The success of energy transition relies on what happens in the contact zone, the area between citizens and municipality governments, which still awaits more thorough research. This article employs the concept of the contact zone both as a theory describing processes of developing energy prosumerism on a local level, and as a research method which enables one to uncover phenomena that are critical to attaining climate objectives. The research field was the Warmia and Mazury Province in Poland, which is the region with the lowest socio-economic potential both in Poland and in the European Union. The analyzed contact zone was divided into two parts: the human administrative legal contact zone and the more-than-human energy contact zone. To describe the relationships occurring in these subzones, the authors used empirical data originating from a survey addressed to citizens living in the above province. The aim was to explore the respondents’ knowledge about current prosumption processes a... [more]

Kitchen waste (KW) has high water content and organic matter, which has great potential for energy application, but how to treat it effectively has always been a difficult problem. In this study, the feasibility of transforming kitchen waste into hydrochar as a solid fuel to replace the primary energy by hydrothermal carbonization (HTC) is put forward. An experimental study of proportioned KW under HTC conditions (reaction temperature, residence time, liquid−solid ratio) is carried out by elemental analysis, industrial analysis, energy density calculation, and calorific value measurement. The results show that a proper extension of the residence time to 3.5 h at a liquid−solid ratio of 10 and a reaction temperature of 265 °C for the kitchen waste after HTC would result in a maximum calorific value of 30.933 MJ/Kg for the prepared hydrochar. The maximum ash content of hydrochar at a 265 °C reaction temperature is 3.94% < 10%, which is much lower than the standard of extra-low-ash coa... [more]

Low insulation strength at the oil−gas surface due to oil leakage and partial discharge of oil-immersed power equipment is a major threat to the safe and reliable operation of power systems. This paper investigates the initiation and development of the oil−gas surface discharge. The oil−gas surface discharge test platform was established, and discharge tests were carried out at different gap distances (1−2.5 mm). By coupling the electric field and flow field, the multi-layer dielectric discharge streamer model was built, and the characteristics of charge and electric field distribution at different gap distances were studied. The test results show that the liquid surface between the electrodes rises during the discharge process. Furthermore, the surface discharge voltage exceeds the air gap discharge voltage. With the simulation analysis, the oil−gas surface discharge is a typical streamer development process. Under 50 kV applied voltage and 2.5 mm gap distance, the average development... [more]

Oil-based drilling fluid is currently widely utilized when drilling shale, in which the oleophilic nano-plugging agent is the major component for wellbore strengthening. However, there have been few effective and straightforward evaluation methods for the nano-plugging agent. In this study, an artificial filter cake was created to simulate the microfissure of shale formation, and the performance of the nano-plugging agent was assessed using the fluid-loss reduction rate as the index. The filter cake was made from compound crystal weights and a high molecular weight polymer, and a nano-plugging agent matching the formation pore structures was selected. The performance of three plugging agents with varying particle sizes (ultrafine CaCO3, emulsified modified rubber MORLF, ULIA nano-plugging agent) was compared. Moreover, the validity of the evaluation process was confirmed, and the underlying plugging mechanism was investigated. The proposed technique can produce an artificial filter cak... [more]

The residential sector is currently responsible for approximately 30% of the final energy consumption and 12% of direct CO2 emissions in Italy, mainly due to the heating and cooling of buildings and the use of domestic hot water. Such figures show a significant potential for reducing non-renewable primary energy utilization to comply with the decarbonization constraints of the European Union. In this context, the purpose of this work is to provide a quantitative assessment of the effect of a different number of actions (eight for energy savings, four for energy efficiency and two for the installation of renewable energy plants) that could be implemented at the national level to reduce the consumption of natural gas in the residential sector. Two typical residential buildings are dynamically simulated using Trnsys®, and the savings from energy, economic and CO2 emissions points of view are evaluated in the different climatic zones of Italy. The most effective action foresees the replace... [more]

Due to the fact that the European Union is striving to achieve its sustainable development goals, in particular goal No. 7, which is to provide users with low-emission, and cheap access to, energy, this article’s aim is to verify whether there is a relationship between R&D expenditure and key energy variables in the EU countries in 2010−2020. Data on R&D expenditures incurred by the EU Member States in the period 2010−2020 were used for the research and were tested using the Autoregressive Distributed Lags Model (ARDL). The study identified a strong positive relationship between total R&D expenditure and the increase in energy consumption from renewable energy sources, and a smaller impact of total R&D expenditure as well as enterprise R&D expenditure on the increase in fossil energy consumption. Also noted was a weak relationship between R&D expenditure and electricity and gas prices for both household and non-household customers. The obtained results prove that in the context of the... [more]

