The relevance of this article is due, on the one hand, to the importance of the oil and gas industry in the development of Iraq and, on the other hand, the inability to enhance the existing capacities of the gas industry due to both serious systemic internal causes and external problems. The objective of this article is to study the prospects of the gas industry in conjunction with the oil industry, and develop a strategy for their development based on the forecasting of future scenarios. In the article, the research methods used included a systematic analysis of economic, social and cultural conditions, considering the history of Iraq, including a review of statistical data and a variety of sources. The article proposes a method for choosing the industry development strategy on the basis of an analytical hierarchy process, based on an algorithm of iterative processes using an analysis of hierarchies. To clarify the actors’ policies and strategic goals and to find the optimal solution,... [more]

Zr2Fe alloys have been widely used in fusion energy and hydrogen energy for hydrogen storage. However, disproportionation reactions occur easily in Zr-based alloys at medium and high temperatures, which greatly reduces the storage capacity of the alloys, and is not conducive to repeated cycle applications. The doping of Zr-based alloys with appropriate transition metal elements has been found to significantly improve their H storage properties and prevent hydrogen disproportionation. A convenient approach is required to efficiently predict the desirable doped structures that are physically stable with optimal properties. In this paper, based on the MatCloud High-Throughput Material Integrated Computing Platform (MatCloud), an automated process algorithm was established to solve the disproportionation reaction of Zr2Fe. Rather than testing the doping materials one by one, such high-throughput material screening is effective in reducing the computational time. The structural stability of... [more]

Combustible renewable energy can be an effective instrument to confirm sustainable development in reducing CO2 emissions to Gross Domestic Product (GDP) per capita in developing countries. However, connecting to some developing regions, the main research question is to what extent, in EU post-communist fast-developing countries (Visegrad Countries/Czech Republic, Slovakia, Hungary, Poland), will meeting the climate change preferences affect the use of biomass for energy and waste incineration, and how will this affect GDP growth? In addition, of course, what the Balkan countries can learn from this is also very important. The study investigates the relationship between GDP per capita, CO2 emissions, and Combustible Energy and Waste Consumption (CEWC). According to the Hausman test, the regression model along with random effect is the appropriate method for panel-balanced data as of 2008 to 2020 concerning Balkan countries. The data was divided into three categories: 10 Balkan countries... [more]

The loss of cold air from the blade edge plates of the turbine has a negative impact on engine performance and safety. Using an experimental method, this paper investigates the effect of geometric and aerodynamic parameters on cold air leakage through pressure and mass flow measurements. Based on the results, it can be concluded that, with a change in sheet spacing, the proportion of bypass leakage and clearance leakage changes. At the same sheet spacing, the edge plate clearance is increased from 1 mm to 1.1 mm, resulting in a 30% increase of total leakage and a 25.7% increase of leakage equivalent mass flow. The edge plate clearance was increased from 1.1 mm to 1.2 mm, the total leakage increased by 19.2%, and the equivalent mass flow of leakage was 19%. The proportion of clearance leakage in the total leakage increased gradually for a given edge plate clearance. When the sheet spacing was 1 mm, bypass leakage accounted for 68% of the total leakage and was the primary source of leaka... [more]

This paper aims to review existing energy-sector and hydrogen-energy-related legal, policy, and strategy documents in the ECOWAS region. To achieve this aim, current renewable-energy-related laws, acts of parliament, executive orders, presidential decrees, administrative orders, and memoranda were analyzed. The study shows that ECOWAS countries have strived to design consistent legal instruments regarding renewable energy in developing comprehensive legislation and bylaws to consolidate it and to encourage investments in renewable energy. Despite all these countries having a legislative basis for regulating renewable energy, there are still weaknesses that revolve around the law and policy regarding its possible application in green hydrogen production and use. The central conclusion of this review paper is that ECOWAS member states presently have no official hydrogen policies nor bylaws in place. The hydrogen rise presents a challenge and opportunity for members to play an important r... [more]

This paper presents a comparative study among switching control strategies for Buck−Boost converters, taking into account essential aspects in practical implementations, as the switching frequency variation concerning different output voltages and the responses in the transient and steady-states. More specifically, we have considered three switching strategies of min-type, where two of them permit high switching frequencies, while the other considers a limited frequency control strategy. Moreover, we have generalized the control techniques available in the literature to make them able to operate under changes in the equilibrium points without the need for a redesign. A conventional PI controller based on pulse-width modulation (PWM) is adopted for comparison purposes. In contrast to PWM-based control, which operates in the maximum switching frequency, the min-type strategies present variation in the switching frequency that depends on the operation point and may lead to a power loss re... [more]

