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Energies, Volume 15, Issue 17 (September-1 2022) – 395 articles

Cover Story (view full-size image): In this study, a fluid–thermal–electrical multiphysics numerical model was developed for thermal and electrical analyses of a heat-sink-based thermoelectric generator (TEG) in a waste heat recovery system used for casting a bronze ingot mold. Moreover, the model was validated based on experimental data. Heat sinks were installed on the hot side of the TEG module to recover the waste heat from the flue gas generated in the casting process. The numerical results of the thermal and electrical characteristics of a plate fin (PF)-based TEG showed good agreement with the experimental findings. Numerical simulations of heat sinks with three different fin structures—PF, cylinder pin fin (CPF), and rectangular pin fin (RPF)—were conducted. Therefore, for low and high flue gas velocities, PF and CPF heat sinks are recommended as the best choices, respectively. View this paper
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Article
Evaluation of Leachate Recirculation as a Stabilisation Strategy for Landfills in Developing Countries
Energies 2022, 15(17), 6494; https://doi.org/10.3390/en15176494 - 05 Sep 2022
Viewed by 709
Abstract
This study evaluated leachate recirculation (LR) as a stabilisation strategy for landfills using bioreactor experiments with excavated waste from a tropical landfill in Colombia. The experimental evaluation was performed in two 115 L bioreactors, one simulating the operation of a landfill with LR, [...] Read more.
This study evaluated leachate recirculation (LR) as a stabilisation strategy for landfills using bioreactor experiments with excavated waste from a tropical landfill in Colombia. The experimental evaluation was performed in two 115 L bioreactors, one simulating the operation of a landfill with LR, Br2, where the leachate produced was recirculated at a rate of 0.8 L d−1, and a control system without LR, Br1. Both systems reached stabilisation indicator values on a dry matter (DM) basis for volatile solids VS (<25% DM) and a biochemical methane potential BMP (≤10 mL CH4 g−1 DM). Likewise, towards the end of the experiment, the leachate generated in Br2 reached stabilisation indicator values for BOD5 (<100 mg L−1) and the BOD (biological oxygen demand)/COD (chemical oxygen demand) ratio (<0.1). Although the stabilisation criterion for COD was not met in any bioreactor (<200 mg L−1), LR helped to release 19% more oxidisable organic matter in Br2 than in Br1, indicating a reduction in the contaminating potential of the waste in the case of uncontrolled discharges of leachate to the environment. Regarding biogas production, the generation of CH4 in Br2 was more intense and its cumulative production was 34.5% higher than Br1; thus, Br2 achieved CH4 emission rates, indicating waste stabilisation (<1.0 L CH4 m−2 h−1) sooner than Br1, showing an accelerating effect of LR on waste degradation. A carbon mass balance indicated that waste degradation, in terms of the initial total organic carbon mineralisation and the C gas discharge via CH4, was greater in Br2. These results demonstrate the LR potential to accelerate the stabilisation of a landfill but also to reduce greenhouse gas emissions in final disposal sites where biogas is also captured and utilised for energy production; a key aspect when improving the sustainability of landfill operations in developing countries. Full article
(This article belongs to the Special Issue Bio-Refineries and Renewable Energies Supported on ICT)
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Article
Alternative Simplified Analytical Models for the Electric Field, in Shoreline Pond Electrode Preliminary Design, in the Case of HVDC Transmission Systems
Energies 2022, 15(17), 6493; https://doi.org/10.3390/en15176493 - 05 Sep 2022
Viewed by 660
Abstract
In Greece, a new bi-polar high voltage direct current (HVDC) transmission system with a ground return was designed with nominal characteristics of ±500 kV, 1 GW, between Attica in the continental country and the island of Crete, which is an autonomous power system [...] Read more.
In Greece, a new bi-polar high voltage direct current (HVDC) transmission system with a ground return was designed with nominal characteristics of ±500 kV, 1 GW, between Attica in the continental country and the island of Crete, which is an autonomous power system based on thermal diesel units. The interconnection line has a total length of about 380 km. The undersea section is 330 km long. In this paper, the use of the Aegean Sea as an active part of the ground return, based on shoreline pond electrodes, was proposed to avoid EUR 200 Μ of expenses. According to the general guidelines for HVDC electrode design by the International Council on Large Electric Systems (CIGRE) working group B4.61/2017, the electric field and ground potential rise of shoreline electrodes should be studied to analyze safety, electrical interference and corrosion impacts related to the operation of the electrodes. Two kinds of studies are available; one is a simplified approach based on a spherical/pointed electrode centered at the edge of the seashore and seabed, assuming it to be sloping to the horizontal, and the other is a detailed simulated model using a suitable electric field software package. The first approach usually gives more unfavorable results than the second one, especially in the near electric field, while it can not take into account obstacles, i.e., dams, near to electrode position. The second approach demands a detailed description of the wider installation area, which cannot be available during the preliminary study, significant computational time and considerable financial resources for the purchase of a reliable specialized software package. In this research, a two-step modification of the CIGRE simplified model was proposed. The first modification deals with the obstacles in the near electric field, and the second modification deals with the use of a linear current source (instead of a point one), which can give more accurate results. Additionally, the electric field for complex electrode formation is calculated by applying the superposition method, which can be easily achieved using a common software package, i.e., MATLAB. The proposed simplified approaches were applied on shoreline pond electrode locations for the Attica–Crete HVDC interconnection line (between Stachtoroi island in Attica and Korakia beach in Crete), allowing the preliminary study to be conducted swiftly, giving satisfactory results about electric field gradient, ground potential rise and resistance to remote earth of electrodes stations for the near and far electric field. Full article
(This article belongs to the Special Issue Power System Dynamics and Renewable Energy Integration)
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Article
Natural Ventilation Enhancement of a Roof Solar Chimney with Wind-Induced Channel
Energies 2022, 15(17), 6492; https://doi.org/10.3390/en15176492 - 05 Sep 2022
Viewed by 530
Abstract
A novel roof solar chimney with wind-induced channel was designed herein to augment indoor natural ventilation under combined action of wind and solar energy. Compared with the traditional solar chimney, the new rooftop solar chimney improves the air flow due to the wind-induced [...] Read more.
