Coal measure gas resources, including coalbed methane (CBM), shale gas, and tight gas are abundant in the Daning−Jixian Block. The complexity of the source−reservoir−cap relationship in the coal measure strata leads to unclear symbiotic characteristics and gas accumulation, which in turn, restrict the exploration and exploitation of the coal measure gas. In this study, the enrichment and accumulation of coal measure gas are discussed and summarized in detail. The results show that there are eight lithofacies and six reservoir combinations in the superposed strata of the coal measures in the study area. Controlled by the tidal flat-lagoon facies, the “sand-mud-coal” type mainly distributes in P1s2 and P1t, showing a good gas indication. Based on the variation of the total hydrocarbon content, key strata, and pressure coefficient of the coal measure gas reservoir, four superposed gas-bearing systems are identified in the vertical direction. According to the relationship between the gas-b... [more]

The paper deals with the self-ignition and combustion of hydrogen jets in a high-speed transverse flow of hot vitiated air in a duct. The Improved Delayed Detached Eddy Simulation (IDDES) approach based on the Shear Stress Transport (SST) model is used, which in this paper is applied to a turbulent reacting flow with finite rate chemical reactions. An original Adaptive Implicit Scheme for unsteady simulations of turbulent flows with combustion, which was successfully used in IDDES simulation, is described. The simulation results are compared with the experimental database obtained at the LAERTE experimental workbench of the ONERA—The French Aerospace Laboratory. Comparison of IDDES with experimental results shows a strong sensitivity of the simulation results to the surface roughness and temperature of the duct walls. The results of IDDES modeling are in good agreement with experimental pressure distributions along the wall and with the results of videoregistration of the excited radic... [more]

Reducing the phenomenon of food waste and effective management of already wasted food in the form of post-consumer waste, included in the source-separated organic fraction of municipal solid waste (SS-OFMSW) from households and catering facilities, are some of the key challenges of the circular economy (CE), in particular in highly urbanized areas. The basis for the effective use of this waste is the knowledge of its physical and chemical properties. The main objective of the paper is to identify the key technological and organizational parameters for selective collection determining the characteristics of the SS-OFMSW and, consequently, the optimal path for its management. This paper presents the results of qualitative research of SS-OFMSW generated in the capital of Poland—Warsaw—coming from three sources: multi- and single-family housing and catering facilities. The collection efficiency of this waste was determined in the form of quality in container rate (QCR = 92−97%) and variabi... [more]

Lithium-ion batteries (LIBs) have already gained significant attention because they have satisfactory energy density and no memory effect, making them one of the most widely used energy storage systems. In commercial LIBs, graphite is widely used as an anode material due to its excellent electrical conductivity and structural stability; however, as they are limited by their restricted theoretical capacity, there is an urgent need for the development of novel anode materials for LIBs. For this purpose, we designed a nitrogen-doped two-dimensional layered porous carbon material (2D-PNC) based on a covalent organic framework (COF) generated by a Schiff base reaction as a precursor. The characterization analysis results show that 2D-PNC is made of stacked two-dimensional ultra-thin carbon sheets with a porous structure. This unique structure is beneficial for electrolyte impregnation and lithium-ion storage, resulting in excellent electrochemical performance of 2D-PNC, which shows a high s... [more]

The delivery of electricity employing an electromagnetic field that extends across an intervening region is called a wireless power transfer (WPT). This approach paves the way for electric vehicles (EVs) to use newly available options to reduce their environmental impact. This article is a review that examines the WPT technology for use in electric vehicle applications from both the technical aspect and the environmental impact. This review will attempt to accomplish the following objectives: (1) describe the present state of the technology behind the development and application of a WPT across the transportation industry; (2) substantiate the actual implementation of WPT EV systems; and (3) estimate the functioning of the autonomous system, as well as detect the potential stumbling blocks and openings for enhancement. The most recent advancements and implementation in compensating topologies, power electronics converters, and control techniques are dissected and debated scientifically... [more]

This paper proposes a recursive conic approximation methodology to deal with the optimal power flow (OPF) problem in unbalanced bipolar DC networks. The OPF problem is formulated through a nonlinear programming (NLP) representation, where the objective function corresponds to the minimization of the expected grid power losses for a particular load scenario. The NLP formulation has a non-convex structure due to the hyperbolic equality constraints that define the current injection/absorption in the constant power terminals as a function of the powers and voltages. To obtain an approximate convex model that represents the OPF problem in bipolar asymmetric distribution networks, the conic relation associated with the product of two positive variables is applied to all nodes with constant power loads. In the case of nodes with dispersed generation, a direct replacement of the voltage variables for their expected operating point is used. An iterative solution procedure is implemented in orde... [more]

