This work uses a hole-transporting copper cobaltite/copper oxide nanocomposite to fabricate carbon-based MAPbI3 PSCs. The copper cobaltite/copper oxide HTM-based PSC results show the highest power conversion efficiency (PCE = 7.32%) compared with an HTM-free device. The highest photocurrent density (Jsc = 15.17 mA/cm2), open-circuit voltage (Voc = 0.82 V), and fill factor (FF = 0.59) are achieved for the PSC fabricated with hydrothermally synthesized copper cobaltite/copper oxide nanocomposites. Electrochemical impedance spectroscopy is used to analyze the charge transfer resistance (Rs) and the capacitive behavior of copper cobaltite/copper oxide nanocomposite. The maximum electron lifetime of 35.16 μs is witnessed for the PSCs fabricated with 3 mg mL−1 of copper cobaltite/copper oxide (H1). The efficiency of the copper cobaltite/copper oxide-based PSC remains unchanged, showing no further perovskite layer degradation.

The aim of this research is to create a theoretical framework for a local energy innovation system based on renewable energy sources. For this purpose, four types of clusters were outlined based on energy-generation capacity and socio-economic factors such as “local wealth”, “relational capital”, “scientific and research capital” and “energy demand”. This classification revealed areas of Poland that have diverse features in terms of energy-generation capacity and innovation abilities. For each type of area, energy potentials combined with innovation abilities were established. To understand how areas with insufficient energy and innovation capacities could be supported in their development of local energy sovereignty, the concept of the regional innovation system has been adjusted. The results of the research can serve as an aid in the development of national and regional energy policies focused on the specificity and capacity of energy generation and innovation of each area.

Vacuum Insulation Panels (VIPs) provide significant adiabatic performance for heat/cooling systems to reduce energy consumption. The application of fibrous porous material (FPM) as the ideal core of VIPs has gained global attention in recent decades. The microstructure and physical properties of FPMs, filled as novel VIPs’ core material, and holding superior thermal performance, affected effective thermal conductivity (ETC) greatly. Aiming to deeply understand heat transfer mechanisms, a holistic simulation method that combined with a developed 3D FPM structure generation method and a D3Q15-Lattice Boltzmann method (LBM) is proposed to simulate the heat transfer in FPM and to illuminate the influence factors of ETC on the microstructure of FPM in a vacuum. The improved and modified mesoscopic 3D fibrous random micro-structure generation approach involved five structural parameters: generation probability of nucleus growth, fiber length, diameter, coincidence rate, and orientation angle... [more]

The paper presents the results of research aimed at evaluating the possibility of using selected biomass wastes to produce solid biofuels. In this work, the thermochemical properties of two lignocellulosic biomasses, namely, miscantshus (Miscanthus × Giganteus) and hops (Humulus lupulus), and non-lignocellulosic biomass, namely, municipal solid waste, and their mixtures (micanthus + municipal solid waste and hops + municipal solid waste) were studied using the torrefaction process as the main method for investigation. The effects of various torrefaction temperatures (250, 300, and 350 °C) and times (30 and 60 min) were evaluated. Proximate and ultimate analyses were performed on the torrefied samples. The following can be stated: as the torrefaction temperature and time increased, mass and energy yields decreased while the higher heating values (HHVs) and fuel ratios (FRs) increased, together with carbon contents (C). In addition, energy on return investment (EROI) was studied; the max... [more]

Both scientific and industrial communities have a growing interest in marine renewable energies. There is a wide variety of technologies in this domain, with different degrees of maturity. This study focuses on two models of a mast-free vertical axis Darrieus tidal turbine with the objective of characterizing the effect of vertical confinement, rotor configuration, and fluid−structure interactions on their performances in free-surface flows. The first model comprised four straight rigid blades maintained by circular flanges on both ends of the rotor and the second model is equipped with free-ended interchangeable blades attached to a single upper flange. Two configurations of the second model mounted with either rigid or flexible blades were used, first for comparison with the dual-flange turbine, then in order to address the effect of fluid−structure interactions on the turbine performances. While the single-flange models exhibit a significantly lower efficiency at all operating point... [more]

