Sustainable Energy Technology

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Topic Information

Dear Colleagues,

The Topic Sustainable Energy Technology covers technologies, products, equipment, and devices as well as energy services based on software and data protected by patents and/or trademarks. Recent trends underline the principles of a circular economy such as sustainable product design, extending the product lifecycle, reusability, and recycling. Climate change, environmental impact, and limited natural resources require scientific research and novel technical solutions. The Topic Sustainable Energy Technology is a publishing platform for scientific and technological approaches to “green”—i.e., environmentally friendly and sustainable—technologies. While a focus lies on energy and bioenergy, it also covers “green” solutions in all aspects of industrial engineering. Sustainable Energy Technology addresses researchers, advanced students, technical consultants as well as decision makers in industries and politics. This Topic will include a comprehensive overview and in-depth technical research paper addressing recent progress in sustainable energy technology. Studies of advanced techniques and methods in sustainable energy technology are also welcome. Research involving experimental and numerical studies, recent developments, and the current state-of-the-art and emerging technologies in this field are highly encouraged.

Prof. Dr. Wei-Hsin Chen
Prof. Dr. Aristotle T. Ubando
Prof. Dr. Chih-Che Chueh
Prof. Dr. Liwen Jin
Topic Editors

Keywords

Participating Journals

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Energies energies	3.2	5.5	2008	16.1 Days	CHF 2600
Journal of Marine Science and Engineering jmse	2.9	3.7	2013	15.4 Days	CHF 2600
Processes processes	3.5	4.7	2013	13.7 Days	CHF 2400
Solar solar	-	-	2021	16.9 Days	CHF 1000
Wind wind	-	-	2021	24.8 Days	CHF 1000

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Published Papers (64 papers)

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11 pages, 2913 KiB  

Open AccessArticle

An Underwater Inductive Power Transfer System with a Compact Receiver and Reduced Eddy Current Loss

by Zhengchao Yan, Chenxu Zhao, Qianyu Hu, Min Wu, Lin Qiao, Kehan Zhang and Yuli Hu

J. Mar. Sci. Eng. 2022, 10(12), 1900; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse10121900 - 05 Dec 2022

Cited by 3 | Viewed by 1240

Abstract

Inductive power transfer (IPT) technology is widely used in autonomous underwater vehicles (AUVs) to achieve safety and flexibility. However, the eddy current loss (ECL) will be generated in the seawater due to the high-frequency alternating current in the transmitter and receiver. An underwater [...] Read more.

Inductive power transfer (IPT) technology is widely used in autonomous underwater vehicles (AUVs) to achieve safety and flexibility. However, the eddy current loss (ECL) will be generated in the seawater due to the high-frequency alternating current in the transmitter and receiver. An underwater IPT system with a series-none (SN) compensation topology is proposed in this paper to achieve a compact receiver for AUVs and reduce the ECL. The analytical model of the IPT system is built to analyze its transfer performance. The phase difference between the transmitter and receiver current of the SN compensation topology is larger than 90° compared to that of the conventional series-series (SS) topology, which can significantly decrease the magnitude of the electric field caused by coil currents; thus, the eddy current loss is reduced. Moreover, the optimal load resistance of the seawater IPT system is lower than that in the air, and the SN compensation topology has a more compact receiver with no compensation capacitor in the receiving side, which can save the internal space in the AUVs. An experimental prototype based on the SN topology is built, and the experimental results have verified the analysis. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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16 pages, 4712 KiB  

Open AccessArticle

Energy-Saving Depth Control of an Autonomous Underwater Vehicle Using an Event-Triggered Sliding Mode Controller

by Yu Qi, Xinyu Wu, Guocheng Zhang and Yushan Sun

J. Mar. Sci. Eng. 2022, 10(12), 1888; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse10121888 - 04 Dec 2022

Cited by 3 | Viewed by 1247

Abstract

In order to improve the endurance of underwater vehicles and make it possible for the underwater vehicle to inspect long-distance water tunnels, a sliding mode control method based on event triggering is proposed for the depth control of underwater vehicles from the perspective [...] Read more.

In order to improve the endurance of underwater vehicles and make it possible for the underwater vehicle to inspect long-distance water tunnels, a sliding mode control method based on event triggering is proposed for the depth control of underwater vehicles from the perspective of energy saving. Firstly, the kinematics and dynamics models of underwater vehicle dive surface are established. Secondly, an event-triggered sliding mode controller is designed. According to the Lyapunov function, the stability of the designed controller is proved by theoretical analysis, and Zeno phenomena will not appear in the closed-loop control system. Compared with other controllers, the simulation results show that this controller can effectively realize the depth control of AUV, has strong adaptability and robustness to unmodeled nonlinear dynamics and bounded disturbances, and has the effect of saving computing resources. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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24 pages, 7403 KiB  

Open AccessArticle

An Optimization Study on the Operating Parameters of Liquid Cold Plate for Battery Thermal Management of Electric Vehicles

by Lichuan Wei, Yanhui Zou, Feng Cao, Zhendi Ma, Zhao Lu and Liwen Jin

Energies 2022, 15(23), 9180; https://0-doi-org.brum.beds.ac.uk/10.3390/en15239180 - 03 Dec 2022

Cited by 2 | Viewed by 1344

Abstract

The development of electric vehicles plays an important role in the field of energy conservation and emission reduction. It is necessary to improve the thermal performance of battery modules in electric vehicles and reduce the power consumption of the battery thermal management system [...] Read more.

The development of electric vehicles plays an important role in the field of energy conservation and emission reduction. It is necessary to improve the thermal performance of battery modules in electric vehicles and reduce the power consumption of the battery thermal management system (BTMS). In this study, the heat transfer and flow resistance performance of liquid cold plates with serpentine channels were numerically investigated and optimized. Flow rate ($$\dot{m}$$), inlet temperature (T_in), and average heat generation (Q) were selected as key operating parameters, while average temperature (T_ave), maximum temperature difference (ΔT_max), and pressure drop (ΔP) were chosen as objective functions. The Response Surface Methodology (RSM) with a face-centered central composite design (CCD) was used to construct regression models. Combined with the multi-objective non-dominated sorting genetic algorithm (NSGA-II), the Pareto-optimal solution was obtained to optimize the operation parameters. The results show that the maximum temperature differences of the cold plate can be controlled within 0.29~3.90 °C, 1.11~15.66 °C, 2.17~31.39 °C, and 3.43~50.92 °C for the discharging rates at 1.0 C, 2.0 C, 3.0 C, and 4.0 C, respectively. The average temperature and maximum temperature difference can be simultaneously optimized by maintaining the pressure drop below 1000 Pa. It is expected that the proposed methods and results can provide theoretical guidance for developing an operational strategy for the BTMS. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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16 pages, 4540 KiB  

Open AccessArticle

Hydrodynamic Response and Tension Leg Failure Performance Analysis of Floating Offshore Wind Turbine with Inclined Tension Legs

by Zhaolin Jia, Han Wu, Hao Chen, Wei Li, Xinyi Li, Jijian Lian, Shuaiqi He, Xiaoxu Zhang and Qixiang Zhao

Energies 2022, 15(22), 8584; https://0-doi-org.brum.beds.ac.uk/10.3390/en15228584 - 16 Nov 2022

Cited by 1 | Viewed by 1437

Abstract

The tension legs are the essential parts of the tension legs platform-type (TLP-type) floating offshore wind turbine (FOWT) against the extra buoyancy of FOWT. Therefore, the TLP-type FOWT will face the risk of tension leg failure. However, there are seldom analyses on the [...] Read more.

The tension legs are the essential parts of the tension legs platform-type (TLP-type) floating offshore wind turbine (FOWT) against the extra buoyancy of FOWT. Therefore, the TLP-type FOWT will face the risk of tension leg failure. However, there are seldom analyses on the hydrodynamic response and tension leg failure performance of FOWT with inclined tension legs. In this paper, a hydrodynamic model was established using three-dimensional hydrodynamic theory and applied in the motion response and tension analyses of FOWT with conventional and new tension leg arrangements on Moses. The influence of draft and tension leg arrangement on the performance of FOWT with inclined tension legs were studied. The optimum draft was the height of the column and lower tensions were obtained for the new tension leg arrangement. Moreover, the tension leg failure performance of FOWT with inclined tension legs was evaluated under different failure conditions. The results illustrated that the FOWT with the new tension leg arrangement can still operate safely after one tension leg fails. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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26 pages, 6158 KiB  

Open AccessArticle

United States Solar Investment: A Feasibility Study of Solar Farms in Kentucky

by Youngil Kim, Allie Skaggs and James Ferrell

Solar 2022, 2(4), 469-494; https://0-doi-org.brum.beds.ac.uk/10.3390/solar2040028 - 27 Oct 2022

Viewed by 3196

Abstract

The United States is experiencing a large growth in the solar sector. The U.S. solar power capacity has grown from 0.34 Gigawatts (GW) in 2008 to an estimated 97.2 GW today. However, some states have had difficulty installing large scale solar farms due [...] Read more.

The United States is experiencing a large growth in the solar sector. The U.S. solar power capacity has grown from 0.34 Gigawatts (GW) in 2008 to an estimated 97.2 GW today. However, some states have had difficulty installing large scale solar farms due to concerns regarding geographic location, political climate, or economic factors. Kentucky (KY) is one of the states which is below the national average for solar energy production. However, KY contains a wealth of potential for these types of farms with decent solar irradiation levels and large tracts of unused land for solar farms. For the study, this paper selects three representative areas of KY by using PVWatts and topographical maps which can theoretically produce enough electricity so that KY can meet or exceed the national generation percentage average (2.3% or 2.06 TWh annually in KY’s case). The study analyzes the economic feasibility of solar photovoltaic systems (PV) farms in terms of Cumulative Cash Flow ($) and Payback Time (Year) by using the Cost of Renewable Energy Spreadsheet Tool (CREST). Furthermore, this paper estimates the Average/Median/High output power (kWh) annually for the scenario among three areas in Kentucky, Smithland, Hickman, and Falls of Rough. In this theoretical scenario, an average 2.27 TWh would be generated annually which exceeds the national generation percentage average. Furthermore, by the sixth year, the cumulative cash flow would exceed the breakeven point, proving the feasibility of these solar farms. The annual average power generation estimates for the areas of Smithland, Hickman, and Falls of Rough are 0.3741 TWh, 1.1628 TWh, and 0.731 TWh respectively. The average profit per MWh estimates for the areas of Smithland, Hickman, and Falls of Rough are $11,130.12/MWh, $10,742.46/MWh, and $11,392.01/MWh respectively. According to CREST, the final cumulative cash flow, after the 25-year life span of the panels, would be approximately $624,566,720. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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18 pages, 2534 KiB  

Open AccessArticle

Image Processing and Measurement of the Bubble Properties in a Bubbling Fluidized Bed Reactor

by Rajan Jaiswal, Britt. M. E. Moldestad, Marianne S. Eikeland, Henrik K. Nielsen and Rajan Kumar Thapa

Energies 2022, 15(21), 7828; https://0-doi-org.brum.beds.ac.uk/10.3390/en15217828 - 22 Oct 2022

Cited by 2 | Viewed by 1622

Abstract

The efficiency of a fluidized bed reactor depends on the bed fluid dynamic behavior, which is significantly influenced by the bubble properties. This work investigates the bubble properties of a bubbling fluidized bed reactor using computational particle fluid dynamic (CPFD) simulations and electrical [...] Read more.

The efficiency of a fluidized bed reactor depends on the bed fluid dynamic behavior, which is significantly influenced by the bubble properties. This work investigates the bubble properties of a bubbling fluidized bed reactor using computational particle fluid dynamic (CPFD) simulations and electrical capacitance tomography (ECT) measurements. The two-dimensional images (along the reactor horizontal and vertical planes) of the fluidized bed are obtained from the CPFD simulations at different operating conditions. The CPFD model was developed in a commercial CPFD software Barracuda Virtual Reactor 20.0.1. The bubble behavior and bed fluidization behavior are characterized form the bubble properties: average bubble diameter, bubble rise velocity, and bubble frequency. The bubble properties were determined by processing the extracted images with script developed in MATLAB. The CPFD simulation results are compared with experimental data (obtained from the ECT sensors) and correlations in the literature. The results from the CPFD model and experimental measurement depicted that the average bubble diameter increased with an increase in superficial gas velocities up to $4.2 U_{mf}$ and decreased with a further increase in gas velocities due to the onset of large bubbles (potential slugging regime). The bubble rise velocity increased as it moved from the lower region to the bed surface. The Fourier transform of the transient solid volume fraction illustrated that multiple bubbles pass the plane with varying amplitude and frequency in the range of 1–6 Hz. Further, the bubble frequency increased with an increase in superficial gas velocity up to $2.5U_{mf}$ and decreased with a further increase in gas velocity. The CPFD model and method employed in this work can be useful for studying the influence of bubble properties on conversion efficiency of a gasification reactor operating at high temperatures. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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11 pages, 711 KiB  

Open AccessArticle

Modular Multilevel Converter for a Linear Generator for Wave Energy Converter

by Henry M. Zapata and Marcelo A. Pérez

Energies 2022, 15(17), 6346; https://0-doi-org.brum.beds.ac.uk/10.3390/en15176346 - 31 Aug 2022

Cited by 1 | Viewed by 1551

Abstract

In this paper we propose a modular multilevel converter for a linear generator for a wave energy converter. The coils of this generator are individually controlled to improve energy harvesting performance. This topology involves two stages. The first stage uses a full-bridge to [...] Read more.