A novel roof solar chimney with wind-induced channel was designed herein to augment indoor natural ventilation under combined action of wind and solar energy. Compared with the traditional solar chimney, the new rooftop solar chimney improves the air flow due to the wind-induced channel. The effects of channel width ratio, chimney inclination at different outdoor wind speeds on the natural ventilation performance of the roof solar chimney were studied by numerical simulation. Finite-volume method was used for the numerical calculation. It was found that the trends of ventilation rate are different when the channel widths increase. The mass flow rate of the new structure increases with the increase in the inclination angle. When the inclination angles increase from 30° to 90°, the ventilation rate increases by 212% for U = 1.0 m·s−1, 166% for U = 2.0 m·s−1, and 127% for U = 3.0 m·s−1 under the condition of and the solar radiation I = 600 W·m−2. Full article
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Article
The Application of the γ-Reθt Transition Model Using Sustaining Turbulence
Energies 2022, 15(17), 6491; https://doi.org/10.3390/en15176491 - 05 Sep 2022
Viewed by 478
Abstract
The freestream turbulence intensity is an important parameter for Tollmien–Schlichting waves and is also used as one of the key variables for the local- and transport-equation-based transition model in the simulations. To obtain the similar turbulence level in the vicinity to the aircraft [...] Read more.
The freestream turbulence intensity is an important parameter for Tollmien–Schlichting waves and is also used as one of the key variables for the local- and transport-equation-based transition model in the simulations. To obtain the similar turbulence level in the vicinity to the aircraft as the turbulence intensity measured in a wind tunnel or in free-flight conditions, the sustaining turbulence term can be used for the transition model. It is important to investigate the model behavior when the sustaining turbulence is coupled with the frequently used SST-variants for transitional flows. Additionally, it is essential to obtain a nearly independent solution using the same transition model for different users on different meshes with similar grid resolution for purposes of verification and validation. So far, the relevant work has not been performed sufficiently and the sustaining turbulence technology introduces non-independent results into the freestream values. Thus, a modified sustaining turbulence approach is adopted and investigated in several test cases, including a computational effort on NACA0021 test case at 10 angles of attack. The results indicate that the modified sustaining turbulence in conjunction with the SST-2003 turbulence model yields results nearly independent to the freestream value of ω for the prediction of both streamwise and crossflow transition for two-dimensional flows without increasing computational effort too much. For three-dimensional flow, the sensitivity to initial value of ω is reduced significantly as well in comparison to the SST-based transition model, and it is highly recommended to use present sustaining turbulence technology in conjunction with the SST-2003-based transition model for engineering applications. Full article
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Article
Energy Consumption Prediction and Analysis for Electric Vehicles: A Hybrid Approach
Energies 2022, 15(17), 6490; https://doi.org/10.3390/en15176490 - 05 Sep 2022
Viewed by 751
Abstract
Range anxiety remains one of the main hurdles to the widespread adoption of electric vehicles (EVs). To mitigate this issue, accurate energy consumption prediction is required. In this study, a hybrid approach is proposed toward this objective by taking into account driving behavior, [...] Read more.
Range anxiety remains one of the main hurdles to the widespread adoption of electric vehicles (EVs). To mitigate this issue, accurate energy consumption prediction is required. In this study, a hybrid approach is proposed toward this objective by taking into account driving behavior, road conditions, natural environment, and additional weight. The main components of the EV were simulated using physical and equation-based models. A rich synthetic dataset illustrating different driving scenarios was then constructed. Real-world data were also collected using a city car. A machine learning model was built to relate the mechanical power to the electric power. The proposed predictive method achieved an R2 of 0.99 on test synthetic data and an R2 of 0.98 on real-world data. Furthermore, the instantaneous regenerative braking power efficiency as a function of the deceleration level was also investigated in this study. Full article
(This article belongs to the Section E: Electric Vehicles)
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Review
Application of Pre-Splitting and Roof-Cutting Control Technology in Coal Mining: A Review of Technology
Energies 2022, 15(17), 6489; https://doi.org/10.3390/en15176489 - 05 Sep 2022
Cited by 2 | Viewed by 658
Abstract
According to the development requirements of green mining of coal resources, it is imperative to improve the extraction rate of coal and the application of safe and efficient mining technology. Pre-splitting and roof cutting technology is widely used in reducing residual coal pillars [...] Read more.
According to the development requirements of green mining of coal resources, it is imperative to improve the extraction rate of coal and the application of safe and efficient mining technology. Pre-splitting and roof cutting technology is widely used in reducing residual coal pillars and safe pressure relief mining, which has become the crucial technology for pillar-free mining methods. Therefore, it is essential to review and discuss the research hotspots, cutting-edge methods, principles of action, and application areas of the development of this technology. Above all, the research data on pre-splitting and roof-cutting development in the past ten years are summarized and outlined. The research’s hot spots are pressure relief technology and gob-side entry retaining technology. Then, the functional forms of pre-splitting and roof cutting technology are discussed and compared, including explosive blasting (directional energy gathering blasting, liquid explosive blasting, and composite blasting), hydraulic fracturing, liquid CO2 gas fracturing, and mechanized roof cutting (chain arm saw machine and directional cutting roof rig). Through the analysis of field application cases, the application field is divided into three major areas: non-coal pillar mining (gob-side entry driving with narrow coal pillar, gob-side entry retaining with the filling body, completely gob-side entry retaining, and “N00” construction method), pressure relief at working face (thick and hard main roof cracking and end area hard roof cracking), and pressure relief at roadway (gob-side roadway pressure relief and blasting pressure relief technology for roadways). By detailing the process of each application technology one by one, the principle and mode of pre-splitting in each technology are expounded. Finally, the development prospects of pre-splitting and roof cutting in new technical methods, deep pressure relief mining, intelligent unmanned mining, and green and efficient mining are prospected, providing references for similar projects. Full article
(This article belongs to the Special Issue Method and Technology of Green Coal Mining)
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Review
Artificial Intelligence Control System Applied in Smart Grid Integrated Doubly Fed Induction Generator-Based Wind Turbine: A Review
Energies 2022, 15(17), 6488; https://doi.org/10.3390/en15176488 - 05 Sep 2022
Cited by 1 | Viewed by 897
Abstract
Wind-driven turbines utilizing the doubly-fed induction generators aligned with the progressed IEC 61400 series standards have engrossed specific consideration as of their benefits, such as adjustable speed, consistent frequency mode of operation, self-governing competencies for voltage and frequency control, active and reactive power [...] Read more.
