Energies

18 pages, 1563 KiB

Open AccessArticle

Effect of Tillage System and Organic Matter Management Interactions on Soil Chemical Properties and Biological Activity in a Spring Wheat Short-Time Cultivation

by Barbara Breza-Boruta, Karol Kotwica and Justyna Bauza-Kaszewska

Energies 2021, 14(21), 7451; https://doi.org/10.3390/en14217451 - 08 Nov 2021

Cited by 4 | Viewed by 2384

Abstract

Properly selected tillage methods and management of the available organic matter resources are considered important measures to enable farming in accordance with the principles of sustainable agriculture. Depending on the depth and intensity of cultivation, tillage practices affect soil chemical composition, structure and [...] Read more.

Properly selected tillage methods and management of the available organic matter resources are considered important measures to enable farming in accordance with the principles of sustainable agriculture. Depending on the depth and intensity of cultivation, tillage practices affect soil chemical composition, structure and biological activity. The three-year experiment was performed on the soil under spring wheat (cv. Tybalt) short-time cultivation. The influence of different tillage systems and stubble management on the soil’s chemical and biological parameters was analyzed. Organic carbon content (OC); content of biologically available phosphorus (Pa), potassium (Ka), and magnesium (Mg); content of total nitrogen (TN), mineral nitrogen forms: N-NO₃ and N-NH₄ were determined in various soil samples. Moreover, the total number of microorganisms (TNM), bacteria (B), actinobacteria (A), fungi (F); soil respiratory activity (SR); and pH in 1 M KCl (pH) were also investigated. The results show that organic matter amendment is of greater influence on soil characteristics than the tillage system applied. Manure application, as well as leaving the straw in the field, resulted in higher amounts of organic carbon and biologically available potassium. A significant increase in the number of soil microorganisms was also observed in soil samples from the experimental plots including this procedure. Full article

(This article belongs to the Special Issue Sustainable Agriculture and Food Supply: Scientific, Economic and Policy Analysis)

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18 pages, 350 KiB

Open AccessReview

Frequency Support Markets and Wind Power Integration

by Anzhelika Ivanova, José Luis Domínguez-García and Cristina Corchero

Energies 2021, 14(21), 7450; https://doi.org/10.3390/en14217450 - 08 Nov 2021

Cited by 5 | Viewed by 1998

Abstract

Europe’s initiative to reduce the emissions of harmful gases has significantly increased the integration of renewable sources into power networks, particularly wind power. Variable renewable sources pose challenges to sustain the balance between generation and demand. Thus, the need for ancillary services to [...] Read more.

Europe’s initiative to reduce the emissions of harmful gases has significantly increased the integration of renewable sources into power networks, particularly wind power. Variable renewable sources pose challenges to sustain the balance between generation and demand. Thus, the need for ancillary services to cope with this problem has increased. In this regard, the integration of larger shares of wind generation would have a clear system benefit when wind generators are able to provide these ancillary services. This would also have implications for electricity markets, enabling these services from wind power plants. This article gives an overview of several European markets for frequency support (FS) services, also referred to as FS markets. It identifies the changes in national regulations of 10 European countries to standardize these services based on the ENTSO-E guidelines. However, most of the countries still use their national service definitions, which presents a problem for researchers to understand the national regulations in relation to the ENTSO-E guidelines. This article provides a classification of the national FS services under the definitions of the ENTSO-E guidelines to facilitate research on this topic. Furthermore, it highlights the main requirements for the market practices that would encourage the participation of wind power generation in the provision of these services. An estimation of the economic benefits for wind producers from the provision of FS services is provided as well to show a possible outcome if changes are not made in national policies. Full article

(This article belongs to the Special Issue Solar PV and Wind Energy Systems for Energy Transition)

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16 pages, 3698 KiB

Open AccessArticle

Optimal Sensor Association and Data Collection in Power Materials Warehouse Based on Internet of Things

by Fangqiuzi He, Junfeng Xu, Jinglin Zhong, Guang Chen and Shixin Peng

Energies 2021, 14(21), 7449; https://doi.org/10.3390/en14217449 - 08 Nov 2021

Cited by 1 | Viewed by 1357

Abstract

In order to realize the intelligent management of a power materials warehouse, the Internet of Things based on wireless sensor networks (WSNs) is a promising effective solution. Considering the limited battery capacity of sensor nodes, the optimization of the topology control and the [...] Read more.

In order to realize the intelligent management of a power materials warehouse, the Internet of Things based on wireless sensor networks (WSNs) is a promising effective solution. Considering the limited battery capacity of sensor nodes, the optimization of the topology control and the determination of the amount of collected data are critical for prolonging the survival time of WSNs and increasing the satisfaction of the warehouse supplier. Therefore, in this paper, an optimization problem on sensor association and acquisition data satisfaction is proposed, and the subproblem of the sensor association is modeled as the knapsack problem. To cope with it, the block coordinate descent method is used to obtain the suboptimal solution. A sensor association scheme based on the ant colony algorithm (ACO) is proposed, and the upper and lower bounds of this optimization problem are also obtained. After this, a cluster head selection algorithm is given to find the optimal cluster head. Finally, the experimental simulations show that the algorithms proposed in this paper can effectively improve the energy utilization of WSNs to ensure the intelligent management of a power materials warehouse. Full article

(This article belongs to the Special Issue Resilient and Cooperative Control of Heterogeneous Cyber-Physical Microgrids)

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14 pages, 104108 KiB

Open AccessArticle

Experimental Study on the Insulation Layer Thickness of a Novel Ice Coring Device in Loose Sandstone-Type Uranium Deposits

by Chaoyang Huang, Jianming Peng, Yanliang Li, Moke Lian, Chao Guo, Yongjiang Luo and Kun Bo

Energies 2021, 14(21), 7448; https://doi.org/10.3390/en14217448 - 08 Nov 2021

Viewed by 1365

Abstract

The target strata of sandstone-type uranium deposits are usually located in the fragile and loose strata, which makes it difficult to obtain core samples; consequently, a novel ice coring device for loose sandstone-type uranium deposits is proposed to solve this problem. Experiments proved [...] Read more.

