The implementation of renewable energy in households can contribute to achieving climate goals, improving air quality and improving energy security. At the local level, this goal may be supported by local authorities, but in Poland, as in many countries, the use of renewable energy is not a mandatory task of local government units. The aim of this study is to analyze the role of local government, i.e., municipalities, in the adaptation of RES installations in residents’ households. The source of empirical materials was a survey of households using renewable energy installations, carried out in 2021 in the Podkarpacie region in Southeastern Poland. It has been shown that the inhabitants benefit from the support of municipalities in financing the installations, as well as information and consulting support. Municipalities support renewable energy in the “civic” segment mainly through the implementation of the so-called umbrella projects. They have a positive effect on the adaptation of R... [more]

Hydrogen technologies have been rapidly developing in the past few decades, pushed by governments’ road maps for sustainability and supported by a widespread need to decarbonize the global energy sector. Recent scientific progress has led to better performances and higher efficiencies of hydrogen-related technologies, so much so that their future economic viability is now rarely called into question. This article intends to study the integration of hydrogen systems in both gas and electric distribution networks. A preliminary analysis of hydrogen’s physical storage methods is given, considering both the advantages and disadvantages of each one. After examining the preeminent ways of physically storing hydrogen, this paper then contemplates two primary means of using it: integrating it in Power-to-Gas networks and utilizing it in Power-to-Power smart grids. In the former, the primary objective is the total replacement of natural gas with hydrogen through progressive blending procedures,... [more]

The optimization of drilling operations is an ongoing necessity since the major proportion of the terrestrial hydrocarbon reservoirs has been exhausted. Furthermore, there is a growing tendency among the space exploration agencies to drill the subsurface formations of the remote planets, such as the Moon and Mars. To optimize the drilling efficiency in such complicated conditions, the mechanical specific energy (MSE) must be efficiently reduced. The available MSE models incorporate the different parameters related to the surface rig, drill bit, and the underlying rocks to estimate the MSE values. In this research, the current status of those MSE models is assessed, and their relevant assumptions, limitations, applications, and pros and cons are profoundly argued. From the current scrutiny, it was deduced that the available MSE models require more geomechanical parameters to be included in their formulations. Furthermore, the use of artificial intelligence (AI) techniques was identified... [more]

Risk assessment and management are some of the major tasks of urban power-grid management. The growing amount of data from, e.g., prediction systems, sensors, and satellites has enabled access to numerous datasets originating from a diversity of heterogeneous data sources. While these advancements are of great importance for more accurate and trustable risk analyses, there is no guidance on selecting the best information available for power-grid risk analysis. This paper addresses this gap on the basis of existing standards in risk assessment. The key contributions of this research are twofold. First, it proposes a method for reinforcing data-related risk analysis steps. The use of this method ensures that risk analysts will methodically identify and assess the available data for informing the risk analysis key parameters. Second, it develops a method (named the three-phases method) based on metrology for selecting the best datasets according to their informative potential. The method,... [more]

Wind energy (WE), which is one of the renewable energy (RE) sources for generating electricity, has been making a significant contribution to obtaining clean and green energy in recent years. Fitting an appropriate statistical distribution to the wind speed (WS) data is crucial in analyzing and estimating WE potential. Once the best suitable statistical distribution for WS data is determined, WE potential and potential yield could be estimated with high accuracy. The main objective of this paper is to propose a novel approach for calculating wind energy potential. For this purpose, the Efficient Global Optimization (EGO) technique was proposed for fitting a statistical distribution to WS data and the performance of the technique was compared with genetic algorithm (GA), simulated annealing (SA), and differential evolution (DE). Performance metrics showed that EGO is providing better estimations compared with GA, SA, and DE. Based on Weibull parameters obtained by using EGO, potential W... [more]

This paper studied the bond performance of full-grouting rock bolts with a theoretical analysis. The variable controlling method was used to study the effect of parameters on the load-carrying force of bars. The results showed that when the bar diameter grew from 15 mm to 25 mm, the maximum force of the bars rose from 194 kN to 349 kN, growing by 80%. As for the stiffness, it grew by 108%. Moreover, when the elastic modulus grew from 50 GPa to 200 GPa, the maximum force rose from 229 kN to 269 kN, only growing by 17%. As for the stiffness, it grew by 100%. When the grouting length increased from 2 m to 3 m, the maximum force rose from 269 kN to 364 kN, growing by 35%. However, the grouting length had almost no effect on the stiffness. Lastly, for the bond slip when the bond strength was reached, when it grew from 1 mm to 3 mm, the maximum force dropped from 281 kN to 258 kN, dropping by 8%. As for the stiffness, it dropped by 44%. This paper is conducive to enriching the base of knowle... [more]

This work presents the synthesis of heat-integrated water networks (HIWNs) by using mathematical programming. A new superstructure is synthesised by combining a water network and a modified heat exchanger network. Based on the proposed superstructure, a mixed-integer nonlinear programming (MINLP) model is developed. The model is solved by using a one-step solution strategy enabling different initialisations and the generation of multiple solutions, from which the best one is chosen. The results show that the proposed model can be effectively used for solving HIWN problems of different complexities, including large-scale problems.