Wind-driven turbines utilizing the doubly-fed induction generators aligned with the progressed IEC 61400 series standards have engrossed specific consideration as of their benefits, such as adjustable speed, consistent frequency mode of operation, self-governing competencies for voltage and frequency control, active and reactive power controls, and maximum power point tracking approach at the place of shared connection. Such resource combinations into the existing smart grid system cause open-ended problems regarding the security and reliability of power system dynamics, which needs attention. There is a prospect of advancing the art of wind turbine-operated doubly-fed induction generator control systems. This section assesses the smart grid-integrated power system dynamics, characteristics, and causes of instabilities. These instabilities are unclear in the wind and nonlinear load predictions, leading to a provisional load-rejection response. Here, machine learning computations and transfer functions measure physical inertia and control system design’s association with power, voltage, and frequency response. The finding of the review in the paper indicates that artificial intelligence-based machine and deep learning predictive diagnosis fields have gained prominence because of their low cost, less infrastructure, reduced diagnostic time, and high level of accuracy. The machine and deep learning methodologies studied in this paper can be utilized and extended to the smart grid-integrated power context to create a framework for developing practical and accurate diagnostic tools to enhance the power system’s accuracy and stability, software requirements, and deployment strategies. Full article
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Article
Detailed Analysis of PAH Formation, Toxicity and Regulated Pollutants in a Diesel Engine Running on Diesel Blends with n-Propanol, n-Butanol and n-Pentanol
Energies 2022, 15(17), 6487; https://doi.org/10.3390/en15176487 - 05 Sep 2022
Viewed by 509
Abstract
There are a number of emissions produced by internal combustion engines that are regulated to limit atmospheric pollution. However, it is equally important for both environmental and human health to also monitor and control polycyclic aromatic hydrocarbons (PAHs). Using high-carbon alcohols with straight-chain [...] Read more.
There are a number of emissions produced by internal combustion engines that are regulated to limit atmospheric pollution. However, it is equally important for both environmental and human health to also monitor and control polycyclic aromatic hydrocarbons (PAHs). Using high-carbon alcohols with straight-chain structures, such as n-propanol (Pro), n-butanol (Bu) and n-pentanol (Pen), together with diesel fuel (D), can be a way to reduce these harmful pollutants. In this study, nine different test fuels were created by mixing each higher alcohol with diesel fuel at 5%, 20% and 30% mixing ratios. In order to compare the effects of these test fuels on regulated pollutants and PAH compounds, fuel blends were evaluated in a diesel engine at partial loads and at a constant speed. Regulated emissions were measured using a standard 5-gas analyzer, and PAHs were detected and quantified using rigorous analytical chemistry methods, such as gas chromatography–mass spectrometry (GC–MS). While higher carbon monoxide (CO) and hydrocarbon (HC) pollutants were emitted by the binary blends due to their high oxygen content and latent heat of evaporation (LHE), a decrease in nitrogen oxides (NOx) emissions between 4.98% and 20.08% was observed depending on the alcohol concentration. With the exception of the 20% n-pentanol mixture, PAH concentrations in the exhaust gas were significantly reduced in other binary blends. The 35% n-butanol mixture stood out in reducing total PAHs by 80.98%. In toxicity reduction, the 20% n-propanol mixture was the most effective with a decrease of 91.23% in toxicity. Overall, higher alcohols have been shown to be effective additives not only in reducing overall PAH emissions and toxicity, but also in reducing high-ring and heavier PAHs, which are more carcinogenic and cause a greater risk to engine lifedue to wet stacking under cold starting or low-load conditions. Full article
(This article belongs to the Section I1: Fuel)
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Article
Real-Time Methane Prediction in Underground Longwall Coal Mining Using AI
Energies 2022, 15(17), 6486; https://doi.org/10.3390/en15176486 - 05 Sep 2022
Cited by 1 | Viewed by 529
Abstract
Detecting the formation of explosive methane–air mixtures in a longwall face is still a challenging task. Even though atmospheric monitoring systems and computational fluid dynamics modeling are utilized to inspect methane concentrations, they are not sufficient as a warning system in critical regions, [...] Read more.
Detecting the formation of explosive methane–air mixtures in a longwall face is still a challenging task. Even though atmospheric monitoring systems and computational fluid dynamics modeling are utilized to inspect methane concentrations, they are not sufficient as a warning system in critical regions, such as near cutting drums, in real-time. The long short-term memory algorithm has been established to predict and manage explosive gas zones in longwall mining operations before explosions happen. This paper introduces a novel methodology with an artificial intelligence algorithm, namely, modified long short-term memory, to detect the formation of explosive methane–air mixtures in the longwall face and identify possible explosive gas accumulations prior to them becoming hazards. The algorithm was trained and tested based on CFD model outputs for six locations of the shearer for similar locations and operational conditions of the cutting machine. Results show that the algorithm can predict explosive gas zones in 3D with overall accuracies ranging from 87.9% to 92.4% for different settings; output predictions took two minutes after measurement data were fed into the algorithm. It was found that faster and more prominent coverage of accurate real-time explosive gas accumulation predictions are possible using the proposed algorithm compared to computational fluid dynamics and atmospheric monitoring systems. Full article
(This article belongs to the Special Issue Volume II: Mining Innovation)
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Article
Inventory Routing for Ammonia Supply in German Ports
Energies 2022, 15(17), 6485; https://doi.org/10.3390/en15176485 - 05 Sep 2022
Cited by 1 | Viewed by 808
Abstract
Following the International Maritime Organization (IMO), in order to safeguard the realization of the Paris Agreement on climate protection, greenhouse gas (GHG) emissions have to be reduced by 50% by the year 2050. This objective shall be reached by decarbonization of maritime traffic, [...] Read more.
Following the International Maritime Organization (IMO), in order to safeguard the realization of the Paris Agreement on climate protection, greenhouse gas (GHG) emissions have to be reduced by 50% by the year 2050. This objective shall be reached by decarbonization of maritime traffic, which is why ship operators currently increasingly search for alternative fuels. Moreover, since the start of the Ukrainian war in February 2022, this issue of alternative fuels has gained central importance in political agendas. A promising candidate for clean shipping that meets the IMO goals is ammonia since it is a carbon-free fuel. Ammonia (NH3) shows good advantages in handling and storage, and it ensures long sea voyages without any significant loss in cargo space for a reasonable price. Hence, ammonia has the potential to improve the environmental footprint of global shipping enormously. Induced by the introduction of stricter regulations in the so-called emission control areas (ECAs) in Northern Europe in 2015 as well as the renewed global sulfur cap, which entered into force in 2020, ship operators had to decide between different compliance methods, among which the most popular solutions are related to the use of expensive low-sulfur fuel oils, newbuilds and retrofits for the usage of liquefied natural gas (LNG) or the installation of scrubber technology. A change to ammonia as a marine alternative fuel represents an additional novel future option, but the successful implementation depends on the availability of NH3 in the ports, i.e., on the installation of the maritime NH3 infrastructure. Currently, the single German NH3 terminal with maritime access is located in Brunsbüttel, the western entrance to Kiel Canal. The distribution of NH3 from the existing NH3 hub to other German ports can be analyzed by the mathematical model of an inventory routing problem (IRP) that is usually solved by combinatorial optimization methods. This paper investigates the interrelated research questions, how the distribution of marine NH3 fuel can be modeled as an IRP, which distribution mode is the most economic one for the German ports and which modal mix for the NH3 supply leads to the greenest distribution. The results of this paper are empirically validated by data that were collected in several EU projects on sustainable supply chain management and green logistics. The paper includes a special section that is dedicated to the discussion of the economic turbulences related to the Ukrainian war together with their implications on maritime shipping. Full article
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Article
Design of Energy-Saving Duct for JBC to Reduce Ship Resistance by CFD Method
Energies 2022, 15(17), 6484; https://doi.org/10.3390/en15176484 - 05 Sep 2022
Viewed by 587
Abstract
The present work is to modify the stern duct of Japan bulk carrier (JBC) to reduce the ship total resistance for Froude number 0.142. The research method is to use the CFD (computational fluid dynamics) tool OpenFOAM to predict the total resistance and [...] Read more.
