Energies

25 pages, 4587 KiB

Open AccessEditor’s ChoiceReview

Design, Integration, and Control of Organic Rankine Cycles with Thermal Energy Storage and Two-Phase Expansion System Utilizing Intermittent and Fluctuating Heat Sources—A Review

by Attila R. Imre, Sindu Daniarta, Przemysław Błasiak and Piotr Kolasiński

Energies 2023, 16(16), 5948; https://doi.org/10.3390/en16165948 - 11 Aug 2023

Cited by 6 | Viewed by 1923

Abstract

In order to lessen reliance on fossil fuels, a rise in interest in the utilization of fluctuating and intermittent heat sources derived from renewable energy (such as solar thermal, ocean thermal, and geothermal) and waste heat has been observed. These heat sources could [...] Read more.

In order to lessen reliance on fossil fuels, a rise in interest in the utilization of fluctuating and intermittent heat sources derived from renewable energy (such as solar thermal, ocean thermal, and geothermal) and waste heat has been observed. These heat sources could be used to generate electricity at relatively low and medium temperatures, for example, through the organic Rankine cycle (ORC). In some case studies, various approaches have been developed to deal with and design ORCs in the desired operating condition utilizing suitable working fluids. This article aims to review some designs and integrated systems of ORC with thermal energy storage (TES) and a two-phase expansion system focusing on the utilization of medium- and low-temperature heat sources in which some subcritical ORCs are presented. Moreover, several possible control systems (both conventional and advanced ones) of ORC with TES and a two-phase expansion system are reported and compared. At the end of this article, the possible future developments of design and control systems are discussed to describe advanced ORC for utilizing low-grade heat sources. This study aims to provide researchers and engineers with an insight into the challenges involved in this process, making industrialization of ORC technology more extensive, in particular when combined with TES and a two-phase expansion system. Full article

(This article belongs to the Section D: Energy Storage and Application)

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19 pages, 4238 KiB

Open AccessEditor’s ChoiceReview

Photovoltaic-Assisted Photo(electro)catalytic Hydrogen Production: A Review

by Mohamad Fakhrul Ridhwan Samsudin

Energies 2023, 16(15), 5743; https://doi.org/10.3390/en16155743 - 1 Aug 2023

Cited by 1 | Viewed by 1839

Abstract

The idea of supporting the Sustainable Development Goals (SDGs) has inspired researchers around the world to explore more environmentally friendly energy generation and production methods, especially those related to solar and hydrogen energy. Among the various available sustainable energy technologies, photo(electro)catalytic hydrogen production [...] Read more.

The idea of supporting the Sustainable Development Goals (SDGs) has inspired researchers around the world to explore more environmentally friendly energy generation and production methods, especially those related to solar and hydrogen energy. Among the various available sustainable energy technologies, photo(electro)catalytic hydrogen production has been competitively explored, benefiting from its versatile platform to utilize solar energy for green hydrogen production. Nevertheless, the bottleneck of this photo(electro)catalytic system lies within its high voltage required for water electrolysis (>1.23 V), which affects the economic prospects of this sustainable technology. In this regard, coupling the photo(electro)catalytic system with a solar-powered photovoltaic (PV) system (PV-PEC) to unleash the fascinating properties and readiness of this system has heightened attention among the scientific community. In this context, this review begins by elucidating the basic principles of PV-PEC systems, followed by an exploration of various types of solar PV technology and the different types of semiconductors used as photocatalysts in the PEC system. Subsequently, the main challenges faced by the PV-PEC system are presented, covering areas such as efficiency, stability, and cost-effectiveness. Finally, this review delves into recent research related to PV-PEC systems, discussing the advancements and breakthroughs in this promising technology. Furthermore, this review provides a forecast for the future prospects of the PV-PEC system, highlighting the potential for its continued development and widespread implementation as a key player in sustainable hydrogen production. Full article

(This article belongs to the Special Issue Energies: Advances in Sustainable PV/Wind Power System)

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30 pages, 5871 KiB

Open AccessEditor’s ChoiceReview

A Review on Analysis Methods and Research Status of Hysteresis Motor

by Bo Gao, Yuan Cheng, Tianxu Zhao, Haodong Sun and Shumei Cui

Energies 2023, 16(15), 5715; https://doi.org/10.3390/en16155715 - 31 Jul 2023

Cited by 4 | Viewed by 5773

Abstract

A hysteresis motor produces output torque through the hysteresis effect of magnetic materials. It has the advantages of a simple structure, high-speed operation, high temperature resistance, low noise and self-starting capability. It can be applied to some special occasions requiring high speed and [...] Read more.

A hysteresis motor produces output torque through the hysteresis effect of magnetic materials. It has the advantages of a simple structure, high-speed operation, high temperature resistance, low noise and self-starting capability. It can be applied to some special occasions requiring high speed and high stationarity. However, its disadvantage is low torque density, low efficiency and low power factor. The permanent magnet hysteresis motor is a compromise of the characteristics of permanent magnet motor and hysteresis motor, and it can be self-starting in the case of having a torque density comparable to that of a permanent magnet motor. In addition, there are some new structures of hysteresis motors, which open up the direction for innovative applications. Due to the complexity of magnetic properties, the calculation methods and dynamic models of hysteresis motors and permanent magnet hysteresis motors are special and also depend on the research of hysteresis materials and hysteresis models. This paper starts from the principle and classification of the hysteresis motor, and different structures and the corresponding analysis methods are reviewed. The motors with new structures and new methods are emphasized, the innovation and contribution of existing research are summarized, and the development trend of hysteresis motors is described. Full article

(This article belongs to the Topic Future Generation Electric Machines and Drives)

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35 pages, 3476 KiB

Open AccessEditor’s ChoiceReview

A Practical Review to Support the Implementation of Smart Solutions within Neighbourhood Building Stock

by Simone Ferrari, Milad Zoghi, Giancarlo Paganin and Giuliano Dall’O’

Energies 2023, 16(15), 5701; https://doi.org/10.3390/en16155701 - 30 Jul 2023

Cited by 3 | Viewed by 2637

Abstract

The construction industry has witnessed an increase in the use of digital tools and smart solutions, particularly in the realm of building energy automation. While realising the potential benefits of smart cities, a broader scope of smart initiatives is required to support the [...] Read more.

The construction industry has witnessed an increase in the use of digital tools and smart solutions, particularly in the realm of building energy automation. While realising the potential benefits of smart cities, a broader scope of smart initiatives is required to support the transition from smart buildings towards smart neighbourhoods, which are considered critical urban development units. To support the interplay of smart solutions between buildings and neighbourhoods, this study aimed to collect and review all the smart solutions presented in existing scientific articles, the technical literature, and realised European projects. These solutions were classified into two main sections, buildings and neighbourhoods, which were investigated through five domains: building-energy-related uses, renewable energy sources, water, waste, and open space management. The quantitative outcomes demonstrated the potential benefits of implementing smart solutions in areas ranging from buildings to neighbourhoods. Moreover, this research concluded that the true enhancement of energy conservation goes beyond the building’s energy components and can be genuinely achieved by integrating intelligent neighbourhood elements owing to their strong interdependencies. Future research should assess the effectiveness of these solutions in resource conservation. Full article

(This article belongs to the Special Issue Energy Efficiency of the Buildings II)

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15 pages, 657 KiB

Open AccessEditor’s ChoiceArticle

Wide-Area Measurement-Based Two-Level Control Design to Tolerate Permanent Communication Failures

by Murilo Eduardo Casteroba Bento

Energies 2023, 16(15), 5646; https://doi.org/10.3390/en16155646 - 27 Jul 2023

Cited by 11 | Viewed by 1214

Abstract

The operation of modern power systems must meet stability requirements to guarantee the supply of electrical energy. One of these requirements is to ensure that the low-frequency oscillation modes have high damping ratios to avoid angular instability and future power system blackouts. Advances [...] Read more.

The operation of modern power systems must meet stability requirements to guarantee the supply of electrical energy. One of these requirements is to ensure that the low-frequency oscillation modes have high damping ratios to avoid angular instability and future power system blackouts. Advances in phasor measurement units (PMUs) have contributed to the development and improvement of wide-area damping controllers (WADCs) capable of increasing the damping rates of the oscillation modes of the system, especially the inter-area modes. Nevertheless, the operation of WADCs is vulnerable to communication failures and cyber-attacks, and if not properly designed the WADC can affect the stability of the entire system. This research proposes a procedure for designing a WADC robust to permanent communication failures using a linear quadratic regulator (LQR) and genetic algorithms. Case studies conducted on an IEEE 68-bus test power system show the effectiveness of the WADC designed by the proposed procedure even when communication failures are occurring in the system. The use of genetic algorithms improves the convergence and results of the LQR-based method. Full article

(This article belongs to the Special Issue Research on Power System Control and Optimization)

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19 pages, 2125 KiB

Open AccessEditor’s ChoiceReview

Open Innovation for the Construction Sector: Concept Overview and Test Bed Development to Boost Energy-Efficient Solutions

by Graziano Salvalai, Marta Maria Sesana, Paolo Dell’Oro and Diletta Brutti

Energies 2023, 16(14), 5522; https://doi.org/10.3390/en16145522 - 21 Jul 2023

Cited by 3 | Viewed by 2421

Abstract

Open innovation has recently emerged as an important concept in both academic research and industrial practice, and it is now also becoming increasingly important in the public policy field due to the innovation challenges in different domains, such as climate change, sustainability, and [...] Read more.

Open innovation has recently emerged as an important concept in both academic research and industrial practice, and it is now also becoming increasingly important in the public policy field due to the innovation challenges in different domains, such as climate change, sustainability, and growth to name a few, but only in some value chains (i.e., automotive, manufacturing, aerospace). According to a report by McKinsey and Co., the construction industry lags behind others in adopting innovations; in fact, less than 1% of the construction industry’s revenue goes back into technology research and development. This work focuses on the current debate on the underdeveloped application of the open innovation (OI) approach to the construction sector. Namely, the foundational question is whether the OI model can be the answer to boosting innovation for the decarbonization of buildings. The research goal is to go a step further by analyzing its internal effectiveness, focusing on introducing and defining the Open Innovation Test Bed (OITB) concept. The study provides a systematic and bibliometric literature review of OI starting from a critical analysis of the concept definition and the evolution of the paradigm from the initial application to the first declination for the construction sector. All the steps analyzed allowed us to make an overall and comprehensive review of the OI concept, which is usually applied to other sectors, considering the ecosystem as the most effective declination of the OI paradigm for OITB development for building envelope solutions, thus providing answers to the two objectives identified in the introduction. Finally, the limitations of prior OI studies and the challenges for the OITB new construction paradigm are discussed, and we make recommendations for future opportunities and approach development to tackle and boost energy-efficient envelope solutions for the construction industries. Full article

(This article belongs to the Special Issue Energy Efficiency of the Buildings II)

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14 pages, 2903 KiB

Open AccessEditor’s ChoiceArticle

Performance Evaluation of Irrigation Canals Using Data Envelopment Analysis for Efficient and Sustainable Irrigation Management in Jharkhand State, India

by Jay Nigam, Totakura Bangar Raju and Ramachandra K. Pavan Kumar Pannala

Energies 2023, 16(14), 5490; https://doi.org/10.3390/en16145490 - 20 Jul 2023

Cited by 1 | Viewed by 1831

Abstract

Across the world, achieving sustainable water resource development and managing limited natural resources like water have proven to be significant issues, and India is no exception to the same. At present, irrigation consumes about 80 percent of the total available water in India [...] Read more.