In this paper we propose a modular multilevel converter for a linear generator for a wave energy converter. The coils of this generator are individually controlled to improve energy harvesting performance. This topology involves two stages. The first stage uses a full-bridge to control the harvested current with a reference generated by means of an MPPT method. The second stage uses a half-bridge to control the voltage of the DC-link and the output current. Furthermore, multilevel modular converters allow the generation of a medium DC voltagethat reduces the losses in energy transmission lines from offshore to a coupling common point on the shore. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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18 pages, 10537 KiB  

Open AccessArticle

Photovoltaic Fuzzy Logical Control MPPT Based on Adaptive Genetic Simulated Annealing Algorithm-Optimized BP Neural Network

by Yan Zhang, Ya-Jun Wang, Yong Zhang and Tong Yu

Processes 2022, 10(7), 1411; https://0-doi-org.brum.beds.ac.uk/10.3390/pr10071411 - 20 Jul 2022

Cited by 7 | Viewed by 1820

Abstract

The P–U characteristic curve of the photovoltaic (PV) cell is a single peak curve with only one maximum power point (MPP). However, the fluctuation of the irradiance level and ambient temperature will cause the drift of MPP. In the maximum power point tracking [...] Read more.

The P–U characteristic curve of the photovoltaic (PV) cell is a single peak curve with only one maximum power point (MPP). However, the fluctuation of the irradiance level and ambient temperature will cause the drift of MPP. In the maximum power point tracking (MPPT) algorithm of PV systems, BP neural network (BPNN) has an unstable learning rate and poor performance, while the genetic algorithm (GA) tends to fall into local optimum. Therefore, a novel PV fuzzy MPPT algorithm based on an adaptive genetic simulated annealing-optimized BP neural network (AGSA-BPNN-FLC) is proposed in this paper. First, the adaptive GA is adopted to generate the corresponding population and increase the population diversity. Second, the simulated annealing (SA) algorithm is applied to the parent and offspring with a higher fitness value to improve the convergence rate of GA, and the optimal weight threshold of BPNN are updated by GA and SA algorithm. Third, the optimized BPNN is employed to predict the MPP voltage of PV cells. Finally, the fuzzy logical control (FLC) is used to eliminate local power oscillation and improve the robustness of the PV system. The proposed algorithm is applied and compared with GA-BPNN, simulated annealing-genetic (SA-GA), particle swarm optimization (PSO), grey wolf optimization (GWO) and FLC algorithm under the condition that both the irradiance and temperature change. Simulation results indicate that the proposed MPPT algorithm is superior to the above-mentioned algorithms with efficiency, steady-state oscillation rate, tracking time and stability accuracy, and they have a good universality and robustness. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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17 pages, 2775 KiB  

Open AccessArticle

Variable Natural Frequency Damper for Minimizing Response of Offshore Wind Turbine: Principle Verification through Analysis of Controllable Natural Frequencies

by Young-Suk You, Ka-Young Song and Min-Young Sun

J. Mar. Sci. Eng. 2022, 10(7), 983; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse10070983 - 18 Jul 2022

Cited by 4 | Viewed by 2044

Abstract

Resonance causes extreme stress, acceleration of fatigue, and reduction in lifespan of offshore wind structures. The main factors that cause resonance are environmental loads such as wind and waves, and dynamic loads caused by rotor movement. Estimation of the natural frequency at the [...] Read more.

Resonance causes extreme stress, acceleration of fatigue, and reduction in lifespan of offshore wind structures. The main factors that cause resonance are environmental loads such as wind and waves, and dynamic loads caused by rotor movement. Estimation of the natural frequency at the design stage is highly uncertain, and natural frequency changes occur due to various factors during long-term operation. Therefore, it is important to ensure structural safety from resonance through a vibration-monitoring system or an additional damper. In this study, the effect of seawater existing inside the substructure on the natural frequency of the structure was dealt with. The natural frequency estimation equation for a fixed offshore wind structure was derived with the “inner fluid simplification assumption”. The finite element modal analysis was performed to verify the principle of Variable Natural Frequency Damper (VNFD), a system that controls the natural frequency of offshore wind structures through a pump, and to find the range of natural frequency control. As a result, interior fluid affects the natural frequency of the wind turbine support structure. Specifically, the variable natural frequency range was very low, at about 0.027% for the monopile model at a depth of 10 m, but increased rapidly to about 3.66% at a depth of 70 m. Furthermore, when estimating the natural frequency of a fixed offshore wind turbine in deep water without consideration of interior fluid, the estimates can be higher than with consideration of it. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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23 pages, 7953 KiB  

Open AccessArticle

Study on the Influence of Working-Fluid’s Thermophysical Properties on the Stirring-Heating

by Xingran Liu, Xianpeng Sun, Jinhong He, Da Wang, Xinyang Qiu, Shengshan Bi and Yanfei Cao

Energies 2022, 15(13), 4835; https://0-doi-org.brum.beds.ac.uk/10.3390/en15134835 - 01 Jul 2022

Viewed by 1485

Abstract

The thermophysical properties of a working-fluid play an important role in the process of stirring-heating. The heating process of stirring is accompanied by two processes: the friction between the solid mechanism and the working-fluid and the viscous dissipation of the working liquid. Traditionally, [...] Read more.

The thermophysical properties of a working-fluid play an important role in the process of stirring-heating. The heating process of stirring is accompanied by two processes: the friction between the solid mechanism and the working-fluid and the viscous dissipation of the working liquid. Traditionally, the sensible heat of water-based working-fluids is low, while that of oil-based working-fluids is higher, but the load capacity is relatively low. In order to find a balance between the two, an optimal stirring working-fluid should be selected. In this study, an experimental method was used to study the heating process of 30 kinds of working-fluids. The numerical evaluation model of the effects of thermophysical properties on the comprehensive evaluation index of heat (CEIH) was established by multiple linear regression methods, and a computational fluid dynamics (CFD) tool was used to analyze the heat generation and flow field of different working-fluids in the stirring-heating device. The results show that viscous dissipation is the most important way of stirring-heating. CFD can completely replace the experiment to study the heating effect of stirring. The thermophysical properties of the working-fluid affect the upper circulation and the overall velocity of the double circulation flow. The experimental results and regression model analysis show that specific heat capacity has the greatest effect on the heating effect, but density will also play a positive role in the stirring-heating. Water-based salt solutions such as KCl can achieve a better heating effect, and oil-based working-fluids are not always the best choice. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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14 pages, 14115 KiB  

Open AccessArticle

A Production and Delivery Model of Hydrogen from Solar Thermal Energy in the United Arab Emirates

by Abdulrahman Joubi, Yutaro Akimoto and Keiichi Okajima

Energies 2022, 15(11), 4000; https://0-doi-org.brum.beds.ac.uk/10.3390/en15114000 - 29 May 2022

Cited by 7 | Viewed by 2483

Abstract

Hydrogen production from surplus solar electricity as energy storage for export purposes can push towards large-scale application of solar energy in the United Arab Emirates and the Middle East region; this region’s properties of high solar irradiance and vast empty lands provide a [...] Read more.

Hydrogen production from surplus solar electricity as energy storage for export purposes can push towards large-scale application of solar energy in the United Arab Emirates and the Middle East region; this region’s properties of high solar irradiance and vast empty lands provide a good fit for solar technologies such as concentrated solar power and photovoltaics. However, a thorough comparison between the two solar technologies, as well as investigating the infrastructure of the United Arab Emirates for a well-to-ship hydrogen pathway, is yet to be fully carried out. Therefore, in this study we aim to provide a full model for solar hydrogen production and delivery by evaluating the potential of concentrated solar power and photovoltaics in the UAE, then comparing two different pathways for hydrogen delivery based on the location of hydrogen production sites. A Solid Oxide Cell Electrolyzer (SOEC) is used for technical comparison, while the shortest routes for hydrogen transport were analyzed using Geographical Information System (GIS). The results show that CSP technology coupled with SOEC is the most favorable pathway for large-scale hydrogen from solar energy production in the UAE for export purposes. Although PV has a slightly higher electricity potential compared to CSP, around 42 GWh/km² to 41.1 GWh/km², respectively, CSP show the highest productions rates of over 6 megatons of hydrogen when the electrolyzer is placed at the same site as the CSP plant, while PV generates 5.15 megatons when hydrogen is produced at the same site with PV plants; meanwhile, hydrogen from PV and CSP shows similar levels of 4.8 and 4.6 megatons of hydrogen, respectively, when electrolyzers are placed at port sites. Even considering the constraints in the UAE’s infrastructure and suggesting new shorter electrical transmission lines that could save up to 0.1 megatons of hydrogen in the second pathway, production at the same site with CSP is still the most advantageous scenario. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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12 pages, 1959 KiB  

Open AccessArticle

Use of Banana Waste as a Source for Bioelectricity Generation

by Segundo Rojas-Flores, Magaly De La Cruz-Noriega, Renny Nazario-Naveda, Santiago M. Benites, Daniel Delfín-Narciso, Luis Angelats-Silva and Emzon Murga-Torres

Processes 2022, 10(5), 942; https://0-doi-org.brum.beds.ac.uk/10.3390/pr10050942 - 09 May 2022

Cited by 11 | Viewed by 9909

Abstract

The large amounts of organic waste thrown into the garbage without any productivity, and the increase in the demand for electrical energy worldwide, has led to the search for new eco-friendly ways of generating electricity. Because of this, microbial fuel cells have begun [...] Read more.

The large amounts of organic waste thrown into the garbage without any productivity, and the increase in the demand for electrical energy worldwide, has led to the search for new eco-friendly ways of generating electricity. Because of this, microbial fuel cells have begun to be used as a technology to generate bioelectricity. The main objective of this research was to generate bioelectricity through banana waste using a low-cost laboratory-scale method, achieving the generation of maximum currents and voltages of 3.71667 ± 0.05304 mA and 1.01 ± 0.017 V, with an optimal pH of 4.023 ± 0.064 and a maximum electrical conductivity of the substrate of 182.333 ± 3.51 µS/cm. The FTIR spectra of the initial and final substrate show a decrease in the peaks belonging to phenolic compounds, alkanes, and alkenes, mainly. The maximum power density was 5736.112 ± 12.62 mW/cm² at a current density of 6.501 A/cm² with a peak voltage of 1006.95 mV. The molecular analysis of the biofilm formed on the anode electrode identified the species Pseudomonas aeruginosa (100%), and Paenalcaligenes suwonensis (99.09%), Klebsiella oxytoca (99.39%) and Raoultella terrigena (99.8%), as the main electricity generators for this type of substrate. This research gives a second use to the fruit with benefits for farmers and companies dedicated to exporting and importing because they can reduce their expenses by using their own waste. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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23 pages, 5259 KiB  

Open AccessReview

Computational Fluid Dynamics on Solar Dish in a Concentrated Solar Power: A Bibliometric Review

by Aristotle T. Ubando, Ariel Conversion, Renyl B. Barroca, Nelson H. Enano, Jr. and Randell U. Espina

Solar 2022, 2(2), 251-273; https://0-doi-org.brum.beds.ac.uk/10.3390/solar2020014 - 06 May 2022

Cited by 4 | Viewed by 3559

Abstract

Concentrated solar power is an alternative renewable energy technology that converts solar energy into electrical energy by using a solar concentrator and a solar receiver. Computational fluid dynamics have been used to numerically design concentrated solar power. This is a powerful numerical analysis [...] Read more.

Concentrated solar power is an alternative renewable energy technology that converts solar energy into electrical energy by using a solar concentrator and a solar receiver. Computational fluid dynamics have been used to numerically design concentrated solar power. This is a powerful numerical analysis approach that is widely used in energy and environmental engineering applications. In this paper, we review previous work on the applications of computational fluid dynamics in the design of concentrated solar power technology. We performed a bibliometric analysis of journal articles relevant to applications to analyze the current trend of utilization of computational fluid dynamics in these technologies. Then, we conducted a comprehensive analysis focused on the design of solar dish technology using computational fluid dynamics. Furthermore, we reviewed in detail the optical modeling of solar concentrators and solar receivers. Of the 83 retrieved publications from Scopus database, 80 were journal articles, and only three were review papers. Among these 80 journal articles, only 54 were relevant to this study, and 23 were relevant to solar dish technology. The documents were analyzed according to their number of citations, journal sources, and keyword evolution and network map. The information presented in this paper is useful to further recognize the contributions of computational fluid dynamics to the development of concentrated solar power, particularly to solar dish technology. In addition, we also discuss the challenges and future research directions to make solar energy a more sustainable source of renewable energy. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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24 pages, 6853 KiB  

Open AccessArticle

Concept for the Use of Cotton Waste Hydrolysates in Fermentation Media for Biofuel Production

by Michal J. Binczarski, Justyna Z. Malinowska, Joanna Berlowska, Weronika Cieciura-Wloch, Sebastian Borowski, Malgorzata Cieslak, Dorota Puchowicz and Izabela A. Witonska

Energies 2022, 15(8), 2856; https://0-doi-org.brum.beds.ac.uk/10.3390/en15082856 - 13 Apr 2022

Cited by 6 | Viewed by 2514

Abstract

Currently, most cotton textile waste is sent to landfill. However, due to the use of synthetic additives and the chemical treatment of cotton fibers, cotton textile waste is difficult to biodegrade. Cotton textile waste can also be subjected to material recycling, or to [...] Read more.