The present work is to modify the stern duct of Japan bulk carrier (JBC) to reduce the ship total resistance for Froude number 0.142. The research method is to use the CFD (computational fluid dynamics) tool OpenFOAM to predict the total resistance and viscous flow field around the ship hull considering the free surface. First, the V&V (verification and validation) analysis was conducted to ensure our CFD method is reliable, and to estimate its error and uncertainty range for the original JBC with and without the original stern duct. Second, the angle of attack (AoA) of the foil section of the stern duct was adjusted, thus forming a series of different ducts axisymmetric along the propeller shaft axis. The CFD simulations were performed for each duct appended behind the ship hull. By comparing the total resistance with and without the duct, the ship hull resistance reduction effect caused by the duct would be obtained. Finally, the duct with 7° AoA achieved the best resistance reduction of 2.49%. The original duct (with 20° AoA) could only provide a 0.6~0.7% reduction. The nominal wake was also analyzed with the ducts, in order to understand the detailed flow phenomena which had an essential influence on propeller inflow. Full article
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Review
Residential Refrigeration MEPS in Colombia: A Review and a Comparative Analysis
Energies 2022, 15(17), 6483; https://doi.org/10.3390/en15176483 - 05 Sep 2022
Viewed by 626
Abstract
This paper addresses the energy efficiency issue in household appliances, which has led to the establishment of policies at a global level in favor of setting minimum energy performance standards (MEPS), which guarantee end users are able to select more efficient equipment. The [...] Read more.
This paper addresses the energy efficiency issue in household appliances, which has led to the establishment of policies at a global level in favor of setting minimum energy performance standards (MEPS), which guarantee end users are able to select more efficient equipment. The countries of the United States, Brazil, Mexico, Chile, and the Community of the European Union were taken as references to review their policies and implementation strategies, in order to be compared with the Colombian panorama (at the market, technical and political levels). This allows the establishment of common aspects and differences related to the determination of energy consumption, adjusted volume, and formalization of efficiency ranges, and in the specific case of domestic refrigeration. Managing to distinguish the most relevant aspects for the successful adoption of these policies in Colombia. It is evident that the implementation of these guidelines has a positive impact on the market of the countries and communities of reference. Similarly, the MEPS are shown as a mechanism to regulate energy consumption in the residential sector. Full article
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Review
A Review of the Energy Potential of Residual Biomass for Coincineration in Kazakhstan
Energies 2022, 15(17), 6482; https://doi.org/10.3390/en15176482 - 05 Sep 2022
Cited by 2 | Viewed by 634
Abstract
Although it has access to hydrocarbon reserves, Kazakhstan has developed a strategy for the transition to a low-carbon economy, which should include the use of renewable energy sources. In this framework, the use of biomass from waste could have the potential to reduce [...] Read more.
Although it has access to hydrocarbon reserves, Kazakhstan has developed a strategy for the transition to a low-carbon economy, which should include the use of renewable energy sources. In this framework, the use of biomass from waste could have the potential to reduce emissions from traditionally fueled energy generation, as well as adding value to the generated waste, which also improves waste management according to the principles of a circular economy. The analysis of the resources and energy potential from residual biomass in Kazakhstan presents an annual production of 37.26 × 106 tons of residual biomass, which could be capable of producing an energy potential of 466.74 PJ/year, little more than half to the total production from all the installed power plants in the country. Agricultural, animal and municipal solid waste are available to produce energy in Kazakhstan based on combustion technologies; however, animal waste and agricultural are the main potential sources with 61.02% and 38.34% of the theoretical total biomass potential energy analyses, respectively. Considering that 80% of Kazakhstan’s electricity generation comes from coal-fired plants, energy from agriculture could be co-fired for the gradual replacement of coal with biomass in operational power plants, without substantially increasing costs or infrastructure investments, thereby making the transition to a low-carbon economy and renewable energy sources in the country easier. Full article
(This article belongs to the Section A: Sustainable Energy)
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Article
Compliance with Corporate Governance Principles by Energy Companies Compared with All Companies Listed on the Warsaw Stock Exchange
Energies 2022, 15(17), 6481; https://doi.org/10.3390/en15176481 - 05 Sep 2022
Viewed by 594
Abstract
Disclosure of non-financial information, especially regarding corporate governance (CG), is an important element of companies’ communication with their stakeholders. This paper sets out to define—from a theoretical and practical perspective—the scope of CG reporting in Polish fuel, gas, and energy (“energy”) companies required [...] Read more.
Disclosure of non-financial information, especially regarding corporate governance (CG), is an important element of companies’ communication with their stakeholders. This paper sets out to define—from a theoretical and practical perspective—the scope of CG reporting in Polish fuel, gas, and energy (“energy”) companies required under EU directives and national regulations. The paper presents the results of a study investigating whether and to what extent annual corporate governance statements (CGSs) prepared by energy companies, compared with other companies listed on the Warsaw Stock Exchange (WSE-LCs), are consistent with “Best Practices for WSE-LCs 2016” (BPs for WSE-LCs). The study group consisted of energy companies submitting their 2017–2020 reports, as well as other companies listed on the WSE, as a comparative group (i.e., a total of 179 reports). We used a monographic method to study theoretical problems and annual CGSs and performed a critical review of the literature, as well as comparative, content, and descriptive analyses. The analysed CGSs helped answer the following question: to what extent do energy companies and other WSE-LCs pursue the CG rules specified in BPs for WSE-LCs? The results indicate that such companies follow various approaches to CG disclosures and reporting obligations. However, what truly matters is not the legal obligation itself, but rather the companies’ social responsibility for maintaining good relations with their stakeholders. The paper will contribute to CG studies, because no Polish theorist has so far analysed CG disclosures in annual non-financial reports. The paper fills a research gap in information on adherence to best practices in CG disclosures in CGSs of all WSE-LCs. The study presents conclusions of CG disclosures by energy companies, which can provide the basis for further research in other sectors. Full article
Article
Characteristics of Cavitation Flow for a Regulating Valve Based on Entropy Production Theory
Energies 2022, 15(17), 6480; https://doi.org/10.3390/en15176480 - 05 Sep 2022
Viewed by 492
Abstract
A regulating valve is a key control element in the coal liquefaction industry, whose flow field distribution is related to the entropy production. In order to make a quantitative evaluation of the energy loss in the cavitation flow and calculate the magnitude and [...] Read more.