Across the world, achieving sustainable water resource development and managing limited natural resources like water have proven to be significant issues, and India is no exception to the same. At present, irrigation consumes about 80 percent of the total available water in India and is predicted to remain the dominant water user. India is already a country with water stress and is on its way to becoming a country with water scarcity. Rising agricultural productivity, expanding urbanisation, growing industrialisation, and accelerating industry create competing demands for water. Most irrigation system issues in India are attributable to poor management of the built infrastructure. The present study aims to rank the irrigation canals based on their efficiencies and inefficiencies to improve the overall performance of WUAs in Jharkhand. The ranking is done for nine irrigation canals based on financial inputs like investments in training and development of WUAs, maintenance and repairs of canals, and outputs like users’ charges collection and yield in crop production. The Comprehensive Efficiency score analysis suggests that while there is room for improvement in the performance, the Water Users’ Associations have generally been successful in improving the technical efficiency of the irrigation system. The findings can be used for further investigation to identify best practises and areas for improvement. Full article

(This article belongs to the Special Issue Data Driven Approaches for Environmental Sustainability 2023)

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26 pages, 10137 KiB

Open AccessEditor’s ChoiceArticle

Optimization Design of a Parallel Flow Field for PEMFC with Bosses in Flow Channels

by Guodong Zhang, Zhen Guan, Da Li, Guoxiang Li, Shuzhan Bai, Ke Sun and Hao Cheng

Energies 2023, 16(14), 5492; https://doi.org/10.3390/en16145492 - 20 Jul 2023

Cited by 5 | Viewed by 2052

Abstract

The proton exchange membrane fuel cell (PEMFC) is a promising energy conversion device due to its high reliability, fast response speed, and low pollutant emission. However, the reality of its commercial application requires further cost reduction and efficiency improvement. The material distribution in [...] Read more.

The proton exchange membrane fuel cell (PEMFC) is a promising energy conversion device due to its high reliability, fast response speed, and low pollutant emission. However, the reality of its commercial application requires further cost reduction and efficiency improvement. The material distribution in the channel and the performance of PEMFC can be improved by setting the boss inside the flow channels. In this paper, the performance of PEMFC with the boss in flow channels in a parallel flow field was analyzed by simulation. The influence of different boss arrangements and heights on gas pressure drop, distribution uniformity, gas component distribution, temperature distribution, and output performance of the fuel cell were analyzed in detail. The bosses would increase the pressure drop and the distribution uniformity of reactive gases in flow channels significantly. The cross-arrangement of bosses is better than the cross-arrangement of bosses and juxtaposition according to increasing performance and pressure drop. The cross-arrangement with a boss height of 0.4 mm is suitable for the parallel flow field in this paper. The improved scheme of flow channel design is proposed to provide a reference for fuel cells for subsequent research. Full article

(This article belongs to the Special Issue Technical Problems in the Production and Distribution of Energy from Renewable Energy Sources)

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23 pages, 5726 KiB

Open AccessEditor’s ChoiceReview

A Comprehensive Review of Distributed MPPT for Grid-Tied PV Systems at the Sub-Module Level

by Yousef Alharbi, Ahmed Darwish and Xiandong Ma

Energies 2023, 16(14), 5468; https://doi.org/10.3390/en16145468 - 19 Jul 2023

Cited by 9 | Viewed by 2979

Abstract

Energy crises and the growth of the energy demand have increased the interest in utilizing unconventional power sources. Thus, renewable energy sources have become a topic of interest to mitigate rising energy concerns and cope with increased electricity demand. With remarkable merits including [...] Read more.

Energy crises and the growth of the energy demand have increased the interest in utilizing unconventional power sources. Thus, renewable energy sources have become a topic of interest to mitigate rising energy concerns and cope with increased electricity demand. With remarkable merits including cleanness and abundance, photovoltaic (PV) solar energy systems are a key to solving these issues. The employed inverters should effectively utilize the maximum available power from the PV solar system and transfer this power to the utility grid without posing any further limitations. However, the unequal power generation of different PV systems caused by partial shading (PS) and other PV panel degradation factors leads to a reduction in generation capacity. One of the relatively new solutions to mitigate the mismatch concerns between the PV modules and sub-modules is to extract the maximum power of each sub-module individually. The main objective of this paper is to present a comprehensive review of such PV grid-connected inverters topologies associated with sub-module connection and control. It will classify the PV grid-tied inverters in accordance with the level where the maximum power point tracking (MPPT) system is implemented. A special focus has been placed on sub-module microinverters (MI) in terms of circuit topologies, conversion efficiency, and controller design. This paper provides a comprehensive analysis of employing the distributed MPPT (DMPPT) approach to maximize the power generation of PV systems by mitigating the mismatch issues inside the PV module. The circuit topology, PV system configuration, and MPPT algorithms used for applying DMPPT solutions in PV SMs are discussed in detail in this study. Full article

(This article belongs to the Collection Renewable Energy and Energy Storage Systems)

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16 pages, 1075 KiB

Open AccessEditor’s ChoiceArticle

Open-Access Model of a PV–BESS System: Quantifying Power and Energy Exchange for Peak-Shaving and Self Consumption Applications

by Joel Alpízar-Castillo, Victor Vega-Garita, Nishant Narayan and Laura Ramirez-Elizondo

Energies 2023, 16(14), 5480; https://doi.org/10.3390/en16145480 - 19 Jul 2023

Cited by 3 | Viewed by 2708

Abstract

Energy storage is vital for a future where energy generation transitions from a fossil fuels-based one to an energy system that relies heavily on clean energy sources such as photovoltaic (PV) solar energy. To foster this transition, engineers and practitioners must have open-access [...] Read more.

Energy storage is vital for a future where energy generation transitions from a fossil fuels-based one to an energy system that relies heavily on clean energy sources such as photovoltaic (PV) solar energy. To foster this transition, engineers and practitioners must have open-access models of PV systems coupled with battery storage systems (BESS). These models are fundamental to quantifying their economic and technical merits during the design phase. This paper contributes in this direction by carefully describing a model that accurately represents the power directions and energy dealings between the PV modules, the battery pack, and the loads. Moreover, the general model can be implemented using two different PV generation methods, the Gaussian model and the meteorological data-based model (MDB). We found that the MDB model is more appropriate for short-term analysis compared to the Gaussian model, while for long-term studies, the Gaussian model is closer to measured data. Moreover, the proposed model can reproduce two different energy management strategies: peak-shaving and maximizing self-consumption, allowing them to be used during PV–BESS sizing stages. Furthermore, the results obtained by the simulation are closed when compared to a real grid-tied PV–BESS, demonstrating the model’s validity. Full article

(This article belongs to the Special Issue Photovoltaic and Other Technologies in Energy Storage)

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19 pages, 2556 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Multi-Parametric Analysis Based on Physico-Chemical Characterization and Biochemical Methane Potential Estimation for the Selection of Industrial Wastes as Co-Substrates in Anaerobic Digestion

by Luz Marina Ruiz, María Fernández, Ana Genaro, Jaime Martín-Pascual and Montserrat Zamorano

Energies 2023, 16(14), 5444; https://doi.org/10.3390/en16145444 - 18 Jul 2023

Cited by 2 | Viewed by 1478

Abstract

Anaerobic digestion is considered as one of the most feasible waste-to-energy technologies for the valorization of organic wastes. It can be applied to many different substrates but the mono-digestion of a single substrate usually has some important drawbacks due to the physico-chemical characteristics [...] Read more.

Anaerobic digestion is considered as one of the most feasible waste-to-energy technologies for the valorization of organic wastes. It can be applied to many different substrates but the mono-digestion of a single substrate usually has some important drawbacks due to the physico-chemical characteristics of the substrate. A feasible solution is the simultaneous co-digestion of several substrates with different composition and characteristics, so that synergetic effects may be generated and physico-chemical characteristics may be compensated, thus reaching higher process efficiencies and biogas production rates. In this work, a multi-parametric analysis for the objective comparison of industrial wastes was developed in order to help with decision making about their suitability as a co-substrate in anaerobic co-digestion. Criteria considered for this analysis included sample composition, C/N ratios, theoretical biochemical methane potential (BMP), and other important issues such as production rates, seasonality, and the distance to the WWTP or pre-treatment requirements. Results showed that, among the 13 evaluated wastes, 2 of them showed a higher potential for being used in anaerobic co-digestion: 1. Fried corn from the snack food industry and 2. Wet fatty pomace from the olive oil industry. Both wastes showed high estimated BMP values, high lipid and carbohydrate content, and C/N ratios in a proper range to improve the low C/N ratio of sewage sludge. Other wastes such as olive pomace (dry), skinless corn (not fried), and grape pomace from the winery industry may also be used as co-substrates. As a conclusion, this procedure based on a selection matrix can be considered as a useful tool to help both producers and WWTP operators to make decisions about the potential applicability of specific industrial wastes as co-substrates in anaerobic co-digestion. Full article

(This article belongs to the Special Issue Biomass and Bio-Energy)

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30 pages, 3099 KiB

Open AccessEditor’s ChoiceReview

A Review of State-of-the-Art and Short-Term Forecasting Models for Solar PV Power Generation

by Wen-Chang Tsai, Chia-Sheng Tu, Chih-Ming Hong and Whei-Min Lin

Energies 2023, 16(14), 5436; https://doi.org/10.3390/en16145436 - 17 Jul 2023

Cited by 16 | Viewed by 4935

Abstract

Accurately predicting the power produced during solar power generation can greatly reduce the impact of the randomness and volatility of power generation on the stability of the power grid system, which is beneficial for its balanced operation and optimized dispatch and reduces operating [...] Read more.

Accurately predicting the power produced during solar power generation can greatly reduce the impact of the randomness and volatility of power generation on the stability of the power grid system, which is beneficial for its balanced operation and optimized dispatch and reduces operating costs. Solar PV power generation depends on the weather conditions, such as temperature, relative humidity, rainfall (precipitation), global solar radiation, wind speed, etc., and it is prone to large fluctuations under different weather conditions. Its power generation is characterized by randomness, volatility, and intermittency. Recently, the demand for further investigation into the uncertainty of short-term solar PV power generation prediction and its effective use in many applications in renewable energy sources has increased. In order to improve the predictive accuracy of the output power of solar PV power generation and develop a precise predictive model, the authors used predictive algorithms for the output power of a solar PV power generation system. Moreover, since short-term solar PV power forecasting is an important aspect of optimizing the operation and control of renewable energy systems and electricity markets, this review focuses on the predictive models of solar PV power generation, which can be verified in the daily planning and operation of a smart grid system. In addition, the predictive methods identified in the reviewed literature are classified according to the input data source, and the case studies and examples proposed are analyzed in detail. The contributions, advantages, and disadvantages of the predictive probabilistic methods are compared. Finally, future studies on short-term solar PV power forecasting are proposed. Full article

(This article belongs to the Special Issue Solar Cells and Photoelectrochemical Cells: Current Status, Challenges, and Future)

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30 pages, 12365 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Study of Combustor–Turbine Interactions by Performing Coupled and Decoupled Hybrid RANS-LES Simulations under Representative Engine-like Conditions

by Stella Grazia Tomasello, Roberto Meloni, Luca Andrei and Antonio Andreini

Energies 2023, 16(14), 5395; https://doi.org/10.3390/en16145395 - 15 Jul 2023

Cited by 2 | Viewed by 1303

Abstract

Combustion–turbine interaction phenomena are attracting ever-growing interest in recent years. As a matter of fact, the strong unsteady and three-dimensional flow field that characterizes the combustor is usually conserved up to the first-stage nozzle, possibly affecting its design and performance in terms of [...] Read more.

Combustion–turbine interaction phenomena are attracting ever-growing interest in recent years. As a matter of fact, the strong unsteady and three-dimensional flow field that characterizes the combustor is usually conserved up to the first-stage nozzle, possibly affecting its design and performance in terms of aerodynamics and the effectiveness of the cooling system as well. Such conditions are also exacerbated by the employment of lean-burn combustors, where high turbulence levels are required for the flame stabilization, resulting in even greater temperature and velocity distortions at the inlet of the first-stage nozzle. Even if it has been proven by several past studies that the best way of studying the combustor–turbine interaction is simulating the two components together, performing coupled simulations is still challenging from a numerical point of view, especially in an industrial context. For this reason, the application and generation of the most representative and reliable boundary conditions possible at the inlet of the S1N have assumed an increased importance in order to study the two components separately by performing decoupled simulations. In this context, the purpose of the present work is to compare fully integrated combustor–stator SBES simulations to isolated stator ones. To perform the stator-only calculations, the fully unsteady inlet conditions of the stator have been recorded at the interface plane between the two components in the integrated SBES simulation and then they have been reconstructed by applying the proper orthogonal decomposition (POD) technique. The SBES simulations of the isolated stator have been so performed with the aim of determining whether the flow field obtained is comparable with the one of the integrated simulation, thus allowing more realistic results to be obtained rather than imposing time-averaged 2D maps, as per standard design practice. Full article

(This article belongs to the Special Issue Experimental Analysis and Numerical Modelling of Heat Transfer and Fluid Flows in Energy Systems II)

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16 pages, 5512 KiB

Open AccessEditor’s ChoiceArticle

Research on IPFC-Based Dynamic Droop Control Strategy

by Chaofan Ding, Xiaopeng Li, Baohong Li, Qin Jiang, Menghao Wen and Tianqi Liu

Energies 2023, 16(14), 5400; https://doi.org/10.3390/en16145400 - 15 Jul 2023

Cited by 1 | Viewed by 1159

Abstract

The interline power flow controller (IPFC) presents a promising solution for managing the directional and quantitative interaction of power between different lines, facilitating a significant improvement in power system stability. Based on such a background, this paper proposes a dynamic droop control strategy [...] Read more.