The target strata of sandstone-type uranium deposits are usually located in the fragile and loose strata, which makes it difficult to obtain core samples; consequently, a novel ice coring device for loose sandstone-type uranium deposits is proposed to solve this problem. Experiments proved that the artificial sample can replace the natural sample, and the coring method has high reliability. Ensuring the allegro formation of an ice valve with a given cold source is critical for this coring system, and reducing the loss of cold energy with help of insulation layer is one of the methods to speed up the formation of ice valve. Since the diameter of the drill tool is limited by its working scenario, the thickness of insulation layer is limited to ensure the size of core. Therefore, this paper conducted laboratory experiments of the insulation layer with different thicknesses to study the effect of the insulation layer on the formation of the sand–ice valve. Results show that the insulation layer can reduce the loss of cold energy during the freezing process and significantly affect the formation time of the sand–ice valve. When the thickness of the aerogel insulation layer is 2 mm, the freezing time is 44% shorter than that without insulation layer. According to the tests, the novel ice coring device is expected to solve the coring problem in loose sandstone-type uranium deposits. Full article

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41 pages, 20456 KiB

Open AccessArticle

Analysing the Performance of Ammonia Powertrains in the Marine Environment

by Thomas Buckley Imhoff, Savvas Gkantonas and Epaminondas Mastorakos

Energies 2021, 14(21), 7447; https://doi.org/10.3390/en14217447 - 08 Nov 2021

Cited by 19 | Viewed by 5464

Abstract

This study develops system-level models of ammonia-fuelled powertrains that reflect the characteristics of four oceangoing vessels to evaluate the efficacy of ammonia as an alternative fuel in the marine environment. Relying on thermodynamics, heat transfer, and chemical engineering, the models adequately capture the [...] Read more.

This study develops system-level models of ammonia-fuelled powertrains that reflect the characteristics of four oceangoing vessels to evaluate the efficacy of ammonia as an alternative fuel in the marine environment. Relying on thermodynamics, heat transfer, and chemical engineering, the models adequately capture the behaviour of internal combustion engines, gas turbines, fuel processing equipment, and exhaust aftertreatment components. The performance of each vessel is evaluated by comparing its maximum range and cargo capacity to a conventional vessel. Results indicate that per unit output power, ammonia-fuelled internal combustion engines are more efficient, require less catalytic material, and have lower auxiliary power requirements than ammonia gas turbines. Most merchant vessels are strong candidates for ammonia fuelling if the operators can overcome capacity losses between 4% and 9%, assuming that the updated vessels retain the same range as a conventional vessel. The study also establishes that naval vessels are less likely to adopt ammonia powertrains without significant redesigns. Ammonia as an alternative fuel in the marine sector is a compelling option if the detailed component design continues to show that the concept is practically feasible. The present data and models can help in such feasibility studies for a range of vessels and propulsion technologies. Full article

(This article belongs to the Special Issue Energy-Saving and Carbon-Neutral Technologies for Maritime Transport)

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25 pages, 7771 KiB

Open AccessArticle

Analysis of Energy Efficient Scheduling of the Manufacturing Line with Finite Buffer Capacity and Machine Setup and Shutdown Times

by Adrian Kampa and Iwona Paprocka

Energies 2021, 14(21), 7446; https://doi.org/10.3390/en14217446 - 08 Nov 2021

Cited by 5 | Viewed by 2001

Abstract

The aim of this paper is to present a model of energy efficient scheduling for series production systems during operation, including setup and shutdown activities. The flow shop system together with setup, shutdown times and energy consumption are considered. Production tasks enter the [...] Read more.

The aim of this paper is to present a model of energy efficient scheduling for series production systems during operation, including setup and shutdown activities. The flow shop system together with setup, shutdown times and energy consumption are considered. Production tasks enter the system with exponentially distributed interarrival times and are carried out according to the times assumed as predefined. Tasks arriving from one waiting queue are handled in the order set by the Multi Objective Immune Algorithm. Tasks are stored in a finite-capacity buffer if machines are busy, or setup activities are being performed. Whenever a production system is idle, machines are stopped according to shutdown times in order to save energy. A machine requires setup time before executing the first batch of jobs after the idle time. Scientists agree that turning off an idle machine is a common measure that is appropriate for all types of workshops, but usually requires more steps, such as setup and shutdown. Literature analysis shows that there is a research gap regarding multi-objective algorithms, as minimizing energy consumption is not the only factor affecting the total manufacturing cost—there are other factors, such as late delivery cost or early delivery cost with additional storage cost, which make the optimization of the total cost of the production process more complicated. Another goal is to develop previous scheduling algorithms and research framework for energy efficient scheduling. The impact of the input data on the production system performance and energy consumption for series production is investigated in serial, parallel or serial–parallel flows. Parallel flow of upcoming tasks achieves minimum values of makespan criterion. Serial and serial–parallel flows of arriving tasks ensure minimum cost of energy consumption. Parallel flow of arriving tasks ensures minimum values of the costs of tardiness or premature execution. Parallel flow or serial–parallel flow of incoming tasks allows one to implement schedules with tasks that are not delayed. Full article

(This article belongs to the Section B1: Energy and Climate Change)

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19 pages, 3096 KiB

Open AccessArticle

Paleoenvironment and Organic Matter Accumulation Mechanism of Marine–Continental Transitional Shales: Outcrop Characterizations of the Carboniferous–Permian Strata, Ordos Basin, North China

by Leifu Zhang, Qun Zhao, Sizhong Peng, Zhen Qiu, Congjun Feng, Qin Zhang, Yuman Wang, Dazhong Dong and Shangwen Zhou

Energies 2021, 14(21), 7445; https://doi.org/10.3390/en14217445 - 08 Nov 2021

Cited by 6 | Viewed by 1991

Abstract

In the Carboniferous–Permian period, several organic-rich black shales were deposited in a marine–continental transitional environment in the Linfen area on the eastern margin of the Ordos Basin. Integrated sedimentological and organic geochemical analyses are performed on an outcrop in order to clarify the [...] Read more.

In the Carboniferous–Permian period, several organic-rich black shales were deposited in a marine–continental transitional environment in the Linfen area on the eastern margin of the Ordos Basin. Integrated sedimentological and organic geochemical analyses are performed on an outcrop in order to clarify the relationship between paleoenvironment and organic matter accumulation. The results of this study show that the marine–continental transitional strata of the Upper Carboniferous Benxi Formation to Lower Permian Taiyuan and Shanxi Formation exposed in the Linfen area are composed of sandstone, shale, coal, and limestone. Total organic carbon (TOC) contents of the studied samples were mainly distributed in the range of 0.59%–35.4%, with an average of 7.32%. From Benxi Formation to Shanxi formation, the humidity gradually increased, and the climate gradually changed from hot and humid to warm and humid during Carboniferous to Permian. The deposition of the Shanxi Formation ended with the climate returning to hot and humid, having an oxic-suboxic conditions and a high paleoproductivity. Paleoredox conditions and paleoproductivity are the two vital factors controlling the formation of organic matter in black shales. The transitional environment characterized by oxic-suboxic, relatively high deposition rate, and various source of organic matter, although different from the marine environment, provides a good material basis for the deposition of organic-rich shales. Full article

(This article belongs to the Special Issue Shale Oil and Gas Accumulation Mechanism)

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10 pages, 5188 KiB

Open AccessArticle

The Elephant Problem—Determining Bulk Thermal Diffusivity

by Robert Beaufait, Sebastian Ammann and Ludger Fischer

Energies 2021, 14(21), 7444; https://doi.org/10.3390/en14217444 - 08 Nov 2021

Cited by 2 | Viewed by 1414

Abstract

This study investigates a measurement method of thermal diffusivity for samples with arbitrary geometries and unknown material properties. The aim is to curve fit the thermal diffusivity with the use of a numerical simulation and transient temperature measurement inside the object of interest. [...] Read more.

