The share of residential building energy consumption in global energy consumption has rapidly increased after the COVID-19 crisis. The accurate prediction of energy consumption under different indoor and outdoor conditions is an essential step towards improving energy efficiency and reducing carbon footprints in the residential building sector. In this paper, a PSO-optimized random forest classification algorithm is proposed to identify the most important factors contributing to residential heating energy consumption. A self-organizing map (SOM) approach is applied for feature dimensionality reduction, and an ensemble classification model based on the stacking method is trained on the dimensionality-reduced data. The results show that the stacking model outperforms the other models with an accuracy of 95.4% in energy consumption prediction. Finally, a causal inference method is introduced in addition to Shapley Additive Explanation (SHAP) to explore and analyze the factors influencing... [more]

This paper deals with the simulation and the experimental confirmation of electromagnetic events that could interfere with the successful formation of the restoration path during the power system restoration procedure. The studied phenomena are more relevant for bulk power systems characterized by a low short circuit power as the restoration backbone. In particular, two case studies have been simulated and analyzed: one related to a transformer energization during the formation of the restoration path, and the other one occurred after the de-energization of some transmission lines and one autotransformer belonging to the restoration path. From the simulation results, it emerged that such events are related to the resonant effects between the supplying transformer and the restored network. Such resonances could have negative effects on the restoration if they are not effectively managed. In order to evaluate the impact of such phenomena in real networks, the measurement recordings of on... [more]

Most power plants, particularly those that burn fossil fuels such as coal, oil, and gas, create CO2, a greenhouse gas that contributes to climate change. By 2060, the Indonesian government has committed to reach net zero emissions. With the lowest CO2 emissions, nuclear power plants are dependable sources of energy. Small modular reactors (SMRs) are a particular kind of nuclear power plant that has the potential to be Indonesia’s first commercial nuclear power plant because of their small size, low capacity, uncomplicated design, and modular characteristics. The purpose of this study is to examine the economics and technological feasibility of SMRs. In this analysis, the levelized cost of electricity (LCOE) comparative method and the technology readiness level (TRL) approach are both applied. The SMRs with a minimum TRL value of 7 were CAREM-25 (TRL7), KLT-40S (TRL8), and HTR-PM (TRL 8), according to the results of this research. Although CAREM-25 and KLT-40S are still in the demonstra... [more]

The increasing number of renewable energy sources (RESs) connected to power grids contributes to the emergence of not only balancing problems but also technical ones, such as the overloading of power lines. If renewable sources with a high generation level are planned to be connected in the area under consideration, then a large number of significant overloads should be expected, especially during contingency analysis. As a rule, high-voltage networks have a mesh topology, which is why the concept of using advanced mathematical algorithms was developed, with the help of which the resulting threats can be eliminated. This article presents a proposal for a new method of eliminating line overloads and determining the currently available nodal generation levels. Its innovation is a new method of eliminating problems related to the capacity of power grids. The high efficiency of the method results from the appropriately defined response of properly selected RES sources to the state of netwo... [more]

Municipal mixed plastic waste (MMPW) recycling is an innovative way to turn environmental waste into energy fuels. In the present study, a thermochemical process was applied to depolymerize MMPW to produce hydrocarbon fuels known as plasto-oil. The obtained plasto-oil was blended with conventional diesel to test the performance of the PCCI-mode single-cylinder, four-stroke, direct-injection diesel engine. The PCCI combustion mixture was tested with 15% and 30% fuel vapor to ensure homogeneity with and without exhaust gas recirculation. The modified engine findings were compared to a standard conventional engine. At higher loads, PCCI combustion showed reduced emission of carbon monoxide and nitrogen oxides. While the thermal braking efficiency was marginally reduced at all engine loads while using the blends. The results showed that with and without 10% exhaust gas recirculation, an increase in air mix reduced NOx emissions; however, in the case of smoke emissions, an opposite trend wa... [more]