The interline power flow controller (IPFC) presents a promising solution for managing the directional and quantitative interaction of power between different lines, facilitating a significant improvement in power system stability. Based on such a background, this paper proposes a dynamic droop control strategy to improve frequency stability through the use of IPFC equipment. To enhance the active power support ability of the IPFC, additional frequency control for the IPFC’s active power control loop is designed with droop control, where each IPFC’s power flow control limitations are also considered to make sure the original power of each line is controllable. Besides the addition of such basic control, the proposed droop strategy is designed in a dynamic style. The droop coefficients of each IPFC can be varied according to each line’s power transmission margin, such that the power fluctuations can be shared more reasonably based on such a dynamic droop coordination strategy. The proposed methods are verified through PSCAD simulations. The results show that the dynamic droop control cannot only suppress the frequency disturbance, but also make power dispatch more efficient. Full article

(This article belongs to the Section F1: Electrical Power System)

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20 pages, 4778 KiB

Open AccessEditor’s ChoiceArticle

Optical Modelling of a Linear Fresnel Concentrator for the Development of a Spectral Splitting Concentrating Photovoltaic Thermal Receiver

by Alois Resch and Robert Höller

Energies 2023, 16(14), 5373; https://doi.org/10.3390/en16145373 - 14 Jul 2023

Viewed by 1151

Abstract

Concentrating photovoltaic thermal (CPVT) solar collectors can be regarded as a promising technology, as they are capable of providing renewable electricity and industrial heat simultaneously. The development of a novel CPVT receiver for a linear Fresnel concentrator requires detailed knowledge about the optical [...] Read more.

Concentrating photovoltaic thermal (CPVT) solar collectors can be regarded as a promising technology, as they are capable of providing renewable electricity and industrial heat simultaneously. The development of a novel CPVT receiver for a linear Fresnel concentrator requires detailed knowledge about the optical performance of the utilised mirror field. Therefore, this paper presents a generic optical model for such concentrating solar systems. The model was developed in MATLAB™ and calculates the sun’s position depending on the location, date and time. The subsequent geometrical computation of each mirror stripe angle is the basis for the detailed consideration of internal shading mechanisms that are typical for Fresnel mirror concentrators. Furthermore, the cosine losses are determined separately for each mirror. The outcomes of the developed model comprise the optical performance parameters of the considered Fresnel mirror field, such as the geometric efficiency, resulting irradiance in the receiver input plane, expected width of the focus image, concentration factor and total radiant flux impinging the receiver. Due to the chosen design of the model, its application is not limited to a particular kind of Fresnel concentrator. By contrast, all geometric parameters, such as the number of mirrors, the dimensions of the mirrors and the receiver, among others, can be freely adjusted. Full article

(This article belongs to the Special Issue Advances in Solar Systems and Energy Efficiency)

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28 pages, 3471 KiB

Open AccessEditor’s ChoiceArticle

Optimal Coordination of Directional Overcurrent Relays Using Hybrid Firefly–Genetic Algorithm

by Tareq Foqha, Maher Khammash, Samer Alsadi, Osama Omari, Shady S. Refaat, Khaled Al-Qawasmi and Ali Elrashidi

Energies 2023, 16(14), 5328; https://doi.org/10.3390/en16145328 - 12 Jul 2023

Cited by 22 | Viewed by 2271

Abstract

The application of directional overcurrent relays (DOCRs) plays an important role in protecting power systems and ensuring their safe, reliable, and efficient operation. However, coordinating DOCRs involves solving a highly constrained and nonlinear optimization problem. The primary objective of optimization is to minimize [...] Read more.

The application of directional overcurrent relays (DOCRs) plays an important role in protecting power systems and ensuring their safe, reliable, and efficient operation. However, coordinating DOCRs involves solving a highly constrained and nonlinear optimization problem. The primary objective of optimization is to minimize the total operating time of DOCRs by determining the optimal values for decision variables such as the time multiplier setting (TMS) and plug setting (PS). This article presents an efficient hybrid optimization algorithm that combines the modified firefly algorithm and genetic algorithm to achieve improved solutions. First, this study modifies the firefly algorithm to obtain a global solution by updating the firefly’s brightness and to prevent the distance between the individual fireflies from being too far. Additionally, the randomized movements are controlled to produce a high convergence rate. Second, the optimization problem is solved using the genetic algorithm. Finally, the solution obtained from the modified firefly algorithm is used as the initial population for the genetic algorithm. The proposed algorithms have been tested on the IEEE 3-bus, 8-bus, 9-bus and 15-bus networks. The results indicate the effectiveness and superiority of the proposed algorithms in minimizing the total operating time of DOCRs compared with other optimization methods presented in the literature. Full article

(This article belongs to the Topic Power System Protection)

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25 pages, 3595 KiB

Open AccessEditor’s ChoiceArticle

pELECTRE-Tri: Probabilistic ELECTRE-Tri Method—Application for the Energy Renovation of Buildings

by Majid Baseer, Christian Ghiaus, Roxane Viala, Ninon Gauthier and Souleymane Daniel

Energies 2023, 16(14), 5296; https://doi.org/10.3390/en16145296 - 11 Jul 2023

Cited by 3 | Viewed by 1700

Abstract

This paper proposes the method pELECTRE Tri, a novel probabilistic Multi-Criteria Decision Making (MCDM) method using the traditional ELECTRE Tri, probability distribution, and Monte Carlo simulation to support informed decision-making in complex and uncertain decision environments. The proposed method is illustrated through a [...] Read more.

This paper proposes the method pELECTRE Tri, a novel probabilistic Multi-Criteria Decision Making (MCDM) method using the traditional ELECTRE Tri, probability distribution, and Monte Carlo simulation to support informed decision-making in complex and uncertain decision environments. The proposed method is illustrated through a case study involving the renovation of three social housing buildings. The paper provides new insights into the application of probabilistic sorting MCDM in the context of energy efficiency in buildings and highlights the benefits of using probabilities rather than crisp values to categorize alternatives enabling stakeholders to make better use of available resources, especially when dealing with a large dataset of energy measures with different features. The methodology implemented in Python (DOI: 10.5281/zenodo.7967655) is available as an open source. Full article

(This article belongs to the Section G: Energy and Buildings)

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25 pages, 1199 KiB

Open AccessEditor’s ChoiceReview

The Risks and Challenges of Electric Vehicle Integration into Smart Cities

by Oluwagbenga Apata, Pitshou N. Bokoro and Gulshan Sharma

Energies 2023, 16(14), 5274; https://doi.org/10.3390/en16145274 - 10 Jul 2023

Cited by 20 | Viewed by 6344

Abstract

The integration of electric vehicles (EVs) into smart cities presents a promising opportunity for reducing greenhouse gas emissions and enhancing urban sustainability. However, there are significant risks and challenges associated with the integration of EVs into smart cities, which must be carefully considered. [...] Read more.

The integration of electric vehicles (EVs) into smart cities presents a promising opportunity for reducing greenhouse gas emissions and enhancing urban sustainability. However, there are significant risks and challenges associated with the integration of EVs into smart cities, which must be carefully considered. Though there are various reviews available on the challenges of integrating EVs into smart cities, the majority of these are focused on technical challenges, thereby ignoring other important challenges that may arise from such integration. This paper therefore provides a comprehensive overview of the risks and challenges associated with the integration of EVs into smart cities in one research paper. The different challenges associated with the integration of EVs into smart cities have been identified and categorized into four groups, namely: technical, economic, social, and environmental, while also discussing the associated risks of EV integration into smart cities. The paper concludes by highlighting the need for a holistic approach to EV integration into smart cities that considers these challenges and risks. It also identifies possible future trends and outlooks to address these challenges and promote the successful integration of EVs into smart cities. Overall, this paper provides valuable insights for policymakers, city planners, and researchers working towards sustainable urban transportation systems. Full article

(This article belongs to the Special Issue Application and Management of Smart Energy for Smart Cities)

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36 pages, 17194 KiB

Open AccessEditor’s ChoiceReview

A Review on the Cost Analysis of Hydrogen Gas Storage Tanks for Fuel Cell Vehicles

by Hyun Kyu Shin and Sung Kyu Ha

Energies 2023, 16(13), 5233; https://doi.org/10.3390/en16135233 - 7 Jul 2023

Cited by 28 | Viewed by 20903

Abstract

The most practical way of storing hydrogen gas for fuel cell vehicles is to use a composite overwrapped pressure vessel. Depending on the driving distance range and power requirement of the vehicles, there can be various operational pressure and volume capacity of the [...] Read more.

The most practical way of storing hydrogen gas for fuel cell vehicles is to use a composite overwrapped pressure vessel. Depending on the driving distance range and power requirement of the vehicles, there can be various operational pressure and volume capacity of the tanks, ranging from passenger vehicles to heavy-duty trucks. The current commercial hydrogen storage method for vehicles involves storing compressed hydrogen gas in high-pressure tanks at pressures of 700 bar for passenger vehicles and 350 bar to 700 bar for heavy-duty trucks. In particular, hydrogen is stored in rapidly refillable onboard tanks, meeting the driving range needs of heavy-duty applications, such as regional and line-haul trucking. One of the most important factors for fuel cell vehicles to be successful is their cost-effectiveness. So, in this review, the cost analysis including the process analysis, raw materials, and manufacturing processes is reviewed. It aims to contribute to the optimization of both the cost and performance of compressed hydrogen storage tanks for various applications. Full article

(This article belongs to the Special Issue Advances in Hydrogen Energy III)

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19 pages, 15993 KiB

Open AccessEditor’s ChoiceArticle

Assessing the Geothermal Potential of Selected Depleted Oil and Gas Reservoirs Based on Geological Modeling and Machine Learning Tools

by Tomasz Topór, Małgorzata Słota-Valim and Rafał Kudrewicz

Energies 2023, 16(13), 5211; https://doi.org/10.3390/en16135211 - 6 Jul 2023

Cited by 2 | Viewed by 1947

Abstract

The study evaluates the geothermal energy potential of two depleted oil and gas reservoirs representing two different lithostratigraphic formations—the carbonate formation of the Visean age from the basement of the Carpathian Flysch and the Rotliegend sandstone formation from the Eastern part of the [...] Read more.

The study evaluates the geothermal energy potential of two depleted oil and gas reservoirs representing two different lithostratigraphic formations—the carbonate formation of the Visean age from the basement of the Carpathian Flysch and the Rotliegend sandstone formation from the Eastern part of the Foresudetic Monocline, Poland. Advanced modeling techniques were employed to analyze the studied formations’ heat, storage, and transport properties. The obtained results were then used to calculate the heat in place (HIP) and evaluate the recoverable heat (Hrec) for both water and CO₂ as working fluids, considering a geothermal system lifetime of 50 years. The petrophysical parameters and Hrec were subsequently utilized in the generalized c-means (GFCM) clustering analysis, which helped to identify plays with the greatest geothermal potential within the studied formations. The central block emerged as the most promising area for the studied carbonate formation with Hrec values of ~1.12 and 0.26 MW when H₂O and CO₂ were used as working fluids, respectively. The central block has three wells that can be easily adapted for geothermal production. The area, however, may require permeability enhancement techniques to increase reservoir permeability. Two prospective zones were determined for the analyzed Rotliegend sandstone formation: one in the NW region and the other in the SE region. In the NW region, the estimated Hrec was 23.16 MW and 4.36 MW, while in the SE region, it was 19.76 MW and 3.51 MW, using H₂O and CO₂ as working fluids, respectively. Both areas have high porosity and permeability, providing good storage and transport properties for the working fluid, and abundant wells that can be configured for multiple injection-production systems. When comparing the efficiency of geothermal systems, the water-driven system in the Visean carbonate formation turned out to be over four times more efficient than the CO₂-driven one. Furthermore, in the case of the Rotliegend sandstone formation, it was possible to access over five times more heat using water-driven system. Full article

(This article belongs to the Special Issue Carbonate Reservoirs, Geothermal Resources and Well Logging)

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29 pages, 7015 KiB

Open AccessEditor’s ChoiceReview

A Review of Sensor Applications in Electric Vehicle Thermal Management Systems

by Anyu Cheng, Yi Xin, Hang Wu, Lixin Yang and Banghuai Deng

Energies 2023, 16(13), 5139; https://doi.org/10.3390/en16135139 - 3 Jul 2023

Cited by 3 | Viewed by 5382

Abstract

With the rapid development of the automotive industry, the application of sensors is of great importance in maintaining the reliability of electric vehicles and ensuring the safe operation of electric vehicles. Faced with the increasing data of thermal management system condition monitoring, sensor [...] Read more.