Currently, most cotton textile waste is sent to landfill. However, due to the use of synthetic additives and the chemical treatment of cotton fibers, cotton textile waste is difficult to biodegrade. Cotton textile waste can also be subjected to material recycling, or to incineration/gasification to produce energy. Here, we present the optimization of acid hydrolysis of cotton yarn fibers for glucose efficiency. The cotton yarn hydrolysates showed great potential for replacing simple sugar solutions in fermentation media. The highest glucose concentration was obtained in the hydrolysates of cotton yarn hydrolyzed in a 2% solution of sulfuric acid or phosphoric acid at 140–160 °C for 2 h. After 2 h of hydrolysis at 140 °C with 2% H₃PO₄, the concentration of glucose in the cotton yarn hydrolysate (13.19 g/L) increased fivefold compared with cotton yarn treated under the same conditions with H₂SO₄ (2.65 g/L). The structural modifications in the solid residues after acid hydrolysis were analyzed using a scanning electron microscope with energy dispersive spectroscopy (SEM-EDS), attenuated total reflectance Fourier-transform infrared spectroscopy (FTIR-ATR), and Raman spectroscopy. The SEM images, IR spectra, and Raman spectra revealed that the most significant changes in the morphology of the fibers occurred when the process was carried out at high temperatures (≥140 °C). Better growth of the yeast strains Saccharomyces cerevisiae Ethanol Red and Saccharomyces cerevisiae Tokay ŁOCK0204 was observed in the medium containing phosphoric acid hydrolysate. The maximum methane yield of 278 dm³/kgVS and the maximum hydrogen yield of 42 dm/kgVS were reported for cotton yarn waste after pretreatment with H₃PO₄. This might have been linked to the beneficial effect of phosphorus, which is a key nutrient for anaerobic digestion. The proposed hydrolysis method does not generate fermentation inhibitors. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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32 pages, 2116 KiB  

Open AccessFeature PaperEditor’s ChoiceReview

Recent Advances in the Decontamination and Upgrading of Waste Plastic Pyrolysis Products: An Overview

by Salma Belbessai, Abir Azara and Nicolas Abatzoglou

Processes 2022, 10(4), 733; https://0-doi-org.brum.beds.ac.uk/10.3390/pr10040733 - 11 Apr 2022

Cited by 25 | Viewed by 7575

Abstract

Extensive research on the production of energy and valuable materials from plastic waste using pyrolysis has been widely conducted during recent years. Succeeding in demonstrating the sustainability of this technology economically and technologically at an industrial scale is a great challenge. In most [...] Read more.

Extensive research on the production of energy and valuable materials from plastic waste using pyrolysis has been widely conducted during recent years. Succeeding in demonstrating the sustainability of this technology economically and technologically at an industrial scale is a great challenge. In most cases, crude pyrolysis products cannot be used directly for several reasons, including the presence of contaminants. This is confirmed by recent studies, using advanced characterization techniques such as two-dimensional gas chromatography. Thus, to overcome these limitations, post-treatment methods, such as dechlorination, distillation, catalytic upgrading and hydroprocessing, are required. Moreover, the integration of pyrolysis units into conventional refineries is only possible if the waste plastic is pre-treated, which involves sorting, washing and dehalogenation. The different studies examined in this review showed that the distillation of plastic pyrolysis oil allows the control of the carbon distribution of different fractions. The hydroprocessing of pyrolytic oil gives promising results in terms of reducing contaminants, such as chlorine, by one order of magnitude. Recent developments in plastic waste and pyrolysis product characterization methods are also reported in this review. The application of pyrolysis for energy generation or added-value material production determines the economic sustainability of the process. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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21 pages, 2927 KiB  

Open AccessArticle

Examination of Using Aluminum-Foam/Finned-Tube Beds Packed with Maxsorb III for Adsorption Ice Production System

by Mahmoud Badawy Elsheniti, Mohamed Shaaban Eissa, Hany Al-Ansary, Jamel Orfi, Osama Elsamni and Abdelrahman El-Leathy

Energies 2022, 15(8), 2757; https://0-doi-org.brum.beds.ac.uk/10.3390/en15082757 - 08 Apr 2022

Cited by 4 | Viewed by 1767

Abstract

Producing ice using adsorption systems can represent a sustainable solution and meet the recent global environmental regulations as they use natural refrigerants and can be driven by solar energy. However, the beds used in these systems still have low thermal and adsorption characteristics. [...] Read more.

Producing ice using adsorption systems can represent a sustainable solution and meet the recent global environmental regulations as they use natural refrigerants and can be driven by solar energy. However, the beds used in these systems still have low thermal and adsorption characteristics. This study investigates numerically the use of an emerging aluminum foamed bed packed with advanced Maxsorb adsorbent in a two-bed adsorption system and reports cases of performance improvements compared to the classical finned-tube based system used to produce ice. A comprehensive 2-D transient pressure distribution model for the two beds was developed and validated. The model considers the temporal and spatial variations of the two beds’ parameters, while the effect of the thermal mass and heat transfer effectiveness of the condenser and evaporator components are imitated at the boundary conditions for bed openings using two zero-dimensional models. The results show the interrelated effects of varying the cycle times from 400 s to 1200 s with 2, 5, and 10 mm foam thicknesses/fin heights on the overall performance of both systems. The Al-foam based system demonstrated the performance superiority at a 2 mm foam thickness with maximum ice production of 49 kg_ice/kg_ads in 8 h, an increase of 26.6% over the counterpart finned-tube based system at a 400 s cycle time. The best COP of 0.366 was attained at a 5 mm foam thickness and 1200 s with an increase of 26.7%. The effective uptake of the Al-foam based system was reduced dramatically at a 10 mm foam thickness, which deteriorated the system performance. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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31 pages, 10449 KiB  

Open AccessArticle

Thermal Stability Calculation and Experimental Investigation of Common Binary Chloride Molten Salts Applied in Concentrating Solar Power Plants

by Jingyu Zhong, Jing Ding, Jianfeng Lu, Xiaolan Wei and Weilong Wang

Energies 2022, 15(7), 2516; https://0-doi-org.brum.beds.ac.uk/10.3390/en15072516 - 29 Mar 2022

Cited by 3 | Viewed by 2204

Abstract

A computational study on thermal stability was conducted the first time, combining the modified quasi-chemical model, the Antoine equation, and the adiabatic flash evaporation calculation principle to design a method to calculate the system pressure-temperature (P-T) phase diagram of binary chloride molten salts. [...] Read more.

A computational study on thermal stability was conducted the first time, combining the modified quasi-chemical model, the Antoine equation, and the adiabatic flash evaporation calculation principle to design a method to calculate the system pressure-temperature (P-T) phase diagram of binary chloride molten salts. The evaporation temperature of the molten salt obtained by analyzing the P-T phase diagram of the eutectic molten salt clearly defined the upper limit of the optimal operating temperature of the mixed molten salt. The results indicated that the upper-temperature limits of NaCl-KCl, NaCl-CaCl₂, KCl-CaCl₂, NaCl-MgCl₂, and KCl-MgCl₂ are determined to be 1141 K, 1151 K, 1176 K, 1086 K, and 1068 K. The maximum working temperature was measured experimentally using a thermogravimetric analysis (TGA), and the relative error between the calculation and experiment was calculated. The maximum error between the calculated and experimental values of the maximum operating temperature was 6.02%, while the minimum was 1.29%, demonstrating the method’s high accuracy. Combined with the lowest eutectic temperature and the upper-temperature limits of binary chloride molten salts, the stable operating temperature ranges of NaCl-KCl, NaCl-CaCl₂, KCl-CaCl₂, NaCl-MgCl₂, and KCl-MgCl₂ are 891~1141 K, 750~1151 K, 874~1176 K, 732~1086 K, and 696~1086 K. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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25 pages, 7906 KiB  

Open AccessArticle

Thermochromic Materials as Passive Roof Technology: Their Impact on Building Energy Performance

by Eva Crespo Sánchez and David Masip Vilà

Energies 2022, 15(6), 2161; https://0-doi-org.brum.beds.ac.uk/10.3390/en15062161 - 16 Mar 2022

Cited by 5 | Viewed by 2637

Abstract

Over the last few years, new materials have been developed which a priori, appear to improve passive energy efficiency in buildings. This article focuses on chromogenic devices that allow changing their optical properties in a reversible manner through some external stimulus. The covering [...] Read more.

Over the last few years, new materials have been developed which a priori, appear to improve passive energy efficiency in buildings. This article focuses on chromogenic devices that allow changing their optical properties in a reversible manner through some external stimulus. The covering of the envelopes may have different textures or colors, which determine the amount of solar radiation absorbed by the material compared to the incident radiation. In buildings with a high percentage of roof relative to façade, the surface finish plays an interesting role in the energy demand. In the present work, the influence of the application of thermochromic materials to the roofs of commercial buildings is analyzed. It has been demonstrated that the application of a thermochromic surface finish can produce savings of annual energy demand between 1% and 12% in kilowatt-hours and kilograms of CO₂ and they become more significant for construction solutions with higher transmittances values. Then, the impact of applying a thermochromic finish per day is analyzed and which transition temperature range will be the most optimal to the highest energy performance is discussed. At the same time, an assessment is made of the optimal cost; although economic investment is not currently amortized, it is a good resource for reducing energy demand in buildings. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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21 pages, 43893 KiB  

Open AccessArticle

Non-Symmetrical (NS) Reconfiguration Techniques to Enhance Power Generation Capability of Solar PV System

by Suresh Mikkili, Akshay Kanjune, Praveen Kumar Bonthagorla and Tomonobu Senjyu

Energies 2022, 15(6), 2124; https://0-doi-org.brum.beds.ac.uk/10.3390/en15062124 - 14 Mar 2022

Cited by 6 | Viewed by 1840

Abstract

At present, primary power generation depends on non-renewable energy resources, which will become extinct. Solar is the best option in renewable energy sources to achieve clean and green power extraction. Solar PV transforms light energy into electrical energy. However, the output power of [...] Read more.

At present, primary power generation depends on non-renewable energy resources, which will become extinct. Solar is the best option in renewable energy sources to achieve clean and green power extraction. Solar PV transforms light energy into electrical energy. However, the output power of solar PV changes with solar insolation. It is also affected by environmental factors and the shading effect. One of the key factors that can reduce the PV system output power is partial shading condition (PSC). The reduction in power output not only depends on shaded region but also depends on pattern of shading and physical position of shaded modules in the array. Due to PSCs, mismatch losses are induced between the shaded modules which can cause several peaks in the output power-voltage (P-V) characteristic. This article describes the non-symmetrical reconfiguration technique and compares it with the primary total cross tied connection. The performance of non-symmetrical reconfiguration techniques is evaluated and compared in terms of global maximum power (GMP), voltage and currents at GMP, open and short circuit voltage and currents, mismatch power loss (MPL), fill factor, efficiency, and number of local maximum power peaks (LMPPs) on a 9 × 9 PV array. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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13 pages, 1163 KiB  

Open AccessArticle

Structural Changes of Alkali Lignin under Ozone Treatment and Effect of Ozone-Oxidized Alkali Lignin on Cellulose Digestibility

by Hongyuan Wang, Lihong Zhao, Junli Ren and Beihai He

Processes 2022, 10(3), 559; https://0-doi-org.brum.beds.ac.uk/10.3390/pr10030559 - 13 Mar 2022

Cited by 3 | Viewed by 2432

Abstract

In this study, the structural changes of alkali lignin induced by ozonation were investigated, and the effect of ozone-treated alkali lignin and its mechanism on Avicel enzymatic hydrolysis was examined. The physicochemical properties of alkali lignin were analyzed by FTIR, ¹H-¹³ [...] Read more.

In this study, the structural changes of alkali lignin induced by ozonation were investigated, and the effect of ozone-treated alkali lignin and its mechanism on Avicel enzymatic hydrolysis was examined. The physicochemical properties of alkali lignin were analyzed by FTIR, ¹H-¹³C HSQC NMR, and GPC. It was revealed that ozone pretreatment increased the content of carboxyl and/or aldehyde groups and the negative zeta potential of alkali lignin, which enhanced the electrostatic repulsion between alkali lignin and cellulase; The S/G ratio was reduced, indicating the hydrophobic interaction was diminished. The Langmuir adsorption isotherm showed that the cellulase binding strength of ozone pretreated alkali lignin (OL-pH3, OL-pH7, and OL-pH12 were 16.67, 13.87, and 44.05 mL/g, respectively) was significantly lower than that of alkali lignin (161.29 mL/g). The 72 h hydrolysis yields of Avicel added with OL-pH3, OL-pH7, and OL-pH12 were 55.4%, 58.6%, and 54.9% respectively, which were 2.6–6.3% higher than that of Avicel added with AL (52.3%). This research aimed to reduce the non-productive adsorption between cellulase and lignin by investigating the structural changes of lignin caused by ozone treatment. For the first time, we discovered that ozone-treated alkali lignin has a further promotion effect on the enzymatic digestion of cellulose, providing a green and feasible pretreatment process for the enzymatic hydrolysis of lignocellulose and aiding in the more efficient utilization of biomass. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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25 pages, 2721 KiB  

Open AccessReview

Managing Technology Transfer Challenges in the Renewable Energy Sector within the European Union

by Siddharth Suhas Kulkarni, Lin Wang and Demetrios Venetsanos

Wind 2022, 2(1), 150-174; https://0-doi-org.brum.beds.ac.uk/10.3390/wind2010009 - 08 Mar 2022

Cited by 6 | Viewed by 4801

Abstract

The use of fossil fuels to generate energy is often associated with serious negative effects on the environment. The greenhouse gas emissions resulting from burning these fuels destroy the ozone layer and lead to global warming. As a strategic approach to the solution [...] Read more.