Li metal has been considered an ideal anode in lithium batteries due to its high theoretical capacity of 3860 mAh·g−1 and lowest negative reduction potential of −3.040 V among the standard hydrogen electrodes. However, lithium dendrites can easily grow on the surface of the negative electrode during charging, which results in a short circuit of the battery and reduces its efficiency. This paper investigated dendrite growth and inhibition mechanisms in lithium metal batteries to improve battery life. The impacts of the initial nucleation spacing, surface energy anisotropy strength, and interfacial electrochemical driving force on lithium dendrite growth were analyzed with electrochemical experiments and mathematical models. The results showed that the smaller nucleation spacing inhibits the growth of dendrite side branches and reduces the roughness of lithium metal deposition on the negative electrode. A lower interfacial energy anisotropy strength can slow down the growth of dendrite t... [more]

Biodiesel production through transesterification results in a large quantity of crude glycerol as a byproduct, the utilization of which is technically and economically challenging. Because of the ability to efficiently process wet feedstocks, supercritical water gasification (SCWG) is utilized in this study to convert crude glycerol into hydrogen-rich syngas. A significant challenge addressed through this study is the decomposition routes of different heterogeneous components of crude glycerol during SCWG. Pure glycerol, methanol and oleic acid were investigated for SCWG as the model compounds of crude glycerol. SCWG of model compounds at temperature, pressure, feedstock concentration and reaction time of 500 °C, 23−25 MPa, 10 wt% and 1 h, respectively, revealed methanol to exhibit the highest H2 yield of 7.7 mmol/g, followed by pure glycerol (4.4 mmol/g) and oleic acid (1.1 mmol/g). The effects of feedstock concentration from 30 wt% to 10 wt% increased H2 yield from all model compound... [more]

The kaolin suspension calcination technology is currently gaining attention as a new process of calcining kaolin. In this paper, the cooling system of the kaolin suspension calcination process designed by CBMI Construction Co., Ltd. is simulated using ANSYS Fluent software to analyze the velocity field and temperature field of the gas−solid two-phase flow using the Eulerian model. A compiled UDF (User-Defined Function) is used to simulate the transfer of mass and heat from the downcomer tube to the different elements. The gas, coming from the gas outlet of the cyclone, enters the next level twin-cylinder cyclone in a spiral state. The results show that the airflow in the cyclone consists of an external spiral flow from the top to the bottom and an internal spiral flow from the bottom to the top. During the downward movement of the airflow, the outer spiral flow is continuously transformed into an inner cyclonic flow. The part of the airflow that rotates close to the inner cylinder is l... [more]

Transient processes that occur in pumped storage power plants can cause high-pressure conditions, which in turn can result in vibrations in the pump−turbine structure and even damage to structural components. It is therefore crucial to research the transient process of the large pump−turbine units and the flow-induced vibrations of the structural components. The three-dimensional flow field and structural field models of a high-head prototype pump−turbine were constructed to study its flow characteristics and structural characteristics under the turbine start-up. Calculations and analyses were performed on the pressure variation and the flow-induced stress concentrations of the pump−turbine during start-up in turbine mode. The simulated pressure distributions during the turbine start-up were mapped onto the finite element calculation model of the structures of the pump−turbine to calculate the flow-induced stress concentrations. This study provides a reference to improve the design and... [more]

Promoting energy efficiency is a key element of the strategic commitment of the European Community. Prominent among the binding measures established by the 2012 Energy Efficiency Directive to further this vision is the requirement for large companies to conduct energy audits every four years. After receiving the second cycle of energy audit reports in December 2019, a new description of the energy situation of Italian companies was made available. This presented the previously inaccessible possibility of comparing the two situations reported in 2015 and 2019 to assess the development of energy efficiency practices in organizations subject to the legislative obligation of energy audits in the country. To this end, in collaboration with the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), a project was initiated with the aim of developing the tools and methodologies necessary to assess in more detail the evolution that has occurred in the... [more]