This paper introduces a simple diesel train energy consumption model that calculates the instantaneous energy consumption using vehicle operational input variables, including the instantaneous speed, acceleration, and roadway grade, which can be easily obtained from global positioning system (GPS) loggers. The model was tested against real-world data and produced an error of −1.33% for all data and errors ranging from −12.4% to +8.0% for energy consumption of four train datasets amounting to a total of 5854 km trips. The study also validated the proposed model with separate data that were collected between Valencia and Cuenca, Spain, which had a total length of 198 km and found that the model was accurate, yielding a relative error of −1.55% for the total energy consumption. These results show that the proposed model can be used by train operators, transportation planners, policy makers, and environmental engineers to evaluate the energy consumption effects of train operational project... [more]

Establishing a renewable marine energy industry demands the development of high-efficiency devices that capture as much energy as possible. The Blow-Jet is a wave energy converter mainly composed of a sloping conical channel in the shape of a brass tube, which concentrates the waves at its widest part and expels a jet of water at its narrow upper end through an orifice that can be turbined. The device has no moving parts and great flexibility in its placement. This research presents an improvement of its geometry, increasing efficiency by minimizing undesired hydrodynamic interactions. The performance of the Blow-Jet was characterized using 3D numerical modeling and laboratory tests in a wave flume. Sixteen geometric configurations of the Blow-Jet were numerically tested, and that showing the best performance was 3D printed and assessed experimentally. The twofold objective was to evaluate the performance of the new Blow-Jet geometry and to validate a numerical tool for further geometr... [more]

This paper presents the status regarding electric vehicles (EVs) and public charging stations managed by Cluj-Napoca City Hall. The types of charging stations and the quantity of the used energy were stated. The behavior of EV owners in charging their vehicles was also studied. The presented work proposes an extension of the EV charging infrastructure to support current and future EV owners. Simulations were carried out in Simulink to create an overview of the existing infrastructure. The simulation results showed the amount of greenhouse gas (CO2 emissions) reduced by using EVs. An estimated number of kilometers traveled with EVs was calculated by tracking the loads in all public charging stations.

With the aim of CO2 emissions reduction in the maritime sector, dual fuel engines operating on natural gas are the most prominent technical and commercially available solution. A promising variant is the two-stroke high-pressure natural gas injection engine, utilizing diesel pilot fuel injection for ignition of the gaseous fuel while being able to operate in diesel-only mode. In this study, a comparative analysis of the performance and the combustion mechanism of dual fuel and diesel mode for this engine type is conducted using experimental data. Studies based on measurements conducted on actual scale are limited in the literature due to the engines’ sheer size not allowing lab testing. The analysis was conducted using measurements acquired during the factory acceptance tests involving conventional operating data and cylinder pressure data acquired using a piezoelectric sensor. In terms of the mean pressure and temperature, only minor differences were found. The specific fuel consumpti... [more]

In industrial settings, mechanical systems for clamping workpieces onto machine tools or for lifting and handling ferrous material are often replaced by magnetic clamping systems. For large lifting applications, the most suitable magnetic clamping systems are electromagnetic (EM) and electro-permanent (EP) approaches. Their configurations, direct and induced poles or direct poles only, need to be discussed in order to choose the most appropriate and economical setup for the specific application. In addition, an evaluation of the difference in the energy efficiency between EM and EP systems, which is often not simple, is presented. To achieve this, a hybrid control system for EM or EP systems was developed and, with the help of this prototype, an analysis of these two magnetic systems was carried out to highlight the main differences. The hybrid control system consists of a single control unit that can be used by both systems, and can be achieved by simply changing the type of lifting m... [more]

The design of naval exhaust funnels has to take into account the interaction between the hot gases and topside structures, which usually includes critical electronic devices. Being able to predict the propagation trajectory, shape and temperature distribution of an exhaust gas plume is highly strategic in different industrial sectors. The propagation of a stack plume can be affected by different uncertainty factors, such as those related to the wind flow and gas flow conditions at the funnel exit. The constant growth of computational resources has allowed simulations to gain a key role in the early design phase. However, it is still difficult to model all the aspects of real physical problems in actual applications and, therefore, to completely rely upon the quantitative results of numerical simulations. One of the most important aspects is related to input variable uncertainty, which can significantly affect the simulation result. With this aim, the discipline of Uncertainty Quantific... [more]

Proton exchange membrane fuel cells (PEMFC) are a promising clean power source that can be used in a variety of applications such as automobiles, stationary power plants, and portable power devices. The application problem of PEM fuel cells is a multiscale application process involving porous media, consisting of a series of mass, momentum, and energy transfers through gas channels, current transfers through membrane electrode assemblies, and electrochemical reactions at three-phase boundaries. In this paper, the recent research progress of PEMFC in multiscale porous-media mass transfer processes is reviewed, the research progress of fuel cell parameter identification is reviewed, and the future development direction is summarized and analyzed. The purpose of this paper is to provide a comprehensive overview of proton exchange membrane fuel cell mass transfer and parameter identification to reference researchers and engineers in the field of fuel cell systems.