A high share of distributed energy resources (DERs) in power distribution grids has posed many challenges for system operation and control. Microgrid (MG) application with different distributed control approaches for DERs has been drawn a lot of attention from the research community to provide more flexibility, reliability and resilience for the system. This paper develops a distributed secondary control for DERs in MGs and on top of that using synchronous condenser (SC) participating in the secondary control for voltage support. The proposed distributed secondary control framework of MGs is designed to obtain four objectives as follows: (i) frequency restoration, (ii) average voltage restoration, (iii) arbitrary active power sharing among SGs and BESSs and (iv) arbitrary reactive power sharing among all SGs, BESSs and SCs. The comparison results under different scenarios show that with SC participating in the distributed secondary control in MGs, the system frequency and voltage respo... [more]

The design of an offshore wind turbine system varies with the turbine capacity, water depth, and environmental loads. The natural frequency of the structure, considering foundation flexibility, forms an important factor in structural design, lifetime performance estimates, and cost estimates. Although nonlinear numerical analysis in the time domain is widely used in the offshore industry for detailed design, it becomes necessary for project planners to estimate the natural frequency at an earlier stage and rapidly within reasonable accuracy. This paper presents a compendium of mathematical expressions to compute the natural frequencies of offshore wind turbine (OWT) structures on various foundation types by assimilating analytical solutions for each type of OWT, obtained by a range of authors over the past decade. The calculations presented can be easily made using spreadsheets. Example calculations are also presented where the compiled solutions are compared against publicly available... [more]

Kron reduction is a general tool of network simplification for flow calculation. With a growing number of flexible loads appearing in distribution networks, traditional Kron reduction cannot be widely used in control and scheduling due to the elimination of controllable and variable load buses. Therefore, this paper proposes an improved Kron reduction based on node ordering optimization whose principles guarantee that all the boundary nodes are retained eventually after eliminating the first row and the first column in every step according to the order, thereby making it possible to take full advantage of their potential to meet different requirements in power system calculation and dispatching. The proposed method is verified via simulation models of IEEE 5-bus and 30-bus systems through illustrating the dynamic consistency of the output active power of the generator nodes and the power flow data of preserved nodes before and after reduction.

The self-oscillation of the cavitating vortices is one of the dangerous phenomena of hydraulic turbine operation near full-load conditions. This work is an attempt to generalize data and expand insight on the phenomenon of self-excited oscillations by comparing the experimental results obtained on a simplified turbine and scaled-down pump−turbine models. In both cases, a series of high-speed imaging was carried out, which made it possible to study these phenomena with high temporal resolution. The high-speed imaging data was subjected to additional processing such as binarization, cropping, and scaling. For a simplified turbine model, the volume of the vapor cavity was calculated based on the assumption of the axial symmetry of the cavity, after which fast Fourier transform (FFT) analysis was carried out. A proper orthogonal decomposition (POD) analysis was also performed to examine individual modes in the original digital imaging data. For the pump−turbine, visualization data on the c... [more]

Europe’s ambition to be the first climate-neutral continent and to achieve net-zero greenhouse gas emissions by 2050 will result in changes to the energy systems of many countries. This overlaps with the principles of circular economy, energy independence, and the continuity of operations enshrined in many national and regional documents. From the above, a scenario based on renewable resources emerges. However, in a country such as Poland, with conventional energy sources and large state participation in the sector, is this feasible? The authors assumed that the urgent need for a turbulence-sensitive analysis of energy sector changes can be met by using a new view, defined by the authors as a matrix of four oceans scenarios. Black, Grey, Red and Green scenarios are determined by the proportion of the state and the local-community sector. Then, assuming the possibility of introducing two of them by 2050—Green (radical) and Red (competitive)—empirical research was carried out on a purpos... [more]

The paper is focused on the formalization of an experimental procedure aimed to characterize the efficiency behaviour of a Permanent Magnet Synchronous Motor-based drive. The characterization is intended to expose the analytical behaviour of the system efficiency by the actual operating condition assigned through torque/speed value. The availability of such a relation in a simple analytical form would allow for real-time adjustment by advanced power management strategies to maximize the whole system efficiency. The proposed method is based on a defined set of measures corresponding to several drive operating conditions. A straightforward elaboration procedure is then formulated with the aim to quantify the different parameters, which intervene in the efficiency characterization. The method has been applied on a 155 kW drive. The results show that good accuracy is achieved while keeping the analytical approach relatively simple.