This study investigates a measurement method of thermal diffusivity for samples with arbitrary geometries and unknown material properties. The aim is to curve fit the thermal diffusivity with the use of a numerical simulation and transient temperature measurement inside the object of interest. This approach is designed to assess bulk material properties of an object that has a composite material structure such as underground soil. The method creates the boundary conditions necessary to apply analytical theory found in the literature. It was found that measurements best correlated with theory and simulation at positions between the center and surface of an object. Full article

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23 pages, 3550 KiB

Open AccessArticle

Day-Ahead Forecasting of the Percentage of Renewables Based on Time-Series Statistical Methods

by Robert Basmadjian, Amirhossein Shaafieyoun and Sahib Julka

Energies 2021, 14(21), 7443; https://doi.org/10.3390/en14217443 - 08 Nov 2021

Cited by 12 | Viewed by 1864

Abstract

Forecasting renewable energy sources is of critical importance to several practical applications in the energy field. However, due to the inherent volatile nature of these energy sources, doing so remains challenging. Numerous time-series methods have been explored in literature, which consider only one [...] Read more.

Forecasting renewable energy sources is of critical importance to several practical applications in the energy field. However, due to the inherent volatile nature of these energy sources, doing so remains challenging. Numerous time-series methods have been explored in literature, which consider only one specific type of renewables (e.g., solar or wind), and are suited to small-scale (micro-level) deployments. In this paper, the different types of renewable energy sources are reflected, which are distributed at a national level (macro-level). To generate accurate predictions, a methodology is proposed, which consists of two main phases. In the first phase, the most relevant variables having impact on the generation of the renewables are identified using correlation analysis. The second phase consists of (1) estimating model parameters, (2) optimising and reducing the number of generated models, and (3) selecting the best model for the method under study. To this end, the three most-relevant time-series auto-regression based methods of SARIMAX, SARIMA, and ARIMAX are considered. After deriving the best model for each method, then a comparison is carried out between them by taking into account different months of the year. The evaluation results illustrate that our forecasts have mean absolute error rates between 6.76 and 11.57%, while considering both inter- and intra-day scenarios. The best models are implemented in an open-source REN4Kast software platform. Full article

(This article belongs to the Section F5: Artificial Intelligence and Smart Energy)

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13 pages, 1903 KiB

Open AccessArticle

Optimal Sizing of Battery Energy Storage Systems Considering Cooperative Operation with Microgrid Components

by Hirotaka Takano, Ryosuke Hayashi, Hiroshi Asano and Tadahiro Goda

Energies 2021, 14(21), 7442; https://doi.org/10.3390/en14217442 - 08 Nov 2021

Cited by 11 | Viewed by 2262

Abstract

Battery energy storage systems (BESSs) are key components in efficiently managing the electric power supply and demand in microgrids. However, the BESSs have issues in their investment costs and operating lifetime, and thus, the optimal sizing of the BESSs is one of the [...] Read more.

Battery energy storage systems (BESSs) are key components in efficiently managing the electric power supply and demand in microgrids. However, the BESSs have issues in their investment costs and operating lifetime, and thus, the optimal sizing of the BESSs is one of the crucial requirements in design and management of the microgrids. This paper presents a problem framework and its solution method that calculates the optimal size of the BESSs in a microgrid, considering their cooperative operations with the other components. The proposed framework is formulated as a bi-level optimization problem; however, based on the Karush–Kuhn–Tucker approach, it is regarded as a type of operation scheduling problem. As a result, the techniques developed for determining the operation schedule become applicable. In this paper, a combined algorithm of binary particle swarm optimization and quadratic programming is selected as the basis of the solution method. The validity of the authors’ proposal is verified through numerical simulations and discussion of their results. Full article

(This article belongs to the Special Issue Advanced Control in Microgrid Systems 2021)

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25 pages, 2977 KiB

Open AccessArticle

Comparative Study of Experimentally Measured and Calculated Solar Radiations for Two Sites in Algeria

by Bouazza Fekkak, Mustapha Merzouk, Abdallah Kouzou, Ralph Kennel, Mohamed Abdelrahem, Ahmed Zakane and Mostefa Mohamed-Seghir

Energies 2021, 14(21), 7441; https://doi.org/10.3390/en14217441 - 08 Nov 2021

Viewed by 1897

Abstract

This paper presents a comparison study between the measured solar radiations on site and the calculated solar radiation based on the most theoretical models presented in the literature up to date. Indeed, for such purposes, this paper focusses on the analysis of the [...] Read more.

This paper presents a comparison study between the measured solar radiations on site and the calculated solar radiation based on the most theoretical models presented in the literature up to date. Indeed, for such purposes, this paper focusses on the analysis of the data of the measured solar radiation collected on two sites in Algeria such as Tlemcen (34°52′58″ N 01°19′00″ W, elevation 842 m) and Senia (35°39′ N 0°38′ W, elevation: 77 m). In order to check the accuracy of the proposed model, the experimental collected data of the solar radiation obtained from the existing radiometric stations installed at the two locations under investigation, are compared with the estimated or predicted solar radiations obtained from the Capderou and R.Sun models, where four days under clear skies are selected from different seasons to achieve this comparison. Second, the daily averages of the experimental global solar irradiation are compared to those predicted by Mefti model for both the sites. Finally, a validation is carried out based on the obtained experimental monthly global irradiations and with those estimated by Coppolino and Sivkov models. A relative difference is used in this case to judge the reliability and the accuracy of each model for both sites. Full article

(This article belongs to the Collection Electrical Power and Energy System: From Professors to Students)

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19 pages, 83717 KiB

Open AccessArticle

Assessment of the Impact of Per Unit Parameters Errors on Wave and Output Parameters in a Transmission Line

by Sebastian Różowicz, Andrzej Zawadzki, Maciej Włodarczyk, Antoni Różowicz and Damian Mazur

Energies 2021, 14(21), 7440; https://doi.org/10.3390/en14217440 - 08 Nov 2021

Cited by 2 | Viewed by 1430

Abstract

The assessment of the impact of per unit length parameter errors on the determination of wave parameters, currents, and voltages at the end of the line has been presented in the paper. The impact on the above-mentioned values has been indicated. This paper [...] Read more.