With the rapid development of the automotive industry, the application of sensors is of great importance in maintaining the reliability of electric vehicles and ensuring the safe operation of electric vehicles. Faced with the increasing data of thermal management system condition monitoring, sensor detection is widely used in the monitoring of electric vehicle thermal management system. In recent years, a large number of related studies and contributions to the literature have been published. Although a number of reviews have summarized this, these reviews lack an overview of the issues and methods raised in these studies. This paper reviews recent sensor applications for electric vehicle thermal management systems. Currently, battery internal sensors, battery external sensors and related multi-sensor fusion, traditional motor sensors, positionless motor sensors, and component-level sensors of air conditioning systems are the main application sensors in the field of thermal management systems. This article introduces the basic principles of each type of sensor, reviews the relevant applications of various thermal management modules, and summarizes the usage characteristics of each type of sensor. The main problems faced by the existing research on the application of thermal management system-based sensors, such as the detection accuracy of traditional sensors and the detection stability of advanced sensors, are summarized, and the solutions proposed by the existing research are also summarized. Finally, some future research directions, trends, and hotspots are outlined. It is hoped that this review can help readers to understand the problems and existing solutions for thermal-management-system-based sensor applications, and to conduct related research more effectively. Full article

(This article belongs to the Special Issue Advancements in New Energy Vehicle Technology)

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30 pages, 12613 KiB

Open AccessEditor’s ChoiceArticle

Designing the Optimal Configuration of a Small Power System for Autonomous Power Supply of Weather Station Equipment

by Boris V. Malozyomov, Nikita V. Martyushev, Elena V. Voitovich, Roman V. Kononenko, Vladimir Yu. Konyukhov, Vadim Tynchenko, Viktor Alekseevich Kukartsev and Yadviga Aleksandrovna Tynchenko

Energies 2023, 16(13), 5046; https://doi.org/10.3390/en16135046 - 29 Jun 2023

Cited by 43 | Viewed by 1957

Abstract

Autonomous power systems serving remote areas with weather stations with small settlements are characterized by a fairly high cost of generating electricity and the purchase and delivery of fuel. In addition, diesel power plants require regular maintenance, have a relatively short service life [...] Read more.

Autonomous power systems serving remote areas with weather stations with small settlements are characterized by a fairly high cost of generating electricity and the purchase and delivery of fuel. In addition, diesel power plants require regular maintenance, have a relatively short service life during continuous operation and produce a large amount of emissions into the environment. This article discusses various methods of placing solar panels in the space for the autonomous power supply of weather station equipment. The principles of these methods are described and their advantages and disadvantages are outlined. The optimal algorithms of functioning for photomodules are described and their comparison regarding the main, significant parameters is carried out. The choice of the most effective algorithm for use at a weather station is made. The effective positioning of solar panels is also calculated, and positioning conditions are determined depending on the territorial location and various environmental conditions. Simulation of the power supply system of a weather station consisting of solar panels, batteries and inverters is performed. As a result, a practical example of the application of the method of selecting the optimal composition of equipment for a hybrid power system of a weather station territorially located in Siberia with different configurations of equipment is considered. In numerical terms, it was possible to reduce the cost of power equipment operation by more than 60% with a fairly low payback period of 5.5 years and an increased reliability of the power system, which is very important for autonomous power systems of northern weather stations. Full article

(This article belongs to the Special Issue Applications of Advanced Control and Optimization Paradigms in Renewable Energy Systems)

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23 pages, 1664 KiB

Open AccessEditor’s ChoiceArticle

Techno-Economic Analysis of Solid Oxide Fuel Cell-Gas Turbine Hybrid Systems for Stationary Power Applications Using Renewable Hydrogen

by Chun Yin Chan, Fabian Rosner and Scott Samuelsen

Energies 2023, 16(13), 4955; https://doi.org/10.3390/en16134955 - 26 Jun 2023

Cited by 6 | Viewed by 2791

Abstract

Solid oxide fuel cell (SOFC)–gas turbine (GT) hybrid systems can produce power at high electrical efficiencies while emitting virtually zero criteria pollutants (e.g., ozone, carbon monoxide, oxides of nitrogen and sulfur, and particulate matters). This study presents new insights into renewable hydrogen (RH [...] Read more.

Solid oxide fuel cell (SOFC)–gas turbine (GT) hybrid systems can produce power at high electrical efficiencies while emitting virtually zero criteria pollutants (e.g., ozone, carbon monoxide, oxides of nitrogen and sulfur, and particulate matters). This study presents new insights into renewable hydrogen (RH₂)-powered SOFC–GT hybrid systems with respect to their system configuration and techno-economic analysis motivated by the need for clean on-demand power. First, three system configurations are thermodynamically assessed: (I) a reference case with no SOFC off-gas recirculation, (II) a case with cathode off-gas recirculation, and (III) a case with anode off-gas recirculation. While these configurations have been studied in isolation, here we provide a detailed performance comparison. Moreover, a techno-economic analysis is conducted to study the economic competitiveness of RH₂-fueled hybrid systems and the economies of scale by offering a comparison to natural gas (NG)-fueled systems. Results show that the case with anode off-gas recirculation, with 68.50%-lower heating value (LHV) at a 10 MW scale, has the highest efficiency among the studied scenarios. When moving from 10 MW to 50 MW, the efficiency increases to 70.22%-LHV. These high efficiency values make SOFC–GT hybrid systems highly attractive in the context of a circular economy as they outcompete most other power generation technologies. The cost-of-electricity (COE) is reduced by about 10% when moving from 10 MW to 50 MW, from USD 1976/kW to USD 1668/kW, respectively. Renewable H₂ is expected to be economically competitive with NG by 2030, when the U.S. Department of Energy’s target of USD 1/kg RH₂ is reached. Full article

(This article belongs to the Section C: Energy Economics and Policy)

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35 pages, 17452 KiB

Open AccessEditor’s ChoiceReview

Combustion Chemistry of Unsaturated Hydrocarbons Mixed with NO_x: A Review with a Focus on Their Interactions

by Ruoyue Tang and Song Cheng

Energies 2023, 16(13), 4967; https://doi.org/10.3390/en16134967 - 26 Jun 2023

Viewed by 5073

Abstract

Unsaturated hydrocarbons are major components of transportation fuels, combustion intermediates, and unburnt exhaust emissions. Conversely, NO_x species are minor species present in the residual and exhaust gases of gasoline-fueled engines and gas turbines. Their co-existence in transportation engines is quite common, particularly [...] Read more.

Unsaturated hydrocarbons are major components of transportation fuels, combustion intermediates, and unburnt exhaust emissions. Conversely, NO_x species are minor species present in the residual and exhaust gases of gasoline-fueled engines and gas turbines. Their co-existence in transportation engines is quite common, particularly with exhaust gas recirculation, which can greatly influence engine combustion characteristics. Therefore, this paper presents a review on the combustion chemistry of unsaturated hydrocarbons and NO_x mixtures, with a focus on their chemical kinetic interactions. First, a comprehensive overview of fundamental combustion experiments is provided, covering mixtures of C₂–C₅ unsaturated/oxygenated species (namely alkenes, alkynes, dienes, alcohols, ethers, ketones, and furans) and three major NO_x species (namely NO, NO₂, and N₂O), as well as reactors including jet-stirred reactors, flow reactors, burners, shock tubes, and rapid compression machines. Then, two widely adopted nitrogen chemistry models are evaluated in conjunction with a core chemistry model (i.e., NUIGMech1.1) via detailed chemical kinetic modeling, and the model similarities and differences across broad temperature ranges are highlighted. Thereafter, the unique interconversions between the three major NO_x species are presented. In particular, the controversy regarding the pathways governing NO and NO₂ conversion is discussed. Following this, the key direct interaction reactions between unsaturated species and NO_x species are overviewed. Finally, the distinguishing features of the combustion chemistry for unsaturated hydrocarbon and NO_x mixtures are summarized, and recommendations for future research on this topic are highlighted. Full article

(This article belongs to the Special Issue Low-Carbon/Carbon-Free Fuels and Advanced Combustion Strategies)

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33 pages, 6186 KiB

Open AccessEditor’s ChoiceReview

Electrochemically Structured Copper Current Collectors for Application in Energy Conversion and Storage: A Review

by Mario Kurniawan and Svetlozar Ivanov

Energies 2023, 16(13), 4933; https://doi.org/10.3390/en16134933 - 25 Jun 2023

Cited by 5 | Viewed by 1985

Abstract

Copper current collectors (Cu CCs) impact the production technology and performance of many electrochemical devices by their unique properties and reliable operation. The efficiency of the related processes and the operation of the electrochemical devices could be significantly improved by optimization of the [...] Read more.

Copper current collectors (Cu CCs) impact the production technology and performance of many electrochemical devices by their unique properties and reliable operation. The efficiency of the related processes and the operation of the electrochemical devices could be significantly improved by optimization of the Cu CCs. Metallic Cu plays an important role in electrochemical energy storage and electrocatalysis, primarily as a conducting substrate on which the chemical processes take place. Li nucleation and growth can be influenced by the current collector by modulating the local current density and Li ion transport. For example, the commonly used planar Cu CC does not perform satisfactorily; therefore, a high number of different modifications of Cu CCs have been proposed and reported in the literature for minimizing the local current density, hindering Li dendrite formation, and improving the Coulombic efficiency. Here, we provide an updated critical overview of the basic strategies of 3D Cu CC structuring, methodologies for analyzing these structures, and approaches for effective control over their most relevant properties. These methods are described in the context of their practical usefulness and applicability in an effort to aid in their easy implementation by research groups and private companies with established traditions in electrochemistry and plating technology. Furthermore, the current overview could be helpful for specialists with experience in associated fields of knowledge such as materials engineering and surface finishing, where electrochemical methods are frequently applied. Motivated by the importance of the final application of Cu CCs in energy storage devices, this review additionally discusses the relationship between CC properties and the functional parameters of the already-implemented electrodes. Full article

(This article belongs to the Section D: Energy Storage and Application)

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31 pages, 749 KiB

Open AccessEditor’s ChoiceReview

Challenges of Application of Green Ammonia as Fuel in Onshore Transportation

by Maciej Chorowski, Michał Lepszy, Krystian Machaj, Ziemowit Malecha, Dominika Porwisiak, Paweł Porwisiak, Zbigniew Rogala and Michał Stanclik

Energies 2023, 16(13), 4898; https://doi.org/10.3390/en16134898 - 23 Jun 2023

Cited by 13 | Viewed by 4765

Abstract

The main purpose of the article is to present a comprehensive and critical review of the challenges and risks associated with the use of green ammonia as an alternative fuel in land transport. The review is motivated by the clear trend toward phasing [...] Read more.