The Vestnesa Ridge, located off the west Svalbard margin, is a >60 km long ridge consisting of fine-grained sediments that host a deep-marine gas hydrate and associated seepage system. Geological and geophysical observations indicate the predominance of vertical fluid expulsion through fractures with pockmarks expressed on the seafloor along the entire ridge. However, despite the apparent evidence for an extended free gas zone (FGZ) below the base of the gas hydrate stability zone (BGHSZ), present-day seafloor seepage has been confirmed only on the eastern half of the sedimentary ridge. In this study, we combine the relationships between aqueous phase pressure, capillary pressure, sediment clay fraction, porosity, and total stress to simulate how much gas is required to open preexisting fractures from the BGHSZ towards the seafloor. Data from four specific sites with different lithology and pressure regime along the ridge are used to constrain the simulations. Results demonstrate that... [more]

Encouraged by the European Union, all European countries need to enforce solutions to reduce non-renewable energy consumption in buildings. The reduction of energy (heating, domestic hot water, and appliances consumption) aims for the vision of near-zero energy consumption as a requirement goal for constructing buildings. In this paper, we review the available standards, tools and frameworks on the energy performance of buildings. Additionally, this work investigates if energy performance ratings can be obtained with energy consumption data from IoT devices and if the floor size and energy consumption values are enough to determine a dwellings’ energy performance rating. The essential outcome of this work is a data-driven prediction tool for energy performance labels that can run automatically. The tool is based on the cutting edge kNN classification algorithm and trained on open datasets with actual building data such as those coming from the IoT paradigm. Additionally, it assesses th... [more]

This paper presents a novel methodology for planning and operating biogas energy systems based on the transactive energy concept to determine multilevel operating regimes for distributed generation. The developed model is used to manage the production, storage, and dispatch of biogas energy systems to meet the load demands of the biogas producer and support the operation of the distribution network operator. An Integer Linear Programming (ILP) is fitted to optimize the biogas production of the biogas producer, including the operation of the biogas storage systems and their interaction with the network operator. The model’s objective is to maximize benefits for the participating agents in a transactive energy context. The model’s effectiveness is validated using seven case studies involving biogas systems having different operating ranges and modes to achieve enhanced flexibility and reliability for the system operation with a large proportion of intermittent energy resources. The simul... [more]

The aim of this paper is to present the results of the Weather Research and Forecasting (WRF) model of solar radiation for moderate climatic zones. This analysis covered the area of northeastern Germany. Due to very unfavorable solar energy conditions in this region for at least 1/3 of the year, we decided to select the dates with the most representative conditions: passing warm fronts, cold fronts, and occluded fronts (two cases each). As the reference, two cloudless conditions during high-pressure situations were chosen. Two different shortwave radiation schemes—Rapid Radiative Transfer Model for general circulation model (RRTMG) and Dudhia—were tested. The obtained results were compared with in situ data measured at Deutscher Wetterdienst (DWD) stations and then with European Medium-Range Weather Forecast reanalysis (ERA5) data. The results showed that for high-pressure situations, the mean correlations with measured data were above 90%. The Dudhia scheme, in addition to the expecte... [more]

The doubly fed induction generator (DFIG) and back-to-back converter are very sensitive to power quality disturbances in grid-connected wind energy conversion systems (WECSs). Special attention has been given to protect the system from voltage sags, considering the introduction of several low-voltage ride-through (LVRT) techniques in the literature. However, only few works have really analyzed the behavior of power semiconductors during such phenomena in terms of the thermal stresses, whereas the existing studies are focused on balanced voltage sags only. In this context, this work presents a thermal profile analysis of power semiconductors in the grid-side converter (GSC) and rotor-side converter (RSC) considering a DFIG-based WECS submitted to symmetrical and asymmetrical voltage sags. The system is modeled using PLECS software and results on a 2.0 MW system are presented and thoroughly discussed. The results show that it is possible to meet the ride-through requirements during both... [more]

