This article proposes a new technique called optimized discontinuous carrier pulse width modulation (ODCPWM), whose main objective is to solve the issue of significant output voltage harmonics of conventional synchronous carrier modulation at low carrier wave ratios. Based on the symmetry principle, the fundamental wave period is divided into regions; the carriers in adjacent regions are flipped, and the carrier width is changed symmetrically in each region to generate an unequal-width optimized discontinuous carrier pulse width modulation. In addition, using the weighted total harmonic distortion (WTHD) of the line voltage as an evaluation index, an optimized multi-mode PWM strategy is proposed to satisfy the system to operate stably in the whole speed range. The experimental results verify the effectiveness of the proposed strategy. The results show that ODCPWM proposed in this article can eliminate harmonics and multiples of three harmonics in line voltage harmonics. The VWTHD is lo... [more]

The appropriate design of the power oscillation damping controllers guarantees that distributed energy resources and sustainable smart grids deliver excellent service subjected to big data for planned maintenance of renewable energy. Therefore, the main target of this study is to suppress the low-frequency oscillations due to disruptive faults and heavy load disturbance conditions. The considered power system comprises two interconnected hydroelectric areas with heavy solar energy penetrations, severely impacting the power system stabilizers. When associated with appropriate controllers, FACTs technology such as the static synchronous series compensator provides efficient dampening of the adverse power frequency oscillations. First, a two-area power system with heavy solar energy penetration is implemented. Second, two neuro-based controllers are developed. The first controller is constructed with an optimized particle swarm optimization (PSO) based neural network, while the second is... [more]

Hydrogen is an attractive, clean, sustainable energy source primarily produced via industry. At present, most reviews on hydrogen mainly focus on the preparation and storage of hydrogen, while the development and utilization of natural hydrogen will greatly reduce its cost. Natural hydrogen has been discovered in many geological environments. Therefore, based on extensive literature research, in this study, the distribution and sources of natural hydrogen were systematically sorted, and the identification method and occurrence state of natural hydrogen were examined and summarized. The results of this research show that hydrogen has been discovered in oceanic spreading centers, transform faults, passive margins, convergent margins, and intraplate settings. The primary sources of the hydrogen include alterations in Fe(II)-containing rocks, the radiolysis of water, degassed magma, and the reaction of water- and silica-containing rocks during the mechanical fracturing. Hydrogen can appear... [more]

The temperature effect caused by high slip has an important influence on the operation performance and reliability of magnetic coupling. Taking the self-developed single disk asynchronous magnetic coupling as the research object, the heat loss equation of the magnetic coupling is established. Based on the three-dimensional transient magnetic field simulation model of the magnetic coupling, the eddy current loss, torque, and eddy current distribution law of the magnetic coupling are obtained through simulation. The space flow field and structure temperature field distribution of the magnetic coupling are analyzed by using the fluid-thermal coupling simulation method, and the heat dissipation coefficient and temperature distribution law of the structure surfaces such as copper disk, the back lining yoke iron disk, and the aluminum disk are obtained. The test platform was built to test the torque and temperature of the magnetic coupling. The results show that the error between the test an... [more]

Building automation and the advancement of sustainability and safety in internal spaces benefit significantly from occupancy sensing. While particular traditional Machine Learning (ML) methods have succeeded at identifying occupancy patterns for specific datasets, achieving substantial performance in other datasets is still challenging. This paper proposes an occupancy detection method using non-intrusive ambient data and a Deep Learning (DL) model. An environmental sensing board was used to gather temperature, humidity, pressure, light level, motion, sound, and Carbon Dioxide (CO2) data. The detection approach was deployed on an edge device to enable low-cost computing while increasing data security. The system was set up at a university office, which functioned as the primary case study testing location. We analyzed two Convolutional Neural Network (CNN) models to confirm the optimum alternative for edge deployment. A 2D-CNN technique was used for one day to identify occupancy in rea... [more]