As a consequence of the COVID-19 pandemic, Korea’s economy has experienced significant setbacks. Thus, this article examines the implications of the COVID-19 pandemic on Korea’s key macroeconomic indicators via the transmission channels of oil prices and production technology. Using Bayesian estimation and impulse response functions for empirical investigation, the results suggest that the COVID-19 pandemic has intensified the reduction in firm production, consumption of oil-based goods, employment, and investment. Increasingly, households rely on non-oil goods rather than oil-based ones. Similarly, the results suggest that the drop in production technology levels brought on by the COVID-19 pandemic has a stronger impact on business output and investment but a lesser influence on household employment. The COVID-19 pandemic has led to a decline in household non-oil consumption as well as household and business consumption of oil-based goods. To sum up, the existing Korean literature on... [more]

The efficiency of electrical complexes depends directly on the level of power supply system reliability, which comprises extensive and branched distribution networks. A complex of single-phase ground fault (SPGF) relay protection and automation devices (RPA) is used to reduce the economic losses from the failure of the electrical receivers’ distribution networks. This paper presents a study of the protection sensitivity factor, taking into account the influence of the network capacity and the resistance during a fault. The results of this study determined the minimum permissible values of the sensitivity factor that ensures the stable operation of the protection device. This was achieved by taking into account the influence of the transient resistance at the point of short circuit. The practical significance of the study is as follows: the obtained characteristics will allow for the development of new functional logic circuits for SPGF protection. The practical implementation of the ob... [more]

An analysis of the operating conditions of the traction drives of an electric rolling stock with asynchronous traction motors was conducted. In the process of operation, the electric traction drive with both direct torque control and vector control was found to possibly experience unstable modes, both in terms of power supply and load. The models of electric locomotive traction drives with asynchronous electric motors with either vector or direct torque control were adapted to account for the possible presence of the aforementioned operational factors. As a result of the modeling, the starting characteristics of the electric traction drives with different control systems were obtained both in the absence and in the presence of power supply and load disturbances. The following cases were investigated for the drive with vector and direct torque control in the absence of power supply and torque disturbances: drive output at the rated speed of rotation of the electric motor shaft; 10% redu... [more]

The proposed changes to the legislation on diesel cars require intensification of work on the possibilities of reducing emissions of harmful substances into the atmosphere by these vehicles. The subject of experimental research included in the manuscript was the Skoda Octavia with a 1.9 TDI (turbocharged direct injection) compression ignition engine (type 1Z). Light absorption measurements of smokiness of the exhaust gases emitted after combustion of various biofuels (conventional diesel, pure hydrotreated vegetable oil, hydrotreated vegetable oil, biobutanol) and their blends with fossil diesel fuel were studied. The measured light absorption coefficient is the reciprocal of the thickness of the layer, after passing through which the light has a ten times lower intensity. Its unit is the reciprocal of the meter (1/m or m−1). The results obtained by means of a standard smokiness meter indicate that the use of biofuels or their blends, in general, reduces smoke formation.

Nonintrusive load monitoring (NILM) is a process that disaggregates individual energy consumption based on the total energy consumption. In this study, an energy disaggregation model was developed and verified using an algorithm based on a recurrent neural network (RNN). It also aimed to evaluate the utility of the occupant location information, which is nonelectrical information. This study developed energy disaggregation models with RNN-based long short-term memory (LSTM) and gated recurrent unit (GRU). The performance of the suggested models was evaluated with a conventional method that uses the factorial hidden Markov model. As a result, when developing the GRU disaggregation model based on an RNN, the energy disaggregation performance improved in accuracy, F1-score, mean absolute error (MAE), and root mean square error (RMSE). In addition, when the location information of the occupants was used, the suggested model showed improved performance and good agreement with the real power... [more]

