All solid-state room-temperature lithium-sulfur (Li-S) batteries have gained increasing attention due to their ability to eliminate the polysulfides shuttle effects and the safety dangers associated with the liquid electrolytes. Herein, a novel composite solid-state electrolyte, which is nickel-tungsten carbides (NiWC) over mesoporous silica (SBA-15) filled polyethylene oxide (PEO), was developed and investigated for Li-S batteries. The filler minimizes the crystallinity of the PEO and increases the ionic conductivity of the electrolyte, resulting in lowering the AC impedance of electrolyte composite from 26,256 ohm to 2416 ohm and to 5734 ohm after adding the electrolyte material with Ni/W ratios of 1:1 and 9:1, respectively. A high initial specific capacity of 1305 mAh g−1 and a capacity retention of 66.7% after 8 cycles at C/10 was obtained at room temperature after adding NiWC/SBA-15 with a Ni/W ratio of 1:1. This novel composite solid-state electrolyte shows a remarkable long-term... [more]

Traditional electricity networks are replaced by smart grids to increase efficiency at a low cost. Several energy projects in Pakistan have been developed, while others are currently in the planning stages. To assess the performance of the smart grids in Pakistan, this article employs a multi-attribute group decision-making (MAGDM) strategy based on power Maclaurin symmetric mean (PMSM) operators. We proposed a T-spherical fuzzy (TSF) power MSM (TSFPMSM), and a weighted TSFPMSM (WTSFPMSM) operator. The proposed work aims to analyze the problem involving smart grids in an uncertain environment by covering four aspects of uncertain information. The idempotency, boundedness, and monotonicity features of the proposed TSFPMSM are investigated. In order to assess Pakistan’s smart grid networks based on the suggested TSFPMSM operators, a MAGDM algorithm has been developed. The sensitivity analysis of the proposed numerical example is analyzed based on observing the reaction of the variation o... [more]

Aiming at the problem that the current dynamic economic dispatch (DED) fails to consider the response risk of spinning reserve caused by the fluctuation and uncertainty of wind power, we work out a DED problem considering time-coupling spinning reserve response risk while the stochasticity and variability arising from RESs are taken into consideration. The developed framwork unified the response risk of reserve caused by forced shutdown of the unit into the response risk caused by time coupling. The expected customer interruption cost (ECOST) and the expected abandoned wind cost considering this reserve response risk are added to the objective function. While seeking the minimum objective function, the system is automatically configured with suitable reserve to ensure the consistency of the system’s response risk in each period. An improved multi-universe parallel quantum genetic algorithm was used to solve the model. Numerical examples and analysis prove the effectiveness and feasibil... [more]

The poor operational stability of electrolytes is a persistent impediment in building redox flow battery technology; choosing suitable stability additives is usually the research direction to solve this problem. The effects of five phosphate containing additives (including 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), hexamethylene diamine tetramethylene phosphonic acid (HDTMPA), amino trimethylene phosphonic acid (ATMPA), sodium ethylenediamine tetramethylene phosphonate (EDTMPS), and diethyl triamine pentamethylene phosphonic acid (DTPMP)) on the thermal stability and electrochemical performance of the positive electrolyte of vanadium redox flow battery were investigated. With 0.5 wt% addition, most of the selected additives were able to improve the thermal stability of the electrolyte. HEDP and HDTMPA extended the stability time of the pentavalent vanadium electrolyte at 50 °C from 5 days (blank sample) to 30 days and 15 days, respectively. The electrochemical performance of the... [more]

The efficiency of a fluidized bed reactor depends on the bed fluid dynamic behavior, which is significantly influenced by the bubble properties. This work investigates the bubble properties of a bubbling fluidized bed reactor using computational particle fluid dynamic (CPFD) simulations and electrical capacitance tomography (ECT) measurements. The two-dimensional images (along the reactor horizontal and vertical planes) of the fluidized bed are obtained from the CPFD simulations at different operating conditions. The CPFD model was developed in a commercial CPFD software Barracuda Virtual Reactor 20.0.1. The bubble behavior and bed fluidization behavior are characterized form the bubble properties: average bubble diameter, bubble rise velocity, and bubble frequency. The bubble properties were determined by processing the extracted images with script developed in MATLAB. The CPFD simulation results are compared with experimental data (obtained from the ECT sensors) and correlations in t... [more]

