Metal halide perovskites are excellent semiconductors materials that can be exploited in many fields, from the vastly explored photovoltaics to the recent applications in photocatalysis. One of the material’s known limitations is the poor resistance to moisture which induces degradation, triggered by the soft and defective nature of its surface. In this study, we explore non-equilibrium plasmas, to deposit a fluorocarbon polymer on the surface of a MAPbI3 film. We found that the treatment generally enhances the film stability over time, and in certain conditions it improves the perovskite optical properties, demonstrating to be a good strategy aiming defects passivation. Thanks to the solvent-free and non-invasive nature of plasmas, this technique has the potential to be extensively applied to a wide range of perovskite materials targeting different applications.

The goal of carbon neutrality is an extensive and profound economic and social change, which will have far-reaching impacts on industrial structure, energy structure, and social consumption structure. Energy sectors will face in-depth adjustment, and it is essential to optimize major structures consequently due to the foresight of talent training. This research first employs Strengths, Weaknesses, Opportunities, and Threats (SWOT) analysis, Analytic Network Process (ANP), and the weighted fuzzy Technique for Order Performance by Similarity to Ideal Solutions (TOPSIS) to formulate and analyze the structure optimization of academic disciplines, and finally, the universities featuring mining are taken as an example to verify the feasibility of the method. Results reveal that the integration of ANP, SWOT, and the fuzzy TOPSIS evaluation method is able to qualify the assessment for academic discipline optimization. The specialty structure optimization results should focus on clean, intellig... [more]

Considering the problem of passive interference caused by electromagnetic scattering effects of transmission lines to neighboring radio stations and other communication equipment, this paper refines the passive interference calculation model for UHV transmission lines. The solution calculation is carried out by the Method of Moments, and the law of passive interference effect of the tower structure, auxiliary angles, and ground roughness under different frequency incident waves, is summarized. By designing an orthogonal test, the degree of influence of the above attributing factors on passive interference results in the established joint model of three towers with two stall distances was explored by using Analysis of Variance. The results demonstrate that both auxiliary angles and rough ground show a pattern of enhanced electromagnetic scattering effect with increasing plane wave frequency in single-factor analysis. When multiple factors are combined, the rough ground has a significant... [more]

The lower price of energy leads to higher coal consumption in China. The idea of an “environment-for-trade policy” could be used to achieve an international competitive advantage, which, in turn, has important implications. To address the issue, we develop properties to examine the link between the low price of energy and strategic environmental policy in China and investigate the choice of policy instruments in a strategic environmental policy model with vertical contracts. In addition, to contribute to the literature on strategic environmental policy, this paper also develops properties to investigate different choices of instruments for the environmental policy and includes the degree of energy marketization for the wholesale price in the study. To do so, we assume that the wholesale price of the polluting input increases with the market price. By using this assumption, this paper analyzes the effects of two instruments of the environmental policy on social welfare and concludes tha... [more]

Recently, false data injection attacks (FDIAs) have been identified as a significant category of cyber-attacks targeting smart grids’ state estimation and monitoring systems. These cyber-attacks aim to mislead control system operations by compromising the readings of various smart grid meters. The real-time and precise locational identification of FDIAs is crucial for smart grid security and reliability. This paper proposes a multivariate-based multi-label locational detection (MMLD) mechanism to detect the presence and locations of FDIAs in real-time measurements with precise locational detection accuracy. The proposed architecture is a parallel structure that concatenates Long Short-Term Memory (LSTM) with Temporal Convolutional Neural Network (TCN). The proposed architecture is trained using Keras with Tensorflow libraries, and its performance is verified using an IEEE standard bus system in the MATPOWER package. Extensive testing has shown that the proposed approach effectively imp... [more]

Coal and organic-rich shale in the Yan’an Formation in the southwestern margin of the Ordos Basin are widely developed, which is an important fact for oil and gas exploration in China that has been widely explored for a long time. In this paper, detailed sequence division and sedimentary environment analyses of the Yan’an Formation in the Pengyang area on the southwestern margin of the Ordos Basin were conducted using field outcrops, drilling cores, logging, wavelet transform and organic geochemistry. The results showed that the succession consists of some units with distinctly different characteristics. Based on the petrographic assemblage and transform wavelet characteristics, the Yan’an Formation in this area can be divided into a long-term cycle, five medium-term cycles, and eleven short-term cycles, among which coal and carbonaceous shale were mainly developed in the short-term cycles I2, III1, III2, V1 and V2. Coal and organic-rich mud shale have been developed in the Yan’an Form... [more]