The search for charging electric vehicles using renewable energy sources and ensuring the stability of the electrical system has been growing. This has led to the development of charging stations that integrate photovoltaic systems, energy storage systems in batteries, and charging stations. The storage system allows for applications that increase the reliability of the electrical network. The objective of this work is to study, based on real operational scenarios, the impacts, and criteria of energy quality of a charging solution containing a photovoltaic system, a storage system, and a charging station. In the solution, the batteries are lead-carbon type and photovoltaics have priority in energy supply, using excess generation to charge the batteries. In this aspect, the work presents relevant contributions to the study of energy quality. An improvement in energy quality is pointed out with the use of batteries, proving that even in the most diverse operating situations, such as part... [more]

In recent years, photovoltaic energy has become a popular alternative to traditional fossil fuels due to its renewable and sustainable nature, and the incentives provided by countries to encourage research and development in this field have accelerated the implementation of photovoltaic roofs. One important factor in maximizing the efficiency of solar panels is their orientation to harness maximum irradiation with minimum roof area. In this article, an optimizer-supported east−west-oriented solar power plant installation is experimentally presented to utilize more solar energy with less area compared to wide-area south orientation. Furthermore, an analysis of different angle placements is simulated by PVSOL and PVGIS to test the robustness of the presented approach, and the pros/cons of the features of the east−west and south orientation are discussed comparatively. The obtained results are promising for the ideal placement of solar systems along with the use of optimizers to further e... [more]

Internet of Things (IoT) and mobile edge computing (MEC) architectures are common in real-time application scenarios for improving the reliability of service responses. Energy conservation (EC) and energy harvesting (EH) are significant concerns in such architectures due to the self-sustainable devices and resource-constraint edge nodes. The density of the users and service requirements are further reasons for energy conservation and the need for energy harvesting in these scenarios. This article proposes decisive task scheduling for energy conservation (DTS-EC). The proposed energy conservation method relies on conditional decision-making through classification disseminations and energy slots for data handling. By classifying the energy requirements and the states of the mobile edge nodes, the allocation and queuing of data are determined, preventing overloaded nodes and dissemination. This process is recurrent for varying time slots, edge nodes, and tasks. The proposed method is foun... [more]

The distribution network reconfiguration problem (DNRP) refers to the challenge of searching for a given power distribution network configuration with better operating conditions, such as minimized energy losses and improved voltage levels. To accomplish that, this paper revisits the branch exchange heuristics and presents a method in which it is coupled with other techniques such as evolutionary metaheuristics and cluster analysis. The methodology is applied to four benchmark networks, the 33-, 70-, 84-, and 136-bus networks, and the results are compared with those available in the literature, using the criteria of the number of power flow executions. The methodology minimized the four systems starting from the initial configuration of the network. The main contributions of this work are the use of clustering techniques to reduce the search space of the DNRP; the consideration of voltage regulation banks and voltage-dependent loads in the feeder, requiring the addition of a constraint... [more]

The energy transition requires increased end-user flexibility in consumption as a response to the more volatile production patterns of renewable resources. Automated demand-side management solutions can provide support in achieving this but struggle with trust and acceptance issues from end-users. This paper contributes insights into how communicating trustworthiness can be achieved through careful and context-aware interaction design in such systems. Core interface features such as feedback, automation transparency, control options, benefit information, and actionable information were identified and fifteen case studies from six countries were analysed with regard to provided interaction features, automation level, and end-user experiences. The results provide insights into the form and frequency of these features used at different automation levels and their varying role in trust and acceptance building. Based on our results, we recommend particular attention to providing actionable... [more]