The journey towards transportation electrification started with electric vehicles and has attracted more and more attention on a global scale in recent years. EVs are seen as a substantial, effective, and urgent solution for transportation electrification. In this paper, we investigate the operation requirements for integrating charger stations into the distribution grid in Vietnam. We also propose a simple evaluation method for assessing the feasibility of integrating planned unidirectional EV chargers into the distribution grid. The assessment method is applied to two main distribution feeders in Danang, Vietnam, where the new charger stations are already planned to be deployed in 2025 and 2030. The results showed that with addition of pre-planned EV chargers, both feeders still meet operation requirements in 2025 and 2030. However, the feeder with voltage indices close to the limit needs to be considered for an upgrade in configuration.

This article presents research conducted in one of the largest mining companies in the EU—Jastrzębska Spółka Węglowa S.A. It relates to how the implementation of sustainable strategic management has affected methane projects. In the study, a literature analysis was first conducted, establishing the existence and significance of the research gap. Then, a group of experts from JSW S.A., during moderated workshops, prepared a multidimensional model describing the structure of the implementation of sustainable strategic management. The model was constructed and verified using the AHP method. As a result of the study, it was found that the implementation of sustainable strategic management resulted in a change of the company’s strategic priorities. Significant professionalization of management in the course of these projects was also observed. The most important and beneficial element of the implementation was the adoption of strategic goals related to the production of their very own energ... [more]

The approaches for predicting output parameters of betavoltaic batteries are reviewed. The need to develop a strategy for predicting these parameters with sufficient accuracy for the optimization of betavoltaic cell design without using the simple trial and error approach is discussed. The strengths and weaknesses of previously proposed approaches for the prediction are considered. Possible reasons for the difference between the calculated and measured parameters are analyzed. The depth dependencies of beta particles deposited energy for Si, SiC, GaN, and Ga2O3 and 20% purity 63Ni and titanium tritide as radioisotope sources are simulated using the Monte Carlo algorithm taking into account the full beta energy spectrum, the isotropic angular distribution of emitted electrons and the self-absorption inside the radioisotope source for homogeneously distributed emitting points. The maximum short circuit current densities for the same semiconductors and radioisotope sources are calculated.... [more]

In order to obtain polyimide-based composite materials for energy storage applications, four synthetic methods towards a polyimide matrix with 2 wt.% pristine or acid-functionalized MWCNTs have been developed. The polyimide is derived from a nitrile aromatic diamine and a fluorene-containing dianhydride which allowed the formation of flexible free-standing nanocomposite films. The films were thoroughly characterized by means of structural identification, morphology, mechanical, thermal and dielectric behavior, as well as the charge storage performance. The obtained data indicated higher homogeneity of the composites loaded with acid-functionalized MWCNTs that enabled significantly increased dielectric properties compared to the matrix. To assess the electrical charge storage capability, cyclic voltammetry and galvanostatic charge−discharge measurements were employed in a three-electrode cell configuration. Due to the higher conductivity of pristine MWCNTs compared to acid-functionalize... [more]

The article presents studies on the impact of the significant process parameters of a paper machine with a Yankee cylinder on its production capacity and heat energy consumption for drying the paper web. Parameters such as machine speed, web moisture content before and after pressing, parameters of steam supplied to the cylinder and parameters of hot air flowing from the nozzles of the hood were analyzed. The study’s results were used to optimize production to improve the energy efficiency and performance of the machine. In order to use the possible methods of improving the production capacity and heat energy consumption, the parameters of the production process were measured and the basic indicators characterizing the operation of the machine were calculated in the Yankee cylinder−dryer hood system. The correct functioning of the machine components and the possibility of their modernization were also analyzed. Technological and construction changes introduced based on the research res... [more]