The use of fossil fuels to generate energy is often associated with serious negative effects on the environment. The greenhouse gas emissions resulting from burning these fuels destroy the ozone layer and lead to global warming. As a strategic approach to the solution of this problem, calls for research and development, as well as the implementation of technologies associated with renewable energy sources within the European Union (EU), have intensified in recent years. One of the keys to a successful outcome from this intensified effort is to identify the challenges associated with the transfer of both intellectual property and technology rights in the renewable energy sector within the EU. The present paper contributes towards this direction. Firstly, data from the literature were used to identify contemporary trends within the European Union with regards to technology transfer and intellectual property within the sector of renewable energy. Then, a statistical analysis utilising an ordinary least squares (OLS) model was conducted to establish a correlation between renewable energy innovations (research and development) and the level of investment associated with renewable energy technologies. Finally, this correlation, along with the associated challenges, was then critically explored for four of the most popular renewable energy sources (namely solar energy, biomass, wind energy, and marine renewable energy), and conclusions are reported. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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28 pages, 4356 KiB  

Open AccessArticle

Scenario-Based Comparative Analysis for Coupling Electricity and Hydrogen Storage in Clean Oilfield Energy Supply System

by Fengyuan Yan, Xiaolong Han, Qianwei Cheng, Yamin Yan, Qi Liao and Yongtu Liang

Energies 2022, 15(6), 1957; https://0-doi-org.brum.beds.ac.uk/10.3390/en15061957 - 08 Mar 2022

Cited by 1 | Viewed by 2072

Abstract

In response to the objective of fully attaining carbon neutrality by 2060, people from all walks of life are pursuing low-carbon transformation. Due to the high water cut in the middle and late phases of development, the oilfield’s energy consumption will be quite [...] Read more.

In response to the objective of fully attaining carbon neutrality by 2060, people from all walks of life are pursuing low-carbon transformation. Due to the high water cut in the middle and late phases of development, the oilfield’s energy consumption will be quite high, and the rise in energy consumption will lead to an increase in carbon emission at the same time. As a result, the traditional energy model is incapable of meeting the energy consumption requirement of high water cut oilfields in their middle and later phases of development. The present wind hydrogen coupling energy system was researched and coupled with the classic dispersed oilfield energy system to produce energy for the oilfields in this study. This study compares four future energy system models to existing ones, computes the energy cost and net present value of an oilfield in Northwest China, and proposes a set of economic evaluation tools for oilfield energy systems. The study’s findings indicate that scenario four provides the most economic and environmental benefits. This scenario effectively addresses the issue of high energy consumption associated with aging oilfields at this point, significantly reduces carbon emissions, absorbs renewable energy locally, and reduces the burden on the power grid system. Finally, sensitivity analysis is utilized to determine the effect of wind speed, electricity cost, and oilfield gas output on the system’s economic performance. The results indicate that the system developed in this study can be applied to other oilfields. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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16 pages, 1541 KiB  

Open AccessReview

Renewable Energy Development in the Gulf Cooperation Council Countries: Status, Barriers, and Policy Options

by Aisha Al-Sarihi and Noura Mansouri

Energies 2022, 15(5), 1923; https://0-doi-org.brum.beds.ac.uk/10.3390/en15051923 - 06 Mar 2022

Cited by 13 | Viewed by 8640

Abstract

The countries of the Gulf Cooperation Council (GCC)—Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, and the United Arab Emirates—hold almost 30% of the world’s total proven oil reserves and around 20% of its total proven natural gas reserves. They are also endowed with a [...] Read more.

The countries of the Gulf Cooperation Council (GCC)—Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, and the United Arab Emirates—hold almost 30% of the world’s total proven oil reserves and around 20% of its total proven natural gas reserves. They are also endowed with a high abundance of renewable energy resources such as solar and wind. Yet, the GCC’s primary energy consumption is still dominated by fossil fuels, and the share of renewable energy still does not exceed 1%. Drawing on secondary data, including journal articles, governmental and companies’ websites, and reports and newspaper articles, this paper assesses the reasons behind their underutilization of renewable energy resources. Whereas technical and economic feasibility issues had been identified as the main barriers to slow the uptake of renewable energy technologies in the GCC, this paper uncovered that various additional factors have remarkably influenced such delays. High hydrocarbon subsidies, low electricity tariff structure, fragmented energy policy, the absence of dedicated renewable energy regulator and regulatory framework, and a highly controlled power market are major barriers to renewable energy adoption in the GCC. The paper concludes with policy options to inform scaling up the adoption of renewable energy in the GCC. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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22 pages, 3836 KiB  

Open AccessArticle

Design and System Evaluation of Mixed Waste Plastic Gasification Process Based on Integrated Gasification Combined Cycle System

by Hui Xu and Bin Shi

Processes 2022, 10(3), 499; https://0-doi-org.brum.beds.ac.uk/10.3390/pr10030499 - 02 Mar 2022

Cited by 10 | Viewed by 4524

Abstract

Plastic products are widely used due to their superior performance, but there are still limitations in the current methods and technologies for recycling and processing of waste plastics, resulting in a huge wasting of resources and environmental pollution. The element composition of waste [...] Read more.

Plastic products are widely used due to their superior performance, but there are still limitations in the current methods and technologies for recycling and processing of waste plastics, resulting in a huge wasting of resources and environmental pollution. The element composition of waste plastics determines its great gasification potential. In this paper, three different waste plastic gasification processes are designed in a process simulator based on the conventional Integrated Gasification Combined Cycle (IGCC) system to achieve waste conversion and utilization as well as carbon capture. Design 1 is based on the cryogenic air separation (CAS) process to obtain oxygen, which is sent to the gasifier together with steam and pretreated waste plastics. The synthesis gas is purified and synthesized into methanol, and the residual gas is passed to the gas turbine and steam turbine to achieve multiple production of heat, electricity, and methanol. Design 2 uses a Vacuum Pressure Swing Adsorption (VPSA) process to produce oxygen, which reduces the energy consumption by 56.3% compared to Design 1. Design 3 adds a calcium-looping (CaL) reaction coupled with a steam conversion reaction to produce high-purity hydrogen as a product, while capturing the generated CO₂ to improve the conversion rate of the reaction. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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19 pages, 10873 KiB  

Open AccessArticle

Numerical and Experimental Investigation of the Effect of Design Parameters on Savonius-Type Hydrokinetic Turbine Performance

by Kuo-Tsai Wu, Kuo-Hao Lo, Ruey-Chy Kao and Sheng-Jye Hwang

Energies 2022, 15(5), 1856; https://0-doi-org.brum.beds.ac.uk/10.3390/en15051856 - 02 Mar 2022

Cited by 7 | Viewed by 3161

Abstract

To meet the increased demand of hydroelectric power generation, a novel drag-based Savonius turbine with the characteristics of a simpler fabrication process and good starting characteristics is designed, fabricated, and analyzed. The newly designed turbine is suitable to be installed in rivers, irrigation [...] Read more.

To meet the increased demand of hydroelectric power generation, a novel drag-based Savonius turbine with the characteristics of a simpler fabrication process and good starting characteristics is designed, fabricated, and analyzed. The newly designed turbine is suitable to be installed in rivers, irrigation channels, ocean currents, etc., for small-scale hydroelectric power generation. In the present study, experiments are carried out to investigate the influence of the design parameters of this turbine on its power performance in order to improve its efficiency, including blade arc angles (180°, 135°), blade placement angles (0°, ±22.5°), and the number of blades (2, 3, 6, and 8). Further, three-dimensional CFD simulations are performed with Re = $6.72\times {10}^5$, matching the experimental conditions, in order to study the changes in the flow field and the rotation characteristics of the turbine. The research results indicate that a six-bladed turbine with a blade arc angle of 135° and a blade placement angle of 0° has higher torque and better power performance, which makes it the most suitable design when also considering cost. Furthermore, it was found that an increase in the number of turbine blades contributes to improving the performance of the turbine. The maximum power coefficient is 0.099 at a tip speed ratio of 0.34. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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23 pages, 19317 KiB  

Open AccessArticle

Micro-Grid Oil Palm Plantation Waste Gasification Power Plant in Indonesia: Techno-Economic and Socio-Environmental Analysis

by Jaka Isgiyarta, Bambang Sudarmanta, Jalu Aji Prakoso, Eka Nur Jannah and Arif Rahman Saleh

Energies 2022, 15(5), 1782; https://0-doi-org.brum.beds.ac.uk/10.3390/en15051782 - 28 Feb 2022

Cited by 4 | Viewed by 2234

Abstract

The utilization of new and renewable energy sources explicitly based on biomass needs to be increased to reduce dependence on fossil fuels. One of the potential biomasses of plantation waste in Indonesia that can be utilized is oil palm plantation waste in the [...] Read more.

The utilization of new and renewable energy sources explicitly based on biomass needs to be increased to reduce dependence on fossil fuels. One of the potential biomasses of plantation waste in Indonesia that can be utilized is oil palm plantation waste in the form of fronds and trunks that are converted with multi-stage downdraft gasification technology. This study aimed to conduct a technical analysis, economic analysis, investment risk analysis, social analysis, and an environmental impact assessment of power plants fueled by oil palm plantation waste. The method used was the upscaling of a prototype of a 10 kW power plant to 100 kW. The results showed that it was technically and economically feasible to apply. The economic indicators were a positive NPV of USD 48.846 with an IRR of 9.72% and a B/C ratio of 1.16. The risk analysis predicted a probability of an NPV 49.94% above the base case. The study of the social aspects suggested that the construction of power plants has a positive impact in the form of increased community income and the growth of new economic sectors that utilize electricity as a primary source. An analysis of the environmental effects is critical so that the impacts can be minimized. Overall, the construction of small-scale power plants in oil palm plantations is worth considering as long as it is carried out following the applicable regulations. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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19 pages, 5632 KiB  

Open AccessArticle

Low-Grade Flow Energy Harvesting by Low-Mass-Ratio Oscillating Bent Plate

by Wei Jiang, Fan Wu, Ziyue Mei, Rui Shi and Danmei Xie

Energies 2022, 15(5), 1606; https://0-doi-org.brum.beds.ac.uk/10.3390/en15051606 - 22 Feb 2022

Viewed by 1213

Abstract

Low-grade renewable energy possesses large reserves and a wide distribution in the environment, but it is far from fully exploited due to the high cost–income ratio when using traditional convertors. A fluid-induced-vibration-based flow energy convertor with a low-cost bent plate as an oscillator [...] Read more.

Low-grade renewable energy possesses large reserves and a wide distribution in the environment, but it is far from fully exploited due to the high cost–income ratio when using traditional convertors. A fluid-induced-vibration-based flow energy convertor with a low-cost bent plate as an oscillator is proposed to achieve better energy converting performance for low-grade flow energy conversion. The energy extraction performance and dynamic response of the bent plate are assessed numerically. The results demonstrate that the prescribed single-DOF (degree of freedom) bent plate can reach the maximum efficiency of 29.6% and power coefficient of 2.36 at the relative plunging amplitude of 3.5, while the double-DOF bent plate achieves a maximum efficiency of 37.3% and power coefficient of 1.42 at a smaller amplitude of 1.4. It is discovered that the adoption of pitching motion can help to control the variation pattern of the effective AOA (angle of attack), while the camber of the bent plate also regulates the effective AOA from the geometrical respect. The FIV-based single-DOF convertor can achieve an energy converting efficiency of 29.3% and approach the ideal sinusoidal motion trajectory closely, indicating that the optimal active motion mode can be realized by the passive motion mode with the appropriate choice of the dynamic parameters. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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16 pages, 5305 KiB  

Open AccessArticle

Savonius Wind Turbine Numerical Parametric Analysis Using Space-Filling Design and Gaussian Stochastic Process

by Aristotle T. Ubando, Rathana San and John Deric P. Cruz

Wind 2022, 2(1), 113-128; https://0-doi-org.brum.beds.ac.uk/10.3390/wind2010007 - 18 Feb 2022

Cited by 2 | Viewed by 3300

Abstract

Wind energy is an alternative source of clean energy to address the growing energy demand and provide pollution-free electricity. With the rapid development of urban areas, high wind energy resources such as high-rise building rooftops are excellent locations for urban wind turbine installation. [...] Read more.