This study provides insights into the experience gained from investigating the thermodynamic behavior of well and reservoir fluids during acid gas injection (AGI) in a hydrocarbon field to enhance oil recovery (EOR) and to reduce greenhouse gas emissions. Unlike conventional water and natural gas injection, AGI involves complicated phase changes and physical property variations of the acid gas and reservoir fluids at various pressure-temperature (P-T) conditions and compositions, and both constitute crucial parts of the EOR chain. A workflow is developed to deal with the reservoir fluid and acid gas thermodynamics, which is a key requirement for a successful design and operation. The workflow focuses firstly on the development of the thermodynamic models (EoS) to simulate the behavior of the reservoir fluids and of the injected acid gas and their integration in the field and in well dynamic models. Subsequently, the workflow proposes the thermodynamic simulation of the fluids’ interact... [more]

In order to clarify the characteristics of fine-grained sedimentary lithofacies and the depositional models in lacustrine environments of the Chang 7 Member of the Upper Triassic Yanchang Formation in the Ordos Basin, we focus on the lacustrine lithofacies classification and controlling factors. Based on the typical field sections of the southern Ordos Basin, combined with the methods of organic geochemical analysis, polarizing microscopic observation, XRD and elemental geochemistry, we summarize the main controlling factors of the lithofacies under different sedimentary environments and establish the sedimentary model under different sedimentary backgrounds. Results show that the Chang 7 Member of the Ordos Basin includes six major lithofacies types, i.e., quasi-laminated clayey shale facies, blocky silty mudstone facies, quasi-laminated silty shale facies, laminated silty shale facies, blocky mixed mudstone facies, and laminated argillaceous siltstone facies. Al2O3, MgO, CaO, Na2O, K... [more]

The transition from the current energy architecture to a new model is evident and inevitable. The coming future promises innovative and increasingly rigorous projects and challenges for everyone involved in this value chain. Technological developments have allowed the emergence of new concepts, such as renewable energy communities, decentralized renewable energy production, and even energy storage. These factors have incited consumers to play a more active role in the electricity sector and contribute considerably to the achievement of environmental objectives. With the introduction of renewable energy communities, the need to develop new management and optimization tools, mainly in generation and load management, arises. Thus, this paper proposes a platform capable of clustering consumers and prosumers according to their energy and geographical characteristics to create renewable energy communities. Thus, this paper proposes a platform capable of clustering consumers and prosumers acc... [more]

This article provides a detailed analysis of issues related to the complications while drilling in hydrate-bearing rocks of permafrost areas. The goal of the paper is to develop recommendations for preventing gas occurrence while drilling gas hydrate deposits and to eliminate gas leakiness of the intercasing space of the well. The results of modeling the effect of drilling mud injection on the temperature field of the well are presented. It is revealed that the most significant role is played by the injection rate of drilling mud and its temperature. The recommended flow rate of the process fluid should be within 0.30−0.45 m3/s, and its temperature should not exceed 20 °C. Controlling the parameters of drilling mud and its flow rate allows for avoiding intensive gas occurrence while drilling in gas hydrates. The presence of gas hydrates may be the cause of gas leakiness of the intercasing space in the permafrost area. One of the ways to eliminate leakiness is colmatation (clogging). A... [more]

Shale oil stored in the shale system occurs mainly in adsorbed and free states, and ascertaining the amount of adsorbed crude oil in shale is a method of ascertaining its free oil content, which determines the accuracy of shale oil resource evaluation. Both inorganic minerals and kerogen have the ability to adsorb crude oil, but there is controversy surrounding which plays the greatest part in doing so; clarifying this would be of great significance to shale oil resource evaluation. Therefore, in this study, the evolution states of inorganic minerals and kerogen in shale were changed using pyrolysis, and the adsorbents were prepared for crude oil adsorption experiments, to explore the effects of inorganic minerals and kerogen on the crude oil adsorption of shale. The results showed that the differences in kerogen’s structural units and content in organic-rich shale (TOC = 1.60−4.52%) had no obvious effects on its crude oil adsorption properties. On the contrary, inorganic minerals, as... [more]

