The anode state of charge (SOC) and degradation information pertaining to lithium-ion batteries (LIBs) is crucial for understanding battery degradation over time. This information about each cell in a battery pack can help prolong the battery pack’s life cycle. Because of the limited observability, estimating the anode state and capacity fade is difficult. This task is even more challenging for the cells in a battery pack, as the current through the individual cell is not constant when cells are connected in parallel. Considering these challenges, this paper presents a novel method to set up three-electrode cells by using the battery’s casing as a reference electrode for building a three-electrode battery pack. This work is a continuation of the authors’ previous research. An unknown input observer (UIO) is employed to estimate the anode SOC of an individual battery in the battery pack. To ensure the stability of a defined Lyapunov function, the UIO parameter matrices are expressed as... [more]

An active heating system has been developed for application in smart clothing for mountain rescuers. It uses a set of sensors and is aimed at gathering necessary data for the elaboration and testing of an automatic control algorithm. The system is powered by a lithium-ion battery pack, which can be additionally charged from flexible PV modules. The article presents an estimation of this system’s power supply requirements and its energy budget. Since the system’s maximum operation time strongly depends on the efficiency of its main power converter, the design of the latter was based on a model enabling power loss estimation in its particular components. Characteristics ultimately measured on a prototype showed a high agreement with simulations. Furthermore, five different arrangements of PV modules were studied in order to find the most effective one. The system was tested in real conditions for the three most promising PV module configurations.

In this article, the authors assumed that the “iGeneration” is the leading driving force for the SMART orientation of modern cities. Dynamic and multidirectional technical and technological processes introduce a new level of changes in urban space, adapting it to the present and future requirements of its inhabitants in a sustainable manner. An important infrastructure element of the urban space is the crosswalk, being an inseparable element of everyday life in the city. As part of a clear emphasis on the issue of vulnerable road users’ protection, the aim of the article is to examine the perception of users regarding crosswalks in Poland, based on the example of Szczecin. The main aim of the article is to identify the dimensions of crosswalk perception. The specific objectives include the determination of the state of knowledge about the essence and typology of crosswalks and the identification of good practices in their designation. Literature analysis, questionnaire research, and a... [more]

Due to a high operating voltage and theoretical capacity, P2-type layered Mn-based metal oxides are considered to be promising cathodes in sodium-ion batteries, but their poor structural stability in the process of Na+ insertion/deinsertion severely hinders their practical application. Here, an interesting K+ pre-intercalation is used to expand the interlayer distance and enhance the electrochemical reversibility of KsFexAlyMnzO2. With a suitable K+ content, the optimized electrode shows a high specific capacity of 135 mAh g−1 at 0.1 C, a good rate capability of 80 mAh g−1 at 5 C and an excellent cycling performance of 76.4% capacity retention after 200 cycles at a high rate of 5 C. This work proves the feasibility of a K+ pre-intercalation strategy in a P2-type layered cathode.

In this paper, research was carried out on borehole protection technology using screen pipes, aiming to address the problems of gas drainage borehole collapse and low gas drainage efficiency in soft coal seams, which have low gas permeability and high gas content. An experiment was conducted to study the compressive resistance and borehole protection effects of polyvinylchloride (PVC), polypropylene (PP), and acrylonitrile−butadiene−styrene (ABS) screen pipes with different sieve opening spacings. The optimal screen pipe material and sieve opening spacing were determined. The borehole protection effect and gas drainage efficiency using three borehole protection methods, namely, bare boreholes, traditional PVC screen pipes, and new ABS screen pipes, were compared and studied on site, and the influence of pipe diameter on borehole protection efficiency was revealed. The results show that the compressive resistance and borehole protection effects of the three types of screen pipes are in... [more]

During the last decades, wind energy has been developed from an emerging technique of yielding sustainable energy into a robustly established technology due to its renewable, sustainable, and clean features [...]

Renewable energy communities are catalysts of social innovation, the citizens’ engagement in energy actions, and the exploitation of local resources. Thus, this paper defines a model for analyzing and optimally sizing energy systems serving renewable energy communities. Then, the proposed and replicable model was tailored to the economic feasibility analysis of a renewable energy community in the municipality of Tirano (Northern Italy). An energy audit was carried out to identify the electricity production and consumption within the perimeter of the primary substation and the thermal energy demand of the existing district heating network. The technical features of the energy conversion systems serving the renewable energy community were determined: an organic Rankine cycle biomass-based cogeneration plant, a mini-hydro plant, and a distributed photovoltaic system. Moreover, several different scenarios have been identified, in terms of cogeneration operating mode, photovoltaic penetrati... [more]