A regulating valve is a key control element in the coal liquefaction industry, whose flow field distribution is related to the entropy production. In order to make a quantitative evaluation of the energy loss in the cavitation flow and calculate the magnitude and location of the hydraulic loss in the flow field more accurately, entropy production theory is employed to analyze the flow field in the regulating valve numerically. The entropy production under cavitation condition and its influence on steady-state flow force are also discussed. When the opening of the valve increases, the entropy production and energy loss change dramatically. The entropy production rate (EPR) is mainly distributed at the orifice and downstream of the regulating valve, the entropy production rate (EPR) reaches the maximum value at the orifice, and turbulent pulsation entropy production (TPEP) is the main part of the total entropy production for flow. When the valve’s opening increases from 40% to 70%, the total entropy production (TEP) increases from 467.14 W/K to 630.04 W/K. The entropy production by cavitation (EPC) increases firstly and then decreases. The smallest value of EPC is 0.103 W/K at the 40% opening, while the maximum value is 0.119 W/K at 60% opening. Furthermore, the relationship between total entropy production (TEP) and steady-state flow force can be approximated by an exponential distribution. When the steady-state flow force increases, the total entropy production for flow also increases. Cavitation effect on the steady-state flow force is strengthened firstly and then weakened with increasing the valve’s opening. Finally, a discriminant method based on the change of the steady-state flow force is proposed to detect whether cavitation occurs in the valve or not. The results in this paper could provided a directional and quantitative evaluation of energy loss in the regulating valve, which is help for the structural shape optimization and service life extension combining with external characteristics of the valve and internal flow field. Full article
(This article belongs to the Special Issue New Insights of Intelligent and Integrated Fluid Power Systems)
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Article
Performance Optimisation of Public Transport Networks Using AHP-Dependent Multi-Aspiration-Level Goal Programming
Energies 2022, 15(17), 6479; https://doi.org/10.3390/en15176479 - 05 Sep 2022
Cited by 2 | Viewed by 525
Abstract
This study proposes an optimisation approach to improve multiple-criteria aspiration-level public transportation performance by combining public transport criteria matrix analytic hierarchy process (PTCM-AHP) models and multi-aspiration-level goal programming. The approach uses the PTCM-AHP to calculate the system weights. Based on the weight values, [...] Read more.
This study proposes an optimisation approach to improve multiple-criteria aspiration-level public transportation performance by combining public transport criteria matrix analytic hierarchy process (PTCM-AHP) models and multi-aspiration-level goal programming. The approach uses the PTCM-AHP to calculate the system weights. Based on the weight values, the approach combines the multi-aspiration goal-level selection process in three different ways. The proposed approach was used to optimise public transportation networks in Bayswater, Cockburn, and Stonnington, Australia, to demonstrate the public transportation network performance optimisation process. By controlling the criteria goal value interval, this new approach combines decision-making plans and strategies to optimise various scenarios. The optimisation outcomes can be applied to provide guidelines for improving the performance of public transportation networks. Full article
(This article belongs to the Special Issue Planning and Management of Sustainable Transport)
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Article
Comprehensive Comparison of Hybrid Cooling of Thermal Power Generation with Airside Serial and Parallel Heat Exchange
Energies 2022, 15(17), 6478; https://doi.org/10.3390/en15176478 - 05 Sep 2022
Viewed by 490
Abstract
Natural draft hybrid cooling (NDHC) for thermal power generating units is proposed to achieve a balance of energy and water consumption for arid areas. This study examines the two main design forms of hybrid cooling with airside in serial and parallel heat exchange [...] Read more.
Natural draft hybrid cooling (NDHC) for thermal power generating units is proposed to achieve a balance of energy and water consumption for arid areas. This study examines the two main design forms of hybrid cooling with airside in serial and parallel heat exchange based on the same tower shell and heat transfer areas. Taking full consideration of the thermal cycle of the power generating unit, simplified simulation models for different cooling systems are established to show the influences of ambient conditions and marketing factors. Results show that both the hybrid cooling designs have a better cooling efficiency than either dry cooling or wet cooling. Expanded inlet areas of hybrid cooling in the parallel heat exchange design bring high heat transfer performance. As for the serial design, the higher temperature of the air at the outlet of the dry section maintains a larger airside mass flow rate, obtaining a high-efficient cooling system. The hybrid cooling in the serial design type relies more on the heat transfer performance of the wet section and is more sensible to ambient humidity, while the performance of hybrid cooling in the parallel design mainly depends on the dry section and is more easily affected by ambient temperature. Considering the unit cost variations of coal and water treatment, hybrid cooling in the parallel design has a wider range of applications compared with the serial design. With the growth in coal cost, there exist more benefits with the serial design. Full article
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Article
Behavior of Glass-like and Mineral-like Phosphate Compounds with an Immobilized Chloride Mixture in Hydrogen Peroxide Solutions
Energies 2022, 15(17), 6477; https://doi.org/10.3390/en15176477 - 05 Sep 2022
Viewed by 508
Abstract
A new type of high-level waste (HLW) is generated during pyrochemical reprocessing of mixed nitride spent uranium–plutonium nuclear fuel. Such waste is a spent electrolyte, which is a mixture of chloride salts containing approximately 25.7 wt.% LiCl + 31.6 wt.% KCl + 4.1 [...] Read more.