The assessment of the impact of per unit length parameter errors on the determination of wave parameters, currents, and voltages at the end of the line has been presented in the paper. The impact on the above-mentioned values has been indicated. This paper presents an assessment of the impact of per unit parameter errors on the determination of both wave parameters, as well as currents and voltages at the end of a transmission line, although it is mainly focused on indicating which of the per unit parameters have the strongest impact on the above-mentioned values. For this purpose, elements of incremental sensitivity have been used. Full article

(This article belongs to the Special Issue Selected Issues of Electrical Engineering, Electronics and Mechatronics)

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20 pages, 7120 KiB

Open AccessArticle

A Method of Comparative Evaluation of the Drive Units of Two Bucket Elevators—A Case Study

by Piotr Sokolski and Justyna Sokolska

Energies 2021, 14(21), 7439; https://doi.org/10.3390/en14217439 - 08 Nov 2021

Cited by 1 | Viewed by 2722

Abstract

Bucket elevators are applied in many industries for bulk material handling. One of the main requirements for these devices is their high operational reliability. This applies in particular to power units that must operate continuously without failure. This article presents a comparative assessment [...] Read more.

Bucket elevators are applied in many industries for bulk material handling. One of the main requirements for these devices is their high operational reliability. This applies in particular to power units that must operate continuously without failure. This article presents a comparative assessment of the drive units of two bucket elevators. The vibration intensity of their bearing units was used as the basis for the comparison. The evaluation was carried out using three independent methods based on the vibration velocity analysis: in the time domain, in the frequency domain and using the probabilistic approach. Full article

(This article belongs to the Special Issue Advances in Fault Detection, Diagnosis and Prognosis in Industrial Motors)

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14 pages, 1276 KiB

Open AccessArticle

Robust Control Design for Autonomous Vehicles Using Neural Network-Based Model-Matching Approach

by Dániel Fényes, Tamás Hegedus, Balázs Németh and Péter Gáspár

Energies 2021, 14(21), 7438; https://doi.org/10.3390/en14217438 - 08 Nov 2021

Cited by 5 | Viewed by 2022

Abstract

In this paper, a novel neural network-based robust control method is presented for a vehicle-oriented problem, in which the main goal is to ensure stable motion of the vehicle under critical circumstances. The proposed method can be divided into two main steps. In [...] Read more.

In this paper, a novel neural network-based robust control method is presented for a vehicle-oriented problem, in which the main goal is to ensure stable motion of the vehicle under critical circumstances. The proposed method can be divided into two main steps. In the first step, the model matching algorithm is proposed, which can adjust the nonlinear dynamics of the controlled system to a nominal, linear model. The aim of model matching is to eliminate the effects of the nonlinearities and uncertainties of the system to increase the performances of the closed-loop system. The model matching process results in an additional control input, which is computed by a neural network during the operation of the control system. Furthermore, in the second step, a robust

H_{\infty}

is designed, which has double purposes: to handle the fitting error of the neural network and ensure the accurate tracking of the reference signal. The operation and efficiency of the proposed control algorithm are investigated through a complex test scenario, which is performed in the high-fidelity vehicle dynamics simulation software, CarMaker. Full article

(This article belongs to the Special Issue Analysis and Synthesis of Coordinated Control Systems for Automated Road Vehicles)

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34 pages, 1836 KiB

Open AccessArticle

A New Hybrid Online and Offline Multi-Factor Cross-Domain Authentication Method for IoT Applications in the Automotive Industry

by Haqi Khalid, Shaiful Jahari Hashim, Sharifah Mumtazah Syed Ahmad, Fazirulhisyam Hashim and Muhammad Akmal Chaudhary

Energies 2021, 14(21), 7437; https://doi.org/10.3390/en14217437 - 08 Nov 2021

Cited by 2 | Viewed by 2520

Abstract

Connected vehicles have emerged as the latest revolution in the automotive industry, utilizing the advent of the Internet of Things (IoT). However, most IoT-connected cars mechanisms currently depend on available network services and need continuous network connections to allow users to connect to [...] Read more.

Connected vehicles have emerged as the latest revolution in the automotive industry, utilizing the advent of the Internet of Things (IoT). However, most IoT-connected cars mechanisms currently depend on available network services and need continuous network connections to allow users to connect to their vehicles. Nevertheless, the connectivity availability shortcoming in remote or rural areas with no network coverage makes vehicle sharing or any IoT-connected device problematic and undesirable. Furthermore, IoT-connected cars are vulnerable to various passive and active attacks (e.g., replay attacks, MiTM attacks, impersonation attacks, and offline guessing attacks). Adversaries could all use these attacks to disrupt networks posing a threat to the entire automotive industry. Therefore, to overcome this issue, we propose a hybrid online and offline multi-factor authentication cross-domain authentication method for a connected car-sharing environment based on the user’s smartphone. The proposed scheme lets users book a vehicle using the online booking phase based on the secured and trusted Kerberos workflow. Furthermore, an offline authentication phase uses the OTP algorithm to authenticate registered users even if the connectivity services are unavailable. The proposed scheme uses the AES-ECC algorithm to provide secure communication and efficient key management. The formal SOV logic verification was used to demonstrate the security of the proposed scheme. Furthermore, the AVISPA tool has been used to check that the proposed scheme is secured against passive and active attacks. Compared to the previous works, the scheme requires less computation due to the lightweight cryptographic algorithms utilized. Finally, the results showed that the proposed system provides seamless, secure, and efficient authentication operation for the automotive industry, specifically car-sharing systems, making the proposed system suitable for applications in limited and intermittent network connections. Full article

(This article belongs to the Special Issue Near Real-Time Smart IoT Applications)

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29 pages, 15434 KiB

Open AccessArticle

Fault-Tolerant Cooperative Control of Large-Scale Wind Farms and Wind Farm Clusters

by Saeedreza Jadidi, Hamed Badihi and Youmin Zhang

Energies 2021, 14(21), 7436; https://doi.org/10.3390/en14217436 - 08 Nov 2021

Cited by 8 | Viewed by 1976

Abstract

Large-scale wind farms and wind farm clusters with many installed wind turbines are increasingly built around the world, and especially in offshore regions. The reliability and availability of these assets are critically important for cost-effective wind power generation. This requires effective solutions for [...] Read more.