Organosolv pre-treatments aiming to selectively remove and depolymerise lignin and hemicellulose and yield an easily digestible cellulose fraction are one of the potential options for industrial implementation within the biorefinery concept. However, the use of high temperatures and/or high catalyst concentrations is still hindering its wide adoption. In this work, mild temperature organosolv processes (140 °C) that were either non-catalysed or catalysed with sulphuric or acetic acid were compared to standard similar conditions using ethanol-based organosolv for both wheat straw (WS) and eucalyptus wood residues (ERs) as agricultural and forestry-derived model raw materials, respectively. The experimental results demonstrated that high cellulose purities could be obtained for the catalysed ethanol-based processing of the WS, which resulted in high saccharification yields (>80%), conversely to the non-catalysed process, which only reached values close to 70%. For eucalyptus residues (ER... [more]

The inherent low thermal conductivity of phase change materials (PCMs) serious limits the thermal performance of latent heat thermal energy storage (LHTES) systems. In this study, the author proposed two operating modes (inside heating/outside cooling and inside cooling/outside heating)and designed seven fin configurations to improve the thermal performance and flexibility of the triple-tube LHTES unit. A transient two-dimensional numerical model was established to study the energy storage, release and simultaneous storage and release processes, and local and global entropy generation was analyzed. A comprehensive evaluation was used to propose the optimal combination of operating mode and fin configuration. Considering various performances, the combination of the operation mode of inside cooling/outside heating and the staggered fin configuration shortened the total time by 66.6% and increased the heat transfer rate by 5.6%, providing the best performance in both the continuous and si... [more]

In this paper, the performance of a high-temperature polymer electrolyte membrane fuel cell (HT-PEMFC) was modeled using literature data. The paper attempted to combine different sources from the literature to find trends in the degradation mechanisms of HT-PEMFCs. The model focused on the activation and ohmic losses. The activation losses were defined as a function of both Pt agglomeration and loss of catalyst material. The simulations revealed that the loss of electrochemical active surface area (ECSA) was a major contributor to the total voltage loss. The ohmic losses were defined as a function of changes of acid doping level in time. The loss of conductivity increased significantly on a percentage basis over time, but its impact on the overall voltage degradation was fairly low. It was found that the evaporation of phosphoric acid caused the ohmic overpotential to increase, especially at temperatures above 180 °C. Therefore, higher temperatures can lead to shorter lifetimes but inc... [more]

As the world’s largest coal consumer, China’s coal consumption in 2021 was 2934.4 million tons of standard coal. Thermal coal occupies an important position in the coal market and industry system, as an important raw material in the power industry, steel industry and other industries. The price of thermal coal in 2021 was at its highest level in a decade, and reached a historical level of about 2587.5 yuan per ton in October 2021. In the same month, the government intervened in the thermal coal price, which fell 51.9% by the end of the year under the influence of the policy. In previous studies, there has been little research on thermal coal and the impact of the variable “policy” on the thermal coal price. Thus, this paper analyzed the factors that affect the price fluctuation of thermal coal, and the impact of economic policy uncertainty on the thermal coal price. The cointegration test and forecast-error variance decomposition (FEVD) are adopted in this study. Our results show that... [more]

Photovoltaic (PV) arrays are gaining popularity for electricity generation due to their simple and green energy production. However, the power transfer efficiency of PV varies depending on the load’s electrical properties, the PV panels’ temperature, and the insolation conditions. Maximum Power Point Tracking (MPPT) is a method formulated as an optimization problem that adjusts the PV output voltage to deliver maximum power to the load based on these criteria (maximum power in the P-V curve). MPPT is a convex optimization problem when the Sun’s rays completely cover the PV surface (full insolation). Several power points are formed in the Power vs. Voltage (P-V) curve, rendering MPPT as a non-convex problem during incomplete insolation (partial shadowing) on the PV surface due to barriers such as passing clouds or trees in the path of the Sun and the PV’s surface. Unfortunately, mathematical programming techniques, such as gradient ascent and momentum, are not good optimization candidat... [more]

Deep water shallow natural gas hydrate (NGH) is a kind of clean energy and has entered the commercial exploitation stage. However, it produces a lot of seabed sediment in the process of large-scale mining, which not only easily causes undersea natural hazards, but also leads to pipeline equipment blockage and high energy consumption in the mining process. A downhole solid−liquid separator can effectively separate natural gas hydrate from sand and backfill sand in situ, which can effectively solve this problem. In this paper, the safety of a downhole solid−liquid separator desander under torsion conditions is determined by a test method. A numerical simulation method was used to simulate the tension and pressure of the downhole solid−liquid separator, and a modal simulation analysis and erosion analysis of the downhole solid−liquid separator were carried out. The experiments showed that the downhole solid−liquid separator could withstand 30 KN/m of torque, and a numerical simulation ana... [more]