Wind energy is an alternative source of clean energy to address the growing energy demand and provide pollution-free electricity. With the rapid development of urban areas, high wind energy resources such as high-rise building rooftops are excellent locations for urban wind turbine installation. One of the practical and simple urban wind turbines is the Savonius design. It has a simple design, easy to maintain, and is very affordable. This work focuses on the design evaluation of a Savonius wind turbine (SWT) by varying the rotor diameter, rotor height, and twist angle for urban applications. A transient computational fluid dynamics (CFD) approach is applied to assess the various design treatments using a space-filling design of experiments. To address the spaces in the hypercube statistical design, a sphere packing design method was adopted which suited the evaluation of computational simulations results such as that of the CFD. The Gaussian stochastic process model was applied to establish the trend of the parametric performance of the optimized SWT design through the model fitting. The results have shown that optimized SWT performs well with its self-starting capability compared to the traditional Savonius design. In addition, the optimized SWT has shown a better peak power coefficient compared with the results of previous works on the design of SWT. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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23 pages, 2976 KiB  

Open AccessArticle

Assessment of the Electricity System Transition towards High Share of Renewable Energy Sources in South Asian Countries

by Aqsa Rana and Gyula Gróf

Energies 2022, 15(3), 1139; https://0-doi-org.brum.beds.ac.uk/10.3390/en15031139 - 03 Feb 2022

Cited by 5 | Viewed by 2328

Abstract

The progressive use of renewable energy sources to ensure a continuous and abundant energy supply is the significant target towards a sustainable and secure energy system. Previously, the countries that had relied on fossil fuel as a dominating energy source are now endorsing [...] Read more.

The progressive use of renewable energy sources to ensure a continuous and abundant energy supply is the significant target towards a sustainable and secure energy system. Previously, the countries that had relied on fossil fuel as a dominating energy source are now endorsing energy system transition towards renewable energy sources. In this study, a comparative assessment of the energy problems of South Asian countries is summarized. Nevertheless, there are many similarities and differences in the electricity supply system of these countries. Long-term planning for renewable energy development is suggested for a diverse population and dispersed geographical location considering all the significant challenges. However, appropriate schemes are imperative for integrating significant renewable energy sources. This study introduces a foresight plan of the electricity model according to the demand and supply balance for extensive technical analysis. The EnergyPLAN modeling tool was employed to work out a more ambitious VRE integration scenario than the official plans. The reference model was validated according to legitimate and authentic data, and then, the technically most feasible renewable energy-based alternate scenario was built. The additional grid integration cost of variable renewable energy was quantitatively investigated for comprehensive power system modeling for a real-time economic analysis. The results may be adapted and support developing more sustainable power generation serving 1787 million in South Asian countries. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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26 pages, 7237 KiB  

Open AccessReview

Electric Vehicles: V2G for Rapid, Safe, and Green EV Penetration

by Abdullah Dik, Siddig Omer and Rabah Boukhanouf

Energies 2022, 15(3), 803; https://0-doi-org.brum.beds.ac.uk/10.3390/en15030803 - 22 Jan 2022

Cited by 41 | Viewed by 8553

Abstract

Low carbon and renewable energy sources (RESs) are fast becoming a key sustainable instrument in meeting the global growth of electricity demand while curbing carbon emissions. For example, the gradual displacement of fossil-fuelled vehicles with electrically driven counterparts will inevitably increase both the [...] Read more.

Low carbon and renewable energy sources (RESs) are fast becoming a key sustainable instrument in meeting the global growth of electricity demand while curbing carbon emissions. For example, the gradual displacement of fossil-fuelled vehicles with electrically driven counterparts will inevitably increase both the power grid baseload and peak demand. In many developed countries, the electrification process of the transport sector has already started in tandem with the installation of multi-GW renewable energy capacity, particularly wind and solar, huge investment in power storage technology, and end-user energy demand management. The expansion of the Electric Vehicle (EV) market presents a new opportunity to create a cleaner and transformative new energy carrier. For instance, a managed EV battery charging and discharging profile in conjunction with the national grid, known as the Vehicle-to-Grid system (V2G), is projected to be an important mechanism in reducing the impact of renewable energy intermittency. This paper presents an extensive literature review of the current status of EVs and allied interface technology with the power grid. The main findings and statistical details are drawn from up-to-date publications highlighting the latest technological advancements, limitations, and potential future market development. The authors believe that electric vehicle technology will bring huge technological innovation to the energy market where the vehicle will serve both as a means of transport and a dynamic energy vector interfacing with the grid (V2G), buildings (V2B), and others (V2X). Full article

(This article belongs to the Topic Sustainable Energy Technology)

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18 pages, 2060 KiB  

Open AccessArticle

Investigation of Biomass Integrated Air Gasification Regenerative Gas Turbine Power Plants

by Momin Elhadi Abdalla, Salah Ahmed Abdalla, Syed Ali Ammar Taqvi, Salman Raza Naqvi and Wei-Hsin Chen

Energies 2022, 15(3), 741; https://0-doi-org.brum.beds.ac.uk/10.3390/en15030741 - 20 Jan 2022

Cited by 7 | Viewed by 1980

Abstract

The results show that Wood Chips of Acacia Nilotica trees available in Sudan lands can be successfully used in the gasification process and, on the same basis, as a bio-renewable energy resource. Simulation models were used to characterize the air gasification process integrated [...] Read more.

The results show that Wood Chips of Acacia Nilotica trees available in Sudan lands can be successfully used in the gasification process and, on the same basis, as a bio-renewable energy resource. Simulation models were used to characterize the air gasification process integrated with a Regenerative Gas Turbine Unit. The results revealed that at a moisture content of 12%, gasification temperature of 1500 K, pressure of 20 bar, and air-like gasification medium, the biomass gasifier’s flow rate is higher at higher syngas rates. The results verified that there is an optimum ER for each syngas rate, in which the slow growth of the ER revealed the maximum gasifier biomass flow rate. For ER growth at lower levels, the specific fuel consumption (SFC) of the RGT Unit declines sharply from the maximum value reached at 0.27 kg/kW·h at an ER of 5% to the minimum value reached at 0.80 kg/kW·h at an ER of 25% for the lowest gasification temperature of 1000 K. Moreover, ER growths at low levels have a significant effect on the RGT plant’s performance, leading to increased RGT thermal efficiency. The increase in the biomass moisture content led to a sharp decrease in the RGT thermal efficiency. The RGT thermal efficiency remains high at higher gasification pressure. The results revealed that the syngas lower heating value remains high at lower produced syngas rates. At the optimum ER, the H₂ mole fraction depicted a value of 1.25%, 0.85% of CO, and 10.50% of CH₄ for a lower heating value of 38 MJ/kg syngas. It is shown that the gasification air entered into the gasifier decreases amid the increase in the biomass moisture content. At different syngas rates (3–10 kg/s) and optimum ER, the results predicted that the Wood Chip biomass flow rates decrease when the gasifier efficiency increases. The simulation model revealed that ER growths at lower levels have a significant effect on increasing the power of the RGT plant. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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13 pages, 3589 KiB  

Open AccessArticle

Equivalent Aerodynamic Design of Blade for Offshore Floating Wind Turbine Model

by Jiahuan Lin, Huawei Duan, Baoming Xu, Yangwei Wang and Jun Zhang

J. Mar. Sci. Eng. 2022, 10(2), 132; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse10020132 - 20 Jan 2022

Cited by 2 | Viewed by 2310

Abstract

The Froude-scaled offshore floating wind turbine model is inevitably affected by the Reynolds number effect, making the model unable to correctly reproduce the thrust performance of the reference wind turbine (RWT). To solve this problem, an Xfoil-AirfoilPrep-Matlab (XAM) system and a wide tip [...] Read more.

The Froude-scaled offshore floating wind turbine model is inevitably affected by the Reynolds number effect, making the model unable to correctly reproduce the thrust performance of the reference wind turbine (RWT). To solve this problem, an Xfoil-AirfoilPrep-Matlab (XAM) system and a wide tip speed ratio search method (WTSM) are proposed to design a wide tip speed ratio (TSR) thrust-match model blade. The XAM system is utilized to select the best airfoil for WTSM by calculating the lift and drag coefficients of several airfoils. The WTSM is utilized to optimize the blade chord and twist. It formalizes the blade chord and twist by polynomials and then optimizes the polynomial coefficients. The thrust coefficients construct the optimization object at different TSRs. For validating the effect of the redesigned blade, the thrust performance is compared to that of the RWT blade. In addition, the thrust performance of redesigned blade at different pitch angles is also calculated and compared to those of the RWT blade. Results show that the thrust performance of redesigned blade matches well with that of the RWT blade at 0 pitch angle, and it can also match the variations of that of the RWT blade at the other pitch angles well. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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19 pages, 3881 KiB  

Open AccessArticle

Analysis of the Influence of Control Strategy and Heating Loads on the Performance of Hybrid Heat Pump Systems for Residential Buildings

by Erica Roccatello, Alessandro Prada, Paolo Baggio and Marco Baratieri

Energies 2022, 15(3), 732; https://0-doi-org.brum.beds.ac.uk/10.3390/en15030732 - 19 Jan 2022

Cited by 7 | Viewed by 2438

Abstract

Air-to-water heat pumps (HPs) are widely installed in new buildings; however, they face performance degradation with high temperature emission systems, which is typical of existing buildings, or during domestic hot water (DHW) production. Hybrid systems (HSs), composed by air-to-water HPs and gas-fired boilers, [...] Read more.

Air-to-water heat pumps (HPs) are widely installed in new buildings; however, they face performance degradation with high temperature emission systems, which is typical of existing buildings, or during domestic hot water (DHW) production. Hybrid systems (HSs), composed by air-to-water HPs and gas-fired boilers, can mitigate these issues by increasing the overall system efficiency. HS performance is strictly dependent on the configuration and control management of the system itself. Moreover, the building and heating plant also have a strong influence. This study presents an overview of the application of HSs that considers both space heating (SH) and DHW production, by comparing the primary energy (PE) consumption obtained by dynamic simulations. Different climates, building typologies, and DHW withdrawal profiles are used to extend the results’ validity. Additionally, several HS control strategies were implemented and compared. The results show a PE savings ranging from 5% to 22% depending on the control strategy and the external parameters applied in the simulation. The comparison of the control strategies shows that the most efficient strategies are the ones maximizing heat pump utilization. The dependence of PE savings of HS on COP values is highlighted, and a correlation is presented to provide designers with guidance on the applicability of HSs. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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14 pages, 7894 KiB  

Open AccessArticle

Development of a Low-Depth Modular GHX through a Real-Scale Experiment

by Kwonye Kim, Sangmu Bae, Yujin Nam, Euyjoon Lee and Evgueniy Entchev

Energies 2022, 15(3), 698; https://0-doi-org.brum.beds.ac.uk/10.3390/en15030698 - 18 Jan 2022

Cited by 3 | Viewed by 1411

Abstract

The global energy sector is aiming to rapidly transform energy systems into those less dependent on fossil fuels to reduce their harmful effects on the climate. Although ground source heat pump (GSHP) systems are more efficient than conventional air-source heat pump (ASHP) systems, [...] Read more.

The global energy sector is aiming to rapidly transform energy systems into those less dependent on fossil fuels to reduce their harmful effects on the climate. Although ground source heat pump (GSHP) systems are more efficient than conventional air-source heat pump (ASHP) systems, the high initial investment cost, particularly for a vertical closed-loop type ground heat exchanger (GHX), makes it difficult to incorporate them into small buildings. This paper proposes a low-depth modular GHX for reducing cost and improving the workability of GSHPs. A modular GHX is a cubical structure comprising tubes and buried using an excavator at a depth 4 m below the ground surface. This GHX is manufactured at a factory, carried by a small truck, and then installed by a small lift or a backhoe such that it can be installed in small buildings or narrow spaces at low depths underground. In this research, the performance and feasibility analyses of modular and vertical GHXs were conducted via a real-scale experiment. The results demonstrate that the modular GHX influences the workability of GSHPs by 91% during the heating period and 70% during the cooling period. In contrast to the conventional HVAC, the modular and vertical GHXs could recover the initial investment costs in 4 years and 10 years, respectively. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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17 pages, 15070 KiB  

Open AccessArticle

Blade-Resolved CFD Simulations of a Periodic Array of NREL 5 MW Rotors with and without Towers

by Lun Ma, Pierre-Luc Delafin, Panagiotis Tsoutsanis, Antonis Antoniadis and Takafumi Nishino

Wind 2022, 2(1), 51-67; https://0-doi-org.brum.beds.ac.uk/10.3390/wind2010004 - 14 Jan 2022

Cited by 2 | Viewed by 2879

Abstract

A fully resolved (FR) NREL 5 MW turbine model is employed in two unsteady Reynolds-averaged Navier–Stokes (URANS) simulations (one with and one without the turbine tower) of a periodic atmospheric boundary layer (ABL) to study the performance of an infinitely large wind farm. [...] Read more.