The paper provides an economic model for the assessment of hydrogen production at the site of an existing thermal power plant, which is then integrated into the existing gas grid. The model uses projections of electricity prices, natural gas prices, and CO2 prices, as well as estimates of the cost of building a power-to-gas system for a 25-year period. The objective of this research is to calculate the yellow hydrogen production price for each lifetime year of the Power-to-gas system to evaluate yellow hydrogen competitiveness compared to the fossil alternatives. We test if an incentive scheme is needed to make this technology economically viable. The research also provides several sensitivity scenarios of electricity, natural gas, and CO2 price changes. Our research results clearly prove that yellow hydrogen is not yet competitive with fossil alternatives and needs incentive mechanisms for the time being. At given natural gas and CO2 prices, the incentive for hydrogen production needs... [more]

In this article, the most important publications on the subject are compiled to highlight the progress in biodiesel production from tropical cultivars, including energy and environmental potential, raw materials, and the advantages and disadvantages of this biofuel. A critical and objective review of biodiesel production as an alternative fuel for power generation systems and its importance in the energy matrix was conducted. A survey of real applications, new computational and experimental trends, and proposals in internal combustion engines employing organic biofuel was performed. The main findings were as follows: (i) there is the possibility of integration and support in the energy matrix of different countries, as well as the competing with and complementing, energetically, other renewable energy sources, such as solar and wind; (ii) Jatropha curcas, sunflowers, soybean, Moringa oleifera, palm, cottonseed, castor, rubber seed, and coconut are tropical cultivars used to obtained oi... [more]

The operation of wireless battery chargers at multiple switching frequencies may lead to a noticeable suppression of conducted and radiated electromagnetic interference (EMI) at the cost of decreased efficiency (mainly at lower load resistances) and increased peak and root mean square values of currents of power components of the wireless battery charger. Moreover, the reduction in conducted EMI is only moderate (<8.3 dB). Therefore, a novel approach based on modified resonant circuits and a modified control technique to obtain better reduction in the conducted and radiated EMI without significantly compromising other performance characteristics of the wireless battery charger is proposed and validated by using simulations and experiments. It is shown in this paper that the wireless charger operating at multiple switching frequencies with the proposed approach for the performance improvement has a more effective implementation of the four-switching frequency spread-spectrum techniqu... [more]

Offshore photovoltaic installations are the future technology in solar energy since they enable the use of the large amount of maritime space, which is especially important when land space is not available. Various research groups are working to create viable installations. However, there are currently no tools available that an offshore system designer can use to quantify the effect of wave response motion on offshore photovoltaic installations. This research presents a new simulation tool termed the Offshore Solar Irradiance Calculator (OSIC) that is able to quantify this effect. Furthermore, a yearly parametric analysis is presented to show the effects of a characteristic wave equation on different offshore tracking systems; namely, horizontal single-axis tracking, vertical single-axis tracking and dual-axis tracking. Finally, another parametric analysis is presented to show the effects of varying wave amplitudes of oscillations on the incident irradiance received by these tracking... [more]

On board a satellite, there are different devices that operate from a common energy source called a power bus. Since there are many devices connected to the same power bus and they are in the close vicinity of each other, it is important that they are able to function adequately in the electromagnetic environment of the satellite without introducing intolerable electromagnetic interference to other devices. On-board devices often require voltage levels different from the bus voltage to function, and this is often produced by switching-mode power supplies (SMPS). Their switching-mode operation guarantees that there is less power loss during conversion; however, they also emit conducted and radiated noises into the direction of the power bus and the payloads. In the case of multiple SMPS powered by the same power bus, we can interleave their switching periods. Thus, their noises will cancel each other out on their common input. In this study, we are going to demonstrate the noise reducti... [more]