Different factors affect solar photovoltaic (PV) systems by decreasing input energy and reducing the conversion efficiency of the system. One of these factors is the effect of snow cover on PV panels, a subject lacking sufficient academic research. This paper reviews and compares current research for snow removal in solar PV modules. Additionally, this paper presents the design, analysis and modelling of a smart heating system for solar PV Electric Vehicle (EV) charging applications. The system is based on a bidirectional DC-DC converter that redirects the grid/EV-battery power into heating of the solar PV modules, thus removing snow cover, as well as providing the function of MPPT when required to charge the EV battery pack. A control scheme for each mode of operation was designed. Subsequently, a performance evaluation by simulating the system under various conditions is presented validating the usefulness of the proposed converter to be used in solar PV systems under extreme winter... [more]

There are rare comparative studies on the geological characteristics of shale in different members of Permian Fengcheng Formation in Mahu Sag, Junggar basin, China. In order to compare the mineral composition, physical properties, and geochemical characteristics of shale in three members of Fengcheng Formation in Mahu Sag, a large number of test data such as X-ray diffraction, high-pressure mercury injection, organic carbon, rock pyrolysis, and vitrinite reflectance were collected and analyzed. Results showed that the content of clay minerals in the shale of the third member of Fengcheng Formation (P1f3) is the highest. The content of carbonate minerals is the highest and the content of clay minerals is the lowest in the shale of the second member of Fengcheng Formation (P1f2). The content of felsic minerals is the highest and the content of carbonate minerals is the lowest in the shale of the first member of Fengcheng Formation (P1f1). The physical properties of the shale of P1f3 are... [more]

Data are an important asset that the electric power industry have available today to support management decisions, excel in operational efficiency, and be more competitive. The advent of smart grids has increased power grid sensorization and so, too, the data availability. However, the inability to recognize the value of data beyond the siloed application in which data are collected is seen as a barrier. Power load time series are one of the most important types of data collected by utilities, because of the inherent information in them (e.g., power load time series comprehend human behavior, economic momentum, and other trends). The area of time series analysis in the energy domain is attracting considerable interest because of growing available data as more sensorization is deployed in power grids. This study considers the shapelet technique to create interpretable classifiers for four use cases. The study systematically applied the shapelet technique to data from different hierarchi... [more]

This article introduces a three-phase capacitor clamped inverter with inherent boost capability by relocating the filter components from the AC side to the configuration’s midpoint. This topology has several distinguishing characteristics, including: (a) low component count; (b) high DC-AC gain; (c) decreased capacitor voltage stresses; (d) improved power quality (extremely low voltage and current THDs) without the use of an AC-side filter; and (e) decreased voltage stresses on power semiconductor devices. Simulations were carried out on the MATLAB Simulink platform, and results under steady-state conditions, load and reference change conditions, and phase sequence change conditions, along with THD profiles, are presented. This inverter’s performance was compared to that of similar converters with intrinsic gain. A 1200 W experimental prototype was built to demonstrate the system’s feasibility and benefits. When compared to existing topologies, simulation and experimental results indic... [more]

The Lower Paleozoic marine shale in southern China has undergone several strong tectonic transformations in an extensive region outside the Sichuan Basin. Although some shale strata underwent strong deformation, they still contain a significant amount of shale gas. The gas preservation mechanism in the strongly deformed shale has become the focus of attention. In this paper, the Lower Cambrian gas-bearing shale samples with a strong deformation taken from an exploration well in northern Chongqing, China, were investigated on their pore types and structure, with the aim to reveal the reason for the gas preservation. The pore types of the Lower Cambrian shale are dominated by microfractures and interparticle (interP) pores occurring mainly between clay minerals and between organic matter (OM) and clay minerals, while pores within OM that can be observed by FE-SEM (field emission-scanning electron microscopy) are rare. The shale has a low porosity, with an average of 1.56%, which is mainl... [more]

Alloy systems comprised of silicon with germanium, lead with tellurium, and bismuth with antimony have constituted a majority of thermoelectric applications during the last half-century. These legacy materials are primarily covalently bonded with a maximum ZT near one. Silicon−germanium alloys have provided the thermal to electrical conversion for many of NASA’s radioisotope thermoelectric generator (RTG) configurations and for nearly all of its deep space and outer planetary flights, such as Pioneer I and II, Voyager I and 11, Ulysses, Galileo, and Cassini. The remarkable success of these materials and their respective devices is evidenced by the fact that there has never been a failure of the RTG systems even after over 1 billion cumulative mission-hours. The history of this alloy system as a thermoelectric conversion material spans over six decades and research to further improve its performance continues to this day. Si-Ge alloys have long been a mainstay of thermoelectric research... [more]