Recently, different mathematical frameworks of the thermostatted kinetic theory approach have been proposed for the modeling of complex systems. In particular, thermostatted kinetic frameworks have been employed for the modeling and time evolution of a hybrid energy-multisource network composed of renewable and nonrenewable energy sources, for the construction of the energy storage and for open networks. In the frameworks of the thermostatted kinetic theory approach, the evolution of an energy source and the interactions with other energy sources are modeled by introducing a distribution function and interaction rates. This paper is a survey of the recent proposed frameworks of the thermostatted kinetic theory for the modeling of a hybrid energy-multisource network and reviews the recent proposed models. The paper is not limited to review the existing frameworks, but it also generalizes the mathematical structures proposed in the pertinent literature and outlines future research perspe... [more]

Although the energy and cost benefits for retrofitting existing buildings are promising, several challenges remain for accurate measurement and verification (M&V) analysis to estimate these benefits. Due to the rapid development in advanced metering infrastructure (AMI), data-driven approaches are becoming more effective than deterministic methods in developing baseline energy models for existing buildings using historical energy consumption data. The literature review presented in this paper provides an extensive summary of data-driven approaches suitable for building energy consumption prediction needed for M&V applications. The presented literature review describes commonly used data-driven modeling approaches including linear regressions, decision trees, ensemble methods, support vector machine, deep learning, and kernel regressions. The advantages and limitations of each data-driven modeling approach and its variants are discussed, including their cited applications. Additionally,... [more]

Although brushless direct current motor (BLDCM) drives are becoming more popular in industrial and commercial applications, there are still significant difficulties and unresolved research issues that must be addressed. In BLDCM drives, commutation current ripple (CCR) and diode freewheeling during non-commutation zone (NCZ) are the major challenges. To overcome these limitations, this paper proposes a novel PWM-Model Antiseptic Control (PWM-MAC) technique to alleviate the freewheeling of the diode. The proposed PWM technique is used to alleviate the diode freewheeling in the NCZ, whereas the DCLV circuit is utilized to obtain variable DC-link voltage to address the CCR in the CZ. The MATLAB/Simulink results are included along with experimental results obtained from a laboratory prototype of 325 W. The proposed module reduces the current ripple by 31.7% and corresponding torque ripples are suppressed by approximately 32.5%. This evidences the performance of the proposed control techniq... [more]

Most cathode materials for Li-ion batteries exhibit a low electronic conductivity. Therefore, a considerable amount of conductive additives is added during electrode production. A mixed phase of carbon and binder provides a 3D network for electron transport and at the same time improves the mechanical stability of the electrodes. However, this so-called carbon binder domain (CBD) hinders the transport of lithium ions through the electrolyte and reduces the specific energy of the cells. Therefore, the CBD content is an important design parameter for optimal battery performance. In the present study, stochastic 3D microstructure modeling, microstructure characterization, conductivity simulations as well as microstructure-resolved electrochemical simulations are performed to identify the influence of the CBD content and its spatial distribution on electrode performance. The electrochemical simulations on virtual, but realistic, electrode microstructures with different active material cont... [more]

The characteristics of a PV (photovoltaic) module is non-linear and vary with nature. The tracking of maximum power point (MPP) at various atmospheric conditions is essential for the reliable operation of solar-integrated power generation units. This paper compares the most widely used maximum power point tracking (MPPT) techniques such as the perturb and observe method (P&O), incremental conductance method (INC), fuzzy logic controller method (FLC), neural network (NN) model, and adaptive neuro-fuzzy inference system method (ANFIS) with the modern approach of the hybrid method (neural network + P&O) for PV systems. The hybrid method combines the strength of the neural network and P&O in a single framework. The PV system is composed of a PV panel, converter, MPPT unit, and load modelled using MATLAB/Simulink. These methods differ in their characteristics such as convergence speed, ease of implementation, sensors used, cost, and range of efficiencies. Based on all these, performances ar... [more]