This paper presents a holistic Reynolds-averaged Navier−Stokes (RANS) turbulence modeling framework for the computational fluid dynamics (CFD) simulations of complex wall-bounded turbulent flows. Based on the elliptic relaxation idea, the deployed eddy viscosity turbulence model reconstructs the near-wall stress anisotropy and nonviscous effects. The appropriate selection of the turbulent quantities that are being solved for, together with the zero value wall boundary condition for the related turbulent quantities, renders the model less sensitive to the near-wall grid nonuniformities and resolution. The unified near-wall velocity profile, obtained based on the boundary layer theory, is used to devise the compound near-wall treatment that ensures the robustness of the numerical simulation. The proposed turbulence modeling framework is implemented into the general-purpose open-source CFD code and validated against the generic test cases with satisfactory agreement.

In the present study, using Life Cycle Assessment (LCA) and Cost−Benefit Analysis (CBA), we assess the economic−environmental performance of an anaerobic digestion (AD) plant, fed by cultured crops (i.e., maize and wheat), in Italy. The biogas generated by the AD plant is used for the production of electricity, imputed into the Italian energy grid. The LCA evaluated potential greenhouse gas (GHG) emissions, measured via Carbon Footprint (CF), while the CBA analysed the financial and economic profiles via the Net Present Value (NPV) and Internal Rate of Return (IRR) indicators. The strength of combining these methodologies is the joint examination of the financial and social−environmental performance of the plant. The results of the CBA are complemented with the GHG emissions avoided by producing electricity from biogas. The CF of 0.28 kg CO2eq·kWh−1 of electricity produced is mainly due to the nitrogen fertilizers involved in the production of the additional feedstock matrix (i.e., mai... [more]

Determination of the heat transfer coefficient (HTC) distribution is important during the design and operation of many devices in microelectronics, construction, the car industry, drilling, the power industry and research on nuclear fusion. The first part of the manuscript shows works describing how a change in the coefficient affects the operation of devices. Next, various methods of determining the coefficient are presented. The most common method to determine the HTC is the use of Newton’s law of cooling. If this method cannot be applied directly, there are other methods that can be found in the open literature. They use analytical formulations, the lumped thermal capacity assumption, the 1D unsteady heat conduction equation for a semi-infinite wall, the fin model, energy conservation and the analogy between heat and mass transfer. The HTC distribution can also be calculated by means of computational fluid dynamics (CFD) modelling if all boundary conditions with fluid and solid prop... [more]

Single-atom catalysts (SACs) within carbon matrix became one of the most promising alternatives to noble metal-based catalysts for oxygen reduction reaction (ORR). Although SACs have significant benefits in reducing the total catalyst cost, it also has the disadvantages of weak interaction between atoms and poor stability. Hence, there is still much room for improvement for the catalyst activity. In response, we designed a Fe-Co-Pt ternary metal single atom catalyst anchored on covalent organic framework (COF)-derived N-doped carbon nanospheres (Pt, Fe, Co/N-C). Due to effective charge transfer between Pt single atom and neighboring Fe-Co components, an intense electron interaction can be established within the Pt, Fe, Co/N-C catalyst. This is beneficial for enhancing charge transfer efficiency, modulating d electronic structure of Pt center and weakening oxygen intermediate adsorption, thus distinctly accelerating ORR catalytic kinetics. As expected, the half-wave potential of Pt, Fe,... [more]

The rapid growth of the global population and urbanization has led to environmental degradation, resulting in a worldwide energy crisis. In response, the quality of architecture has evolved to prioritize energy efficiency, impacting indoor human health in the process. Green buildings have emerged as a solution to this problem, aiming to improve indoor environmental quality (IEQ) and human well-being while minimizing negative environmental impacts. This comprehensive review focuses on the role of green buildings in enhancing indoor human health and energy efficiency. It examines the published research on the effects of green buildings on IEQ and occupant health, highlighting sustainable architectural practices that promote good health. The study concludes that green buildings provide healthier environments for their occupants by creating healthy indoor environments, and minimizing negative environmental impacts. The study also explores the link between sustainable architecture and healt... [more]