High-order harmonics in the traction power supply show negative effects on the safe and stable operation of the railway transportation system. There is a fixed resonant frequency in the traction network. When the harmonic current frequency produced by the locomotive matches the resonant frequency of the traction network, it will cause high-frequency resonant overvoltage. The propagation path of the high-order harmonics of the traction load is analyzed based on a V/v wiring traction transformer. The propagation characteristics of high-order harmonics on self-used equipment at 380 V low-voltage side and 27.5 kV high-voltage side are expounded. A simulation model for the low-voltage self-consumption power system is established and the singular value decomposition algorithm is proposed to identify the harmonic impedance. The simulation results show that the proposed method can reduce the error to within 0.1%. Under realistic conditions, the overvoltage caused by high-order harmonics is dif... [more]

Recent years have seen an increase in surface water temperatures in several streams and fisheries, which has a detrimental effect on cold-water species such as trout. One possibility to resolve this issue is to create localized refugia of colder water generated through active cooling. The current work focuses on a prototype thermal refugia design and field testing. Various configurations of the prototype thermal refugia were tested in a stream, which could benefit from additional refugia regions. The prototypes featured a staggered, tube-bundle heat exchanger placed inside an enclosure with an aperture. The results demonstrate that in remote locations, man-made refugia can be provided. While the base enclosure (91.5 cm × 91.5 cm × 45.8 cm) allowed for excess mixing with the warmer free stream and resulted in low performance (dimensionless temperature difference of θ¯avg= 0.07), additional modifications improved performance. By utilizing a panel or an extension, the dimensionless temper... [more]

The integration of solar photovoltaic (PV) systems and utility grids has gradually gained significant interest in improving the sustainability of clean power supply for society. However, power quality remains a challenge due to partial shading conditions and harmonics. To overcome these drawbacks, a flexible radial movement optimization based on a dynamic safety perimeter maximum power point tracking algorithm is employed to track maximum power out of a PV system and to ensure that the optimum voltage level at the common DC bus is obtained under partial shading conditions using fixed-tilt installation configuration. Furthermore, a novel inverter control loop system with a double second order generalized integrator phase-locked loop (DSOGI-PLL) is also proposed to mitigate harmonics and improve the power quality of the grid interfacing PV system using MATLAB SIMULINK software. The proposed system has several merits, such as better harmonic suppression capability, control adaptivity, rap... [more]

In recent years, medium-voltage variable-speed drives have become popular in the industry. However, in some applications, the use of long cables can lead to overvoltages at the motor terminals, affecting the motor lifespan. Under such conditions, the use of passive filters is recommended. However, the use of inductive capacitive (LC) filters results in resonances, leading to control stability issues. This issue can be mitigated by introducing a resonance damping strategy. In this work, four damping strategies are implemented and designed: Passive damping, capacitor current feedback, capacitor voltage feedback, and notch filter-based damping. The paper performs a comparative study on the current control phase margin, current and voltage harmonic spectra, and overall changes in the control structure. Then, the effect of the damping strategy on the VSD control is evaluated, creating guidelines to support the selection of the appropriate damping strategy. The results indicate that capacito... [more]

Electricity Price Forecasting (EPF) influences the sale conditions in the energy sector. Proper models of electricity price prognosis can be decisive for choice between energy sources as a start point of transformation toward renewable energy sources. This article aims to present and compare various EPF models scientific publications. Adopted in this study procedure, the EPF publications models are compared into two main categories: the most popular and the most accurate. The adopted method is a bibliometric study as a variation of Systematic Literature Review (SLR) with specified automated queries supported by the VOSviewer bibliometric maps exploration. The subject of this research is the exploration of EPF models in two databases, Web of Science and Scopus, and their content comparison. As a result, the SLR research queries were classified into two groups, the most cited and most accurate models. Queries characteristics were explained, along with the graphical presentation of the re... [more]

Groundwater pumping systems using photovoltaic (PV) energy are increasingly being implemented around the world and, to a greater extent, in rural and electrically isolated areas. Over time, the cost of these systems has decreased, providing greater accessibility to freshwater in areas far from urban centers and power grids. This paper proposes a novel sustainability analysis of the groundwater pumping systems in Tenerife Island as an example of a medium-size isolated system, analyzing the current status and the business-as-usual projection to 2030, considering the water reservoirs available and the final use of water. The 2030 projection focused on the PV deployment, evaluation of the levelized cost of electricity (LCOE), and the availability of the groundwater resource. HOMER software was used to analyze the LCOE, and ArcGIS software was used for the visual modeling of water resources. As a result, the average LCOE for a purely PV installation supplying electricity to a pumping system... [more]