This work investigates how to balance the electricity supply and demand in a carbon-neutral northern Europe. Applying a cost-minimizing electricity system model including options to invest in eleven different flexibility measures, and cost-efficient combinations of strategies to manage variations were identified. The results of the model were post-processed using a novel method to map the net load before and after flexibility measures were applied to reveal the contribution of each flexibility measure. The net load was mapped in the space spanned by the amplitude, duration and number of occurrences. The mapping shows that, depending on cost structure, flexibility measures contribute to reduce the net load in three different ways; (1) by reducing variations with a long duration but low amplitude, (2) by reducing variations with a high amplitude but short duration and low occurrence or (3) by reducing variations with a high amplitude, short duration and high occurrence. It was found that... [more]

Predicting energy demand in adverse scenarios, such as the COVID-19 pandemic, is critical to ensure the supply of electricity and the operation of essential services in metropolitan regions. In this paper, we propose a deep learning model to predict the demand for the next day using the “IEEE DataPort Competition Day-Ahead Electricity Demand Forecasting: Post-COVID Paradigm” database. The best model uses hybrid deep neural network architecture (convolutional network−recurrent network) to extract spatial-temporal features from the input data. A preliminary analysis of the input data was performed, excluding anomalous variables. A sliding window was applied for importing the data into the network input. The input data was normalized, using a higher weight for the demand variable. The proposed model’s performance was better than the models that stood out in the competition, with a mean absolute error of 2361.84 kW. The high similarity between the actual demand curve and the predicted dema... [more]

In this paper, an inductive power transfer (IPT) system without compensation elements is presented for small house appliances. The proposed system’s transmitter side is an independent induction heating cooktop. IPT can be achieved when the kettle with the receiving coils is placed on the transmitter coil. The coils are designed with a high coupling coefficient. The magnetic system model consisting of aligned transmitter and receiver coils is created in the Maxwell program. In the created model, the analysis depends on the air gap and frequency, which are the variables that affect the wireless power transfer. The electronic circuit simulation uses the coil model to examine the system’s dynamic behavior. The design of the transmitter/receiver coils of the IPT system is made with a cylindrical coil with a diameter of 145 mm, taking into account that it is compatible with the dimensions of the existing kettle and induction heating cooktops coil. A half-bridge series resonant converter circ... [more]

Building energy management systems (BEMSs), dedicated to sustainable buildings, may have additional duties, such as hosting efficient energy management systems (EMSs) algorithms. This duty can become crucial when operating renewable energy sources (RES) and eventual electric energy storage systems (ESSs). Sophisticated EMS approaches that aim to manage RES and ESSs in real time may need high computing capabilities that BEMSs typically cannot provide. This article addresses and validates a fuzzy logic-based EMS for the optimal management of photovoltaic (PV) systems with lead-acid ESSs using an edge computing technology. The proposed method is tested on a real smart grid prototype in comparison with a classical rule-based EMS for different weather conditions. The goal is to investigate the efficacy of islanding the building local network as a control command, along with ESS power control. The results show the implementation feasibility and performance of the fuzzy algorithm in the optim... [more]

This paper proposes a novel approach to optimizing the structure of the electricity market by mitigating market power through the use of forward contracts. The IEEE 30 node test system is used as a case study for the paper, which employs nodal pricing and a Cournot model with recursive optimization. The findings show that forward contracts can reduce market power and lead to a more competitive market structure with fewer participants. The study emphasizes the importance of successor companies having a well-balanced mix of generation technology. Six players with a different generational mix are optimal in the constrained nodal pricing scenario, while five players with slightly different mixes are optimal in the Cournot case study. These findings have important implications for policymakers and industry stakeholders involved in the design and implementation of efficient electricity markets. Market power can be reduced by using forward contracts and establishing an appropriate number of m... [more]

Nowadays, energy generation systems that include renewable energies, substations, distribution, transmission, control, measurement, and storage applications, among others, and are interrelated are known as Smart Grids. All these techniques and technologies involve extensive research and development, which allows for the solving of key aspects, such as control, diagnosis, and fault recovery, as well as communication systems focused directly on the operation of the electrical networks. Due to the relevance of knowledge concerning developments in these areas of Smart Grids, this paper presents a review of the research related to the control systems applied to Smart Grids and Micro Grids, both in supply and demand. Likewise, some control models relate to different processes, with a special focus on techniques related to Petri nets. The paper shows, among other outcomes, the advances in the control of smart grids, the types of generation and their influence on the design of transmission lin... [more]