Integrated energy systems (IES) for combined power, heat and refrigeration supply achieved a wide application due to high flexibility in matching current loading. So as electricity is easily convertible into any other form of energy, gas engines are widely applied as driving engines characterized by high electrical and overall efficiency of about 45% and 90%, respectively. However, the highest thermal efficiency is achieved at full matching heat generated by the engine and heat transformed. This is often impossible in actual practice, especially if the heat is transformed into refrigeration by the most efficient and widespread absorption lithium-bromide chillers (ACh) and the heat not consumed by the ACh is removed from the atmosphere through an emergency radiator. The unused heat might be transformed by an ejector chiller (ECh) as the simplest and cheapest. So as the thermodynamic efficiency of any combustion engine is influenced essentially by the sucked air temperature, the excessiv... [more]

This research presents the design and simulation of a distributed secondary control based on a consensus algorithm for the efficient management of an isolated DC microgrid (MG-DC) that secures the distribution of active power according to the capacities of each storage unit, reducing duty cycles and extending its life cycle. The balance of powers is fulfilled through a photovoltaic (PV) generation unit and an energy storage system (ESS) based on batteries. The PV Boost converter has a maximum power point tracking (MPPT) controller based on the perturb and observe (P & O) method. In contrast, a Buck−Boost converter is integrated into each battery, which is bidirectionally controlled through a local controller and a primary droop control that balances the required power at the loads. It produces a voltage deviation on the DC bus. To compensate for this deviation, a distributed secondary control strategy based on consensus is proposed to restore the voltage while managing the power sharin... [more]

One of the key areas of the UN’s sustainable development goals is growing affordable and clean energy. Utilizing solar energy that is now accessible will significantly lessen the demand for fossil fuels. Around the world, cooking is a crucial activity for homes and uses a lot of non-renewable energy. Uncontrolled firewood usage results in deforestation, whereas using biomass-related fuels in inefficient stoves can result in smoke emanating from the kitchen and associated health issues. The benefits of solar cooking include reducing smoke-related problems and saving on fossil fuels and firewood. Applying thermal storage systems in cooking helps households have all-day cooking. This review article presents the research and development of a solar cooking system that transfers solar energy into the kitchen and integrates with the thermal energy storage system, finding the factors affecting indoor solar cooking performance. Adding portable cooking utensils helps in improved solar indoor coo... [more]

In the context of increased energy demands and finding solutions for energetic autonomy, the use of waste base materials has increased in recent years in all areas of research. In this context, waste waters, sludge or slurry, biodegradable materials, second generation effluents, and their byproducts are some of the key substrates of interest to obtain biogas through AD (anaerobe digestion). The goal is to utilize these materials as a base for the generation of renewable energy and thereby make it the main source of energy for households or industries. This paper aims to characterize, from a physical and chemical point of view, wastewater from Timis county as a base substrate material in the co-fermentation process with cereal residual biomass. We aimed to determine the energetic potential of the wastewater and perform preliminary testing at a small and pilot-sized experimental installation for biogas production with Timis wastewater as the main energy carrier. The novelty of the paper... [more]

Pollutant emission standards and, in particular, those concerning particles from an internal combustion engine (ICE) are becoming increasingly restrictive. Thus, it is important to determine the main factors related to the production of particulate matter. In this article, the phenomenon of oil sweeping by the blowby gases between the rings/piston/cylinder is investigated. First, a blowby gas simulation model based on experimental results from a Turbocharged Gasoline Direct Injection (TGDI) is developed. From this model, it is possible to characterise the amount of oil swept by the blowby gases. This depends on the endgap position of both the compression and sealing rings. It also depends on the intensity of the blowby flow rate, which is highest at low rpm and high load. At 1500 rpm and full load, this flowrate exceeds 25 mg.cycle−1. From this result, it is possible to quantify the amount of oil swept by these gases as a function of the endgap position. For θrings=180°,  the quan... [more]