The main purpose of the article is to present a comprehensive and critical review of the challenges and risks associated with the use of green ammonia as an alternative fuel in land transport. The review is motivated by the clear trend toward phasing out fossil fuel vehicles and replacing them with emission-free alternatives. Topics covered include safety aspects such as safety of powering of vehicles, the production of green ammonia, the use of ammonia in the context of various fuel solutions (combustion engines and fuel cell engines), and the discussion of ammonia-powered vehicles in the context of air pollution. The paper offers new insights into identifying the challenges and obstacles that may arise in the case of the massive use of green ammonia as a fuel for land transport. In addition, the review presents the latest information on the technological readiness of the necessary infrastructure for the production, transport, storage, and utilization of green ammonia in internal combustion or electric engines. Full article

(This article belongs to the Special Issue Challenges of Transition to a Net-Zero Emissions Energy System)

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29 pages, 4483 KiB

Open AccessEditor’s ChoiceArticle

Optimization of Polypropylene Waste Recycling Products as Alternative Fuels through Non-Catalytic Thermal and Catalytic Hydrocracking Using Fresh and Spent Pt/Al₂O₃ and NiMo/Al₂O₃ Catalysts

by Murtadha S. Al-Iessa, Bashir Y. Al-Zaidi, Riaydh S. Almukhtar, Zaidoon M. Shakor and Ihsan Hamawand

Energies 2023, 16(13), 4871; https://doi.org/10.3390/en16134871 - 22 Jun 2023

Cited by 6 | Viewed by 2008

Abstract

In this work, the conversion of waste polypropylene to alternative fuels (liquid and gas) was performed through non-catalytic thermal and catalytic hydrocracking over NiMo/Al₂O₃ and Pt/Al₂O₃ catalysts. The process was carried out in an autoclave batch reactor [...] Read more.

In this work, the conversion of waste polypropylene to alternative fuels (liquid and gas) was performed through non-catalytic thermal and catalytic hydrocracking over NiMo/Al₂O₃ and Pt/Al₂O₃ catalysts. The process was carried out in an autoclave batch reactor at a temperature of 450 °C and a pressure of 20 bar, which were selected based on experimental optimization. The spent catalyst was also successfully regenerated at 700 °C under a hot airflow. Experiments were conducted to determine the optimum conditions to completely separate the deactivated catalyst from the solid residue easily. The regenerated catalyst was reused to facilitate the economic cost reduction of the process. The reactivated catalysts have almost the same catalytic properties as the fresh catalysts; this was confirmed by several characterization techniques, such as TGA, XRD, SEM, EDX, BET and FTIR. The produced liquids/gases were quantified and classified into their fractions by the number of carbon atoms and gasoline to diesel ratio using GC/MS. The viscosity, density, API gravity, pour point and flash point of oil cuts were also investigated to evaluate the quality of the resulting liquid from the reactions. The NiMo/Al₂O₃ catalyst gave the highest liquid hydrocarbons yield of 86 wt%, while the highest weight products of gasoline range hydrocarbon fractions of 49.85 wt% were found over the Pt/Al₂O₃ catalyst. Almost the same catalytic behavior was found with the regenerated catalysts compared to the fresh catalysts. However, the highest gaseous products at 20.8 wt% were found in the non-catalytic thermal products with an increase in the diesel fuel range of 80.83 wt%. The kinetic model was implemented using six lumps and fifteen reactions, and the apparent activation energies for the gasoline and diesel fractions were calculated. In general, all primary and secondary reactions show greater activation energy values on the Pt/Al₂O₃ catalyst than on the NiMo/Al₂O₃ catalyst. Full article

(This article belongs to the Section B: Energy and Environment)

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20 pages, 5333 KiB

Open AccessEditor’s ChoiceArticle

Economic Viability of Implementing Structural Health Monitoring Systems on the Support Structures of Bottom-Fixed Offshore Wind

by Mario Vieira, Brian Snyder, Elsa Henriques, Craig White and Luis Reis

Energies 2023, 16(13), 4885; https://doi.org/10.3390/en16134885 - 22 Jun 2023

Viewed by 1631

Abstract

Offshore wind (OSW) energy is a renewable source with strong prospects of development that may decisively contribute towards energy independence. Offshore wind is, however, not yet ubiquitously cost competitive, and frequently requires support schemes to finance its extensive capital requirements. Therefore, cost reduction [...] Read more.

Offshore wind (OSW) energy is a renewable source with strong prospects of development that may decisively contribute towards energy independence. Offshore wind is, however, not yet ubiquitously cost competitive, and frequently requires support schemes to finance its extensive capital requirements. Therefore, cost reduction strategies are necessary for the future development of offshore wind technologies. Even if structural health monitoring (SHM) systems are currently applied for the inspection of critical mechanical structures, they have not been the focus of research from offshore wind stakeholders. The main goal of this study is to evaluate the viability of SHM systems on the support structures of bottom-fixed offshore wind (BFOSW), alongside the impact of implementing these systems on life-cycle. Economic models are used to estimate the impact of implementing these systems, explained using a case-study of the Kaskasi farm in the German North Sea. General results indicate that installing SHM systems on the support structures of offshore wind can shift the maintenance strategies from preventive to predictive, allowing the intervals between inspections to be increased without a reduction on equipment availability. The greatest benefit is related with the possibility of extending the operational life of the farm. Full article

(This article belongs to the Special Issue Wind Energy End-of-Life Options: Theory and Practice)

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32 pages, 538 KiB

Open AccessEditor’s ChoiceSystematic Review

A Review of Cybersecurity Concerns for Transactive Energy Markets

by Daniel Sousa-Dias, Daniel Amyot, Ashkan Rahimi-Kian and John Mylopoulos

Energies 2023, 16(13), 4838; https://doi.org/10.3390/en16134838 - 21 Jun 2023

Cited by 5 | Viewed by 2206

Abstract

Advances in energy generation and distribution technology have created the need for new power management paradigms. Transactive energy markets are integrated software and hardware systems that enable optimized energy management and direct trading between prosumers. This literature review covers unresolved security and privacy [...] Read more.

Advances in energy generation and distribution technology have created the need for new power management paradigms. Transactive energy markets are integrated software and hardware systems that enable optimized energy management and direct trading between prosumers. This literature review covers unresolved security and privacy vulnerabilities in the proposed implementations of such markets. We first performed a coarse search for such implementations. We then combed the resulting literature for references to privacy concerns, security vulnerabilities, and attacks that their system was either vulnerable to or sought to address. We did so with a particular focus on threats that were not mitigated by the use of blockchain technology, a commonly employed solution. Based on evidence from 28 peer-reviewed papers, we synthesized 14 categories of concerns and their proposed solutions. We found that there are some concerns that have been widely addressed, such as protecting trading history when using a public blockchain. Conversely, there were serious threats that are not sufficiently being considered. While a lack of real-world deployment has limited information about which attacks are most likely or feasible, there are clear areas of priority that we recommend to address going forward, including market attacks, false data injection attacks, single points of failure, energy usage data leakage, and privacy. Full article

(This article belongs to the Special Issue Digitization of Energy Supply and Demand Sides)

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21 pages, 3982 KiB

Open AccessEditor’s ChoiceArticle

Integrating Smart Energy Management System with Internet of Things and Cloud Computing for Efficient Demand Side Management in Smart Grids

by M. Usman Saleem, Mustafa Shakir, M. Rehan Usman, M. Hamza Tahir Bajwa, Noman Shabbir, Payam Shams Ghahfarokhi and Kamran Daniel

Energies 2023, 16(12), 4835; https://doi.org/10.3390/en16124835 - 20 Jun 2023

Cited by 48 | Viewed by 7069

Abstract

The increasing price of and demand for energy have prompted several organizations to develop intelligent strategies for energy tracking, control, and conservation. Demand side management is a critical strategy for averting substantial supply disruptions and improving energy efficiency. A vital part of demand [...] Read more.

The increasing price of and demand for energy have prompted several organizations to develop intelligent strategies for energy tracking, control, and conservation. Demand side management is a critical strategy for averting substantial supply disruptions and improving energy efficiency. A vital part of demand side management is a smart energy management system that can aid in cutting expenditures while still satisfying energy needs; produce customers’ energy consumption patterns; and react to energy-saving algorithms and directives. The Internet of Things is an emerging technology that can be employed to effectively manage energy usage in industrial, commercial, and residential sectors in the smart environment. This paper presents a smart energy management system for smart environments that integrates the Energy Controller and IoT middleware module for efficient demand side management. Each device is connected to an energy controller, which is the inculcation of numerous sensors and actuators with an IoT object, collects the data of energy consumption from each smart device through various time-slots that are designed to optimize the energy consumption of air conditioning systems based on ambient temperature conditions and operational dynamics of buildings and then communicate it to a centralized middleware module (cloud server) for management, processing, and further analysis. Since air conditioning systems contribute more than 50% of the electricity consumption in Pakistan, for validation of the proposed system, the air conditioning units have been taken as a proof of concept. The presented approach offers several advantages over traditional controllers by leveraging real-time monitoring, advanced algorithms, and user-friendly interfaces. The evaluation process involves comparing electricity consumption before and after the installation of the SEMS. The proposed system is tested and implemented in four buildings. The results demonstrate significant energy savings ranging from 15% to 49% and highlight the significant benefits of the system. The smart energy management system offers real-time monitoring, better control over the air conditioning systems, cost savings, environmental benefits, and longer equipment life. The ultimate goal is to provide a practical solution for reducing energy consumption in buildings, which can contribute to sustainable and efficient use of energy resources and goes beyond simpler controllers to address the specific needs of energy management in buildings. Full article

(This article belongs to the Special Issue Applications of Advanced Control and Optimization Paradigms in Renewable Energy Systems)

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23 pages, 4348 KiB

Open AccessEditor’s ChoiceReview

Enhancing the Levelized Cost of Hydrogen with the Usage of the Byproduct Oxygen in a Wastewater Treatment Plant

by Franziska Hönig, Ganesh Deepak Rupakula, Diana Duque-Gonzalez, Matthias Ebert and Ulrich Blum

Energies 2023, 16(12), 4829; https://doi.org/10.3390/en16124829 - 20 Jun 2023

Cited by 6 | Viewed by 3037

Abstract

In order to harmonizFranziska Hönige the supply and demand of green energy, new future-proof technologies are needed. Here, hydrogen plays a key role. Within the current framework conditions, the production of green hydrogen is not yet economically viable. The use of the oxygen [...] Read more.

In order to harmonizFranziska Hönige the supply and demand of green energy, new future-proof technologies are needed. Here, hydrogen plays a key role. Within the current framework conditions, the production of green hydrogen is not yet economically viable. The use of the oxygen produced and the possible increase in efficiency associated with it mostly remain unconsidered. The aim is to demonstrate that the economic efficiency of a power-to-gas (PtG) project can be increased by using the byproduct oxygen. In this research project, a water electrolyzer connected to grid is powered to supply hydrogen to a hydrogen refueling station. By utilizing the byproduct oxygen from water electrolysis for a wastewater treatment plant (WWTP), it is shown that the net present value (NPV) of the project can be improved by up to 13% compared to the initial scenario. If a photovoltaic (PV) system is used in addition to grid electricity for higher green hydrogen production, the NPV can be further improved by up to 58%. The levelized cost of hydrogen (LCOH) is calculated for different scenarios with and without oxygen configuration. A sensitivity analysis is then performed to find important parameters. Full article

(This article belongs to the Special Issue Hydrogen in the Energy Transition: From Production to End-Use)

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22 pages, 1289 KiB

Open AccessEditor’s ChoiceArticle

An Exploratory Study on Swedish Stakeholders’ Experiences with Positive Energy Districts

by Moa Mattsson, Thomas Olofsson, Liv Lundberg, Olga Korda and Gireesh Nair

Energies 2023, 16(12), 4790; https://doi.org/10.3390/en16124790 - 19 Jun 2023

Cited by 2 | Viewed by 1360

Abstract

Positive energy district (PED) is a novel idea aimed to have an annual surplus of renewable energy and net zero greenhouse gas emissions within an area. However, it is still an ambiguous concept, which might be due to the complexity of city district [...] Read more.