Large-scale wind farms and wind farm clusters with many installed wind turbines are increasingly built around the world, and especially in offshore regions. The reliability and availability of these assets are critically important for cost-effective wind power generation. This requires effective solutions for online fault detection, diagnosis and fault accommodation to improve the overall reliability and availability of wind turbines and entire wind farms. To meet this requirement, this paper proposes a novel active fault-tolerant cooperative control (FTCC) scheme for large-scale wind farms and wind farm clusters (WFCs). The proposed scheme is based on a signal correction method at wind turbine level that is augmented with two innovative “control reallocation” mechanisms at wind farm and network operator levels. Applied to a WFC, this scheme detects, identifies and accommodates the effects of both mild and severe power-loss faults in wind turbines. Various simulation studies on an advanced WFC benchmark indicate the high efficiency and effectiveness of the proposed solutions. Full article

(This article belongs to the Special Issue Diagnosis and Fault Tolerant Control of Wind Energy Conversion Systems)

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27 pages, 41499 KiB

Open AccessArticle

Designing Virtual Reality Environments through an Authoring System Based on CAD Floor Plans: A Methodology and Case Study Applied to Electric Power Substations for Supervision

by Camilo de Lellis Barreto Junior, Alexandre Cardoso, Edgard Afonso Lamounier Júnior, Paulo Camargos Silva and Alexandre Carvalho Silva

Energies 2021, 14(21), 7435; https://doi.org/10.3390/en14217435 - 08 Nov 2021

Cited by 12 | Viewed by 2718

Abstract

The adoption of Virtual Reality (RV) technologies in prototype design and process revision has contributed to multiple industry areas. Nonetheless, the development of VR systems for engineering is a complex task, as it involves specialized teams handling low-level code development. Given these problems, [...] Read more.

The adoption of Virtual Reality (RV) technologies in prototype design and process revision has contributed to multiple industry areas. Nonetheless, the development of VR systems for engineering is a complex task, as it involves specialized teams handling low-level code development. Given these problems, the goal of this study is presenting a methodology for designing VR, through an Authoring System based on Computer-Aided Design (CAD). The presented methodology provides an easy integration of electric power substation floor plans and Virtual Reality software (VRS), as well as three-dimensional and symbol modeling conventions. Centralized software architecture was developed, composed of the CAD Editor, input manager and VRS. The methodology was evaluated through a case study applied to the conception (elaboration) of electric power substations (EPS) as part of a Research and Development (R&D) project for training and field assets supervision. The results demonstrated visual precision and high integrity in elaboration of a VR environment from the CAD floor plan. This work also presents a comparative analysis between manual conception and the Authoring System. Full article

(This article belongs to the Special Issue Volume II: Advanced Solutions for Monitoring, Protection and Control of Modern Power Transmission System)

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23 pages, 2566 KiB

Open AccessReview

Review of Data and Data Sources for the Assessment of the Potential of Utility-Scale Hybrid Wind–Solar PV Power Plants Deployment, under a Microgrid Scope

by Luis Arribas, Yolanda Lechón, Alberto Perula, Javier Domínguez, Manuel Ferres, Jorge Navarro, Luis F. Zarzalejo, Carolina García Barquero and Ignacio Cruz

Energies 2021, 14(21), 7434; https://doi.org/10.3390/en14217434 - 08 Nov 2021

Cited by 4 | Viewed by 2699

Abstract

Utility-scale hybrid wind–solar PV power plants (which might include some storage as well) are an attractive option for the transition of conventional grids to incorporate high renewable energy (RE) shares. Along with lower generation costs, they offer increased dispatch capabilities and flexible operation. [...] Read more.

Utility-scale hybrid wind–solar PV power plants (which might include some storage as well) are an attractive option for the transition of conventional grids to incorporate high renewable energy (RE) shares. Along with lower generation costs, they offer increased dispatch capabilities and flexible operation. However, when assessing their potential, they present higher needs in terms of input data, as they are forced to consider both spatial and temporal variations to evaluate their techno-economic viability, as well as other common inputs such as economic, social or environmental data. The availability of the different data influences the type of analysis to be implemented. The microgrid approach of segmenting the information into layers will be adopted for the classification of data. Three different levels of analysis are sought: long-term energy scenarios, geo-spatial planning, and production cost estimation. The analysis of necessary data for each planning stage, and the available data sources for the assessment of utility-scale hybrid power plants, under this microgrid approach, is the main focus of this review. Full article

(This article belongs to the Special Issue Analysis of Microgrid Integrated with Renewable Energy System)

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16 pages, 3189 KiB

Open AccessArticle

Influence of Selected Factors on the Duration and Energy Efficiency of Autoclave Steaming Regimes of Non-Frozen Prisms for Veneer Production

by Nencho Deliiski, Ladislav Dzurenda, Dimitar Angelski and Natalia Tumbarkova

Energies 2021, 14(21), 7433; https://doi.org/10.3390/en14217433 - 08 Nov 2021

Cited by 7 | Viewed by 1595

Abstract

This paper puts forward a methodology for calculating the duration and energy efficiency of regimes for autoclave steaming of wooden prisms for veneer production at limited heat power of the steam generator, depending on the dimensions of the prism’s cross section, wood moisture [...] Read more.

This paper puts forward a methodology for calculating the duration and energy efficiency of regimes for autoclave steaming of wooden prisms for veneer production at limited heat power of the steam generator, depending on the dimensions of the prism’s cross section, wood moisture content, and loading level of the autoclave. The methodology is based on the use of two personal mathematical models: the 2D non-linear model of the temperature distribution in non-frozen wooden prisms subjected to steaming and subsequent conditioning in an air medium, and the model of the non-stationary heat balance of autoclaves for steaming wood materials. Using the suggested methodology, the calculation and research into the duration and energy efficiency of regimes for heating of beech prisms have been carried out. The variables used were an initial temperature of 0 °C, cross-section dimensions 0.3 × 0.3 m, 0.4 × 0.4 m, and 0.5 × 0.5 m, moisture content of 0.4, 0.6, and 0.8 kg·kg⁻¹, during their steaming in an autoclave with a diameter of 2.4 m, length of 9.0 m and loading level of 40, 50, and 60% at a limited heat power of the steam generator, equal to 500 kW. It has been determined that the duration of the autoclave steaming regimes, at a loading level of 50% being most often used in the practice beech prisms with moisture of 0.6 kg·kg⁻¹, does not exceed 9 h, 13 h, and 20 h for prisms with cross-section 0.3 × 0.3 m, 0.4 × 0.4 m, and 0.5 × 0.5 m, respectively. This duration is less than half of the corresponding duration of the steaming regimes at atmospheric pressure. The energy needed for warming up such prisms themselves does not exceed 60, 65, and 69 kWh·m⁻³, respectively, and the energy consumption of the whole autoclave then is equal to about 90, 99, and 105 kWh·m⁻³, respectively. The energy efficiency of the autoclave steaming regimes changes between 62.2% and 68.8% for the studied ranges of the influencing factors and it turns out to be more than 2–3 times larger in comparison with the efficiency of the steaming at atmospheric pressure. The methodology can be used for various calculations with ANSYS and to create the software for systems used for computing and model-based automatic realization of energy-efficient regimes for autoclave steaming of different wood materials from various species. This could be useful in developing similar methodologies in different areas of thermal treatment at increased pressure of various capillary-porous materials of plant or technical origin. Full article

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20 pages, 6506 KiB

Open AccessArticle

Analysis and Output Power Control of Unidirectional Secondary-Resonant Single-Active-Half-Bridge DC-DC Converter

by Cao Anh Tuan and Takaharu Takeshita

Energies 2021, 14(21), 7432; https://doi.org/10.3390/en14217432 - 08 Nov 2021

Cited by 2 | Viewed by 2555

Abstract

Development of high-frequency-isolated DC-DC converters is underway for charging and discharging electric vehicle batteries. As a charger, a Single Active Bridge (SAB) converter, which is composed of a primary full-bridge converter, a high-frequency transformer, and a secondary full-bridge diode rectifier circuit, has been [...] Read more.