A new type of high-level waste (HLW) is generated during pyrochemical reprocessing of mixed nitride spent uranium–plutonium nuclear fuel. Such waste is a spent electrolyte, which is a mixture of chloride salts containing approximately 25.7 wt.% LiCl + 31.6 wt.% KCl + 4.1 wt.% CsCl + 5.1 wt.% BaCl2 + 3.8 wt.% SrCl2 + 29.7 wt.% LaCl3, and its immobilization in reliable matrices is an actual radiochemical problem. The structure and hydrolytic stability of sodium aluminoironphosphate (NAFP) glass and a low-temperature mineral-like magnesium potassium phosphate (MPP) matrix, which are promising for spent electrolyte immobilization in the presence of hydrogen peroxide solutions simulating natural water radiolysis products, were studied in this work. The structure of the samples was studied using the SEM-EDS method. It was shown that the initial samples of NAFP glass after leaching in hydrogen peroxide solutions are prone to precipitation of crystalline phases on the surface, which are mainly represented by a mixture of sodium–iron–aluminum pyrophosphates. It was established that the leaching rate of structure-forming components of NAFP and MPP matrices generally increase, but remain at a low level, meeting modern requirements for HLW immobilization. This confirms the effectiveness of the studied matrices for the industrial use of the spent electrolyte. Full article
(This article belongs to the Special Issue Treatment of Radioactive Waste and Sustainability Energy)
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Article
Why LNG Can Be a First Step in East Asia’s Energy Transition to a Low Carbon Economy: Evaluation of Challenges Using Game Theory
Energies 2022, 15(17), 6476; https://doi.org/10.3390/en15176476 - 05 Sep 2022
Viewed by 691
Abstract
As countries scramble for cleaner energy production and to meet carbon reduction targets, natural gas seems to become an increasingly attractive option with liquified natural gas (LNG) as a popular transportation choice. In this paper, we first conduct a literature review and discuss [...] Read more.
As countries scramble for cleaner energy production and to meet carbon reduction targets, natural gas seems to become an increasingly attractive option with liquified natural gas (LNG) as a popular transportation choice. In this paper, we first conduct a literature review and discuss the various factors affecting the global natural gas market, its recent history, current state, and future. Then we look at the possibility of East Asia becoming an alternative market to Europe for Russian LNG. We also bring in the US both as a political force that employs economic sanctions and as a potential LNG supplier. As a case study, we define a 3-player game between Russia, The United States, and Japan which results in relative market stability. In the case of sanctions against Russia, we conclude that it will lose its foothold in the Japanese market in the long term. Finally, we discuss the potential of LNG trading as the first step for East Asia’s energy transition to a low-carbon economy. Full article
(This article belongs to the Special Issue Policies and Strategies for Clean Energy Transition)
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Article
Forecast of Coal Demand in Shanxi Province Based on GA—LSSVM under Multiple Scenarios
Energies 2022, 15(17), 6475; https://doi.org/10.3390/en15176475 - 05 Sep 2022
Cited by 1 | Viewed by 522
Abstract
Under the “carbon peaking and carbon neutrality” goal, Shanxi Province adjusts the power supply structure and promotes the development of a high proportion of new energy, which has a certain impact on the demand for thermal coal. Therefore, constructing a reasonable forecasting model [...] Read more.
Under the “carbon peaking and carbon neutrality” goal, Shanxi Province adjusts the power supply structure and promotes the development of a high proportion of new energy, which has a certain impact on the demand for thermal coal. Therefore, constructing a reasonable forecasting model for thermal coal demand can play a role in stabilizing coal supply and demand. This paper analyzes various factors related to coal demand, and uses Pearson coefficient to screen out six variables with strong correlation. Then, based on the scenario analysis method, combined with the “14th Five-Year Plan” of Shanxi Province, different scenarios of economic development and carbon emission reduction development are set. Finally, a multi-scenario GA–LSSVM forecasting model of thermal coal demand in Shanxi Province is constructed, and the future development trend of thermal coal demand in Shanxi Province is predicted. The results show that the demand for thermal coal is the largest in the mode of high-speed economic development and low emission reduction, and the demand for thermal coal is the lowest in the mode of low-speed economic development and strong emission reduction, which provides a scientific basis for the implementation of Shanxi Province’s thermal coal supply policy. Full article
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Article
Wind Turbine Gust Load Alleviation with Active Flow Control
Energies 2022, 15(17), 6474; https://doi.org/10.3390/en15176474 - 05 Sep 2022
Viewed by 706
Abstract
Large wind turbine rotors are becoming more common in utility-scale wind power, especially for offshore wind plants. However, the trend toward large rotors can be limited by their ability to manage dynamic and extreme loads. To provide a safety margin for the rotor [...] Read more.
Large wind turbine rotors are becoming more common in utility-scale wind power, especially for offshore wind plants. However, the trend toward large rotors can be limited by their ability to manage dynamic and extreme loads. To provide a safety margin for the rotor design and avoid catastrophic events such as tower strikes, extreme loads need to be controlled. The objective of this study is to develop and evaluate a feedback control system to alleviate extreme loads and reduce blade deflections under gust events using active flow control devices. We also propose a modification in the turbine controller to achieve further reduction in extreme loads. The extreme load reductions are evaluated under gust wind conditions with direction changes according to the IEC standard. The effects of the gust alleviation controller on turbine performance and fatigue loads are investigated as well. With the deployment of the gust alleviation controller and modified turbine baseline controller, the extreme loads and deflections reduce by up to 23%. The energy captured by the turbine is not affected by the proposed gust alleviation controller. The fatigue loads of various wind turbine components are either reduced or remain unchanged. Full article
(This article belongs to the Special Issue Innovative Methods for the Control of Very Large Wind Turbines)
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Article
Operation Method of On-Load Tap Changer on Main Transformer Considering Reverse Power Flow in Distribution System Connected with High Penetration on Photovoltaic System
Energies 2022, 15(17), 6473; https://doi.org/10.3390/en15176473 - 05 Sep 2022
Viewed by 562
Abstract
The increasing use of photovoltaics (PVs) in distribution systems owing to the low-carbon policy has given rise to the need for various technological changes. In particular, the operation of on-load tap changers (OLTCs) has attracted attention. In traditional distribution systems, the OLTC operates [...] Read more.
The increasing use of photovoltaics (PVs) in distribution systems owing to the low-carbon policy has given rise to the need for various technological changes. In particular, the operation of on-load tap changers (OLTCs) has attracted attention. In traditional distribution systems, the OLTC operates via a line-drop compensator (LDC), which focuses on the load to solve the low-voltage problem; however, the problem of over-voltage caused by PVs persists. Currently, a method for operating an OLTC using the measured voltage is being researched; however, solving the voltage problem for several feeders connected to a main transformer (MT) is not viable. Therefore, this study proposes an OLTC operation method to address the feeder with the largest voltage problem depending on the direction of power flow. The proposed method selects a point where the OLTC operates using the difference between the measured and reference voltages. Setting the reference voltage can solve the problem that occurs due to the direction of power flow. Finally, the effectiveness of the proposed method is verified via case studies. Based on the results, we can conclude that the proposed method effectively solves the voltage problem, and an increase in hosting capacity can be expected. Full article
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Article
Experimental Study on the Compressive and Shear Mechanical Properties of Cement–Formation Interface Considering Surface Roughness and Drilling Mud Contamination
Energies 2022, 15(17), 6472; https://doi.org/10.3390/en15176472 - 05 Sep 2022
Viewed by 494
Abstract
In a casing-cement sheath-formation system, the cement–formation interface is usually weakly cemented for the residual of drilling mud, in which a leakage path would easily form, threatening the safe operation of underground energy exploitation and storage. To evaluate the compressive and shear mechanical [...] Read more.