The high separation of crude oil supply and demand markets has led to the formation of a global crude oil trading system. This paper constructs global crude oil trade networks, integrates macro, meso, and micro network analysis methods, combines geospatial visualization techniques, and then portrays the spatiotemporal patterns and topological evolution of the global crude oil trade networks. Thus, it attempts to dig deeper into the world crude oil competition and cooperation links and evolution laws and provides a scientific reference for a comprehensive understanding of the global crude oil market dynamics. The results show that: (1) After three fluctuations of increase and decrease since 2000, the global crude oil trade volume is entering the adjustment period, and the scale of the crude oil market is rising slowly. (2) The international crude oil trade has formed trade network patterns with complex structures, clear hierarchy and unbalanced distribution. The “rich club” phenomenon i... [more]

This article is written within the European Project “THREE-Lanka” which has the aim of modernizing the higher education related to Renewable Energy (RE) in Sri Lanka. The paper presents the outcomes of analysing various incentive schemes to stimulate RE development. In Europe, there was substantial growth in RE installation through generous incentives in the first years. Then, to regulate this growth, in recent years, the auction system has been introduced to improve the competition among companies that install RE plants. In Sri Lanka, on the other hand, the main energy tariff policies focus on the spread of PhotoVoltaics (PV) through contributions based on the electricity fed into the grid. This paper provides an updated view of the evolution of the energy tariff policies in the relevant European countries with respect to Sri Lanka, covering some recent policy developments. Within the Sri Lankan framework, four case studies involving residential, commercial, and industrial users are o... [more]

The national carbon emission trading mechanism is an important policy tool for the Chinese government to control and reduce greenhouse gas emissions by using the market mechanism. The Beijing−Tianjin−Hebei power market is the focus of energy conservation and consumption reduction in China. Problems have already existed in the synergic development of the Beijing−Tianjin−Hebei power market and carbon trading market. In this article, the development status of the Beijing−Tianjin−Hebei power market is analyzed and the coupling mechanism between the carbon market and power market is combed out to build a synergism model of the carbon market and the Beijing−Tianjin−Hebei power market based on the system dynamics. From the research results, firstly, the Beijing−Tianjin−Hebei power market comes with a high energy consumption intensity and a high proportion of carbon emissions. The coupling of carbon market and power market forces the power industry to reduce carbon emissions through the effect... [more]

The article presents the results of a simulation of changes in gallium phosphide (GaP) resistivity under the influence of lighting. The adopted model of the defect structure is presented along with the defect parameters. Initial conditions created on the basis of a tested material sample, labeled GaP-1, made of monocrystals of semi-insulating gallium phosphide (SI GaP), are presented. The simulation methodology and the created model of the kinetics equations are described. As a result of the simulation, the values of the photocurrent and the electron-hole pair generation coefficient G were assigned to data obtained experimentally depending on the carrier lifetime coefficient τ. Changes in resistivity and concentration of electrons and holes in the bands for gallium phosphide with a structure consisting of five defects are presented. The proposed simulation method can be used to calculate switch-on and -off times and photocurrent values for the semiconductor materials used to construct... [more]

Europe is currently facing the potentially biggest energy crisis in history. There are many reasons for this, and the current geopolitical situation makes it clear that we are being forced to take immediate action to ensure sufficient energy supplies to consumers. Until recently, the European Union was dependent on Russian energy resources (mainly oil and gas). For many years, the EU countries had been shutting down their own production and importing much cheaper raw material from Russia. The threat of a blackout is becoming increasingly possible. European governments are preparing businesses and households for the energy crisis in various ways, but there is also a great deal of mobilization to accelerate the development of renewable energy sources (RES). The aim of this study was to identify the barriers and prospects for RES development in Poland in the current geopolitical conditions. The reasons for insufficient grid HC were analyzed. Additionally, the article aimed to assess the p... [more]

The development of low-carbon technologies that will facilitate the efficient use of hydrogen (H2) as an energy carrier is a critical requirement of contemporary society. To this end, it is anticipated that the cost of H2 production will become a key factor in tandem with production efficiency, process safety, and transport. Much effort has been made to create and develop new, reversible, and sustainable H2 storage systems. Among current techniques, formic acid (FA) has been identified as an efficient energy carrier for H2 storage. Numerous homogeneous catalysts based on transition metals with high activity and selectivity have been reported for selective FA dehydrogenation. In this review, we outline the recent advances in transition-metal molecular catalysts for FA dehydrogenation. Selected catalytic systems that could be implemented on an industrial scale and considered potential materials in fuel cell (FC) technology have been cost-evaluated. We highlight some critical engineering... [more]