Electricity production in Poland is stable and ranges from 160−170 TWH a year. The share of renewable energy sources (RES) is increasing. Poland increased its share from 6.9% in 2010 to 12.7% in 2019 and 16.1% in 2020. The share of hard and brown coal decreased in Poland from 87.8% in 2010 to 73.5% in 2019. Wind energy (9.2%) and natural gas (9.2%) are the most important sources of RES in electricity production. The purpose of this research is to discover the changes in renewable energy production, and the impact on electricity production in Poland. Our research showed the extent of development of RES in Poland and other countries of the European Union. The share of renewable energy sources in electricity production increased as the effect of energy policy of the European Union. We also evaluated the impact of the COVID-19 crisis on the renewable energy market and electricity production in Poland, and other countries of the European Union. Because of the shortage of data, we presented... [more]

In times of the pandemic and the beginning of the energy crisis, the financial situation of enterprises operating in the energy generation sector may be a problem. This sector includes companies that generate energy in different ways and from different sources. The aim of this study is to determine the general financial situation of enterprises in the energy sector listed on the Warsaw Stock Exchange. The subject of the paper are the annual financial reports of these entities for the years 2015−2021. Tree hypotheses were formulated regarding various aspects of the financial situation of the entities under study. The following research methods were used in this paper: analysis of the literature on the subject and financial statements, and methods of descriptive statistics. The indicators of liquidity, profitability, debt and activity were calculated. The values of the maximum, minimum, median, upper and lower quartiles, the arithmetic mean, kurtosis and skewness were then calculated for... [more]

Due to complexities in geologic structure, heterogeneity, and insufficient borehole information, shale formation faces challenges in accurately estimating the elastic properties of rock which triggers severe technical challenges in safe drilling and completion. These geomechanical properties could be computed from acoustic logs, however, accurate estimation is critical due to log deficit and a higher recovery expense of inadequate datasets. To fill the gap, this study focuses on predicting the sonic properties of rock using deep neural network (Bi-directional long short-time memory, Bi-LSTM) and random forest (RF) algorithms to estimate and evaluate the geomechanical properties of the potential unconventional formation, Permian Basin, situated in West Texas. A total of three wells were examined using both single-well and cross-well prediction algorithms. Log-derived single-well prediction models include a 75:25 ratio for training and testing the data whereas the cross-well includes two... [more]

In recent years, Taiwan has firmly committed itself to pursue the green energy transition and a nuclear-free homeland by 2025, with an increase in renewable energy from 5% in 2016 to 20% in 2025. Offshore wind power (OWP) has become a sustainable and scalable renewable energy source in Taiwan. Maritime Spatial Planning (MSP) is a fundamental tool to organize the use of the ocean space by different and often conflicting multi-users within ecologically sustainable boundaries in the marine environment. MSP is capable of definitively driving the use of offshore renewable energy. Lessons from Germany and the UK revealed that MSP was crucial to the development of OWP. This paper aims to evaluate how MSP is able to accommodate the exploitation of OWP in Taiwan and contribute to the achievement of marine policy by proposing a set of recommendations. It concludes that MSP is emerging as a solution to be considered by government institutions to optimize the multiple use of the ocean space, reduc... [more]

The global changes which are affecting countries at the moment act as a ‘censor’ of modern energy relations and energy market development strategies in general. The development of the energy market is no longer considered in terms of its efficiency but more in terms of its survivability under the influence of external environmental factors and its ability to maintain an acceptable level of energy safety. In order to fully balance a country’s internal interests and increase its competitiveness in the global energy market, the importance of the problem of choosing a development strategy—following the path of energy independence or cooperative development—is becoming evident. The purpose of this paper is to identify an effective energy strategy for a country under the influence of contemporary challenges. The object of the study is the Russian energy market and the energy companies as its key players. In this context, it examines the situations where Russia and other energy market players... [more]