The COVID-19 pandemic has had a significant impact on the supply chains of traditional fossil fuels. According to a report by the International Energy Agency (IEA) from 2020, oil-refining activity fell by more than the IEA had anticipated. It was also assumed that the demand in 2021 would likely be 2.6 million bpd below the 2019 levels. However, renewable markets have shown strong resilience during the crisis. It was determined that renewables are on track to meet 80% of the growth in electricity demand over the next 10 years and that sustainable energy will act as the primary source of electricity production instead of coal. On the other hand, the report also emphasized that measures for reducing environmental pollution and CO2 emissions are still insufficient and that significant current investments should be further expanded. The Sustainable Development of Energy, Water and Environment Systems (SDEWES) conference series is dedicated to the advancement and dissemination of knowledge... [more]

Minimising dry matter losses during storage of comminuted forest fuels is desirable from both an economic and a sustainability perspective. This study examined fuel quality and amount of recovered energy during the storage of forest wood chips stored at full industrial scale at three locations, and the effect of sieving and covering piles with a water-resistant, vapour-permeable fabric. Sieving wood chips before storage, that is, reducing the number of fines smaller than 8 mm, reduced the cumulative dry matter losses to <2%, while cumulative dry matter losses after storage for 4−6 months using current practices, that is, unsieved and uncovered, reached 10.6%. The combined effect of storage management led to a value loss of 11.5%, while both covering and sieving led to lower losses, with the combination of sieving and covering giving a 1.3% value increase, and thus, increased storability.

To address such challenges as an uncertain number of demagnetization poles of the permanent magnet synchronous motor (PMSM) and cases in which the fault cannot be located, this paper proposes a fault identification and location methodology based on the analysis of the motor stator current. First, the influence of the irreversible demagnetization of permanent magnets on the analytical model of the back electromotive force (Back-EMF) of the rotor in a single motor stator slot is analyzed. Moreover, considering the topology of the motor, the influence of the demagnetization fault on the stator phase current and branch current is analyzed. Since the stator phase currents cannot diagnose the partial demagnetization faults of PMSM with some topological structures, the stator branch current is selected as the signal for the identification and localization of the demagnetization fault. Secondly, the demagnetization fault diagnosis and mode recognition of the motor are carried out through the a... [more]

Condensation heat transfer characteristics (using R410A as the working fluid) were studied experimentally to evaluate the heat transfer performance in copper and stainless-steel heat transfer tubes (smooth and enhanced). Experiments were carried out for a mass flux that varied from 250 to 450 kg m−2 s−1, at a saturation temperature of 318 K. Single-phase heat balance verification found that the heat loss is less than 6%, and the deviation between single-phase experimental results and various prediction correlations is less than 15%. Additionally, tube side condensation flow patterns were observed and recorded. Experimental results found that the enhancement ratio of the condensation heat transfer coefficient (enhanced tube/smooth tube) of the three-dimensional surface (1EHT) tube is in the range of 1.15~1.90, while the ratio of the micro-fin (HX) tube is in the range of 1.18~1.80. Heat transfer performance is affected by material conductivity, with the thermal conductivity of the smoot... [more]

This research focuses on improving the photoelectrochemical performance of binary heterostructure Ag2S/ZnO NRs/ITO by manipulating synthesis conditions, particularly the concentrations of sliver nitrate AgNO3 and thiourea CS(NH2)2. The photoelectrochemical performance of Ag2S/ZnO nanorods on indium tin oxide (ITO) nanocomposite was compared to pristine ZnO NRs/ITO photoanode. The hydrothermal technique, an eco-friendly, low-cost method, was used to successfully produce Ag2S/ZnO NRs at different concentrations of AgNO3 and CS(NH2)2. The obtained thin films were characterized using field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-vis), and photoelectrochemical studies (PECs). We observed that there was an enhancement in absorbance in the visible region and effective photoelectron transfer between the Ag2S/ZnO NRs/ITO photoelectrode and the electrolyte Red-Ox when illuminated with... [more]

This Special Issue aims at collecting new research contributions and perspectives on the topic of the monitoring and automation of modern power systems [...]

Shale oil is an unconventional oil resource that needs to be developed and utilized urgently. However, the Chang 7 shale in the Ordos Basin, as the most typical continental source rock in China, is limited by the study of organic matter (OM) enrichment factors in continental lacustrine facies, and there are still controversies about the controlling factors, which limit the progress of oil and gas exploration. This paper aims to reconstruct the paleoenvironment of Chang 7 shale in the southern margin of Ordos Basin and reveal the controlling factors of organic rich shale by organic and elemental analysis, X-ray diffraction (XRD) analysis, thin section observation, and scanning electron microscopy-energy dispersive spectrometer (SEM-EDS) analysis. The results show that during the deposition period of Chang 7 shale, the climate was warm and humid, the lake water has strong reducing, low salinity and rapid depth changes. Total organic carbon (TOC) is positively correlated with salinity and... [more]