This work evaluated the effects of condensable syngas impurities on the cell viability and product distribution of Butyribacterium methylotrophicum in syngas fermentation. The condensates were collected during the gasification of two technical lignins derived from wheat straw (WST) and softwood (SW) at different temperatures and in the presence or absence of catalysts. The cleanest syngas with 169 and 3020 ppmv of H2S and NH3, respectively, was obtained at 800 °C using dolomite as catalyst. Pyridines were the prevalent compounds in most condensates and the highest variety of aromatics with cyanide substituents were originated during WST lignin gasification at 800 °C without catalyst. In contrast with SW lignin-based condensates, the fermentation media supplemented with WST lignin-derived condensates at 1:100 vol. only supported residual growth of B. methylotrophicum. By decreasing the condensate concentration in the medium, growth inhibition ceased and a trend toward butyrate productio... [more]

Coal’s rising prominence in the power industry has raised concerns about future CO2 emissions and energy reliability. As of 2017, it is estimated that Malaysia’s existing natural gas production can only be maintained for another 40 years. Consequently, the carbon intensity of electricity production has increased due to the increasing share of coal-fired plants and electricity infrastructure inefficiencies. To summarise, energy industries have been the highest emitters of CO2 emissions, with a 54-percent share. In response to these challenges, the government implemented a series of renewable energy (RE) policy measures. Whether these policies are sufficient in driving Malaysian energy decarbonisation is yet to be seen. In this study, we simulated different scenarios from 2015 to 2050 with an agent-based model to explore the roles of renewable energy policies towards emission reduction in the energy sector. The simulation results reveal that when all renewables initiatives were implement... [more]

This paper presents a literature review on magnetic gears, highlighting the advantages of using these technologies for mechanical power transmission applications in wind energy conversion systems and transportation, such as in electric vehicles. Magnetic gear technologies have important advantages over their mechanical counterparts. They can perform the speed change and torque transmission between input and output shafts by a contactless mechanism with a quiet operation and overload protection without the issues associated with conventional mechanical gears. The paper describes the fundamentals and operating principle of the field-modulated magnetic gear topologies and investigates the magnetic torque transmission mechanism. However, despite all the advantages highlighted in different research and development reports, there is still no convincing evidence to show that magnetic gear technologies are an acceptable alternative for industrial applications. The aim of this paper is to summa... [more]

Solar PhotoVoltaics (PV) integration into the electricity grids significantly increases the complexity of Transmission Expansion Planning (TEP) because solar PV power generation is uncertain and difficult to predict. Therefore, this paper proposes the optimal planning method for transmission expansion combined with uncertain solar PV generation. The problem of uncertain solar PV generation is solved by using Long Short-Term Memory (LSTM) for forecasting solar radiation with high accuracy. The objective function is to minimize total system cost, including the investment cost of new transmission lines and the operating cost of power generation. The optimal TEP problem is solved by the Binary Differential Evolution (BDE) algorithm. To investigate and demonstrate the performance of the proposed method, the IEEE 24-bus system and solar radiation data in Thailand are selected as a study case for TEP. The MATPOWER program written in MATLAB software is used for solving optimal power flow probl... [more]

In recent years, the interest in renewable fuels has increased mainly due to regulations regulating the permissible limits of toxic components of exhaust gases emitted by reciprocating engines. This paper presents the results of a comparison of the effects of fueling a compression-ignition piston engine with a mixture of diesel fuel and n-butanol, as well as RME (Rapeseed Oil Methyl Esters) biodiesel and n-butanol. The tests were carried out for a constant load and a wide energetic share of fuels in the mixture. The main focus was on the assessment of combustion stability, the uniqueness of the combustion stages, and the assessment of the fuel type influence on the CA50 angle. The tests show that RME offers the possibility of efficient combustion with n-butanol with up to 80% energy share. The share of n-butanol has a positive effect on the engine’s efficiency and very effectively reduces soot emissions. Without the influence on COVIMEP, the share of n-butanol up to 40% in the mixture... [more]

Based on the theories of mass conservation and coalbed methane (CBM) adsorption/desorption, this paper first establishes a novel reservoir pressure model for CBM production, following which, the CBM concentration and production models are also proposed. Then, these models are programmed and solved by means of the finite element method. Taking the Hunchun CBM field in Jilin province, China, as an example, the reservoir pressure, gas concentration, and production characteristics under different hydraulic fracture forms are simulated and investigated. In conclusion, the reservoir pressure decreases very rapidly in a small region near the fracture tip, which we called the “reservoir pressure singularity”. The existence of a hydraulic fracture greatly reduces the reservoir pressure in the process of CBM exploitation. The permeability sensitivity coefficient of reservoir pressure, Rpk, is defined to quantitatively describe the influence of coal seam permeability on the evolution of reservoir... [more]