Extreme fast charging (XFC) for electric vehicles (EVs) has emerged recently because of the short charging period. However, the extreme high charging power of EVs at XFC stations may severely impact distribution networks. This paper addresses the estimation of the charging power demand of XFC stations and the design of multiple XFC stations with renewable energy resources in current distribution networks. First, a Monte Carlo (MC) simulation tool was created utilizing the EV arrival time and state-of-charge (SOC) distributions obtained from the dataset of vehicle travel surveys. Various impact factors are considered to obtain a realistic estimation of the charging power demand of XFC stations. Then, a method for determining the optimal energy capacity of the energy storage system (ESS), ESS rated power, and size of photovoltaic (PV) panels for multiple XFC stations in a distribution network is presented, with the goal of achieving an optimal configuration. The optimal power flow techni... [more]

In this paper, cement mortar IN200 integrated with solid−solid PlusIce X25 commercial PCM was fully characterized for the first time via experimental tests and numerical simulations. An experimental setup was designed and built to evaluate the thermal performance of the composite. Experimental results confirmed the expected advantages of the PCM-loaded plaster in terms of inner surface temperature, inbound heat flux reduction, and the enhanced damping effect on the average temperature. The experimental results were used to validate and calibrate a finite element model implemented in COMSOL Multiphysics® 5.6. The model was adopted to carry out a parametric analysis assessing the influence of PCM mass fraction, phase transition temperature, and PCM mortar thickness. The composite thickness was the most influential parameter, resulting in an energy saving increase from 3.29% to 72.72% as it was increased from 10 mm to 30 mm. Moreover, the model was used in a set of dynamic simulations, re... [more]

Recent technological developments have led to a significant increase in energy consumption in daily life. The search for alternative means of energy production has become an important task for applied sciences and modern technology. Hydrogen technology has great potential as a source of clean energy. The production of green hydrogen is a desirable and beneficial way to contribute to the decarbonization of the energy sector. In response to the demand for environmentally friendly and economically feasible approaches, biohydrogen production from waste materials has recently attracted interest. Waste materials from industrial or municipal production can be used as low-cost substrates for biohydrogen production through microbial degradation. Green energy needs could be met through a form of sustainable development that moves hand in hand with the harnessing of the microbial potential of waste biomass. Reuse of waste materials leads to pollution reductions and energy recycling. The aim of th... [more]

Power transformers play a crucial role in maintaining the stability and reliability of energy systems. Accurate moisture assessment of transformer oil-paper insulation is critical for ensuring safe operating conditions and power transformers’ longevity in large interconnected electrical grids. The moisture can be predicted and quantified by extracting moisture-sensitive dielectric feature parameters. This article suggests a deep learning technique for transformer moisture diagnostics based on long short-term memory (LSTM) networks. The proposed method was tested using a dataset of transformer oil moisture readings, and the analysis revealed that the LSTM network performed well in diagnosing oil insulation moisture. The method’s performance was assessed using various metrics, such as R-squared, mean absolute error, mean squared error, root mean squared error, and mean signed difference. The performance of the proposed model was also compared with linear regression and random forest (RF)... [more]

In this paper, we analyze the role of economic policy in prompting energy efficiency. This study reviews three aspects, theoretical, empirical, and existing policies to evaluate the relationship of energy efficiency and economic policy. This study furthermore identifies the existing issues from a policy perspective in energy efficiency. Although not all public policies may be justified, it suggests that these types of financial incentives, particularly those based on economic instruments, can play a crucial role in advancing energy efficiency. Additionally, this study identifies existing issues in energy efficiency target achievement and proposes solutions based on the literature review. Finally, it provides possible future research pathways from the aspect of economic policy tools in energy efficiency.