Development of high-frequency-isolated DC-DC converters is underway for charging and discharging electric vehicle batteries. As a charger, a Single Active Bridge (SAB) converter, which is composed of a primary full-bridge converter, a high-frequency transformer, and a secondary full-bridge diode rectifier circuit, has been proposed as a unidirectional high frequency isolated DC-DC converter. In this paper, as a simple circuit configuration, a Secondary-Resonant Single-Active-Half-Bridge (SR-SAHB) converter, in which the primary and secondary circuits of the SAB converter are both half-bridge circuits, and a resonant capacitor connected in parallel to each secondary diode, is created. Due to the partial resonance on the secondary side, power transmission with unity transformer turn ratio and unity voltage conversion ratio can be realized, and a high total input power factor of the transformer can be achieved. As a result, the maximum voltage and current of the switching devices and the transformer voltage can be reduced. Moreover, soft switching in all commutations can be realized. The operation waveform is analyzed, and output power control is derived using the variable frequency control method. The effectiveness of the proposed SR-SAHB has been verified by experimental results using a 2.4 kW 20 kHz, 265 V laboratory prototype. Full article

(This article belongs to the Special Issue DC-DC Converters Technologies, Applications and Optimization)

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23 pages, 5707 KiB

Open AccessArticle

Field-Based Prediction Models for Stop Penalty in Traffic Signal Timing Optimization

by Suhaib Alshayeb, Aleksandar Stevanovic and B. Brian Park

Energies 2021, 14(21), 7431; https://doi.org/10.3390/en14217431 - 08 Nov 2021

Cited by 7 | Viewed by 1829

Abstract

Transportation agencies optimize signals to improve safety, mobility, and the environment. One commonly used objective function to optimize signals is the Performance Index (PI), a linear combination of delays and stops that can be balanced to minimize fuel consumption (FC). The critical component [...] Read more.

Transportation agencies optimize signals to improve safety, mobility, and the environment. One commonly used objective function to optimize signals is the Performance Index (PI), a linear combination of delays and stops that can be balanced to minimize fuel consumption (FC). The critical component of the PI is the stop penalty “K”, which expresses an FC stop equivalency estimated in seconds of pure delay. This study applies vehicular trajectory and FC data collected in the field, for a large fleet of modern vehicles, to compute the K-factor. The tested vehicles were classified into seven homogenous groups by using the k-prototype algorithm. Furthermore, multigene genetic programming (MGGP) is utilized to develop prediction models for the K-factor. The proposed K-factor models are expressed as functions of various parameters that impact its value, including vehicle type, cruising speed, road gradient, driving behavior, idling FC, and the deceleration duration. A parametric analysis is carried out to check the developed models’ quality in capturing the individual impact of the included parameters on the K-factor. The developed models showed an excellent performance in estimating the K-factor under multiple conditions. Future research shall evaluate the findings by using field-based K-values in optimizing signals to reduce FC. Full article

(This article belongs to the Special Issue Vehicle Energy Consumption and Emissions in Intelligent and Sustainable Transportation Systems)

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23 pages, 2818 KiB

Open AccessArticle

Examining the Impacts of Economic, Social, and Environmental Factors on the Relationship between Urbanization and CO₂ Emissions

by Yang Ding, Qing Yang and Lanjuan Cao

Energies 2021, 14(21), 7430; https://doi.org/10.3390/en14217430 - 08 Nov 2021

Cited by 6 | Viewed by 2074

Abstract

This study examines the relationship between urbanization, economic growth, industrial transformation, technological change, public services, demographical change, urban and natural environmental changes, and carbon emissions using a dataset of 182 prefecture-level cities in China between 2001 and 2010. Specifically, this paper differs from [...] Read more.

This study examines the relationship between urbanization, economic growth, industrial transformation, technological change, public services, demographical change, urban and natural environmental changes, and carbon emissions using a dataset of 182 prefecture-level cities in China between 2001 and 2010. Specifically, this paper differs from previous studies in two aspects. First, the extant literature has focused on how economic processes accompanying rapid urbanization affect carbon emissions in urban areas but gives little attention to the other dimensions of urbanization, including social and environmental changes, which may have important effects on carbon emissions. We assessed the effects of 17 key processes accompanying urbanization in a full range of economic, social, and environmental dimensions on carbon dioxide emissions in urban areas. The results showed that social processes accompanied with rapid urbanization had distinct effects on carbon emissions, compared to economic and environmental processes. Specifically, improvement in public services, indicated by education and cultural developments, reduces the increase in carbon emissions during urbanization, while economic growth and urban construction reinforces the growth in carbon emissions. Second, we examined the impact of various urbanization processes on carbon dioxide emissions using a unique dataset of 182 prefecture-level cities that covers a wide span of regions in China. The results of our analyses on the city level have important implications for the formulation of comprehensive policies aimed at reducing carbon dioxide emission in urban areas, focusing on different urbanization processes in economic, social, and environmental phases. Full article

(This article belongs to the Section B3: Carbon Emission and Utilization)

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12 pages, 17250 KiB

Open AccessArticle

Delamination-Free In-Air and Underwater Oil-Repellent Filters for Oil-Water Separation: Gravity-Driven and Cross-Flow Operations

by Bishwash Shrestha, Mohammadamin Ezazi and Gibum Kwon

Energies 2021, 14(21), 7429; https://doi.org/10.3390/en14217429 - 08 Nov 2021

Cited by 4 | Viewed by 1842

Abstract

Separating oil-water mixtures is critical in a variety of practical applications, including the treatment of industrial wastewater, oil spill cleanups, as well as the purification of petroleum products. Among various methodologies that have been utilized, membranes are the most attractive technology for separating [...] Read more.