Nowadays, the integration of distributed generators with the main utility grid is highly increasing due to the benefits which can be obtained, such as increasing the system efficiency and reliability. Apart from that, many technical and safety issues appear in the system due to this integration. One of these issues is the islanding condition, which has to be detected effectively and quickly before having any detrimental effects on the protection, stability, and security of the system. This study provides a detailed overview of several islanding detection approaches, which are divided into traditional methods, including local and remote methods, and modern methods, including methods based on signal processing and computational intelligence. Moreover, a comparison between each method based on various criteria, such as non-detected zone, quality factor, response time, implementation cost, degrading power quality, reliability, suitability for the type of distributed generators, suitability... [more]

Sustainable energy projects in Africa are particularly vulnerable in terms of sourcing vital alternative fuels due to the complexity of sourcing processes, contract agreements and relationships between society managers or directors and supplier chain entities. These challenges can affect any phase of a sustainable project, and the losses can be as high as 3.2 EURO/GJ. In addition, there is reduced competition and fair trade, low profits and poor quality of the fuel purchased. Technology (mobile application) is one powerful tool that can solve the above challenges by controlling or managing the supply and demand of biomass-based fuels, agriculture residue, industrial waste and many more. Thus, the main objective of this study is to evaluate the feasibility of a developed digital platform to remove barriers in the trade of alternative fuels. Data collection began with the identification of the key production areas (sources) and quantities of three selected AFs. Secondly, data on the seas... [more]

Cities are currently responsible for an important part of energy consumption and greenhouse gas emissions, justifying the need to develop measures to help them become more sustainable. One of those measures can be to address under-utilized assets in cities, such as derelict buildings with high potential for rehabilitation, and the establishment of new residence hubs within cities. Consequently, this work establishes a novel framework for evaluating the impact of rehabilitating these buildings in an urban area in Lisbon, considering the energy consumption associated with the usage of the dwelling as well as the impact on mobility, since it was considered that these buildings will be occupied by people who currently work nearby but live in the outskirts of Lisbon, favouring an urban planning of proximity between home and work. To this extent, a methodology was developed for selecting the buildings to be analysed and the commuting movements to be replaced. Then, buildings were simulated i... [more]

This paper conducts a comparative analysis of three wind farm simulators, examining the influence of wake on the local wind speed and power output for downstream turbines using experimental data. The study features experiments in three distinct scenarios, evaluating differences among the simulators by calculating the local wind speed and power for each. Each simulator employs a unique wake model, which substantially affects the local wind speed experienced by downstream turbines. Furthermore, the experiment involves adjusting parameter values for each simulator to assess their respective impacts on wind farm performance. The findings of this research are expected to play an important role in investigations related to power optimization and wake effects in the wind farm control.

Hydraulic turbines contribute to 60% of renewable energy in the world; however, they also entail some adverse effects on the aquatic ecology system. One such effect is their excessive noise and vibration. To minimize this effect, one of the most effective and feasible solutions is to modify the design of the turbine rotor blade by introducing a skew. In this study, two 0.3-meter tidal turbines with 0-degree (no-skewness) and positive 90-degree skewness made of stainless steel 316L were designed and printed using a 3-D printing powder bed fusion technique. These rotors were then tested at the Emerson Cavitation Tunnel (ECT) at Newcastle University, UK, and the variation in the skewness of the blades of the turbines as a function of the power coefficient on a given tip speed ratio (TSR) value was ascertained. Results showed that the highly skewed rotor had significantly lower drag and torque fluctuations, with a slight decrease in efficiency compared to the non-skewed one, which warrants... [more]