The high-efficiency operation of photovoltaic and wind systems is affected by many factors and parameters that should be continuously monitored. Since most of the variable factors are related to weather conditions, they are difficult to predict. Therefore, in order to optimize the operating point of a photovoltaic or wind power plant, it is necessary to observe changes in the subject area. The operation of photovoltaic and wind power plants can complement each other. The results recorded at the hybrid power plant of the Faculty of Electrical Engineering of Bialystok University of Technology are useful for a comprehensive analysis of the power plant operation and the ways to optimize it. This paper presents the influence of environmental factors on the operation of a hybrid photo-voltaic−wind power plant located in the city of Bialystok, Poland. The aim of the study was to present the variable factors on the optimal adjustment of the location of the power plant elements at the stage of... [more]

This work deals with the application of the temperature oscillation method to measure local values of the heat transfer coefficient in laminar flow in a straight horizontal pipe and in a pipe with a bend. This method, applied here for the first time in such experimental conditions, uses a time-varying heat flux as a boundary condition, which is a condition of the third kind. Since an analytical solution for such conditions could not be identified in the existing literature, a numerical study of this problem is applied here. Experimental data for a straight horizontal pipe confirm the numerical results within a reasonable level of error. Experimental measurements on a straight horizontal tube are consistent with predicted results in the literature for both total and local heat transfer coefficient values. The measurements on bent tubes show a very significant influence on the local values compared to the straight tube and in the overall values this change appears as an increase in the h... [more]

Synchronized phasor measurement systems are being widely used around the world and have become essential elements in the evolution of the operation of large electrical power systems (EPS). These systems, called Phasor Measurement Units (PMUs), are capable of recording and communicating dynamic data from the EPSs in a synchronized way by GPS and with a high sampling rate, generate a huge set of data that, among many applications, has the capacity to detect events. In this way, this work presents a data management system architecture applied to a real PMU system located in the state of Paraná, Brazil that detects and storages events using principal component analysis and Pearson correlation. This method can detect and store electrical events that occurred during the operation of the national interconnected system of Brazil with good results.

The planning of efficient policies based on forecasting electricity demand is essential to guarantee the continuity of energy supply for consumers. Some techniques for forecasting electricity demand have used specific procedures to define input variables, which can be particular to each case study. However, the definition of independent and casual variables is still an issue to be explored. There is a lack of models that could help the selection of independent variables, based on correlate criteria and level of importance integrated with artificial networks, which could directly impact the forecasting quality. This work presents a model that integrates a multi-criteria approach which provides the selection of relevant independent variables and artificial neural networks to forecast the electricity demand in countries. It provides to consider the particularities of each application. To demonstrate the applicability of the model a time series of electricity consumption from a southern re... [more]

The development of efficient and sustainable marine energy converter systems is a great challenge, especially in remote areas such as oceanic islands. This work proposes a numerical modeling methodology to assess the mechanical behavior of a wave energy converter (WEC) to be applied outside Fernando de Noronha Island (Pernambuco, Brazil). First, oceanographic data collected in situ were analyzed to determine different sea state scenarios in the region. The Airy theory and second-order Stokes’ theory were used to obtain the velocity profiles for the maximum and operational swells. These profiles were then implemented in a flow model developed in COMSOL Multiphysics software (Burlington, MA, USA) to calculate the wave distributions of pressure on the WEC structure. Finally, wave pressure distributions obtained from simulations were implemented in a static analysis of the system by the finite element method using SolidWorks (France). The results highlighted the most critical system inclin... [more]

This study identifies the optimal operational strategy for floating photovoltaic power plants and pumped hydroelectric power plants in the day-ahead Iberian electricity market. Different operating scenarios were analysed based on forecast accuracy in addition to any deviations occurring in the day-ahead market, taking into account the rules of the electricity market and the technical operational limitations of both plants. These scenarios show the choice between the independent mode of operation and the joint mode of operation of both plants. Five scenarios have been studied, with upward and downward deviations of 5%, 10%, 25% and 50% considered. These scenarios can be classified into two groups. If there are deviation penalties, group 1; or without deviation penalties, group 2. Scenarios 3 and 4 belong to the first group and scenarios 1, 2 and 5 to the second group. In the scenarios of the first group, the price deviations are used, and in the scenarios of the second group, the margin... [more]

This manuscript proposes a novel approach for determining phase and neutral-current-ripple RMS in grid-connected four-leg inverters with the neutral inductor. The harmonic pollution is determined for any arbitrary pulse width modulation (PWM) technique and a generic value of the neutral inductor. Thanks to the proposed approach, it is possible to describe the neutral inductor in a parametric way with respect to phase inductors and obtain a wide range of results, ranging from a direct neutral connection (no neutral inductor) to a conventional three-phase inverter (no fourth wire) for any value of modulation index and common mode injection. The results permit one to compare different design choices in multiple scenarios effectively. The findings were validated by numerical simulations and experimental tests employing the most popular PWM techniques, such as space vector PWM (SVPWM) and discontinuous PWM (DPWM).