The article is devoted to solving the problem of charge equalization of multi-element batteries with rated voltage up to 1000 V, operating in dynamic modes with different charge and discharge depths. This article proposes a method of balancing the voltages of power battery elements. The essence of the proposed method is to form a reference signal equivalent to the reference voltage of the battery element for the current state of charge. The novelty of the method presented in this article, in comparison with relevant existing techniques, lies in active control over the balancing circuit proportional to real cell voltage deviation from the reference value. The proposed method can be used both for passive balancing techniques based on ballast resistors, and for circuits made on electromagnetic energy redistribution systems between galvanic cells. A number of Simulink models were developed to determine the electrical parameters of active and passive balancing circuits. Performance and accu... [more]

The increase in industrialization and development has tremendously diminished fossil fuel resources. Moreover, the excessive use of fossil fuels has resulted in the release of various toxic gases and an increase in global warming. Hence, necessitating the need to search for a renewable energy source. In this study, sesame waste biomass (SWB), which is abundantly available in Pakistan, has been used as feedstock for obtaining bio-oil using the pyrolysis technique. Pyrolysis was carried out using thermogravimetry and a pyrolysis chamber. Firstly, thermogravimetric analysis was performed on biomass with/without a laboratory synthesized catalyst Ni/Co/MCM-41 in nitrogen at different temperature programmed rates of 5, 10, 15, and 20 °C/min. A four-stage weight loss was observed that pointed toward the vaporization of water, and degradation of hemicelluloses, cellulose, and lignin. The kinetics parameters were determined using the Kissinger equation. The activation energy for the decompositi... [more]

Cyclic ethers (CEs) can be promising future biofuel candidates. Most CEs possess physico-chemical and combustion indicators comparable to conventional fuels, making them suitable for internal combustion engines. This work computationally investigates the kinetic behaviors of hydrogen abstraction from 2-methyl tetrahydrofuran (2MTHF), one of the promising CEs, by hydroxyl radicals under combustion and atmospheric relevant conditions. The various reaction pathways were explored using the CCSD(T)/cc-pVTZ//M06-2X/aug-cc-pVTZ level of theory. The Rice−Ramsperger−Kassel−Marcus-based master equation (RRKM-ME) rate model, including treatments for hindered internal rotation and tunneling, was employed to describe time-dependent species profiles and pressure and temperature-dependent rate coefficients. Our kinetic model revealed that the H-abstraction proceeds via an addition-elimination mechanism forming reaction complexes at both the entrance and exit channels. Eight different reaction channel... [more]

Recent R&D activities in nuclear fusion have identified the DEMO reactor as the ITER successor, aiming at demonstrating the technical feasibility of fusion plants, along with their commercial exploitation. However, the pulsed operation of the machine causes an “unconventional” operation of the system, posing unique challenges to the functional feasibility of the steam generator, for which it is necessary to define and qualify a reference configuration for DEMO. In order to facilitate the transitions between different operational regimes, the Once Through Steam Generator (OTSG) is considered to be a suitable choice for the DEMO primary heat transfer systems, being characterized by lower thermal inertia with respect to the most common U-tube steam generators. In this framework, the ENEA has undertaken construction of the STEAM facility at Brasimone R.C., aiming at characterizing the behavior of the DEMO OTSG and related water coolant systems in steady-state and transient conditions. A de... [more]

The accurate quantification of the performance loss rate of photovoltaic systems is critical for project economics. Following the current research activities in the photovoltaic performance and reliability field, this work presents a comparative assessment between common change point methods for performance loss rate estimation of fielded photovoltaic installations. An extensive testing campaign was thus performed to evaluate time series analysis approaches for performance loss rate evaluation of photovoltaic systems. Historical electrical data from eleven photovoltaic systems installed in Nicosia, Cyprus, and the locations’ meteorological measurements over a period of 8 years were used for this investigation. The application of change point detection algorithms on the constructed monthly photovoltaic performance ratio series revealed that the obtained trend might not always be linear. Specifically, thin film photovoltaic systems showed nonlinear behavior, while nonlinearities were als... [more]