In a casing-cement sheath-formation system, the cement–formation interface is usually weakly cemented for the residual of drilling mud, in which a leakage path would easily form, threatening the safe operation of underground energy exploitation and storage. To evaluate the compressive and shear mechanical behavior of the cement–formation interface, cement–rock composite cylindrical specimens were prepared. Uniaxial and triaxial compression and direct shear tests were implemented. The flushing efficiency of the rock surface, compressive strength, interface incompatible deformation, parameters of shear strength, and morphology of shear failure surface were acquired and analyzed. Results show that the flushing efficiency of shale surface decreases from 76.7% to 64.2% with the surface roughness increasing from 0 to 2 mm. The flushing efficiency of sandstone is only 44.7%, remarkably lower than that of shale. With the stress condition transforming from uniaxial to triaxial compression, the feature of the stress–strain curves changes from elastic-brittle to elastoplastic, and the compressive strength increases from 20.6~60.1 MPa to 110~120 MPa. The cement part presents noteworthy plastic deformation and several micro shear fractures develop. There is incompatible deformation between cement and rock, which induces interface debonding for almost all the composite specimens. The internal friction angle and cohesive strength both decrease with the increase in pollution degree of drilling mud, and increase with the rise in surface roughness. The shear facture surface is not exactly the rock–cement interface, but usually manifests as a shear zone, in which the rock, cement, and interface all contribute to the final shear failure. The above findings would be valuable for the revealing of cement–formation interface failure mechanism. Full article
(This article belongs to the Special Issue Advances in the Utilization of Underground Energy and Space)
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Article
Particle Number Emission from Vehicles of Various Drives in the RDE Tests
Energies 2022, 15(17), 6471; https://doi.org/10.3390/en15176471 - 05 Sep 2022
Cited by 2 | Viewed by 566
Abstract
In this study, the authors assessed the road emissions of several passenger cars using specialised instrumentation, of the PEMS type, to measure particle number emissions in real traffic conditions. The tests were performed on a RDE test route developed and compliant with EU [...] Read more.
In this study, the authors assessed the road emissions of several passenger cars using specialised instrumentation, of the PEMS type, to measure particle number emissions in real traffic conditions. The tests were performed on a RDE test route developed and compliant with EU guidelines. The results of the tests were discussed in terms of the direct (created in the internal combustion engine) emission of particulate matter in various road conditions. Additionally, an index was determined that characterizes the number of particles according to their diameter in relation to the content of particles in the air. A characteristic of combustion engines (gasoline, diesel) is that during a cold start of the engine, the concentration of the number of particles with diameters around 100 nm increases more than 200 times (for hybrids—300 times). On this basis, it can be concluded that particle emissions with diameters smaller than 23 nm are significant in motor vehicles powered by combustion engines, regardless of whether they are conventional or hybrid vehicles. The share of particles with diameters less than 5 nm is 66% (for diesel engines) and 40% (for gasoline engines) of all the particles. Full article
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Article
Development of a Control-Oriented Ignition Delay Model for GCI Combustion
Energies 2022, 15(17), 6470; https://doi.org/10.3390/en15176470 - 05 Sep 2022
Viewed by 546
Abstract
Increasingly stringent pollutant emission limits and CO2 reduction policies are forcing the automotive industry toward cleaner and decarbonized mobility. The goal is to achieve carbon neutrality within 2050 and limit global warming to 2 °C (possibly 1.5 °C) with respect to pre-industrial [...] Read more.
Increasingly stringent pollutant emission limits and CO2 reduction policies are forcing the automotive industry toward cleaner and decarbonized mobility. The goal is to achieve carbon neutrality within 2050 and limit global warming to 2 °C (possibly 1.5 °C) with respect to pre-industrial levels as stated in both the European Green Deal and the Paris Agreement and further reiterated at the COP26. With the aim of simultaneously reducing both pollutants and CO2 emissions, a large amount of research is currently carried out on low-temperature highly efficient combustions (LTC). Among these advanced combustions, one of the most promising is Gasoline Compression Ignition (GCI), based on the spontaneous ignition of a gasoline-like fuel. Nevertheless, despite GCI proving to be effective in reducing both pollutants and CO2 emissions, GCI combustion controllability represents the main challenge that hinders the diffusion of this methodology for transportation. Several works in the literature demonstrated that to properly control GCI combustion, a multiple injections strategy is needed. The rise of pressure and temperature generated by the spontaneous ignition of small amounts of early-injected fuel reduces the ignition delay of the following main injection, responsible for the torque production of the engine. Since the combustion of the pre-injections is chemically driven, the ignition delay might be strongly affected by a slight variation in the engine control parameters and, consequently, lead to misfire or knocking. The goal of this work was to develop a control-oriented ignition delay model suitable to improve the GCI combustion stability through the proper management of the pilot injections. After a thorough analysis of the quantities affecting the ignition delay, this quantity was modeled as a function of both a thermodynamic and a chemical–physical index. The comparison between the measured and modeled ignition delay shows an accuracy compatible with the requirements for control purposes (the average root mean squared error between the measured and estimated start of combustion is close to 1.3 deg), over a wide range of operating conditions. As a result, the presented approach proved to be appropriate for the development of a model-based feed-forward contribution for a closed-loop combustion control strategy. Full article
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Article
A Proposed Three-Phase Induction Motor Drive System Suitable for Golf Cars
Energies 2022, 15(17), 6469; https://doi.org/10.3390/en15176469 - 05 Sep 2022
Cited by 1 | Viewed by 589
Abstract
In this paper, a proposed electric drive system for a three-phase induction motor is presented. The proposed drive system is suggested for a golf car as one type of electric vehicle. The suggested system consists of three similar single-phase buck–boost converters. Hence, each [...] Read more.