A fully resolved (FR) NREL 5 MW turbine model is employed in two unsteady Reynolds-averaged Navier–Stokes (URANS) simulations (one with and one without the turbine tower) of a periodic atmospheric boundary layer (ABL) to study the performance of an infinitely large wind farm. The results show that the power reduction due to the tower drag is about 5% under the assumption that the driving force of the ABL is unchanged. Two additional simulations using an actuator disc (AD) model are also conducted. The AD and FR results show nearly identical tower-induced reductions of the wind speed above the wind farm, supporting the argument that the AD model is sufficient to predict the wind farm blockage effect. We also investigate the feasibility of performing delayed-detached-eddy simulations (DDES) using the same FR turbine model and periodic domain setup. The results show complex turbulent flow characteristics within the farm, such as the interaction of large-scale hairpin-like vortices with smaller-scale blade-tip vortices. The computational cost of the DDES required for a given number of rotor revolutions is found to be similar to the corresponding URANS simulation, but the sampling period required to obtain meaningful time-averaged results seems much longer due to the existence of long-timescale fluctuations. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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11 pages, 3266 KiB  

Open AccessArticle

Flight Simulator’s Energy Consumption Depending on the Conditions of the Air Operation

by Michał Gołębiewski, Marta Galant-Gołębiewska and Remigiusz Jasiński

Energies 2022, 15(2), 580; https://0-doi-org.brum.beds.ac.uk/10.3390/en15020580 - 14 Jan 2022

Cited by 4 | Viewed by 1964

Abstract

Protection of the natural environment is a key activity driving development in the transport discipline today. The use of simulators to train civil aviation pilots provides an excellent opportunity to maintain the balance between efficiency and limit the negative impact of transport on [...] Read more.

Protection of the natural environment is a key activity driving development in the transport discipline today. The use of simulators to train civil aviation pilots provides an excellent opportunity to maintain the balance between efficiency and limit the negative impact of transport on the environment. Therefore, we decided to determine the impact of selected simulations of air operations on energy consumption. The aim of the research was to determine the energy consumption of the flight simulator depending on the type of flight operation and configuration used. We also decided to compare the obtained result with the energy consumption of an aircraft of a similar class, performing a similar aviation operation and other means of transport. In order to obtain the results, a research plan was proposed consisting of 12 scenarios differing in the simulated aircraft model, weather conditions and the use of the simulator motion platform. In each of the scenarios, energy consumption was measured, taking into account the individual components of the simulator. The research showed that the use of a flight simulator has a much smaller negative impact on the natural environment than flying in a traditional plane. Use of a motion platform indicated a change in energy consumption of approximately 40% (in general, flight simulator configuration can change energy consumption by up to 50%). The deterioration of weather conditions during the simulation caused an increase in energy consumption of 14% when motion was disabled and 18% when motion was enabled. Energy consumption in the initial stages of pilot training can be reduced by 97% by using flight simulators compared to aircraft training. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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14 pages, 1127 KiB  

Open AccessArticle

Machine Intelligent Hybrid Methods Based on Kalman Filter and Wavelet Transform for Short-Term Wind Speed Prediction

by Yug Patel and Dipankar Deb

Wind 2022, 2(1), 37-50; https://0-doi-org.brum.beds.ac.uk/10.3390/wind2010003 - 10 Jan 2022

Cited by 6 | Viewed by 3375

Abstract

Wind power’s increasing penetration into the electricity grid poses several challenges for power system operators, primarily due to variability and unpredictability. Highly accurate wind predictions are needed to address this concern. Therefore, the performance of hybrid forecasting approaches combining autoregressive integrated moving average [...] Read more.

Wind power’s increasing penetration into the electricity grid poses several challenges for power system operators, primarily due to variability and unpredictability. Highly accurate wind predictions are needed to address this concern. Therefore, the performance of hybrid forecasting approaches combining autoregressive integrated moving average (ARIMA), machine learning models (SVR, RF), wavelet transform (WT), and Kalman filter (KF) techniques is essential to examine. Comparing the proposed hybrid methods with available state-of-the-art algorithms shows that the proposed approach provides more accurate prediction results. The best model is a hybrid of KF-WT-ML with an average R2 score of $0.99967$ and RMSE of $0.03874$, followed by ARIMA-WT-ML with an average R2 of $0.99796$ and RMSE of $0.05863$ over different datasets. Moreover, the KF-WT-ML model evaluated on different terrains, including offshore and hilly regions, reveals that the proposed KF based hybrid provides accurate wind speed forecasts for both onshore and offshore wind data. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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16 pages, 2613 KiB  

Open AccessArticle

Energy-Saving Potential of Thermal Diode Tank Assisted Refrigeration and Air-Conditioning Systems

by Mingzhen Wang, Eric Hu and Lei Chen

Energies 2022, 15(1), 206; https://0-doi-org.brum.beds.ac.uk/10.3390/en15010206 - 29 Dec 2021

Cited by 4 | Viewed by 1539

Abstract

Lowering the condensing temperature of the Refrigeration and Air-conditioning (RAC) system has been proven to effectively increase the system’s Coefficient of Performance (COP). This paper revolves around evaluating the energy-saving generated by applying a Thermal Diode Tank (TDT) in the RAC systems. The [...] Read more.

Lowering the condensing temperature of the Refrigeration and Air-conditioning (RAC) system has been proven to effectively increase the system’s Coefficient of Performance (COP). This paper revolves around evaluating the energy-saving generated by applying a Thermal Diode Tank (TDT) in the RAC systems. The TDT is a novel invention, which is an insulated water tank equipped with gravity heat pipes. If the TDT was placed outdoors overnight, its inside water would theoretically be at the minimum ambient temperature of the previous night. When the TDT water is used to cool the condenser of RAC systems that operate during the daytime, a higher COP of this TDT assisted RAC (TDT-RAC) system could be achieved compared with the baseline system. In this study, a steady-state performance simulation model for TDT-RAC cycles has been developed. The model reveals that the COP of the TDT-RAC cycle can be improved by 10~59% over the baseline cycle depending on the compressor types. The TDT-RAC cycle with a variable speed compressor can save more energy than that with a fixed speed compressor. In addition, TDT-RAC cycles can save more energy with a higher day/night ambient temperature difference. There is a threshold tank size for a given TDT-RAC cycle to save energy, and the energy-saving can be improved by enlarging the tank size. A desk-top case study based on real weather data for Adelaide in January 2021 shows that 9~40% energy could be saved by TDT-RAC systems every summer day on average. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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23 pages, 4283 KiB  

Open AccessArticle

Economic Feasibility of Green Hydrogen Production by Water Electrolysis Using Wind and Geothermal Energy Resources in Asal-Ghoubbet Rift (Republic of Djibouti): A Comparative Evaluation

by Mohamed Osman Awaleh, Abdi-Basid Adan, Omar Assowe Dabar, Mohamed Jalludin, Moussa Mahdi Ahmed and Ismael Abdillahi Guirreh

Energies 2022, 15(1), 138; https://0-doi-org.brum.beds.ac.uk/10.3390/en15010138 - 26 Dec 2021

Cited by 15 | Viewed by 5005

Abstract

The Republic of Djibouti has untapped potential in terms of renewable energy resources, such as geothermal, wind, and solar energy. This study examines the economic feasibility of green hydrogen production by water electrolysis using wind and geothermal energy resources in the Asal–Ghoubbet Rift [...] Read more.

The Republic of Djibouti has untapped potential in terms of renewable energy resources, such as geothermal, wind, and solar energy. This study examines the economic feasibility of green hydrogen production by water electrolysis using wind and geothermal energy resources in the Asal–Ghoubbet Rift (AG Rift), Republic of Djibouti. It is the first study in Africa that compares the cost per kg of green hydrogen produced by wind and geothermal energy from a single site. The unit cost of electricity produced by the wind turbine (0.042 $/kWh) is more competitive than that of a dry steam geothermal plant (0.086 $/kWh). The cost of producing hydrogen with a suitable electrolyzer powered by wind energy ranges from $0.672/kg H₂ to $1.063/kg H₂, while that produced by the high-temperature electrolyzer (HTE) powered by geothermal energy ranges from $3.31/kg H₂ to $4.78/kg H₂. Thus, the AG Rift area can produce electricity and green hydrogen at low-cost using wind energy compared to geothermal energy. The amount of carbon dioxide (CO₂) emissions reduced by using a “Yinhe GX113-2.5MW” wind turbine and a single flash geothermal power plant instead of fuel-oil generators is 2061.6 tons CO₂/MW/year and 2184.8 tons CO₂/MW/year, respectively. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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19 pages, 981 KiB  

Open AccessArticle

Evaluating LNG Supply Chain Resilience Using SWOT Analysis: The Case of Qatar

by Sara Al-Haidous, Mohammed Al-Breiki, Yusuf Bicer and Tareq Al-Ansari

Energies 2022, 15(1), 79; https://0-doi-org.brum.beds.ac.uk/10.3390/en15010079 - 23 Dec 2021

Cited by 7 | Viewed by 8086

Abstract

The demand for liquefied natural gas (LNG) as an energy commodity is increasing, although its respective supply chain is subjected to risks, uncertainties, and disturbances. An analysis of experiences from the global LNG supply chain highlights many of these risks. As such, there [...] Read more.

The demand for liquefied natural gas (LNG) as an energy commodity is increasing, although its respective supply chain is subjected to risks, uncertainties, and disturbances. An analysis of experiences from the global LNG supply chain highlights many of these risks. As such, there is an incumbent need to develop resilient LNG supply chains. In this study, the risks associated with the LNG supply chain are categorized into four dimensions: Political and regulatory, safety and security, environmental effects, and reliability of new technologies. A SWOT method is then implemented to identify strengths, weaknesses, opportunities, and threats within the LNG supply chain, where the LNG supply chain of Qatar is considered as a case study. Relevant strategies are then recommended using a SWOT matrix to maximize strengths and opportunities, while avoiding or minimizing weaknesses and threats within the LNG supply chain. Finally, major parameters to be considered to develop a resilient LNG management model are listed based on the level of priority from LNG producer and receiver perspectives. Thus, as part of creating a robust LNG supply chain, decision-makers and stakeholders are urged to use the learnings from the SWOT analysis and experiences from LNG supply chain management. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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19 pages, 4328 KiB  

Open AccessArticle

Improvement of Properties of an Insulated Wall for Refrigerated Trailer-Numerical and Experimental Study

by Konrad Zdun and Tadeusz Uhl

Energies 2022, 15(1), 51; https://0-doi-org.brum.beds.ac.uk/10.3390/en15010051 - 22 Dec 2021

Cited by 3 | Viewed by 2396

Abstract

In the paper, we report our research on the improvement of thermal efficiency of refrigerated trailers by modification of their wall structure by placing a layer of phase change material inside them. The research was carried out in the field of transport, meeting [...] Read more.

In the paper, we report our research on the improvement of thermal efficiency of refrigerated trailers by modification of their wall structure by placing a layer of phase change material inside them. The research was carried out in the field of transport, meeting the requirements of all classes provided for in the ATP agreement for refrigerated trailers. As part of the research, we formulated a numerical model of the proposed design of the refrigerator walls, which was subsequently validated by comparing the modeling results with the results of experimental tests carried out on a test bench designed specifically for this purpose. Based on the validated simulation conditions, we formulated the numerical model of a full-scale refrigerated semi-trailer, which was numerically tested under the conditions specified in the ATP Agreement. The results proved that adding a 6 mm layer of the SP-24 phase change material in each of the walls of the cold store allows the temperature inside the trailer to be kept below −20 °C for a period of 24 h without the need to supply cold from the outside during operation. The passive refrigerated semi-trailer system implemented in this manner with 6 mm PCM layer allows for a reduction in primary energy consumption by up to 86% in a period of 22 h. The mentioned percentage did not take into account the efficiency of the cooling system of the phase change material. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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18 pages, 406 KiB  

Open AccessReview

Social Learning for Energy Transition—A Literature Review

by Malgorzata Rozkwitalska

Energies 2021, 14(24), 8531; https://0-doi-org.brum.beds.ac.uk/10.3390/en14248531 - 17 Dec 2021

Cited by 2 | Viewed by 2209

Abstract

With increasing concerns regarding environmental sustainability, energy transition has emerged as a vital subtopic in transition studies. Such socio-technical transition requires social learning, which, however, is poorly conceptualized and explained in transition research. This paper overviews transition research on social learning. It attempts [...] Read more.

With increasing concerns regarding environmental sustainability, energy transition has emerged as a vital subtopic in transition studies. Such socio-technical transition requires social learning, which, however, is poorly conceptualized and explained in transition research. This paper overviews transition research on social learning. It attempts to portray how social learning has been studied in the context of energy transition and how research could be advanced. Due to the underdevelopment of the field, this paper employs a narrative review method. The review indicates two clusters of studies, which portray both direct and indirect links concerning the phenomena. The overview reveals that social learning is a force in energy transition and may occur at different levels of analysis, i.e., micro, meso, and macro, as well as different orders of learning. The author proposes to develop the academic research on the topic through quantitative and mixed-methods research as well as contributions and insights from disciplines other than sociology and political science. Some relevant topics for further inquiry can be clustered around: orders of social learning and their antecedents in energy transition; boundary-spanning roles in social learning in the context of energy transition; social learning triggered by stories about energy transition; and other theoretical underpinnings of energy transition research on social learning. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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21 pages, 8182 KiB  

Open AccessArticle

Regulation Characteristics and Load Optimization of Pump-Turbine in Variable-Speed Operation

by He Wang and Zhijie Ma

Energies 2021, 14(24), 8484; https://0-doi-org.brum.beds.ac.uk/10.3390/en14248484 - 15 Dec 2021

Cited by 4 | Viewed by 2453

Abstract

In order to improve the operating and regulation characteristics of the hydropower unit and to stabilize the load fluctuations, variable-speed pumped storage technology based on converters has been proposed and given more attention recently. However, different from the conventional units, due to the [...] Read more.