In recent years, the increased distributed generation (DG) capacity in electric distribution systems has been observed. Therefore, it is necessary to research existing structures of distribution networks as well as to develop new (future) system structures. There are many works on the reliability of distribution systems with installed DG sources. This paper deals with a reliability analysis for both present and future medium voltage (MV) electric distribution system structures. The impact of DG technology used and energy source location on the power supply reliability has been analyzed. The reliability models of electrical power devices, conventional and renewable energy sources as well as information and communications technology (ICT) components have been proposed. Main contribution of this paper are the results of performed calculations, which have been analyzed for specific system structures (two typical present network structures and two future network structures), using detailed... [more]

Within the context of sustainable development and a low-carbon economy, electric vehicles (EVs) are regarded as a promising alternative to engine vehicles. Since the increase of charging EVs brings new challenges to charging stations and distribution utility in terms of economy and reliability, EV charging should be coordinated to form a friendly and proper load. This paper proposes a novel approach for pricing of charging service fees in a public charging station based on prospect theory. This behavioral economics-based pricing mechanism will guide EV users to coordinated charging spontaneously. By introducing prospect theory, a model that reflects the EV owner’s response to price is established first, considering the price factor and the state-of-charge (SOC) of batteries. Meanwhile, the quantitative relationship between the utility value and the charging price or SOC is analyzed in detail. The EV owner’s response mechanism is used in modeling the charging load after pricing optimiza... [more]

The characteristics of solar and wind energy determine that the optimization of a standalone hybrid wind turbine (WT)/photovoltaic panel (PV) system depends on the natural resources of the installation location. In order to ensure system reliability and improve the resource utilization, a method for determining the installed capacity ratio of a hybrid renewable energy system is required. This study proposes a calculation method to optimize the installed capacity ratio, considering the system reliability to meet the needs of the hybrid system to adapt to different natural resources. In this paper, a standalone hybrid WT/PV system to provide electricity for rural areas is designed. Taking the power supply guarantee rate and electricity supply continuity as indicators, the system is simulated by using the Transient System Simulator solver. The results show that the recommended installed capacity ratio of the WT and PV is 5:1 when the total solar irradiation is less than 5040 MJ/(m2·a) and... [more]

Three-dimensional (3D) seismic data and well log data were used to investigate the sandstone architecture of the Middle Jurassic deltaic reservoirs of the Zhetybay Oilfield, Mangeshrak Basin, Kazakhstan. The base-level cycles of different scales were identified and divided using well log and 3D seismic data. Five types of sedimentary boundaries were identified in the mouth bar sandstones. The boundaries divide single mouth bars. Vertically, the spatial distribution of sand bodies can be divided into superposed, spliced, and isolation modes. Laterally, contact modes can be divided into superposition, lateral, and isolation modes. We found that the base-level cycle controls the evolution of the delta front sand body architecture. In the early decline or late rise of the base-level cycle, the superimposed or spliced modes dominate the sand body. By contrast, the lateral or isolation modes dominate the sand body in the late decline or early rise of the base-level cycle. This paper proposes... [more]

This article presents a new method for the classification of machine failures using an example of selected generating sets. Measurements and an analysis of the electrical parameters, such as the phase-to-phase voltages at the terminals of a synchronous generator, armature current, and voltage and excitation current of a synchronous generator, are the basis for determining the failure symptoms. The existing energy quality coefficients are adopted as symptoms for the assessment of failures in the monitored generating set. We assume in this method that the description of the input−output relationship is in the form of a black box and use the binary diagnostics matrix (BDM) to investigate the failure−symptom relationships between the inputs (intentional failures) and outputs (failures symptoms = fault-sensitive power quality (PQ) coefficients). The method presented in this article enables the detection and classification of both electrical damage in a synchronous generator and mechanical d... [more]

Shifting from heating using fossil fuel combustion to electrified heating, dominated by heat pumps, is central to many countries’ decarbonisation strategy. The consequent increase in electricity demand, combined with that from electric vehicles, and the shift from non-renewable to renewable generation requires increased demand flexibility to support system operation. Demand side response through interrupting heating during peak demands has been widely proposed and simulation modelling has been used to determine the technical potential. This paper proposes an empirical approach to quantifying a building’s potential to operate flexibly, presenting a metric based on measured temperature drop in a dwelling under standard conditions after heating is switched off, using smart meter and internal temperature data. A result was derived for 96% of 193 homes within a test dataset, mean temperature drop of 1.5 °C in 3 h at 15 °C inside-outside temperature differential. An empirical flexibility met... [more]