Separating oil-water mixtures is critical in a variety of practical applications, including the treatment of industrial wastewater, oil spill cleanups, as well as the purification of petroleum products. Among various methodologies that have been utilized, membranes are the most attractive technology for separating oil-water emulsions. In recent years, selective wettability membranes have attracted particular attention for oil-water separations. The membrane surfaces with hydrophilic and in-air oleophobic wettability have demonstrated enhanced effectiveness for oil-water separations in comparison with underwater oleophobic membranes. However, developing a hydrophilic and in-air oleophobic surface for a membrane is not a trivial task. The coating delamination process is a critical challenge when applying these membranes for separations. Inspired by the above, in this study we utilize poly(ethylene glycol)diacrylate (PEGDA) and 1H,1H,2H,2H-heptadecafluorodecyl acrylate (F-acrylate) to fabricate a hydrophilic and in-air oleophobic coating on a filter. We utilize methacryloxypropyl trimethoxysilane (MEMO) as an adhesion promoter to enhance the adhesion of the coating to the filter. The filter demonstrates robust oil repellency preventing oil adhesion and oil fouling. Utilizing the filter, gravity-driven and continuous separations of surfactant-stabilized oil-water emulsions are demonstrated. Finally, we demonstrate that the filter can be reused multiple times upon rinsing for further oil-water separations. Full article

(This article belongs to the Special Issue Liquid-Liquid, Oil-Water Energy Efficient Separations)

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27 pages, 6673 KiB

Open AccessArticle

Reliability Metrics for Generation Planning and the Role of Regulation in the Energy Transition: Case Studies of Brazil and Mexico

by Ana Werlang, Gabriel Cunha, João Bastos, Juliana Serra, Bruno Barbosa and Luiz Barroso

Energies 2021, 14(21), 7428; https://doi.org/10.3390/en14217428 - 08 Nov 2021

Cited by 5 | Viewed by 1946

Abstract

In recent years electricity sectors worldwide have undergone major transformations, referred to as the “energy transition”. This has required energy planning to quickly adapt to provide useful inputs to the regulation activity so that a cost-effective electricity market emerges to facilitate the integration [...] Read more.

In recent years electricity sectors worldwide have undergone major transformations, referred to as the “energy transition”. This has required energy planning to quickly adapt to provide useful inputs to the regulation activity so that a cost-effective electricity market emerges to facilitate the integration of renewables. This paper analyzes the role of system planning and regulations on two specific elements in the energy market design: the concept of firm capacity and the presence of distributed energy resources, both of which can be influenced by regulation. We assess the total cost of different regulatory mechanisms in the Brazilian and Mexican systems using optimization tools to determine optimal long-term expansion for a given regulatory framework. In particular, we quantitatively analyze the role of the current regulation in the total cost of these two electricity systems when compared to a reference “efficient” energy planning scenario that adopts standard cost-minimization principles and that is well suited to the most relevant features of the new energy transformation scenario. We show that two very common features of regulatory designs that can lead to distortions are: (i) renewables commonly having a lower “perceived cost” under the current regulations, either due to direct incentives such as tax breaks or due to indirect access to more attractive contracts or financing conditions; and (ii) requirements for reliability are often defined more conservatively than they should be, overstating the hardships imposed by renewable generation on the existing system and underestimating their potential to form portfolios. Full article

(This article belongs to the Special Issue Energy Planning)

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19 pages, 8390 KiB

Open AccessArticle

The Connection between Architectural Elements and Adaptive Thermal Comfort of Tropical Vernacular Houses in Mountain and Beach Locations

by Hermawan Hermawan and Jozef Švajlenka

Energies 2021, 14(21), 7427; https://doi.org/10.3390/en14217427 - 08 Nov 2021

Cited by 7 | Viewed by 2692

Abstract

Passive thermal comfort has been widely used to test the thermal performance of a building. The science of active thermal comfort is important to be connected with the science of architecture. The currently developing active thermal comfort is adaptive thermal comfort. Vernacular houses [...] Read more.

Passive thermal comfort has been widely used to test the thermal performance of a building. The science of active thermal comfort is important to be connected with the science of architecture. The currently developing active thermal comfort is adaptive thermal comfort. Vernacular houses are believed to be able to create thermal comfort for the inhabitants. The present study seeks to analyze the connection between the architectural elements of vernacular houses and adaptive thermal comfort. A mixed method was applied. A quantitative approach was used in the measurement of variables of climate, while a qualitative methodology was employed in an interview on thermal sensations. The connection between architectural elements and adaptive thermal comfort was analyzed by considering the correlation among architectural features, the analysis results of thermal comfort, and the Olgyay and psychrometric diagrams. At the beginning of the rainy season, residents of exposed stone houses had the highest comfortable percentage of 31%. In the middle of the rainy season, the highest percentage of comfort was obtained by residents of exposed brick and wooden houses on the beach at 39%. The lowest comfortable percentage experienced by residents of exposed stone houses at the beginning of the dry season was 0%. The beginning of the dry season in mountainous areas has air temperatures that are too low, making residents uncomfortable. The study results demonstrate that adaptive thermal comfort is related to using a room for adaptation to create thermal comfort for the inhabitants. Full article

(This article belongs to the Special Issue Thermal Energy Storage and Solar Thermal Energy Systems)

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26 pages, 67668 KiB

Open AccessArticle

Technical and Economic Analysis of Low-Emissions Modernization of Existing Heating Plants in Poland

by Anna Hnydiuk-Stefan, Aleksandra Otawa, Krzysztof Stefan and Dariusz Zmarzły

Energies 2021, 14(21), 7426; https://doi.org/10.3390/en14217426 - 08 Nov 2021

Cited by 3 | Viewed by 1365

Abstract

An analysis is performed with regards to technologically outdated heating plants operating in many areas where fossil fuels such as coal and gas are utilized, in order to consider the alternatives of their modernization. By application of a chart using a variety of [...] Read more.

An analysis is performed with regards to technologically outdated heating plants operating in many areas where fossil fuels such as coal and gas are utilized, in order to consider the alternatives of their modernization. By application of a chart using a variety of alternatives, the economic feasibility of executing two types of modernization of heating plants are explored: a single-fuel gas–steam CHP plant and a coal-fired heating plant to a coal-fired CHP plant with a condensing turbine. This study demonstrates how the selection of modernization technology is affected, in terms of profitability, by the value and variability in time of the price relationships between energy carriers, rapidly growing charges related to CO₂ emission allowances, and costs depending on other pollutant emissions that originate from the operation of electricity and heat sources powered by fossil fuels. In both technical cases of modernization, lower prices of energy carriers coupled with CO₂ emissions allowances lead to higher prices of electricity that can be sold as additional products following this modernization, and consequently, the specific cost of heat production in the repowered heat sources is lowered. The calculations were performed by the application of models of heating plant modernization applying continuous time notations, which offer the determination of the most suitable time of initiation of this modernization. Such relationships would be difficult to describe in the case of the use of traditional discrete models. In the case of a simultaneous increase in the prices of all main factors affecting the cost of heat generation, such as the price of gas, electricity and CO₂ emissions, the fastest modernization of the heating plant to single-fuel gas–steam CHP provides the possibility of the best economic performance. Full article

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18 pages, 1145 KiB

Open AccessArticle

Trust as an Element of the Functioning of the Information System in Management in Conditions of Forced Remote Work

by Tomasz Lis, Aleksandra Ptak and Marek Lis

Energies 2021, 14(21), 7425; https://doi.org/10.3390/en14217425 - 08 Nov 2021

Cited by 1 | Viewed by 2253

Abstract

Information management, an important element of which is the information system, has a direct impact on the functioning of a company, including its competitive position. Information management is related to the shape of the organizational culture, represented, inter alia, by the context of [...] Read more.