The slow pyrolysis characteristics of lignocellulosic biomass and its three major components via a Thermogravimetric Analyzer coupled with a Fourier Transform Infrared Spectrometer (TGA-FTIR) was studied. Different compositions and ratios of cellulose, hemicellulose, and lignin, olive pomace, sunflower waste, and pinecone were selected. The main decomposition temperature ranges of xylose (hemicellulose) and lignin showed a broad range between 173−690 and 170−835 °C, respectively, whereas that of cellulose was detected to be 291−395 °C. All biomass samples presented a three-stage pyrolysis model that is explained by the superposition of the weight losses of major components. Simultaneous FTIR analysis of the evolved gases demonstrated that the greater the cellulose and hemicellulose contents, the higher the CO and CO2 concentrations. Chemical kinetics were computed with the Coats−Redfern model. The activation energy required for the initiation of the thermal decomposition of biomass sam... [more]

In the manufacturing of power transformers, the impregnation of the solid electric insulation systems (cellulosic materials) with a dielectric liquid is a key issue for increasing the breakdown voltage of the insulation, and this prevents the apparition of partial discharges that deteriorate the insulation system. After introducing the problem, this article presents the theory of impregnation and later carries out a bibliographical review. Traditionally, mineral oils have been used as the dielectric liquid in electrical transformers, but for environmental (low biodegradability) and safety (low ignition temperature) reasons, since the mid-1980s, their substitution with other ester-type fluids has been studied. However, these liquids have some drawbacks, including their higher viscosity (especially at low temperatures). This property, among other aspects, makes the impregnation of cellulosic materials, which is part of the transformer manufacturing process, difficult, and therefore this... [more]

In this research, the effects of different channel cross-section shapes on the flow, heat transfer and pyrolysis characteristics of n-decane were analyzed and compared based on CFD simulations. The interactions between cracking, heat transfer and flow field in a circular tube and a rectangular tube were studied. The results showed that the mean pressure drop in the rectangular channel is 1.18 times as high as that in the circular channel with pyrolysis due to its smaller equivalent diameter. The maximum value of the chemical heat sink in the rectangular channel is 1.6 times as high as that in the circular channel. The high temperature zone of any cross section in the rectangular channel is much larger than that in the circular channel due to the superposition of the boundary layer and lower turbulent kinetic energy in the corners of the rectangular channel. The maximum value of the Nu in the circular channel is 1.3 times as high as that in the rectangular channel with pyrolysis due to... [more]

South Africa’s energy network is under severe pressure due to low supply and overwhelming demand. With an increase in renewable energy providers, specifically wind energy, knowing how the supply can satisfy the electricity demand may relieve apprehensions. This research aims to provide insight into the wind energy supply of South Africa and question how well this supply meets the demand of South Africa. The methodology used in this work highlights the importance of access to public datasets to dispel misconceptions in the energy industry. Additionally, the work supports network planning and the arguments for increasing wind energy penetration on the South African grid. Wind profiles and the typical energy production of South African wind farms are compared to electricity demand. The geographical spacing of the operational wind farms is considered. It is observed that wind energy supply assists in the peak electricity hourly demand as well as seasonal peaks. Furthermore, South Africa’s... [more]

In this study, the aerodynamic performance of the exhaust system of a two-shaft gas turbine was investigated experimentally and numerically. The investigation focused on the system “Turbine Stage-Diffuser—Collector Box” and aimed to examine the impact of inlet conditions and geometry particularities on the efficiency of the exhaust system. The experiments were conducted on the Test Ring ET4 (Experimental Turbine-4) at the Peter the Great St.Petersburg Polytechnic University, which was equipped with a special diversion channel to examine the non-axisymmetric outlet of the exhaust duct. The collector box was designed to rotate by 180 degrees around the turbine axis to investigate its impact on the system’s performance. Flow traversing parameters were measured with the five-channel pneumatic pressure probes, and numerical simulations were performed with CFX 15.0. The RANS (Reynolds-averaged Navier−Stokes) equations were closed with the SST (k-ω) turbulence model (Shear Stress Transport mo... [more]