The antlion optimizer (ALO) algorithm is used in this article for maximum power point tracking (MPPT) of a solar array. The solar array consists of a single module, while there are 20 cells in the module. The voltage and current ratings of each cell are 2 V and 2.5 A, making a 100 W array in ideal condition. However, the voltage and current characteristics of the PV cell are unable to achieve maximum power. Therefore, the ALO was used for MPPT. The results of the ALO are compared with the traditional metaheuristic approaches, perturb and observe (P&O) and flower pollination (FP) algorithms. Comparison of the ALO with the stated algorithms is conducted for two cases: when solar irradiance is 1000 W/m2 and when it drops to 200 W/m2 at first then reaches 1000 W/m2. The change of irradiance is performed to simulate the partial shading condition. The simulation results depict that maximum power for the first case using the ALO reaches 91.3 W in just 0.05 s, while the P&O and PFA reach 90 W... [more]

Inspired by pigeon feathers, the drag-reducing contribution of spanwise grooves was studied. Surface topography of the wing feather was scanned by an instrument of white light interference. Three types of grooves of triangle, rectangle, and trapezoid were adopted based on the unsymmetric microstructures found on the feather surface. Numerical simulations were conducted to analyze drag-reducing mechanisms. According to the simulation results, the rectangular groove reduced the wall shear stress more efficiently but with greater additional pressure drag, while the triangular groove was the opposite. For the trapezoidal groove similar to the feather structure, drag reduction was the best out of the three. Wind tunnel experiments for the trapezoidal groove were performed by using a cylindrical model and large-area plate. Drag reduction was confirmed from the cylindrical model at a series of velocities from 15 m/s to 90 m/s (about 16% at velocity of 30 m/s and about 8.5% at velocity of 60 m... [more]

While international trade drives countries’ economic growth and promotes employment, it also has some environmental impact. To investigate the impact of trade on carbon emissions and employment, this study performs a detailed decomposition and measurement of embodied carbon emissions and employment in value-added trade between China, Japan, and Korea from 2007−2019. The current study established that, while China’s trade with Japan and Korea created many domestic jobs, it also resulted in significant domestic carbon emissions. While Japan and Korea’s trade with China reduced carbon emissions, employment in their own countries was reduced and replaced by employment in China. At the value chain route level, trade among the three countries through each value chain route either achieves employment promotion at the cost of increased carbon emissions or promotes domestic emissions reduction at the cost of employment loss. However, it is worth noting that, when trade between Japan and Korea w... [more]

A high load of inorganics in raw lignocellulosic biomass is known to inhibit the yield of bio-oil and alter the chemical reactions during fast pyrolysis of biomass. In this study, palm kernel shell (PKS), an agricultural residue from palm oil production, and two other woody biomass samples (mahogany (MAH) sawdust and iroko (IRO) sawdust) were pretreated with distilled water or an acidic solution (either acetic, formic, hydrochloric (HCl) or sulfuric acid (H2SO4)) before fast pyrolysis in order to investigate its effect on the primary products and pyrolysis reaction pathways. The raw and pretreated PKS, MAH and IRO were pyrolysed at 600 °C and 5 s with a micro-pyrolyser connected to a gas chromatograph−mass spectrometer/flame ionisation detector (GC-MS/FID). Of the leaching solutions, HCl was the most effective in removing inorganics from the biomass and enhancing the primary pyrolysis product formed compared to the organic acids (acetic and formic acid). The production of levoglucosan... [more]

Cementitious material based on synergistic industrial wastes can be used as a new product for low-carbon transformation. It can aid in resource recycling and suitable consumption and utilisation of various industrial wastes. The proposed material can reduce a large amount of CO2 emitted during calcination in cement production and the decomposition of raw limestone. In addition, the material exhibits high durability and high resistance to corrosion in the marine environment that can further reduce CO2 emissions over the lifecycle of the carbon footprint of the building. Currently, many similar chemical kinetic processes and mineralogical reaction processes of particle migration and rebinding exist in the hydration and hardening reactions, service processes and durability evolution of different industrial waste cementitious systems for low-carbon production. The theoretical basis of preparing various low-carbon cementitious materials (LCCMs) with industrial waste systems is discussed her... [more]