In order to ensure safe working conditions for miners underground, many works are carried out in mines to strengthen and seal mining excavations. This article presents the successfully applied technology for removing water inflow from the unique Salt Mine. Failure to take such action may ultimately lead to the flooding of the “Wieliczka” Salt Mine (KSW). On the basis of the authors’ research studies, some of the implemented works at the “Wieliczka” Salt Mine are presented, the purpose of which is to better protect the mine against the risk of flooding with water. Thanks to this, the mine can safely survive for many more years. This article presents two innovative technologies in salt mines: (1) sealing of the rock mass surrounding the Kościuszko shaft casing in the “Wieliczka” Salt Mine, where jet injection was used as the basic method of making an anti-filter screen outside the shaft casing and classic injection as a supplementary method for sealing the anthropogenic embankment; (2) r... [more]

To increase combustion efficiency and reduce pollutant emissions, this study presents an online closed-loop optimization method and its application in a boiler combustion system. To begin with, three adaptive dynamic models are established to predict NOx emission, the carbon content of fly ash (Cfh), and exhaust gas temperature (Teg), respectively. In these models, the orders of the input variables are considered to enable them to reflect the dynamics of the combustion system under load changes. Meanwhile, an adaptive least squares support vector machine (ALSSVM) algorithm is adopted to cope with the nonlinearity and the time-varying characteristics of the combustion system. Subsequently, based on the established models, an economic model predictive control (EMPC) problem is formulated and solved by a sequential quadratic programming (SQP) algorithm to calculate the optimal control variables satisfying the constraints on the control and control moves. The closed-loop optimization syste... [more]

This editorial provides a synopsis of the contributions published during 2020−2021 in a Special Issue of Energies entitled “Cogeneration Economics” [...]

This Special Issue was intended to consolidate the most recent advances in the field of power electronics for renewable energy sources and electric drives [...]

This paper presents a mathematical model of heat transfer behavior between the liquid inside vertical underground geothermal pipes and the surrounding ground for heating (in the winter) and cooling (in the summer) modes in a ground heat exchanger (GHE) that can optimize its output temperature. The GHE’s output temperature reaches the appropriate value when the water velocity is lowered enough. Subsequently, the proposed model was applied to a case study of a 400-ton geothermal heat pump system (GHPS) at Oakland University, in both the heating and cooling modes, to assess its validity and improve the GHE’s performance. The model was implemented in MATLAB using an ordinary differential equation (ODE) solver. Four different water velocities were used to demonstrate the significant effect of velocity on the loop exit temperature. Model predictive control (MPC) was designed to optimize the GHE’s output temperature by controlling the water velocity, which could reduce the energy consumption... [more]

The efficiency potential of a small-size solar-pumped laser is studied here. The solar laser head was composed of a fused silica aspheric lens and a conical pump cavity, which coupled and redistributed the concentrated solar radiation from the focal zone of a parabolic mirror with an effective collection area of 0.293 m2 to end-side pump a Ce (0.1 at%):Nd (1.1 at%):YAG rod of 2.5 mm diameter and 25 mm length. Optimum solar laser design parameters were found through Zemax© non-sequential ray-tracing and LASCAD™ analysis. The utilization of the Ce:Nd:YAG medium with small diameter pumped by a small-scale solar concentrator was essential to significantly enhance the end-side pump solar laser efficiency and thermal performance. For 249 W incoming solar power at an irradiance of 850 W/m2, 11.2 W multimode solar laser power was measured, corresponding to the record solar-to-laser power conversion efficiency of 4.50%, being, to the best of our knowledge, 1.22 times higher than the previous re... [more]

The penetration of renewable energy sources (RESs) in the electrical power system has increased significantly over the past years due to increasing global concern about climate change. However, integrating RESs into the power market is highly problematic. The output of RESs such as wind turbines (WTs) and photovoltaics (PVs) is highly uncertain. Their correlation with load demand is not always guaranteed, which compromises system reliability. Distributed energy resources (DERs), especially demand response (DR) programs and energy storage systems (ESSs), are possible options to overcome these operational challenges under the virtual power plant (VPP) setting. This study investigates the impact of using a DR program and battery energy storage system (BESS) on the VPP’s internal electricity market, and also cost-minimization analysis from a utility viewpoint. Three different constrained optimal power flow (OPF) problems are solved such as base case, DR case, and BESS case to determine tot... [more]