In this paper, a proposed electric drive system for a three-phase induction motor is presented. The proposed drive system is suggested for a golf car as one type of electric vehicle. The suggested system consists of three similar single-phase buck–boost converters. Hence, each single-phase buck–boost converter is used as a buck–boost inverter and is used to energize only one phase of the induction motor. The suggested system has the advantage of high reliability, as it can deal with different fault conditions such as battery and motor winding faults. The suggested electric drive system depends on a buck–boost converter which gives variable voltages as well as variable frequencies. Thus, variable speeds of the electric vehicles can be easily achieved. A variable DC voltage (positive or negative) can be achieved at the output of the adopted buck–boost converter, which is considered another advantage of the proposed drive system. This DC voltage can be used to achieve braking of the induction motor used to drive the electric vehicle. Therefore, this advantage can be used instead of ordinary mechanical braking to increase vehicle reliability. To demonstrate our proposed idea, a simulation study is presented. The simulation is carried out using Power Simulation Program (PSIM) software. The simulation study takes into consideration the performance of the adopted buck–boost converter under different conditions to present its advantages. Furthermore, a performance study of the suggested induction motor drive system is carried out under different conditions ranging from healthy to faulty conditions to test system reliability. For more illustration, an experimental prototype of the adopted buck–boost converter is built, and its performance is studied. From all the obtained results, the efficacy of the proposed system is demonstrated. Full article
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Article
An Optimized Solution for Fault Detection and Location in Underground Cables Based on Traveling Waves
Energies 2022, 15(17), 6468; https://doi.org/10.3390/en15176468 - 05 Sep 2022
Cited by 2 | Viewed by 658
Abstract
Faults in the power system affect the reliability, safety, and stability. Power-distribution systems are familiar with the different faults that can damage the overall performance of the entire system, from which they need to be effectively cleared. Underground power systems are more complex [...] Read more.
Faults in the power system affect the reliability, safety, and stability. Power-distribution systems are familiar with the different faults that can damage the overall performance of the entire system, from which they need to be effectively cleared. Underground power systems are more complex and require extra accuracy in fault detection and location for optimum fault management. Slow processing and the unavailability of a protection zone for relay coordination are concerns in fault detection and location, as these reduce the performance of power-protection systems. In this regard, this article proposes an optimized solution for a fault detection and location framework for underground cables based on a discrete wavelet transform (DWT). The proposed model supports area detection, the identification of faulty sections, and fault location. To overcome the abovementioned facts, we optimize the relay coordination for the overcurrent and timing relays. The proposed protection zone has two sequential stages for the current and time at which it optimizes the current and time settings of the connected relays through Newton–Raphson analysis (NRA). Moreover, the traveling times for the DWT are modeled, which relate to the protection zone provided by the relay coordination, and the faulty line that is identified as the relay protection is not overlapped. The model was tested for 132 kV/11 kV and 16-node networks for underground cables, and the obtained results show that the proposed model can detect and locate the cable’s faults speedily, as it detects the fault in 0.01 s, and at the accurate location. MATLAB/Simulink (DigSILENT Toolbox) is used to establish the underground network for fault location and detection. Full article
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Review
Techno-Economic Analysis of Hydrogen Storage Technologies for Railway Engineering: A Review
Energies 2022, 15(17), 6467; https://doi.org/10.3390/en15176467 - 05 Sep 2022
Cited by 3 | Viewed by 1537
Abstract
According to the specific requirements of railway engineering, a techno-economic comparison for onboard hydrogen storage technologies is conducted to discuss their feasibility and potentials for hydrogen-powered hybrid trains. Physical storage methods, including compressed hydrogen (CH2), liquid hydrogen (LH2), and [...] Read more.
According to the specific requirements of railway engineering, a techno-economic comparison for onboard hydrogen storage technologies is conducted to discuss their feasibility and potentials for hydrogen-powered hybrid trains. Physical storage methods, including compressed hydrogen (CH2), liquid hydrogen (LH2), and cryo-compressed hydrogen (CcH2), and material-based (chemical) storage methods, such as ammonia, liquid organic hydrogen carriages (LOHCs), and metal hydrides, are carefully discussed in terms of their operational conditions, energy capacity, and economic costs. CH2 technology is the most mature now but its storage density cannot reach the final target, which is the same problem for intermetallic compounds. In contrast, LH2, CcH2, and complex hydrides are attractive for their high storage density. Nevertheless, the harsh working conditions of complex hydrides hinder their vehicular application. Ammonia has advantages in energy capacity, utilisation efficiency and cost, especially being directly utilised by fuel cells. LOHCs are now considered as a potential candidate for hydrogen transport. Simplifying the dehydrogenation process is the important prerequisite for its vehicular employment. Recently, increasing novel hydrogen-powered trains based on different hydrogen storage routes are being tested and optimised across the world. It can be forecasted that hydrogen energy will be a significant booster to railway decarbonisation. Full article
(This article belongs to the Special Issue Prospective Electric and Hybrid Vehicle Technologies)
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Editorial
Advances in High-Order Sensitivity Analysis for Uncertainty Quantification and Reduction in Nuclear Energy Systems
Energies 2022, 15(17), 6466; https://doi.org/10.3390/en15176466 - 05 Sep 2022
Viewed by 458
Abstract
The computational models of physical systems comprise parameters, independent and dependent variables [...] Full article
(This article belongs to the Section B: Energy and Environment)
Article
Load Management and Optimal Sizing of Special-Purpose Microgrids Using Two Stage PSO-Fuzzy Based Hybrid Approach
Energies 2022, 15(17), 6465; https://doi.org/10.3390/en15176465 - 05 Sep 2022
Cited by 2 | Viewed by 652
Abstract
The sizing of microgrids depends on the type of load and its operational hours. The significance of understanding the load operational characteristics in special purpose islanded microgrids is much needed for economic system sizing. The load operation of special-purpose microgrids often consumes high [...] Read more.
The sizing of microgrids depends on the type of load and its operational hours. The significance of understanding the load operational characteristics in special purpose islanded microgrids is much needed for economic system sizing. The load operation of special-purpose microgrids often consumes high power for a short duration and remains idle most of the time, thus reducing the load factor. The inclusion of such loads in microgrid sizing causes huge capital costs making islanded microgrids an unfeasible solution. The islanded microgrid under study is an agricultural microgrid in a village having a small Crab Processing Plant (CPP) and a Domestic Sector (DS). The CPP constitutes the major power consumption. The community has a unique load consumption trend that is dependent on the highly uncertain parameter of availability of the crabs. Interestingly, crab availability is an independent parameter and cannot be accurately scheduled. The existing system sizing of the microgrid is performed based on the conventional methods that consider the CPP for full-day operation. However, the microgrid sources, especially the storage system may be reflected as oversized if the crab processing plants do not operate for several days due to the uncertain behavior of CPP causing enormous power wastage. In this paper, an integrated fixed and operational mode strategy for uncertain heavy loads is formulated. The proposed algorithm is based on the optimal sizing methodology aided by the load scheduling control strategy. The Particle Swarm Optimization technique is used for the optimal sizing integrated with the fuzzy logic controller to manage the available load. The membership functions are available excess power and the state of the charge of storage that defines the operational conditions for CPP. Based on input membership functions, the fuzzy controller decides on power dispatch in DS or CPP, keeping considerable SoC available for night hours. The simulation result shows that the time-dependent fuzzy controller approach manages to provide power to both sectors under optimal sizing while reducing the overall cost by 24% less than the existing microgrid. Full article
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