Positive energy district (PED) is a novel idea aimed to have an annual surplus of renewable energy and net zero greenhouse gas emissions within an area. However, it is still an ambiguous concept, which might be due to the complexity of city district projects with interconnected infrastructures and numerous stakeholders involved. This study discusses various aspects of PED implementation and presents practitioners’ experiences with the PED concept, challenges, and facilitators they have faced with real projects. The study is based on interviews with ten Swedish professionals. The major challenges reported for PED implementation were local energy production and energy flexibility, sub-optimization, legislation, suitable system boundaries, and involvement of stakeholders. Most of the interviewees mentioned improved collaboration, integrated innovative technology, political support, and climate change mitigation goals as important facilitators. The interviewees highlighted the importance of a local perspective and considered each city’s preconditions when developing a PED project. The study emphasizes that to facilitate PED implementation and replication in cities, more knowledge and clarity is required about PED such as on the definition and system boundaries. Full article

(This article belongs to the Special Issue Energy Efficiency of the Buildings II)

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28 pages, 12095 KiB

Open AccessEditor’s ChoiceArticle

Hybrid Source Multi-Port Quasi-Z-Source Converter with Fuzzy-Logic-Based Energy Management

by Gorkem Say, Seyed Hossein Hosseini and Parvaneh Esmaili

Energies 2023, 16(12), 4801; https://doi.org/10.3390/en16124801 - 19 Jun 2023

Cited by 2 | Viewed by 1343

Abstract

In this paper, a fuzzy-logic-based energy management system and a multi-port quasi-z-source converter that utilizes hybrid renewable energy sources are proposed. The system ensures that each energy source module can be used individually by employing fuzzy logic to define the power modes. This [...] Read more.

In this paper, a fuzzy-logic-based energy management system and a multi-port quasi-z-source converter that utilizes hybrid renewable energy sources are proposed. The system ensures that each energy source module can be used individually by employing fuzzy logic to define the power modes. This approach also helps to prevent switching losses resulting from the extra switching of the source modules. In addition, the proposed energy management does not have a mathematical model, so its applicability is simple, and it is suitable for different multiple-input topologies. The Mamdani fuzzy inference system can be designed to capture the nonlinear behavior of the system owing to linguistic rules. Moreover, the switching losses of the multiport modules were significantly reduced by adopting the quasi-z-source network to the end of the multiport converter. Furthermore, different errors, such as the root mean square error (RMSE), average squared error (ASE), average absolute error (AAE), average time-weighted absolute error (ATWAE), tracking error (TE), and unscaled mean bounded relative absolute error (UMBRAE), were applied to evaluate the fuzzy logic performance from different perspectives. The simulation results were obtained using MATLAB Simulink, and the experimental results were obtained by connecting the circuit to MATLAB Simulink using an Arduino Due. Full article

(This article belongs to the Special Issue Recent Challenges and Advances in Power Converters for Emerging Renewable Energy Integrated Systems)

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22 pages, 3167 KiB

Open AccessEditor’s ChoiceArticle

A Machine-Learning-Based Approach for Natural Gas Futures Curve Modeling

by Oleksandr Castello and Marina Resta

Energies 2023, 16(12), 4746; https://doi.org/10.3390/en16124746 - 15 Jun 2023

Viewed by 2441

Abstract

This work studies the term structure dynamics in the natural gas futures market, focusing on the Dutch Title Transfer Facility (TTF) daily futures prices. At first, using the whole dataset, we compared the in-sample fitting performance of three models: the four-factor dynamic Nelson–Siegel–Svensson [...] Read more.

This work studies the term structure dynamics in the natural gas futures market, focusing on the Dutch Title Transfer Facility (TTF) daily futures prices. At first, using the whole dataset, we compared the in-sample fitting performance of three models: the four-factor dynamic Nelson–Siegel–Svensson (4F-DNSS) model, the five-factor dynamic De Rezende–Ferreira (5F-DRF) model, and the B-spline model. Our findings suggest that B-spline is the method that achieves the best in-line fitting results. Then, we turned our attention to forecasting, using data from 20 January 2011 to 13 May 2022 as the training set and the remaining data, from 16 May to 13 June 2022, for day-ahead predictions. In this second part of the work we combined the above mentioned models (4F-DNSS, 5F-DRF and B-spline) with a Nonlinear Autoregressive Neural Network (NAR-NN), asking the NAR-NN to provide parameter tuning. All the models provided accurate out-of-sample prediction; nevertheless, based on extensive statistical tests, we conclude that, as in the previous case, B-spline (combined with an NAR-NN) ensured the best out-of-sample prediction. Full article

(This article belongs to the Section H: Geo-Energy)

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19 pages, 5204 KiB

Open AccessEditor’s ChoiceArticle

Landfill Biogas Recovery and Its Contribution to Greenhouse Gas Mitigation

by Dek Vimean Pheakdey, Vongdala Noudeng and Tran Dang Xuan

Energies 2023, 16(12), 4689; https://doi.org/10.3390/en16124689 - 13 Jun 2023

Cited by 7 | Viewed by 2643

Abstract

This study assesses the biomethane (CH₄) generation and greenhouse gas (GHG) emissions resulting from municipal solid waste landfilling in Phnom Penh, Cambodia, with a focus on the impact of fugitive CH₄ emissions and operation processes in four landfilling scenarios: simple [...] Read more.

This study assesses the biomethane (CH₄) generation and greenhouse gas (GHG) emissions resulting from municipal solid waste landfilling in Phnom Penh, Cambodia, with a focus on the impact of fugitive CH₄ emissions and operation processes in four landfilling scenarios: simple dumping (S1), improved management with leachate treatment (S2), engineered landfill with flaring (S3), and engineered landfill with energy recovery (S4). The study also considered the environmental benefits of carbon sequestration and landfill gas utilization. The LandGEM and IPCC FOD models were used to calculate CH₄ generation over the period of 2009–2022, and it was found that approximately 18 and 21 M kg/year of CH₄ were released, respectively. The energy potential from CH₄ recovery was 51–61 GWh/year. Overall, GHG emissions in S2 were the highest, amounting to 409–509 M kg CO₂-eq/year, while S1 had lower emissions at 397–496 M kg CO₂-eq/year. Flaring-captured CH₄ in S3 could reduce GHG emissions by at least 55%, and using captured CH₄ for electricity production in S4 could mitigate at least 83% of GHG emissions. Electricity recovery (S4) could avoid significant amounts of GHG emissions (−52 to −63 kg CO₂-eq/tMSW). The study suggests that landfill gas-to-energy could significantly reduce GHG emissions. Full article

(This article belongs to the Special Issue Optimal Energy Recovery through Anaerobic Processes and Environmental Protection)

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25 pages, 14686 KiB

Open AccessEditor’s ChoiceArticle

Evaluation of Slag Foaming Behavior Using Renewable Carbon Sources in Electric Arc Furnace-Based Steel Production

by Lina Kieush, Johannes Schenk, Andrii Koveria, Andrii Hrubiak, Horst Hopfinger and Heng Zheng

Energies 2023, 16(12), 4673; https://doi.org/10.3390/en16124673 - 12 Jun 2023

Cited by 11 | Viewed by 2571

Abstract

The influence of different carbon sources, including anthracite, calcined petroleum coke, three samples of high-temperature coke, biochar, and a mixture of 50 wt.% biochar and 50 wt.% coke, on slag foaming behavior was studied. The slag’s composition was set to FeO-CaO-Al₂O [...] Read more.

The influence of different carbon sources, including anthracite, calcined petroleum coke, three samples of high-temperature coke, biochar, and a mixture of 50 wt.% biochar and 50 wt.% coke, on slag foaming behavior was studied. The slag’s composition was set to FeO-CaO-Al₂O₃-MgO-SiO₂, and the temperature for slag foaming was 1600 °C. The effect of the carbon sources was evaluated using foaming characteristics (foam height, foam volume, relative foaming height, and gas fraction), X-ray diffraction (XRD), chemical analysis of the slag foams, Mossbauer spectroscopy, observation by scanning electron microscope (SEM), and energy-dispersive spectroscopy (EDS) mapping. Different foaming phenomena were found among conventional sources, biochar as a single source, and the mixture of coke and biochar. Biochar showed the most inferior foaming characteristics compared to the other studied carbon sources. Nevertheless, the slag foaming process was improved and showed slag foaming characteristics similar to results obtained using conventional carbon sources when the mixture of 50 wt.% coke and 50 wt.% biochar was used. The XRD analysis revealed a difference between the top and bottom of the slag foams. In almost all cases, a maghemite crystalline phase was detected at the top of the slag foams, indicating oxidation; metallic iron was found at the bottom. Furthermore, a difference in the slag foam (mixture of coke and biochar) was found in the presence of such crystalline phases as magnesium iron oxide (Fe₂MgO₄) and magnetite (Mg₀.₄Fe₂.₉₆O₄). Notwithstanding the carbon source applied, a layer between the foam slag and the crucible wall was found in many samples. Based on the SEM/EDS and XRD results, it was assumed this layer consists of gehlenite (Ca₂(Al(AlSi)O₇) and two spinels: magnesium aluminate (MgAl₂O₄) and magnesium iron oxide (Fe₂MgO₄). Full article

(This article belongs to the Special Issue Recent Progress in Biomass Pyrolysis and High Value Utilization of Pyrolytic Carbon)

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20 pages, 4805 KiB

Open AccessEditor’s ChoiceArticle

A Hybrid Experimental-Numerical Method to Support the Design of Multistage Pumps

by Federico Fontana and Massimo Masi

Energies 2023, 16(12), 4637; https://doi.org/10.3390/en16124637 - 11 Jun 2023

Viewed by 1165

Abstract

The paper uses a hydraulic performance analysis method to support the design of stock production multistage pumps. The method relies on a hybrid numerical–experimental approach conceived as a trade-off between accuracy and cost. It is based on CFD analyses incorporating experimental data of [...] Read more.

The paper uses a hydraulic performance analysis method to support the design of stock production multistage pumps. The method relies on a hybrid numerical–experimental approach conceived as a trade-off between accuracy and cost. It is based on CFD analyses incorporating experimental data of leakage flows across the sealing elements to obtain accurate predictions without the need of inclusion in the CFD model of small-scale features, which strongly increase the model complexity and computational effort. The aim of the paper is to present and validate this method. To this end, a 6-stage vertical pump manufactured by the stainless-steel metal-sheets-forming technique was considered as the benchmark. A series of experimental tests were performed to hydraulically characterize the impeller and return-channels-sealing elements by means of an “ad hoc” designed test rig. The characteristic curves of the sealing elements were embedded on the CFD model implemented in accordance with the strategy proposed in a previous authors’ work to obtain satisfactory predictions of multistage pumps’ hydraulic performance with minimum computational effort with the analytical correction of single-stage single-channel computations to account for the interaction between adjacent stages. To further explore the capabilities of the hybrid model, axial thrust measurements were performed by means of another “ad hoc” designed experimental apparatus. The application of the method to the benchmark pump shows that the hybrid model predicts the static head and efficiency with an error value lower than 1% at its best efficiency operation, and estimates the axial thrust with a 5% average error in the operating range from approximately 70% to 120% of the best efficiency duty. Full article

(This article belongs to the Special Issue Experimental and Numerical Methods for the Design of Internal Combustion Engines and Turbomachines)

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22 pages, 34507 KiB

Open AccessEditor’s ChoiceArticle

Route Planning for Electric Vehicles Including Driving Style, HVAC, Payload and Battery Health

by Alberto Ponso, Angelo Bonfitto and Giovanni Belingardi

Energies 2023, 16(12), 4627; https://doi.org/10.3390/en16124627 - 10 Jun 2023

Cited by 1 | Viewed by 1994

Abstract

The increasing environmental awareness paired with the rise of global warming effects has led, in the past few years, to an increase in the sales of electric vehicles (EVs), partly but not only, caused by governmental incentives. A significant roadblock in the mass [...] Read more.

The increasing environmental awareness paired with the rise of global warming effects has led, in the past few years, to an increase in the sales of electric vehicles (EVs), partly but not only, caused by governmental incentives. A significant roadblock in the mass transition to EVs can be found in the so-called range anxiety: not only do EVs have, generally, considerably shorter ranges than their internal combustion engine vehicle (ICEV) equivalents, but recharge takes significantly longer than does filling up a gas tank, and charging stations are less widespread than are petrol stations. To counteract this, EV manufacturers are developing route planners which select the best route to go from A to B according to the range of the vehicle and the availability of charging stations. These tools are indeed powerful but do not account for the state of health (SoH) of the battery or for temperature conditions, two factors which may severely degrade the range of an EV. This article presents an innovative route planning method which takes into account SoH, temperature and driving style and selects, along the planned route, the charging stations among those which can be reached with the energy of the battery. To verify its proper operativity, simulations were conducted, highlighting the risk of running out of battery before destination, considering if the route is planned based on the declared range, and taking into account battery SoH, external temperature and driving style. Full article

(This article belongs to the Special Issue Power Electronics and Energy Management for Battery Storage Systems 2023)

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27 pages, 8461 KiB

Open AccessEditor’s ChoiceArticle

Comparison of the Performance of New and Traditional Numerical Methods for Long-Term Simulations of Heat Transfer in Walls with Thermal Bridges

by Issa Omle, Ali Habeeb Askar, Endre Kovács and Betti Bolló

Energies 2023, 16(12), 4604; https://doi.org/10.3390/en16124604 - 8 Jun 2023

Cited by 6 | Viewed by 2207

Abstract

Several previous experiments showed that the leapfrog–hopscotch and the adapted Dufort–Frankel methods are the most efficient among the explicit and stable numerical methods to solve heat transfer problems in building walls. In this paper, we extensively measure the running times of the most [...] Read more.