In order to improve the operating and regulation characteristics of the hydropower unit and to stabilize the load fluctuations, variable-speed pumped storage technology based on converters has been proposed and given more attention recently. However, different from the conventional units, due to the variability of operation conditions, variable-speed units need to develop a load optimization strategy in terms of operating parameter identification to ensure state matching for operation. Therefore, this paper proposes an optimization search step based on the model test curve, and the process of parameter optimization search is elaborated and calculated in the turbine operating condition and pump operating condition, respectively. A mathematical model of the turbine regulation system is established to analyze the influence of speed and guide vane related parameters on the regulation characteristics, and the achievable operating range and regulation capacity in the variable-speed condition is pointed out based on pump-turbine model test, as well as the advantages over the fixed-speed operation. The results show that by applying the load optimization method, the variable-speed unit can be significantly improved in terms of operating efficiency, especially at low head and low power conditions. Meanwhile, a certain range of active power regulation can be realized by the decoupling control of the converter and measuring the guide vane opening in both modes. The analysis of the model test verifies the effectiveness of the variable-speed regulation operation of pump-turbine and provides a reference for the design and operation of the variable-speed hydropower units. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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12 pages, 1931 KiB  

Open AccessArticle

Effect of the Presence of HCl on Simultaneous CO₂ Capture and Contaminants Removal from Simulated Biomass Gasification Producer Gas by CaO-Fe₂O₃ Sorbent in Calcium Looping Cycles

by Forogh Dashtestani, Mohammad Nusheh, Vilailuck Siriwongrungson, Janjira Hongrapipat, Vlatko Materic, Alex C. K. Yip and Shusheng Pang

Energies 2021, 14(23), 8167; https://0-doi-org.brum.beds.ac.uk/10.3390/en14238167 - 06 Dec 2021

Cited by 5 | Viewed by 1861

Abstract

This study investigated the effect of HCl in biomass gasification producer gas on the CO₂ capture efficiency and contaminants removal efficiency by CaO-Fe₂O₃ based sorbent material in the calcium looping process. Experiments were conducted in a fixed bed reactor [...] Read more.

This study investigated the effect of HCl in biomass gasification producer gas on the CO₂ capture efficiency and contaminants removal efficiency by CaO-Fe₂O₃ based sorbent material in the calcium looping process. Experiments were conducted in a fixed bed reactor to capture CO₂ from the producer gas with the combined contaminants of HCl at 200 ppmv, H₂S at 230 ppmv, and NH₃ at 2300 ppmv. The results show that with presence of HCl in the feeding gas, sorbent reactivity for CO₂ capture and contaminants removal was enhanced. The maximum CO₂ capture was achieved at carbonation temperatures of 680 °C, with efficiencies of 93%, 92%, and 87%, respectively, for three carbonation-calcination cycles. At this carbonation temperature, the average contaminant removal efficiencies were 92.7% for HCl, 99% for NH₃, and 94.7% for H₂S. The outlet contaminant concentrations during the calcination process were also examined which is useful for CO₂ reuse. The pore structure change of the used sorbent material suggests that the HCl in the feeding gas contributes to high CO₂ capture efficiency and contaminants removal simultaneously. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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19 pages, 3155 KiB  

Open AccessArticle

Thermal Comfort and Energy Analysis of a Hybrid Cooling System by Coupling Natural Ventilation with Radiant and Indirect Evaporative Cooling

by Pradeep Shakya, Gimson Ng, Xiaoli Zhou, Yew Wah Wong, Swapnil Dubey and Shunzhi Qian

Energies 2021, 14(22), 7825; https://0-doi-org.brum.beds.ac.uk/10.3390/en14227825 - 22 Nov 2021

Cited by 8 | Viewed by 2677

Abstract

A hybrid cooling system which combines natural ventilation with a radiant cooling system for a hot and humid climate was studied. Indirect evaporative cooling was used to produce chilled water at temperatures slightly higher than the dew point. With this hybrid system, the [...] Read more.

A hybrid cooling system which combines natural ventilation with a radiant cooling system for a hot and humid climate was studied. Indirect evaporative cooling was used to produce chilled water at temperatures slightly higher than the dew point. With this hybrid system, the condensation issue on the panel surface of a chilled ceiling was overcome. A computational fluid dynamics (CFD) model was employed to determine the cooling load and the parameters required for thermal comfort analysis for this hybrid system in an office-sized, well-insulated test room. Upon closer investigation, it was found that the thermal comfort by the hybrid system was acceptable only in limited outdoor conditions. Therefore, the hybrid system with a secondary fresh air supply system was suggested. Furthermore, the energy consumptions of conventional all-air, radiant cooling, and hybrid systems including the secondary air supply system were compared under similar thermal comfort conditions. The predicted results indicated that the hybrid system saves up to 77% and 61% of primary energy when compared with all-air and radiant cooling systems, respectively, while maintaining similar thermal comfort. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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15 pages, 899 KiB  

Open AccessReview

Analyzing Electricity Markets with Increasing Penetration of Large-Scale Renewable Power Generation

by Chris Johnathon, Ashish Prakash Agalgaonkar, Joel Kennedy and Chayne Planiden

Energies 2021, 14(22), 7618; https://0-doi-org.brum.beds.ac.uk/10.3390/en14227618 - 15 Nov 2021

Cited by 9 | Viewed by 2182

Abstract

Global electricity markets are undergoing a rapid transformation in their energy mix to meet commitments towards sustainable electric grids. This change in energy mix engenders significant challenges, specifically concerning the management of non-dispatchable energy resources. System and market operators are required to meet [...] Read more.

Global electricity markets are undergoing a rapid transformation in their energy mix to meet commitments towards sustainable electric grids. This change in energy mix engenders significant challenges, specifically concerning the management of non-dispatchable energy resources. System and market operators are required to meet power system security and reliability requirements whilst providing electricity at competitive prices. An overview of electricity markets is provided in this paper with a critical appraisal of each market’s ability to manage the large-scale energy mix transition. This paper provides a commentary on the distinct features of electricity market models implemented around the world and highlights the barriers within these market models that are hindering the energy mix transition. Various researchers and policymakers are proposing solutions and market reforms for the smooth transitioning of the energy mix. This paper presents a systematic review of the proposed solutions in the literature and critiques the effectiveness and ease of implementation of the reviewed solutions. Research gaps and future research directions are indicated to promote further exploration towards the effective integration of large-scale renewable energy technologies. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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14 pages, 2677 KiB  

Open AccessArticle

Formation and Growth Behavior Analysis of Slagging Rings in Rotary Kiln-Type Hazardous Waste Incineration Systems

by Jing Zhao, Zirui Zhang, Bo Li and Xiaolin Wei

Energies 2021, 14(22), 7561; https://0-doi-org.brum.beds.ac.uk/10.3390/en14227561 - 12 Nov 2021

Cited by 2 | Viewed by 2422

Abstract

Rotary kiln incineration technology has the advantages of strong material adaptability and a simple treatment process and has been widely used in hazardous waste treatment. However, the actual incineration process has caused problems such as ring formation in the treatment system due to [...] Read more.

Rotary kiln incineration technology has the advantages of strong material adaptability and a simple treatment process and has been widely used in hazardous waste treatment. However, the actual incineration process has caused problems such as ring formation in the treatment system due to the lack of research on the slagging mechanisms. In this paper, slagging phenomena occurring in the second half of the rotary kiln, the exit flue of the secondary combustion chamber, and the wall of the quench tower are analyzed and discussed in detail through characterization methods. The results indicate that the adhesion of low-melting alkali metal salts on the refractory surface in the second half of the rotary kiln is the key factor in forming the initial slagging layer. In the growth process of the slagging ring, the formed liquid phase can bond incineration residues of different sizes together and form a dense embryo body through liquid phase sintering. The deposition and solidification of molten/semi-molten fly ashes cause slagging formation in the exit flue of the secondary combustion chamber. The slagging phenomenon occurring in the inner wall of the quench tower belongs to the “crystalline-coalesce-hardening” process of the inorganic salts precipitating out of the high-salt wastewater. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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14 pages, 3575 KiB  

Open AccessArticle

Economic Model and Risk Analysis of Energy Investments Based on Cogeneration Systems and Renewable Energy Sources

by Michał Gołębiewski and Marta Galant-Gołębiewska

Energies 2021, 14(22), 7538; https://0-doi-org.brum.beds.ac.uk/10.3390/en14227538 - 11 Nov 2021

Cited by 4 | Viewed by 1481

Abstract

Today, distributed energy production is a key activity supporting energy systems in many countries around the world. Applicable regulations, fees and subsidies encourage entrepreneurs to look for solutions that will reduce operating costs and limit their negative impact on the natural environment. In [...] Read more.

Today, distributed energy production is a key activity supporting energy systems in many countries around the world. Applicable regulations, fees and subsidies encourage entrepreneurs to look for solutions that will reduce operating costs and limit their negative impact on the natural environment. In the article, it was decided to carry out a technical and economic analysis and investment risk analysis for the distributed production of electricity and heat based on natural gas. Six scenarios were taken into account, depending on the number of gas engines, the use of the photovoltaic installation and the Organic Rankine Cycle (ORC) system. It has been shown that the most advantageous of the presented solution is the use of a system adjusted to the power of an industrial plant (return on investment in 4th year). The least beneficial for the investor are solutions aimed at the use and resale of energy supplemented with photovoltaic panels and an ORC system. An investment risk analysis and a sensitivity analysis were also performed. It shows how changes in electricity and gas prices and the environmental fee affect the profitability of investments. It has been shown that solutions with variable power are characterised by the lowest investment risk. The summary indicates the possible activities leading to greater economic efficiency. Such actions will be forced in the future by the market, political and environmental situation. Analyses such as these will allow entrepreneurs to thoroughly prepare for the European Union energy modernization process. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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17 pages, 310 KiB  

Open AccessArticle

The Potential of Using Renewable Energy Sources in Poland Taking into Account the Economic and Ecological Conditions

by Mariusz Niekurzak

Energies 2021, 14(22), 7525; https://0-doi-org.brum.beds.ac.uk/10.3390/en14227525 - 11 Nov 2021

Cited by 20 | Viewed by 2031

Abstract

The aim of the manuscript was to present the collective results of research on the profitability of using various renewable sources in Poland with the greatest development potential. In the paper, the economic parameters of various investment projects were determined and calculated, i.e., [...] Read more.

The aim of the manuscript was to present the collective results of research on the profitability of using various renewable sources in Poland with the greatest development potential. In the paper, the economic parameters of various investment projects were determined and calculated, i.e., Net Capital Value (NPV), Internal Rate of Return (IRR) and the Period of Return on Invested Capital (PBT). The economic assessment of the use of RES technologies was supplemented with the assessment of environmental benefits. The ecological criterion adopted in the study was the assessment of the potential and costs of reducing greenhouse gas emissions as a result of replacing fossil fuels with renewable energy technologies. On the basis of the constructed economic model to assess the profitability of investments, it has been shown that the analyzed projects will start to bring, depending on their type and technical specification, measurable economic benefits in the form of a reduction in the amount of energy purchased on an annual basis and environmental benefits in the form of reduction of carbon dioxide emissions to the atmosphere. Moreover, the calculations show a high potential for the use of certain renewable sources in Poland, which contributes to the fulfillment of energy and emission obligations towards the EU. The analyzes and research of the Polish energy market with the use of the presented models have shown that the project is fully economically justified and will allow investors to make a rational decision on the appropriate selection of a specific renewable energy source for their investment. The presented economic models to assess the profitability of investments in renewable energy sources can be successfully used in other countries and can also be a starting point for a discussion about the direction of energy development. Due to the lack of collective, original and up-to-date research on the domestic market, the manuscript provides the reader with the necessary knowledge regarding the legitimacy of using renewable energy sources, investment and environmental profitability. Full article

(This article belongs to the Topic Sustainable Energy Technology)

21 pages, 7280 KiB  

Open AccessArticle

Theoretical and Empirical Analysis of the Influence of Technology Gap on Carbon Emission: The Case of China

by Qin Ye, Weiwei Wen and Chenglei Zhang

Processes 2021, 9(11), 2013; https://0-doi-org.brum.beds.ac.uk/10.3390/pr9112013 - 11 Nov 2021

Cited by 2 | Viewed by 1587

Abstract

Numerous studies have examined the relationship between technological development and pollution. From a global economic perspective, the narrowing of one country’s technological gap relative to the world technology frontier (due to the technological progress) may affect its environmental pollution. However, few studies have [...] Read more.

Numerous studies have examined the relationship between technological development and pollution. From a global economic perspective, the narrowing of one country’s technological gap relative to the world technology frontier (due to the technological progress) may affect its environmental pollution. However, few studies have focused on this issue. This study examined the relationship between technology gap and air pollution both theoretically and empirically. The theoretical model shows that narrowing the technology gap may help reduce pollution. Using patent data from USPTO, as well as industrial level pollution and socio-economic data in China, this paper found that the narrowing of technology gap plays a role in reducing air pollution emissions in China, which confirms the theoretical model. This study provides a new perspective on the relationship between technology progress and pollution. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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18 pages, 4395 KiB  

Open AccessArticle

A Method to Analyze the Performance of Geocooling Systems with Borehole Heat Exchangers. Results in a Monitored Residential Building in Southern Alps

by Marco Belliardi, Nerio Cereghetti, Paola Caputo and Simone Ferrari

Energies 2021, 14(21), 7407; https://0-doi-org.brum.beds.ac.uk/10.3390/en14217407 - 07 Nov 2021

Cited by 5 | Viewed by 2074

Abstract

Geothermal heat is an increasingly adopted source for satisfying all thermal purposes in buildings by reversible heat pumps (HP). However, for residential buildings located in moderate climates, geocooling, that implies the use of geothermal source for cooling buildings without the operation of HP, [...] Read more.