Information management, an important element of which is the information system, has a direct impact on the functioning of a company, including its competitive position. Information management is related to the shape of the organizational culture, represented, inter alia, by the context of trust, relationship, and communication. The shape of the organizational culture, including the functioning of the information system, is particularly influenced by factors (usually external) that appear in a sudden and unpredictable manner. This impact increases with the intensity and scale of their influence. The recent COVID-19 pandemic should undoubtedly be considered such a factor. As a result, many enterprises suddenly had to switch to remote work. The aim of this paper is to analyze the essence and recognize the impact of the forced transition to a remote form of work on trust as a shaping and effective factor in the functioning of the company’s information system. To achieve this goal, the results of qualitative research conducted by the authors during the period March 2020–February 2021 and quantitative research conducted in February 2021 were used. In connection with the conducted research, it was found that trust is a very important factor influencing the efficiency and quality of employees’ work. It was also found that the forced need to switch to remote work mode was a problem for most people. This was influenced by both the time of the pandemic, as well as technical and organizational problems. As a result of observations, own experiences, interviews, and a questionnaire survey, the authors state that the necessity to switch from traditional to remote work resulted in an increase in the costs of functioning of people, including employees. Full article

(This article belongs to the Special Issue Management and Information Technology in the Energy Sector)

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17 pages, 46948 KiB

Open AccessArticle

Improvement of BIPV Efficiency by Application of Highly Reflective Surfaces at the Building Envelope

by Dominika Knera, Pablo Roberto Dellicompagni and Dariusz Heim

Energies 2021, 14(21), 7424; https://doi.org/10.3390/en14217424 - 08 Nov 2021

Cited by 3 | Viewed by 1762

Abstract

The use of concentrated solar irradiation for the improvement of electric generation improvement has been implemented on different scales, mainly in photovoltaic systems. High-concentration Fresnel lenses are widely chosen for this approach in large installations, while low-concentration systems are rather applied in medium-low [...] Read more.

The use of concentrated solar irradiation for the improvement of electric generation improvement has been implemented on different scales, mainly in photovoltaic systems. High-concentration Fresnel lenses are widely chosen for this approach in large installations, while low-concentration systems are rather applied in medium-low scales. For the latter, the improvement on electric performance was revealed, even when no solar tracking was implemented. The presented work aims to analyse a low-concentration photovoltaic installation by a numerical approach. First, the reflective surfaces were designed geometrically considering the optimal slope determined for each month. Subsequently, different simulation techniques were used separately for prediction of solar irradiation and energy production. Three criteria were selected to analyze power generation: the highest increase in total annual solar irradiance on panels with reflective surfaces, the highest total annual solar irradiance collected, and the optimal slope of panels for the entire year. The increase in energy was found to not exceed 10% in the winter months. Whereas in the spring and summer months the energy improvement is about 15–20%. Moreover, it was observed that the temperature of the proposed concentration photovoltaic system increased significantly, reaching more than 90 °C, while for traditional PV panels it did not exceed 75 °C. Full article

(This article belongs to the Special Issue Application of Renewable Energy Sources (Solar, Geothermal, Wind, Biomass and Hydro Energies) in Buildings)

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15 pages, 5448 KiB

Open AccessArticle

Eco-Friendly and Economical Solar Heater Design Using Internal Structure and Phase Change Materials

by Jihu Lee, Sung-Hun Son and Kibum Kim

Energies 2021, 14(21), 7423; https://doi.org/10.3390/en14217423 - 08 Nov 2021

Cited by 2 | Viewed by 1813

Abstract

Indoor heating systems currently used are highly dependent on fossil fuels; hence, it is urgent to develop a new heating system to achieve carbon zero-emission. A solar air heater is eco-friendly because it generates nearly zero greenhouse gases. In this study, a parametric [...] Read more.

Indoor heating systems currently used are highly dependent on fossil fuels; hence, it is urgent to develop a new heating system to achieve carbon zero-emission. A solar air heater is eco-friendly because it generates nearly zero greenhouse gases. In this study, a parametric study was conducted for optimizing solar air heater design applicable to indoor heating. Installing the internal structure in the solar heater changes the interior flow characteristic, resulting in the air temperature increased by about 14.2 K on average compared to the heater without the internal structure. An additional case study was carried out to optimize the ideal quantity of phase change materials (PCM) in terms of mass fraction and heat capacity for various operating conditions. An excessive amount of PCM (e.g., 66% of the storage space filled with PCM) deteriorates the performance of the air heater unless the entire PCM could be melted during the daytime. After heating, the air temperature was maintained the longest when only 33% of the internal space was filled with PCM. The solar air heater can fully replace or partly assist a conventional heater for indoor heating, and it could reduce approximately 0.6 tCO₂ per year. Full article

(This article belongs to the Special Issue Technologies for Carbon Emission Mitigation)

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10 pages, 3386 KiB

Open AccessArticle

Design and Demonstration of Large Scale Cu₂O Photocathodes with Metal Grid Structure for Photoelectrochemical Water Splitting

by Min-Kyu Son

Energies 2021, 14(21), 7422; https://doi.org/10.3390/en14217422 - 08 Nov 2021

Cited by 9 | Viewed by 2300

Abstract

Upscaling of photoelectrode for a practical photoelectrochemical (PEC) water splitting system is still challenging because the PEC performance of large-scale photoelectrode is significantly low, compared to the lab scale photoelectrode. In an effort to overcome this challenge, sputtered gold (Au) and copper (Cu) [...] Read more.

Upscaling of photoelectrode for a practical photoelectrochemical (PEC) water splitting system is still challenging because the PEC performance of large-scale photoelectrode is significantly low, compared to the lab scale photoelectrode. In an effort to overcome this challenge, sputtered gold (Au) and copper (Cu) grid lines were introduced to improve the PEC performance of large-scale cuprous oxide (Cu₂O) photocathode in this work. It was demonstrated that Cu grid lines are more effective than Au grid lines to improve the PEC performance of large-scale Cu₂O photocathode because its intrinsic conductivity and quality of grid lines are better than ones containing Au grid lines. As a result, the PEC performance of a 25-cm² scaled Cu₂O photocathode with Cu grid lines was almost double than one without grid lines, resulting in an improved charge transport in the large area substrate by Cu grid lines. Finally, a 50-cm² scaled Cu₂O photocathode with Cu grid lines was tested in an outdoor condition under natural sun. This is the first outdoor PEC demonstration of large-scale Cu₂O photocathode with Cu grid lines, which gives insight into the development of efficient upscaled PEC photoelectrode. Full article

(This article belongs to the Section A2: Solar Energy and Photovoltaic Systems)

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