The presented paper shows a hypothetical large solar farm that would be the only source of electricity for the entire country. The energy crisis in Europe raises the question of whether it is possible to supply an electrical system based only on renewable energy sources. What should the surface area of the solar panels be in a hypothetical large solar farm to power the entire country? In this work, we will show what requirements must be met to make this feasible. Very important differences between the installed power capacity in a coal-fired or nuclear power plant and a solar power plant are discussed. The article presents calculations of the surface area of photovoltaic panels in that solar farm for four exemplary countries in Central Europe: Poland, Germany, the Czech Republic and the Slovak Republic. These studies are particularly important for Poland, whose electrical system is still mainly based on coal-fired power plants. The hypothetical solar farm could, in practice, take the f... [more]

“Short-term load forecasting (STLF)” is increasingly significant because of the extensive use of distributed energy resources, the incorporation of intermitted RES, and the implementation of DSM. This paper provides a novel ensemble forecasting model with wavelet transform for the STLF depending on the decomposition principle of load profiles. The model can effectively capture the portion of daily load profiles caused by seasonal variations. The results indicate that it is possible to improve STLF accuracy with the proposed method. The proposed approach is tested with the data taken from Ontario’s electricity market in Canada. The results show that the proposed technique performs well in-terms of prediction when compared to existing traditional and cutting-edge methods. The performance of the model was validated with different datasets. Moreover, this approach can provide accurate load forecasting using ensemble models. Therefore, utilities and smart grid operators can use this approac... [more]

Data-driven normal behaviour models have gained traction over the last few years as a convenient way of modelling turbine operational health to detect anomalies. By leveraging high-dimensional operational relationships, temperature thresholds can be automatically calculated based on each individual turbine unique operating envelope, in theory minimising false alarms and providing more reliable diagnostics. The aim of this work is to provide further insight into practical uses and limitations of implementing normal behaviour temperature models in practice, to inform practitioners, as well as assist in improving wind turbine generator fault detection systems. Results suggest that, on average, as little as two months of data are adequate to produce stable temperature alarm thresholds, with the worst case example requiring approximately 200−290 days of data depending on the component and desired convergence criteria.

This study aimed to determine whether the wind zone that characterizes a given area of the country in open area is reflected in the built-up area lying within the zone. Analysis included four Polish cities located in different wind zones. The two-parameter Weibull density distribution function was used to present the wind conditions at each location. Two 3 kW VAWT devices were selected to evaluate the productivity of wind turbines at the locations analyzed. It was shown that the wind zones characterizing the wind potential of a region in an open area have no significant influence on the wind conditions in the built-up area located in that area. It was determined that the study location’s did not exhibit wind potential that could be economically justified by a wind turbine. WTs in the city do not reach their nominal productivity. A decisive advantage of very light winds was observed (up to 2 m/s) and a large proportion of so-called atmospheric calms. It was shown that the installation o... [more]

A linear engine generator with a compact double-acting free piston mechanism allows for full integration of the combustion engine and generator, which provides an alternative chemical-to-electrical energy converter with a higher volumetric power density for the electrification of automobiles, trains, and ships. This paper aims to analyse the performance of the integrated engine with alternative permanent magnet linear tubular electrical machine topologies using a coupled dynamic model in Siemens Simcenter software. Two types of alternative generator configurations are compared, namely long translator-short stator and short translator-long stator linear machines. The dynamic models of the linear engine and linear generator, validated with lab-scale prototypes, are applied to investigate the influence of alternative topologies of the generator on system performance. The coupled model will facilitate the early design phase and reveal the optimal match of the key parameters of the engine a... [more]

Accidents on gas pipelines cause significant damage to the national economy and the economy of the state. Thus, it is necessary to always be prepared for such situations in order to restore the normal operation of the gas pipeline as soon as possible. An important role is played by the execution time of the control actions to localize the accident, pump out the gas, and change the operating modes. It is essential that such control be undertaken, especially if such a situation occurs near a gas-measuring installation for measuring the amount of vented gas. Therefore, the control actions must be error-free in order to quickly stop the non-stationary process, which can lead to undesirable consequences. The paper presents a mathematical model of the operation of the pipeline, developed for the management of the pipeline in an emergency. The analysis of the problem of the occurrence of accidents was carried out, and the effect of liquid on its walls was modeled when the operating mode of th... [more]