The holistic green energy transition of non-interconnected islands faces several challenges if all the energy sectors are included, i.e., electricity, heating/cooling, and mobility. On the one hand, the penetration of renewable energy systems (RES) is limited due to design restrictions with respect to the peak demand. On the other hand, energy-intensive heating and mobility sectors pose significant challenges and may be difficult to electrify. The focus of this study is on implementing a hybrid Wind−PV system on the non-interconnected island of Anafi (Greece) that utilizes surplus renewable energy production for both building heating through heat pumps and hydrogen generation. This comprehensive study aims to achieve a holistic green transition by addressing all three main sectors—electricity, heating, and transportation. The produced hydrogen is utilized to address the energy needs of the mobility sector (H2 mobility), focusing primarily on public transportation vehicles (buses) and s... [more]

The energy group structure of a multi-group cross section library matched with a deterministic method has a significant influence on shielding calculation. The complex resonance cross section of Fe-56 has a significant influence on accuracy with different energy group structures when processing multi-group cross section data. In this study, in order to more accurately test the influence of the iron resonance phenomenon on shielding calculations, this group structure is modified by the 199-group with 69 points interpolated into its group boundaries at an energy range from 1.1 keV to 3.1164 MeV. The new 269-group library is then tested with selected SINBAD iron sphere benchmarks and compared with the results of 199-group, 299-group, and 172-group libraries and measurements. Upon analysis, it is shown that the resonance of Fe-56 has a great influence on the accuracy of the calculated leakage. Further, it is noted that the finer the energy group division, the greater the calculated leakage... [more]

Power flow calculation is the foundation of security analyses in a power system, and the phenomenon of convergence failure is becoming more prominent with the expansion of the power grid. The existing convergence failure diagnosis methods based on optimization modeling and local feature recognition are no longer viable for bulk power systems. This paper proposes a diagnosis method based on intermediate iteration data and the identification of the transmission power congested channel. Firstly, the transmission power congestion index is constructed, and then a method for identifying transmission congestion channels is proposed. The reasons for convergence failure of the power flow are diagnosed from two aspects: excessive power to be transmitted and insufficient transmission capacity. Finally, with the aim of alleviating transmission channel congestion, a correction strategy for power flow injection space data was constructed, which generates relaxation schemes for operational variables.... [more]

Auditing activity, in the last decade, is one of the most dynamically changing types of economic activity, on the one hand, due to an increase in the number of state projects implemented by many countries, and on the other hand, due to technological innovations and digitalization. Russian auditing practices are also being actively reformed. For example, the Ministry of Energy is updating their audit methodology. The subject of this study is to ensure the efficiency of spending public funds for the implementation of strategic projects. The object of this study is the methodology of a state audit. An analysis of the currently used Russian and international standards for public audits shows that there are many opportunities to improve the methodology for conducting financial, strategic and performance audits. First of all, there is a need to solve methodological problems in monitoring the efficiency of investment developments, since partnerships between private investors and government bo... [more]

Low load is one of the most challenging combustion stages for a fixed-speed diesel electric generator. Due to incomplete combustion during this phase, a significant proportion of contaminants form inside the cylinder. This can lead to numerous chemical and mechanical harms to the diesel engine, resulting in friction, efficiency reduction, increased fuel consumption, and prematurely ending the generator’s life. These phenomena are qualified as underperformance, possibly due to a misfire and/or a low-efficiency value (air fuel−fuel ratio). Therefore, detecting and preventing underperformance and reducing its extended operation is crucial. This paper deals with the performance and emission analysis of a multicylinder fixed-speed diesel engine driving an electric generator (300 kW) fueled with ultra-low sulfur diesel (≤15 mg/kg) to provide energy in an isolated Canadian community. The tests were carried out according to ISO 3046-1:2002 standard in a remote site to identify clues that can p... [more]

The conventional energy source in cement industries is fossil fuels, mainly coal, which has a high environmental footprint. On average, energy expenditures account for 40% of the overall production costs per ton of cement. Reducing both the environmental impact and economic expenditure involves incorporating alternative energy sources (fuels) such as biomass, solid-derived fuel (SDF), refuse-derived fuel (RDF) etc. However, within cement plants, the substitution of conventional fossil fuels with alternative fuels poses several challenges due to the difficulty in incorporating additional fuel-saving techniques. Typically, an additional 3000 MJ of electricity per ton of clinker is required. One of the most effective solutions to this is thermal optimization through co-processing and pre-processing, which makes it possible to implement additional fossil-fuel-saving techniques. In developing nations such as Togo, waste-management systems rely on co-processing in cement factories through a... [more]