In this work, the performance of on-board vehicle exhaust emission sensors is investigated and compared to reference laboratory and on-road instrumentation for two modern diesel light-duty commercial vehicles, type-approved as Euro 6d-TEMP-EVAP-ISC and Euro 6d-ISC-FCM. The first step of the analysis was to perform emissions tests in the laboratory and compare the NOx concentrations registered by the vehicle sensors available at the engine-out and tailpipe positions with those recorded by reference laboratory instrumentation. In a second step, tests were also conducted on road, comparing the performance of on-board sensors with those of Portable Emission Measurement System (PEMS) analysers, which were taken as references. The uncertainty related to exhaust flow measurements was also addressed. In particular, emissions factors calculated using the flow rates measured either in the laboratory or on-road were compared to those obtained by computing exhaust flows with on-board recorded data... [more]

The shift toward renewable energy resources, and photovoltaic systems specifically, has gained a huge focus in the past two decades. This study aimed to assess several environmental and economic impacts of a photovoltaic system that installed on the rooftop of an industrial facility in Dubai, United Arab Emirates (UAE). The life cycle assessment method was employed to study all the flows and evaluate the environmental impacts, while several economic indicators were calculated to assess the feasibility and profitability of this photovoltaic system. The results showed that the production processes contributed the most to the environmental impacts, where the total primary energy demand was 1152 MWh for the whole photovoltaic system, the total global warming potential was 6.83 × 10−2 kg CO2-eq, the energy payback time was 2.15 years, the carbon dioxide payback time was 1.87 years, the acidification potential was 2.87 × 10−4 kg SO2-eq, eutrophication potential was 2.45 × 10−5 kg PO43-eq, th... [more]

Hydrogen energy leads us in an important direction in the development of clean energy, and the comprehensive utilization of hydrogen energy is crucial for the low-carbon transformation of the power sector. In this paper, the demand for hydrogen energy in various fields is predicted based on the support vector regression algorithm, which can be converted into an equivalent electrical load when it is all produced from water electrolysis. Then, the investment costs of power generators and hydrogen energy equipment are forecast considering uncertainty. Furthermore, a planning model is established with the forecast data, initial installed capacity and targets for carbon emission reduction as inputs, and the installed capacity as well as share of various power supply and annual carbon emissions as outputs. Taking Gansu Province of China as an example, the changes of power supply structure and carbon emissions under different scenarios are analysed. It can be found that hydrogen production th... [more]

In this study, a pitch H-infinity control algorithm was developed for variable-speed−variable-pitch (VSVP) wind turbines to improve the rotor standard deviation of the wind turbines under normal and extreme wind conditions. The pitch H-infinity control algorithm only uses H-infinity control in the blade pitch control loop in the rated power region, and conventional torque gain scheduling algorithms are applied in the partial power region. The performance of this controller was verified using simulations of a 5 MW wind turbine using the commercial aeroelastic simulation code Bladed. The performance of the pitch H-infinity controller was compared with that of the conventional proportional-integral (PI) control algorithm under three different operating conditions: normal operating conditions without sensor noise, normal operating conditions with sensor noise, and extreme operating conditions without sensor noise based on the wind turbine design standard by IEC. Based on the simulation res... [more]

Being the primary cause of inter-area oscillations and due to the fact that they limit the generation’s output, Low-Frequency Electromechanical Oscillations (LFEOs) represent a real threat to power system networks. Mitigating their effects is therefore crucial as it may lead to system collapse if not properly damped. As rotor angle instability is the primary cause of LFEOs, this paper presents a novel Model-Reference Adaptive Control (MRAC) scheme that enhances its stability. The proposed scheme is tested using the Single-Machine Infinite Bus (SMIB) network. The results obtained validate the proposed decentralized control architecture. The robustness of this oscillation damping controller is verified through simulations in MATLAB/SIMULINK. With Gaussian noise added to the structure of the generator to emulate small load variations responsible for the rotor angle instability, the results of the simulations show that the rotor angle remains stable. Furthermore, when subjected to faults,... [more]