In recent decades, works have been published on the Hybrid Renewable Energy System (HRES) to provide available, feasible, and efficient renewable energy systems. Several studies have looked at the efficiency of the systems in terms of sustainability through performance parameters. This study aims at estimating the optimum HRES based on biomass and photovoltaic (PV) using the case study of 94 residential buildings with an electricity demand of 84.5 kWp. The influence of key parameters (global solar irradiation, component efficiencies, fuel consumption, economic convenience) and their impact on the performance and cost of the system is investigated. The optimum system is evaluated by the simulation software HOMER Pro. A single year of hourly data is used to analyze the component performance and the overall system performance. In this work, a mathematical model based on the IEC 61724 standard is used to incorporate numerous performance indicators that are critical for estimating the perfo... [more]

The Kingdom of Saudi Arabia (KSA) is committed to transition its fossil fuel-driven electricity generation to that from renewable energy technologies, such as solar photovoltaic (PV) and wind. The need to reduce greenhouse gas emissions has led it to announce an ambitious target of 40 GW of PV power capacity by 2030. The deployment of such a capacity needs to be augmented with analyses to overcome the challenges faced in terms of the technical capability of the country. This work contributes to this goal by investigating the utilisation of solar photovoltaic PV systems to supply medium-size entities such as universities with clean power, displacing the current fossil fuel power supply. Currently, such considerations are not fully addressed in KSA. The study used the University of Jeddah campus electrical load profile, taking into account future power needs. The methodology encompassed modelling the installation of multi-MW PV systems for the university by considering weather conditions... [more]

In the wake of the United Nation’s Sustainable Development Goals—zero hunger and affordable modern/clean energy for all—many developing countries have taken serious steps in recent years to increase clean energy access for the rural population. The government of Pakistan has similarly made numerous efforts to promote the use of clean energy sources in the rural areas of the country. Therefore, this study examines rural households’ energy choices for cooking and lighting in Pakistan. In doing so, a comprehensive dataset is collected from three different districts of Pakistan between 2020 and 2021, and multivariate probit (MVP) model and Chi-square tests are employed. The Chi-square results indicate that the age, education level, and occupation of the household-head; household size and income; distance to market and wood source; and biogas system ownership are the significant factors affecting cooking choices. The MVP results show that an increase in education level, school-going childre... [more]

Two methods for estimating the near-optimal positions and sizes of capacitors in radial distribution networks are presented. The first model assumes fixed-size capacitors, while the second model assumes controllable variable-size capacitors by changing the tap positions. In the second model, we limit the number of changes in capacitor size. In both approaches, the models consider many load scenarios and aim to obtain better voltage profiles by minimizing voltage deviations and active power losses. We use two recently developed heuristic algorithms called Salp Swarm Optimization algorithm (SSA) and Dragonfly algorithm (DA) to solve the proposed optimization models. We performed numerical simulations using data by modifying an actual distribution network in Almaty, Kazakhstan. To mimic various load scenarios, we start with the baseline load values and produce random variations. For the first model, the optimization algorithms identify the near-optimal positioning and sizes of fixed-size... [more]

Short-term load forecasting plays a significant role in the operation of power systems. Recently, deep learning has been generally employed in short-term load forecasting, primarily in the extraction of the characteristics of digital information in a single dimension without taking into account of the impact of external variables, particularly non-digital elements on load characteristics. In this paper, we propose a joint MFF-SAM-GCN to realize short-term load forecasting. First, we utilize a Bi-directional Long Short-Term Memory (Bi-LSTM) network and One-Dimensional Convolutional Neural Network (1D-CNN) in parallel connection to form a multi-feature fusion (MFF) framework, which can extract spatiotemporal correlation features of the load data. In addition, we introduce a Self-Attention Mechanism (SAM) to further enhance the feature extraction capability of the 1D-CNN network. Then with the deployment of a Graph Convolutional Network (GCN), the external non-digital features such as wea... [more]

The analysis of the implementation effect of the supply-side reform (SSR) in the industrial sector of China’s provinces and the reasons behind them are of great significance for China to formulate relevant policies in the future. However, this work has not yet been carried out. Industrial development performance is closely related to energy and environmental efficiency (EEE), and the effect of the SSR implementation is directly reflected in EEE. This study fills this gap by analyzing the EEE of 30 provinces in China from 2012 to 2017 using data envelopment analysis and Malmquist index methods. The results show that the positive effect of China’s implementation of SSR has emerged. This positive effect is mainly reflected in the implementation of measures such as reducing overcapacity, which has promoted the technological innovation of enterprises. However, the low management level and resource-allocation efficiency hinder the further improvement of the implementation effect of the SSR,... [more]

In this study, maximum power point tracking (MPPT) control of a grid-connected doubly fed induction generated (DFIG)-based wind energy conversion system (WECS) at variable wind speed was designed and analyzed. The real wind speed data of the Edremit/Balıkesir region in Turkey was used as the wind speed profile. A N90/2.5 MW wind turbine model of Nordex Company was used in the study. Firstly, a conventional PI controller was applied to both rotor and grid side converters. The rotor-side converter (RSC) controls the power generated from the DFIG, whereas the grid-side converter (GSC) controls the DC bus voltage. An MPPT controller was applied to the RSC to generate reference torque at instant variable wind speeds. Thus, the system’s response time, electromagnetic torque, generated power, and grid-side currents parameters were improved. In the MPPT controller, the reference torque value is produced by using the angular velocity and reference angular velocity values of the DFIG. The propos... [more]

