanced data-driven methods and latest technologies such as the Internet of Things (IoT), big data analytics, and machine learning for the efficient operation of P2X-related processes... [more]

In this paper, a bidirectional converter with multi-mode control strategies is proposed for a battery energy storage system (BESS). This proposed converter, which is composed of a half-bridge-type dual-active-bridge (HBDAB) converter and an H-bridge inverter, is able to operate the BESS with different power conditions and achieve the DC−AC function for lower input DC voltage applications. For the HBDAB converter, the variable-frequency control (VFC) and phase-shift control (PSC) are both adopted to achieve zero-voltage switching over a wider power range and the battery module balance control capability for BESS, respectively. In addition, the interleaved configuration is used to reduce the current ripple and increase the overall current rating. For the H-bridge inverter, the unipolar control mode (UCM) and totem-pole control mode (TPCM) are adopted to manage the real and reactive current control under different AC grid conditions. The UCM offers a reduction in current ripple for real a... [more]

During a turbine’s lifetime, minimizing the cost of power production should be the primary aim in addition to attaining high technical efficiency. Thus, this paper was aimed at enhancing the aerodynamic efficiency of a site-specific small wind turbine considering the cost of energy as one of the design parameters. The wind distribution of a specific site was employed to characterize the wind using the Weibull distribution method. The aerodynamics of a typical 5 kW wind turbine blade were investigated by implementing a blade element method (BEM) using a MATLAB code that applied the advancements and improvements with different modifications and which was validated by engaging computational fluid dynamics (Ansys-Fluent). The optimal pitch angle was then employed to further promote the performance characteristics of the blade. The cost of energy was reformulated in terms of rated power considering a cost variation of the main components that deviates with the rated power. Accordingly, the... [more]

Photovoltaic installations (PVs) are currently one of the fastest-growing sources of renewable energy. Expanded forms of financial support and higher electricity prices have resulted in a large increase in its installed capacity. PV installations are increasingly being ordered by industry and privates, often for installations capacity of several hundred kilowatts. In addition to the advantages, photovoltaic installations also have drawbacks. One of these is that the increase in the voltage in the power grid leads to the exclusion of individual installations from the grid. An important issue in the operation of photovoltaic installations is also their reliability during their lifetime. The reliability of photovoltaic installations depends on the random nature of the cloud cover as well as the material’s mechanical degradations. This paper presents a literature analysis using Citespace software in terms of reliability. A detailed bibliometric analysis has been performed to outline the ma... [more]

The low permeability of coal seams has always been the main bottleneck restricting coalbed methane drainage. In this paper, a coal seam anti-reflection technology with solid-propellant blasting was proposed, and the composition and proportion of the solid propellants were determined based on the principle of oxygen balance. The authors designed a solid-propellant blasting damage fracture experiment of simulation coal, tested the impact pressure on a blast hole wall, measured the ultrasonic wave velocity, explosive strain and crack propagation velocity, and then revealed the blasting damage fracture process and mechanism of coal based on the experimental results and damage fracture mechanics theory. The history curve of impact pressure time can be divided into three processes including the slow pressurization process, dramatic increase process, and nonlinear pressure relief process. The pressure distribution along the whole blasting hole was uneven, and the peak pressure was relatively... [more]