Several previous experiments showed that the leapfrog–hopscotch and the adapted Dufort–Frankel methods are the most efficient among the explicit and stable numerical methods to solve heat transfer problems in building walls. In this paper, we extensively measure the running times of the most successful methods and compare them to the performance of other available solvers, for example, ANSYS transient thermal analysis and the built-in routines of MATLAB, where three different mesh resolutions are used. We show that the running time of our methods changes linearly with mesh size, unlike in the case of other methods. After that, we make a long-term simulation (one full winter month) of two-dimensional space systems to test the two best versions of the methods. The real-life engineering problem we solve is the examination of thermal bridges with different shapes in buildings to increase energy efficiency. Full article

(This article belongs to the Section G: Energy and Buildings)

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23 pages, 4406 KiB

Open AccessEditor’s ChoiceArticle

Grass from Road Verges as a Substrate for Biogas Production

by Robert Czubaszek, Agnieszka Wysocka-Czubaszek, Piotr Banaszuk, Grzegorz Zając and Martin J. Wassen

Energies 2023, 16(11), 4488; https://doi.org/10.3390/en16114488 - 2 Jun 2023

Cited by 1 | Viewed by 1536

Abstract

Maintenance of urban green infrastructure generates a large amount of biomass that can be considered a valuable feedstock for biogas production. This study aims to determine the effect of the cutting time and method of substrate preservation on the specific methane yield (SMY) [...] Read more.

Maintenance of urban green infrastructure generates a large amount of biomass that can be considered a valuable feedstock for biogas production. This study aims to determine the effect of the cutting time and method of substrate preservation on the specific methane yield (SMY) of urban grass collected from road verges and median strips between roadways in wet (WF) and dry fermentation (DF) technology. The grass was collected three times in a growing season, including in spring, summer, and autumn. The biochemical methane potential (BMP) test was performed on fresh grass, grass ensiled without additives, and grass ensiled with microbiological additives. In addition, the energy potentially produced from biogas and the avoided CO₂ emissions were calculated. The highest SMY (274.18 ± 22.59 NL kg_VS⁻¹) was observed for the fresh grass collected in spring and subjected to WF. At the same time, the lowest CH₄ production (182.63 ± 0.48 NL kg_VS⁻¹) was found in the grass ensiled without additives, collected in summer, and digested in DF technology. A comparison of the SMY obtained from the same grass samples in the WF and DF technologies revealed that higher CH₄ yields were produced in WF. The electricity and heat production were affected by the time of grass cutting, ensilage method, and AD technology. Generally, less electricity but more heat was produced in DF technology. The least electricity (469–548 kWh t_DM⁻¹) was produced from the grass cut in spring and subjected to DF, while the most electricity (621–698 kWh t_DM⁻¹) was obtained from the grass collected in autumn and subjected to WF. In the case of heat production, the situation was reversed. The least heat (1.4–1.9 GJ t_DM⁻¹) was produced by the grass collected in spring and subjected to WF, while the most heat (2.2–2.7 GJ t_DM⁻¹) was produced by the grass collected in autumn and subjected to DF. Ensilage decreased the electricity and heat production in almost all the cuttings. The total reduction in CO₂ emissions may amount to 2400 kg CO₂ per 1 hectare of road verges. This significant reduction demonstrates that the use of grass from roadside verges in biogas plants should be considered a feasible option. Even though urban grass should be considered a co-substrate only, it can be a valuable feedstock that may partially substitute energy crops and reduce the area needed for energy purposes. Our results reveal that biogas production from the grass waste in WF technology is a stable process. The cutting time and preservation method do not affect the AD process. In DF technology, fresh grass, especially from the late growing season used as feedstock, extends the time of biomass decomposition and, therefore, should be avoided in a real-life biogas plant. Full article

(This article belongs to the Special Issue Effective and Efficient Management Practices in Energy Sources and Energy Consumption)

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19 pages, 316 KiB

Open AccessEditor’s ChoiceReview

Exploring the Impact of Economic Growth on the Environment: An Overview of Trends and Developments

by George Ekonomou and George Halkos

Energies 2023, 16(11), 4497; https://doi.org/10.3390/en16114497 - 2 Jun 2023

Cited by 13 | Viewed by 5589

Abstract

In our modern world, energy keeps the global economy running, and economic growth concerns are profoundly interrelated with environmental quality issues. Interestingly, scientists engage with empirical research to identify the impacts and causalities at the interface of economic activities, energy supply, and demand. [...] Read more.

In our modern world, energy keeps the global economy running, and economic growth concerns are profoundly interrelated with environmental quality issues. Interestingly, scientists engage with empirical research to identify the impacts and causalities at the interface of economic activities, energy supply, and demand. The importance of the present study lies in a discussion of all contemporary research efforts bridging two strands of empirical literature in environmental economics: developments in energy growth nexus discussion and the environmental Kuznets curve. Furthermore, it highlights the inclusion of untested explanatory variables and the impacts on environmental degradation levels. In the context of the EKC hypothesis, the most popular indicators are greenhouse gas emissions (GHGs) and carbon dioxide emissions in conceptualizing environmental degradation. A review of relevant empirical studies disclosed additional research opportunities that can consider currently untested and less visible proxies of economic growth. For both strands in the literature, results differ based on the group of countries investigated, the econometric models adopted, the format of data, e.g., time series or panel analyses, the time frames due to data availability, and the proxies used to conceptualize energy, environmental degradation, and economic growth. Practical implications indicate that environmental degradation can be avoided or significantly limited within sustainable economic growth to reduce carbon dioxide emissions and increase the use of renewables in the energy mix. Furthermore, one particular implication is the concept of energy efficiency to reduce relevant demand to produce the same outcome or task. Full article

(This article belongs to the Special Issue Economic Analysis and Policies for the Environment, Natural Resources and Energy)

25 pages, 8213 KiB

Open AccessEditor’s ChoiceArticle

Eco-Efficiency as a Decision Support Tool to Compare Renewable Energy Systems

by Dominik Huber, Ander Martinez Alonso, Maeva Lavigne Philippot and Maarten Messagie

Energies 2023, 16(11), 4478; https://doi.org/10.3390/en16114478 - 1 Jun 2023

Cited by 1 | Viewed by 1496

Abstract

Even though eco-efficiency (EE) is already applied to various energy systems, so far, no study investigates in detail the hourly, marginal and seasonal impacts of a decentralized energy system. This study assesses the hourly EE of the Research Park Zellik (RPZ), located in [...] Read more.

Even though eco-efficiency (EE) is already applied to various energy systems, so far, no study investigates in detail the hourly, marginal and seasonal impacts of a decentralized energy system. This study assesses the hourly EE of the Research Park Zellik (RPZ), located in the Brussels metropolitan area for 2022 composed of photovoltaic installations, wind turbines and batteries. A cradle-to-grave life cycle assessment (LCA) to identify the carbon footprint (CF) and a levelized cost of electricity (LCOE) calculation is conducted. An existing design optimization framework is applied to the RPZ. Consumption data are obtained from smart meters of five consumers at the RPZ on a one-hour time resolution for 2022 and upscaled based on the annual consumption of the RPZ. As the EE is presented as the sum of the CF and the LCOE, a lower EE corresponds to an economically and environmentally preferable energy system. In a comparative framework, the developed method is applied to two different case studies, namely, (i) to an energy system in Vega de Valcerce in Spain and (ii) to an energy system in Bèli Bartoka in Poland. The average EE of the RPZ energy system in 2022 is 0.15 per kWh, while the average EE of the Polish and Spanish energy systems are 1.48 and 0.36 per kWh, respectively. When analyzing four selected weeks, both the LCOE and CF of the RPZ energy system are driven by the consumption of the Belgian electricity grid mix. In contrast, due to the very low LCOE and CF of the renewable energy sources, in particular wind turbines, the RPZ energy system’s EE benefits and lies below the EE of the Belgium electricity grid mix. Full article

(This article belongs to the Special Issue Life Cycle Assessment in Renewable and Sustainable Energy)

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21 pages, 2012 KiB

Open AccessEditor’s ChoiceReview

Integrated Demand Response Programs in Energy Hubs: A Review of Applications, Classifications, Models and Future Directions

by Innocent Kamwa, Leila Bagherzadeh and Atieh Delavari

Energies 2023, 16(11), 4443; https://doi.org/10.3390/en16114443 - 31 May 2023

Cited by 9 | Viewed by 1926

Abstract

In the traditional power system, customers respond to their primary electricity consumption pattern based on price or incentive to take additional advantages. By developing energy hubs (EHs) where electricity, heat, natural gas and other forms of energy are coupled together, all types of [...] Read more.

In the traditional power system, customers respond to their primary electricity consumption pattern based on price or incentive to take additional advantages. By developing energy hubs (EHs) where electricity, heat, natural gas and other forms of energy are coupled together, all types of energy customers, even the inelastic loads, can participate in the demand response (DR) program. This novel vision has led to the concept of “integrated demand response (IDR)”. IDR programs (IDRPs) in EHs involve coordinating multiple DR activities across different energy systems, such as buildings, industrial complexes and transportation networks. The main purpose of IDR is so that multi-energy users can respond not only by shifting or reducing their energy consumption from the demand side, but also by changing the type of energy consumed in response to the dispatching center. The integration of IDRPs in EHs can help to reduce energy costs, improve grid stability and increase the penetration of renewable energy sources (RES) in the power system. Moreover, by synchronizing DR activities across different energy systems, IDRPs can provide additional benefits, such as improved energy efficiency, reduced greenhouse gas emissions and increased resilience to power outages and other disruptions. In this paper, we provide an overview of the IDRP across EH areas, encompassing different aspects of it. First, the nature behind IDRP and its basic concept is introduced. Then, a categorization of fundamental principles within the IDRP is undertaken. Furthermore, modelling formulation and optimization techniques of IDRP in EHs are conducted. In addition to the IDRP content and model, this article deals with the research performed in this field from different perspectives. Finally, the advantages and prospect challenges of IDRPs are discussed. Full article

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12 pages, 1765 KiB

Open AccessEditor’s ChoiceArticle

Machine Learning Requirements for Energy-Efficient Virtual Network Embedding

by Xavier Hesselbach and David Escobar-Perez

Energies 2023, 16(11), 4439; https://doi.org/10.3390/en16114439 - 31 May 2023

Cited by 1 | Viewed by 1230

Abstract

Network virtualization is a technology proven to be a key enabling a family of strategies in different targets, such as energy efficiency, economic revenue, network usage, adaptability or failure protection. Network virtualization allows us to adapt the needs of a network to new [...] Read more.

Network virtualization is a technology proven to be a key enabling a family of strategies in different targets, such as energy efficiency, economic revenue, network usage, adaptability or failure protection. Network virtualization allows us to adapt the needs of a network to new circumstances, resulting in greater flexibility. The allocation decisions of the demands onto the physical network resources impact the costs and the benefits. Therefore it is one of the major current problems, called virtual network embedding (VNE). Many algorithms have been proposed recently in the literature to solve the VNE problem for different targets. Due to the current successful rise of artificial intelligence, it has been widely used recently to solve technological problems. In this context, this paper investigates the requirements and analyses the use of the Q-learning algorithm for energy-efficient VNE. The results achieved validate the strategy and show clear improvements in terms of cost/revenue and energy savings, compared to traditional algorithms. Full article

(This article belongs to the Special Issue Machine Learning and Deep Learning for Energy Systems II)

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23 pages, 4220 KiB

Open AccessEditor’s ChoiceReview

Comprehensive Review on Thin Film Homojunction Solar Cells: Technologies, Progress and Challenges

by Omar M. Saif, Yasmine Elogail, Tarek M. Abdolkader, Ahmed Shaker, Abdelhalim Zekry, Mohamed Abouelatta, Marwa S. Salem and Mostafa Fedawy

Energies 2023, 16(11), 4402; https://doi.org/10.3390/en16114402 - 30 May 2023

Cited by 8 | Viewed by 2403

Abstract

With the aim of achieving high efficiency, cost-effectiveness, and reliability of solar cells, several technologies have been studied. Recently, emerging materials have appeared to replace Si-based cells, seeking economic fabrication of solar cells. Thin-film solar cells (TFSCs) are considered strong candidates for this [...] Read more.