This paper demonstrates the possibility of active magnetohydrodynamic (MHD) control of supersonic flows containing shock waves. The shock wave configurations that occur at the inlet to a supersonic diffuser and in front of a streamlined semicylindrical model are used for the purpose of investigation. The impact is carried out by organizing local gas discharge regions when applying a magnetic field transverse to gas discharge currents. It has been shown that by changing the local region of application, the intensity and the direction of the gas discharge currents, it is possible to change the intensity and direction of the ponderomotive force acting on the gas flow during MHD interaction. The ponderomotive force control allows for acting locally on the shape and position of shock waves, the speed and direction of the flow, and the increase or reduction of pressure near the surface of the streamlined body. The experiments were carried out on a gas dynamic setup based on a shock tube in a... [more]

Hydrothermal liquefaction (HTL) of sewage sludge is considered in the article as an analogue of the natural processes of oil formation (catagenesis). A comparison of the physicochemical composition of primary and secondary sludge with type II kerogen (natural precursor of oil) showed their similarity. Both types of sludge have a slightly higher level of oxygen and nitrogen. The study tested the hypothesis that the elements included in the inorganic part of the oil source rocks can have a catalytic effect on the oil formation processes. For the conducted studies of sludge HTL, the catalysts containing cations and substances found in oil source rocks were chosen: as homogeneous catalysts (KOH, NaOH, NH4Fe(SO4)2, CoCl6, NiSO4, CuSO4, ZnSO4, MoO3) and as heterogeneous catalysts (MgO, Zeolite, Al2O3). The effectiveness of catalysts containing metal ions, zeolite and aluminum oxide has been proven. The highest biocrude yield was achieved in a process with NiSO4 as the catalyst in a dose 2 g... [more]

To facilitate the automated online monitoring of power plants, a systematic and qualitative strategy for anomaly detection is presented. This strategy is essential to provide credible reasoning on why and when an empirical versus hybrid (i.e., physics-supported) approach should be used and to determine the ideal mix of these two approaches for a defined anomaly detection scope. Empirical methods are usually based on pattern, statistical, and causal inference. Hybrid methods include the use of physics models to train and test data methods, reduce data dimensionality, reduce data-model complexity, augment data, and reduce empirical uncertainty; hybrid methods also include the use of data to tune physics models. The presented strategy is driven by key decision points related to data relevance, simple modeling feasibility, data inference, physics-modeling value, data dimensionality, physics knowledge, method of validation, performance, data availability, and suitability for training and te... [more]

In the next decade, further digitalisation of the entire wind energy project lifecycle is expected to be a major driver for reducing project costs and risks. In this paper, a literature review on the challenges related to implementation of digitalisation in the wind energy industry is first carried out, showing that there is a strong need for new solutions that enable co-innovation within and between organisations. Therefore, a new collaboration method based on a digital ecosystem is developed and demonstrated. The method is centred around specific “challenges”, which are defined by “challenge providers” within a topical “space” and made available to participants via a digital platform. The data required in order to solve a particular “challenge” are provided by the “challenge providers” under the confidentiality conditions they specify. The method is demonstrated via a case study, the EDP Wind Turbine Fault Detection Challenge. Six submitted solutions using diverse approaches are eval... [more]

The paper is concerned with water vapor condensation on vertical pipes. The vertical position of pipes in a condenser is not discussed very often. Its application has a number of particularities in terms of the numerical determination of heat transfer. In the first stage of this paper, the authors focus on the experimental identification of heat transfer during vapor condensation on vertical pipes with a diameter of 14.0 × 1.0 mm. The pipes are placed in a narrow channel and the steam flows around them in a perpendicular direction. Two channel widths were tested, i.e., 20.0 and 24.0 mm. In the second stage, numerical modelling (CFD) is used for a detailed identification of the vapor velocity fields near the pipes. In the third stage, the results of the experimental measurements and numerical modelling are compared with data published by various authors. There are studies in the literature dealing with axial flow around vertical pipes; however, the associated results are based on condit... [more]

The aim of this research is to develop an architectural style commensurate with the requirements of residential buildings in the hot and dry climate of Najran. The courtyard concept is one of the most important passive design strategies most in tune with the desert climate. The courtyard concept also meets the sociocultural requirements of the region. The success of this strategy can be verified by selecting a typical residential unit (villa) and assessing its indoor environmental conditions and energy performance. The villa can then be redesigned with the same functional and spatial determinants while creating a courtyard at the heart of the new villa configuration. To determine the level of improvement resulting from the proposed solution, the energy consumption per square meter is measured, and the results are compared with the DesignBuilder simulation program. The results indicate that with the proposed design focused mainly on the courtyard and some passive design strategies, the... [more]