The large fluctuation of net torque and the existence of negative torque on the crank output shaft of the beam pumping unit are the decisive factors leading to its low efficiency and high energy consumption. The conventional pumping unit CYJ10-4.2-53HF was selected as the study object on the basis of the fixed shaft secondary balance principle and the positive torque modulation scheme was first proposed according to the following secondary balance principle based on the linkage. The kinematics analysis of the suspension point and the secondary incremental velocity mechanism were carried out using the theory of rigid body plane kinematics. The force analysis of each moving part of the pumping unit was carried out, the net torque expression of the crank output shaft was obtained, and an example calculation was performed. The positive torque beam pumping unit was developed and tested in a field test. The tests showed that the positive torque beam pumping unit was able to fully realize pos... [more]

This review article discusses the effects of inorganic content and mechanisms on raw biomass and char during gasification. The impacts of the inherent inorganics and externally added inorganic compounds are summarized based on a literature search from the most recent 40 years. The TGA and larger-scale studies involving K-, Ca-, and Si-related mechanisms are critically reviewed with the aim of understanding the reaction mechanisms and kinetics. Differences between the reaction pathways of inorganic matter, and subsequent effects on the reactivity during gasification, are discussed. The present results illustrate the complexity of ash transformation phenomena, which have a strong impact on the design of gasifiers as well as further operation and process control. The impregnation and mixing of catalytic compounds into raw biomass are emphasized as a potential solution to avoid reactivity-related operational challenges during steam and CO2 gasification. This review clearly identifies a gap... [more]

The field data from an integrated CO2 refrigeration system installed in a supermarket located north of the capital of Lisbon was analyzed. The goal was to demonstrate the effect and performance of multi-ejectors on a refrigeration system operating in a warm climate. The measurement results for the system with and without activating ejectors were compared. It was observed that the system with a multi-ejector operation had considerable performance superiority. The ejectors improved the cooling capacity of the medium temperature stage of the system by 17.4%. The system with active ejectors had 7.5% less total power consumption compared to the ejector off mode of the same system.

This paper concerns a multi-physical modeling framework based on the spectral element method (SEM) for axisymmetric wireless power transfer systems. The modeling framework consists of an electromagnetic and a thermal model. The electromagnetic model allows for eddy currents in source- and non-source regions to be included in the analysis. The SEM is a numerical method, which is particularly advantageous in 2D problems for which the skin-depth is several orders of magnitude smaller compared to the object dimensions and complex geometrical shapes are absent. The SEM applies high-order trial functions to obtain the approximate solution to a boundary-value problem. To that end, the approximation is expressed as an interpolation at a set of nodal points, i.e., the nodal representation. The trial functions are Legendre polynomials, which reduces the complexity of the formulation. Furthermore, numerical integration is performed through Gaussian quadratures. In order to verify the SEM, a bench... [more]

In order to achieve the European Union’s climate and energy goals, investments are required, mainly in the areas of energy efficiency, renewable energy sources and infrastructure. Buildings are responsible for almost half of total energy consumption, and nearly 80% of them are energy and ecologically inefficient. The policy of European countries is increasingly more focused on facilities with the highest potential in the areas of energy and matter saving and the possibly circular economy. The aim of the work was to assess the environmental loads occurring in the life cycle of an existing retail and service building. The analysis was performed using the Life Cycle Assessment (LCA) method. By using the IMPACT 2002+ model, it has become possible to assess the impact of the life cycle of the studied facility on human health, environmental quality, climate change and raw material resources. The highest level of negative consequences in the above-mentioned areas was recorded for the life cyc... [more]

In IoT applications, energy supply, especially wireless power transfer (WPT), has attracted the most attention in the relevant literature. In this paper, we present a new approach to laser irradiance solar cell panels and predicting energy transfer efficiency. From the previous experimental datasets, it has been discovered that in the laser charging (LC) process, temperature has a great impact on the efficiency, which is highly correlated with the laser intensity. Then, based on artificial neural network (ANN), we set the above temperature and laser intensity as inputs, and the efficiency as output through back propagation (BP) algorithm, and use neural network and BP to train and modify the network parameters to approach the real efficiency value. We also propose the genetic algorithm (GA) to optimize the learning rate of the BP, which achieved slightly superior results. The results of the experiment indicate that the prediction method reaches a high accuracy of about 99.4%. The resea... [more]