With the aim of achieving high efficiency, cost-effectiveness, and reliability of solar cells, several technologies have been studied. Recently, emerging materials have appeared to replace Si-based cells, seeking economic fabrication of solar cells. Thin-film solar cells (TFSCs) are considered strong candidates for this mission, specifically perovskite-based solar cells, reporting competitive power convergence efficiencies reaching up to 25.7%. Substantial efforts have been invested in experimental and research work to surpass the Si-based cells performance. Simulation analysis is a major tool in achieving this target by detecting design problems and providing possible solutions. Usually, a TFSC adopts p-i-n heterojunction architecture by employing carrier transport materials along with the absorber material in order to extract the photogenerated electrons and holes by realizing a built-in electric field. Eventually, this dependency of conventional heterojunction TFSCs on carrier transport layers results in cost-ineffective cells and increases the possibility of device instability and interface problems. Thus, the design of p-n homojunction TFSCs is highly desirable as an essential direction of structural innovation to realize efficient solar cell operation. In this review, a summary of the fundamentals of TFSC materials, recent design and technology progress, and methodologies for improving the device performance using experimental research studies will be discussed. Further, simulation analysis will be provided by demonstrating the latest research work outcomes, highlighting the major achievements and the most common challenges facing thin film homojunction solar cell structures and the methods to improve them. Full article

(This article belongs to the Special Issue Modeling and Simulation of Solar Cells)

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24 pages, 22093 KiB

Open AccessEditor’s ChoiceArticle

Techno-Economic Potential of V2B in a Neighborhood, Considering Tariff Models and Battery Cycle Limits

by Yannick Pohlmann and Carl-Friedrich Klinck

Energies 2023, 16(11), 4387; https://doi.org/10.3390/en16114387 - 29 May 2023

Cited by 1 | Viewed by 1245

Abstract

To limit climate change, decarbonization of the transportation sector is necessary. The change from conventional combustion vehicles to vehicles with electric drives is already taking place. In the long term, it can be assumed that a large proportion of passenger cars will be [...] Read more.

To limit climate change, decarbonization of the transportation sector is necessary. The change from conventional combustion vehicles to vehicles with electric drives is already taking place. In the long term, it can be assumed that a large proportion of passenger cars will be battery–electric. On the one hand, this conversion will result in higher energy and power requirements for the electricity network; on the other hand, it also offers the potential for vehicles to provide energy for various systems in the future. Battery–electric vehicles can be used to shift grid purchases, optimize the operation of other components and increase the self-consumption rate of photovoltaic systems. An LP model for the optimal energy management of the neighborhood consisting of buildings with electricity and heat demand, a PV system, a BEV fleet, a heat pump and thermal storage was formulated. The potential of the BEV fleet to provide energy via V2B in the neighborhood was investigated, considering electricity tariff models and individual charging/discharging efficiencies of vehicles and stochastic mobility profiles. The vehicle fleet provides between

4.8

kWh

⁻¹

sqm

⁻¹

a

(flat-fee) and

25.3

kWh

⁻¹

sqm

⁻¹

a

(dynamic tariff) per year, corresponding to 6.7, 9.5% and 35.7% of the annual energy demand of the neighborhood. All tariff models lead to optimization of self-consumption in summer. Dynamic pricing also leads to arbitrage during winter, and a power price tariff avoids peaks in grid draw. Due to individual charging efficiencies, the power supplied by the fleet is distributed unevenly among the vehicles, and setting limits for additional equivalent full cycles distributes the energy more evenly across the fleet. The limits affect the V2B potential, especially below the limits of 20 yearly cycles for flat and power tariffs and below 80 cycles for a dynamic tariff. Full article

(This article belongs to the Special Issue Advanced Coordinated Optimization Strategy of Electric Vehicle and Smart Grids)

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20 pages, 746 KiB

Open AccessEditor’s ChoiceReview

Review on Separation Processes of End-of-Life Silicon Photovoltaic Modules

by Jongwon Ko, Kyunghwan Kim, Ji Woo Sohn, Hongjun Jang, Hae-Seok Lee, Donghwan Kim and Yoonmook Kang

Energies 2023, 16(11), 4327; https://doi.org/10.3390/en16114327 - 25 May 2023

Cited by 10 | Viewed by 4495

Abstract

Solar energy has gained prominence because of the increasing global attention received by renewable energies. This shift can be attributed to advancements and innovations in solar cell technology, which include developments of various photovoltaic materials, such as thin film and tandem solar cells, [...] Read more.

Solar energy has gained prominence because of the increasing global attention received by renewable energies. This shift can be attributed to advancements and innovations in solar cell technology, which include developments of various photovoltaic materials, such as thin film and tandem solar cells, in addition to silicon-based solar cells. The latter is the most widely commercialized type of solar cell because of its exceptional durability, long-term stability, and high photoconversion efficiency; consequently, the demand for Si solar cells has been consistently increasing. PV modules are designed for an operation lifespan of 25–30 years, which has led to a gradual increase in the number of end-of-life PV modules. The appropriate management of both end-of-life and prematurely failed PV modules is critical for the recovery and separation of valuable and hazardous materials. Effective methods for end-of-life PV waste management are necessary to minimize their environmental impact and facilitate transition to a more sustainable and circular economy. This paper offers a comprehensive overview of the separation processes for silicon PV modules and summarizes the attempts to design easily recyclable modules for sustainable solar module development. Based on the studies summarized in this paper, suggestions are provided for future research. Full article

(This article belongs to the Topic Sustainable Environmental Technologies)

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21 pages, 2088 KiB

Open AccessEditor’s ChoiceArticle

Roadmap to a Sustainable Energy System: Is Uncertainty a Major Barrier to Investments for Building Energy Retrofit Projects in Wide City Compartments?

by Laura Gabrielli, Aurora Greta Ruggeri and Massimiliano Scarpa

Energies 2023, 16(11), 4261; https://doi.org/10.3390/en16114261 - 23 May 2023

Cited by 4 | Viewed by 1625

Abstract

Along the roadmap to a Sustainable Real Estate-Scape, energy retrofit campaigns on wide city compartments represent a pivotal task, where the importance of the collaboration between the public and private sectors is crucial. Energy retrofit programs on building assets are subject to multiple [...] Read more.

Along the roadmap to a Sustainable Real Estate-Scape, energy retrofit campaigns on wide city compartments represent a pivotal task, where the importance of the collaboration between the public and private sectors is crucial. Energy retrofit programs on building assets are subject to multiple uncertainty factors (e.g., climate, energy-economy forecasts, etc.) that act as a primary barrier to investment in this field. This paper aims to discuss risk management techniques to understand better how to deal with this kind of uncertainty. The research specifically addresses the techniques of sensitivity analysis and Monte Carlo simulation, focusing first on the phase of variables selection and their probability definition, including climatic, environmental, energy, economic, financial, and stochastic parameters. In this article, it is suggested to include correlation coefficients in the input variables of risk analysis, preferring the two-dimension Monte Carlo simulation to its simple version, since the results are more reliable when separating aleatory from epistemic uncertainty; thus, the results are more reliable. Moreover, it is seen how a sensitivity analysis based on percentile variations of the inputs provides a more accurate representation of risk if compared to the most common sensitivity analysis based on percentage deviations of the inputs. Conducting a sensitivity analysis using percentile variations gives realistic and reliable results, reflecting the tailored definition of uncertainty around the inputs on the basis of specific market analyses or historical series. Full article

(This article belongs to the Special Issue Development in Smart and Energy-Efficient Buildings and Renewable Energy Systems)

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26 pages, 6195 KiB

Open AccessEditor’s ChoiceReview

Recent Advances in the Study of In Situ Combustion for Enhanced Oil Recovery

by Andrey V. Minakov, Victoria D. Meshkova, Dmitry Viktorovich Guzey and Maksim I. Pryazhnikov

Energies 2023, 16(11), 4266; https://doi.org/10.3390/en16114266 - 23 May 2023

Cited by 9 | Viewed by 2725

Abstract

Global estimates for our remaining capacity to exploit developed oil fields indicate that the currently recoverable oil (light oil) will last for approximately 50 years. This necessitates the development of viscous and superviscous oil fields, which will further compensate for the loss of [...] Read more.

Global estimates for our remaining capacity to exploit developed oil fields indicate that the currently recoverable oil (light oil) will last for approximately 50 years. This necessitates the development of viscous and superviscous oil fields, which will further compensate for the loss of easily produced oil. In situ combustion is the most promising production method, which allows for increased oil recovery from a reservoir. This being the case, this study provides an overview of global trends regarding the research and implementation of the method under consideration, in order to promote understanding of its applicability and effectiveness. The background to the development of the method is discussed in detail, illustrating the growing interest of researchers in its study. Cases of both successful as well as inefficient implementations of this method in real oil fields are considered. The main focus of the article is to investigate the influence of the parent rock and catalysts on the combustion process, as this is a new and actively developing area in the study of enhanced oil recovery using in situ combustion. Geological surveys, in addition to experimental and numerical studies, are considered to be the main methods that are used to investigate processes during in situ combustion. The analysis that we carried out led us to understand that the processes which occur during the combustion of heavy oil are practically unpredictable and, therefore, poorly understood. The specificity of the oil composition under consideration depends on the field, which can lead to a change in the required temperature regimes for its production. This indicates that there exists multiple specific applications for the method under consideration, each requiring additional full studies into both the fractional composition of oil and its reservoirs. The article also considers various technologies for implementing the in situ combustion method, such as ND-ISC, THAITM, COSH, CAGD, and SAGD. However, the literature review has shown that none of the technologies presented is widely used, due to the lack of an evidence base for their successful application in the field. Moreover, it should be noted that this method has no limits associated with the oil occurrence depth. This technology can be implemented in thin reservoirs, as well as in flooded, clayey, sandy, and carbonate reservoirs. The review we have presented can be considered as a guide for further research into the development of global solutions for using the proposed method. Full article

(This article belongs to the Special Issue Enhanced Oil Recovery Processes Evaluation, Design and Implementation)

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36 pages, 26895 KiB

Open AccessEditor’s ChoiceArticle

Optimal Inverter Control Strategies for a PV Power Generation with Battery Storage System in Microgrid

by Md Jahidur Rahman, Tahar Tafticht, Mamadou Lamine Doumbia and Iqbal Messaïf

Energies 2023, 16(10), 4228; https://doi.org/10.3390/en16104228 - 21 May 2023

Cited by 2 | Viewed by 2171

Abstract

Power generation from Renewable Energy Sources (RESs) is unpredictable due to climate or weather changes. Therefore, more control strategies are required to maintain the proper power supply in the entire microgrid. This paper presents a simulation scheme utilizing a solar system instanced by [...] Read more.

Power generation from Renewable Energy Sources (RESs) is unpredictable due to climate or weather changes. Therefore, more control strategies are required to maintain the proper power supply in the entire microgrid. This paper presents a simulation scheme utilizing a solar system instanced by Photovoltaic (PV) panels coupled to the grid, loads, and an energy storage device. At first, modeling the PV panels cell and their operation were analyzed. The synthesis of the adaptive notch filter was designed to compensate for the input currents. The power converter’s/inverter’s efficiency and control facility allowed us to link the energy storage system with an electrical grid. Several simulations were accomplished consistently with nonlinear control techniques for the simple inverter, multi-variable filter, notch filter, and without a filter. Finally, the performances of the nonlinear controller with various filters were carried out to regulate the DC bus of the proposed grid. The advantage of these controllers is compensating the reactive power and harmonic currents to obtain a disturbance-free power network. The overall installations and simulations were established using the Matlab/Simulink software. Full article

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