Geothermal heat is an increasingly adopted source for satisfying all thermal purposes in buildings by reversible heat pumps (HP). However, for residential buildings located in moderate climates, geocooling, that implies the use of geothermal source for cooling buildings without the operation of HP, is an efficient alternative for space cooling not yet explored enough. Geocooling allows two main benefits: to cool the buildings by high energy efficiencies improving summer comfort; to recharge the ground if space heating is provided by HP exploiting the geothermal source (GSHP). In these cases, geocooling allows to avoid the decreasing of the performances of the GSHP for space heating over the years. To explore these issues, a method has been developed and tested on a real case: a new residential building in Lugano (southern Switzerland) coupled with 13 borehole heat exchangers. The system provides space heating in winter by a GSHP and space cooling in summer by geocooling. During a 40 months monitoring campaign, data such as temperatures, heat flows and electricity consumptions were recorded to calibrate the model and verify the benefits of such configuration. Focusing on summer operation, the efficiency of the system, after the improvements implemented, is above 30, confirming, at least in similar contexts, the feasibility of geocooling. Achieved results provides knowledge for future installations, underlining the replication potential and the possible limits. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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12 pages, 21172 KiB  

Open AccessArticle

Particle Image Velocimetry Test for the Inter-Blade Vortex in a Francis Turbine

by Lianchen Xu, Xiaohui Jin, Zhen Li, Wanquan Deng, Demin Liu and Xiaobing Liu

Processes 2021, 9(11), 1968; https://0-doi-org.brum.beds.ac.uk/10.3390/pr9111968 - 04 Nov 2021

Cited by 9 | Viewed by 1631

Abstract

Hydropower units are usually operated in non-design conditions because of power grid requirements. In a partial-load condition, an inter-blade vortex phenomenon occurs between the runner blades of a Francis turbine, causing pressure pulsation and unit vibration, which hinder the safe and stable operation [...] Read more.

Hydropower units are usually operated in non-design conditions because of power grid requirements. In a partial-load condition, an inter-blade vortex phenomenon occurs between the runner blades of a Francis turbine, causing pressure pulsation and unit vibration, which hinder the safe and stable operation of power stations. However, the mechanism through which the inter-blade vortex generation occurs is not entirely clear. In this study, a specific model of the Francis turbine was used to investigate and visually observe the generation of the blade vortex in Francis turbines in both the initial inter-blade and vortex development zones. Particle image velocimetry was used for this purpose. In addition, we determined the variation law of the inter-blade vortex in the Francis turbine. We found that the size and strength of the inter-blade vortex depend on the unit speed of the turbine. The higher the unit speed is, the stronger the inter-blade vortex becomes. We concluded that the inter-blade vortex of such turbines originates from the pressure surface or secondary flow and stall of the blade at the inlet side of the runner at high unit speeds, and also from the backflow zone of the suction surface of the blade at low unit speeds. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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23 pages, 9405 KiB  

Open AccessArticle

Investigation on Thrust Characteristics of a Downstream Offshore Floating Wind Turbine under Yawed Inflow Conditions

by Yangwei Wang, Jiahuan Lin, Huawei Duan and Jun Zhang

J. Mar. Sci. Eng. 2021, 9(11), 1215; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse9111215 - 03 Nov 2021

Cited by 3 | Viewed by 1642

Abstract

In the natural marine environment, offshore floating wind turbines (OFWTs) inevitably experience yawed inflow conditions, which will make their aerodynamics more complicated than those experiencing uniform inflow conditions and difficult to understand. In the present study, the thrust characteristics of a wake-influenced OFWT [...] Read more.

In the natural marine environment, offshore floating wind turbines (OFWTs) inevitably experience yawed inflow conditions, which will make their aerodynamics more complicated than those experiencing uniform inflow conditions and difficult to understand. In the present study, the thrust characteristics of a wake-influenced OFWT under dynamic, static, and coupled yawed inflow conditions are investigated thoroughly. Analytical characterizations of yawed inflow and upstream wake are integrated into the blade element momentum (BEM) method to achieve the investigation. Based on this method, simulations by the FAST code have been conducted, and the results are analyzed. It is shown that the three inflow conditions have considerable influences on the thrust coefficient of the wind rotor or the normal force at the blade section, especially in the wake case where the downstream OFWT is located at a specific offset from the central line of a single upstream wake. In order to validate the analyses of simulation results, experimental tests by a set of dedicated apparatus are conducted. The comparison results are good, proving the reliability of simulation results. This work can provide some theoretical contributions to the aerodynamic design and control of OFWTs. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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22 pages, 339 KiB  

Open AccessReview

Use of Learning Mechanisms to Improve the Condition Monitoring of Wind Turbine Generators: A Review

by Ana Rita Nunes, Hugo Morais and Alberto Sardinha

Energies 2021, 14(21), 7129; https://0-doi-org.brum.beds.ac.uk/10.3390/en14217129 - 01 Nov 2021

Cited by 4 | Viewed by 2481

Abstract

The main goal of this paper is to review and evaluate how we can take advantage of state-of-the-art machine learning techniques and apply them in wind energy operation conditions monitoring and fault diagnosis, boosting wind turbines’ availability. To accomplish this, we focus our [...] Read more.

The main goal of this paper is to review and evaluate how we can take advantage of state-of-the-art machine learning techniques and apply them in wind energy operation conditions monitoring and fault diagnosis, boosting wind turbines’ availability. To accomplish this, we focus our work on analysing the current techniques in predictive maintenance, which are aimed at acting before a major failure occurs using condition monitoring. In particular, we start framing the predictive maintenance problem as an ML problem to detect patterns that indicate a fault on turbine generators. Then, we extend the problem to detect future faults. Therefore, this review will consist of analysing techniques to tackle the challenges of each machine learning stage, such as data pre-processing, feature engineering, and the selection of the best-suited model. By using specific evaluation metrics, the expected final result of using these techniques will be an improvement in the early prediction of a future fault. This improvement will have an increase in the availability of the turbine, and therefore in energy production. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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15 pages, 4567 KiB  

Open AccessFeature PaperArticle

Biogas, Solar and Geothermal Energy—The Way to a Net-Zero Energy Wastewater Treatment Plant—A Case Study

by Sylwia Myszograj, Dariusz Bocheński, Mirosław Mąkowski and Ewelina Płuciennik-Koropczuk

Energies 2021, 14(21), 6898; https://0-doi-org.brum.beds.ac.uk/10.3390/en14216898 - 21 Oct 2021

Cited by 6 | Viewed by 2718

Abstract

Wastewater treatment plants designed to meet the requirements of discharging wastewater to a receiving water body are often not energy optimised. Energy requirements for conventional activated sludge wastewater treatment plants are estimated to range from 0.30 to 1.2 kWh/m³, with the [...] Read more.

Wastewater treatment plants designed to meet the requirements of discharging wastewater to a receiving water body are often not energy optimised. Energy requirements for conventional activated sludge wastewater treatment plants are estimated to range from 0.30 to 1.2 kWh/m³, with the highest values achieved using the nitrification process. This article describes the energy optimisation process of the wastewater treatment plant in Gubin (Poland) designed for 90,000 PE (population equivalent) using renewable energy sources: solar, biogas, and geothermal. At the analysed wastewater treatment plant electricity consumption for treating 1 m³ of wastewater was 0.679 kWh in 2020. The combined production of electricity and heat from biogas, the production of electricity in a photovoltaic system, and heat recovery in a geothermal process make it possible to obtain a surplus of heat in relation to its demand in the wastewater treatment plant, and to cover the demand for electricity, with the possibility of also selling it to the power grid. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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24 pages, 24856 KiB  

Open AccessArticle

A Method of Analyzing the Residual Values of Low-Emission Vehicles Based on a Selected Expert Method Taking into Account Stochastic Operational Parameters

by Piotr Wróblewski and Wojciech Lewicki

Energies 2021, 14(21), 6859; https://0-doi-org.brum.beds.ac.uk/10.3390/en14216859 - 20 Oct 2021

Cited by 33 | Viewed by 3599

Abstract

Increasing the market share of low-emission vehicles in relation to individual mobility is one of the main postulates of modern transport policy. In the discussion on low-emission and the new structure of the car fleet, the role of new vehicles is emphasized above [...] Read more.

Increasing the market share of low-emission vehicles in relation to individual mobility is one of the main postulates of modern transport policy. In the discussion on low-emission and the new structure of the car fleet, the role of new vehicles is emphasized above all, ignoring the importance of the secondary market. In recent years, both in Poland and in other European Union countries, there has been a noticeable dynamic development of electromobility implementation processes in urban areas, the initial effect of which is increasing market accessibility to commercial vehicles with electric EV/BEV, hybrid HEV/PHEV and fuel cell powered FCEV. As in the case of vehicles powered by conventional ICEV fuels, also in relation to those defined as low-emission, their residual value is lost along with the operational process. Information on this variable is important both for the owner of a newly purchased vehicle, which after the period of its operation will decide to sell it as well as to the future buyer. The scientific aim of the study is to analyze the residual values of selected vehicle models from the primary and secondary market, with particular emphasis on stochastic operational phenomena. The subject of the research is to obtain extensive knowledge on the achieved changes in the residual values of low-emission vehicles in relation to ICEVs. For this purpose, a comparative analysis of the commercial program, data approximated from auction portals and own numerical modeling tool based on a neural network was performed. The research sample included, among others, selected models of passenger cars, the purchase offer of which included the choice of a drive unit powered by conventional and low-emission fuels. The use of this method allowed to answer the question whether low-emission vehicles are characterized by a greater or lesser loss of value in relation to conventionally powered vehicles ICEV. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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18 pages, 6843 KiB  

Open AccessArticle

An Experimental and Kinetic Modelling Study on Laminar Premixed Flame Characteristics of Ethanol/Acetone Mixtures

by Yangxun Liu, Weinan Liu, Huihong Liao, Wenhua Zhou and Cangsu Xu

Energies 2021, 14(20), 6713; https://0-doi-org.brum.beds.ac.uk/10.3390/en14206713 - 15 Oct 2021

Cited by 4 | Viewed by 1462

Abstract

Since both ethanol and acetone are the main components in many alternative fuels, research on the burning characteristics of ethanol-acetone blends is important to understand the combustion phenomena of these alternative fuels. In the present study, the burning characteristics of ethanol-acetone fuel blends [...] Read more.

Since both ethanol and acetone are the main components in many alternative fuels, research on the burning characteristics of ethanol-acetone blends is important to understand the combustion phenomena of these alternative fuels. In the present study, the burning characteristics of ethanol-acetone fuel blends are investigated at a temperature of 358 K and pressure of 0.1 MPa with equivalence ratios ranging from 0.7 to 1.4. Ethanol at 100% vol., 25% vol. ethanol/75% vol. acetone, 50% vol. ethanol/50% vol. acetone, 75% vol. ethanol/25% vol. acetone, and 100% vol. acetone are studied by the constant volume combustion chamber (CVCC) method. The results show that the laminar burning velocities of the fuel blends are between that of 100% vol. acetone and 100% vol. ethanol. As the ethanol content increases, the laminar burning velocities of the mixed fuels increase. Furthermore, a detailed chemical kinetic mechanism (AramcoMech 3.0) is used for simulating the burning characteristics of the mixtures. The directed relation graph (DRG), DRG with error propagation (DRGEP), sensitivity analysis (SA), and full species sensitivity analysis (FSSA) are used for mechanism reduction. The flame structure of the skeletal mechanism does not change significantly, and the concentration of each species remains basically the same value after the reaction. The numbers of reactions and species are reduced by 90% compared to the detailed mechanism. Sensitivity and reaction pathway analyses of the burning characteristics of the mixtures indicate that the reaction C₂H₂+H(+M)<=>C₂H₃(+M) is the key reaction. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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Supplementary material:
Supplementary File 1 (ZIP, 186 KiB)

36 pages, 3683 KiB  

Open AccessReview

A Review of Multi-Objective Optimization in Organic Rankine Cycle (ORC) System Design

by Shuozhuo Hu, Zhen Yang, Jian Li and Yuanyuan Duan

Energies 2021, 14(20), 6492; https://0-doi-org.brum.beds.ac.uk/10.3390/en14206492 - 11 Oct 2021

Cited by 18 | Viewed by 3413

Abstract

Organic Rankine cycle (ORC) is considered a promising heat-to-power technology to utilize waste heat and renewable energy, including solar, biomass and geothermal. However, since the thermodynamic, economic and environmental performance is usually conflict, the single objective design could no longer meet the requirements [...] Read more.

Organic Rankine cycle (ORC) is considered a promising heat-to-power technology to utilize waste heat and renewable energy, including solar, biomass and geothermal. However, since the thermodynamic, economic and environmental performance is usually conflict, the single objective design could no longer meet the requirements of the ORC system, putting forward urgent requirements for multi-objective optimization, which has attracted increasing attention with lots of papers published. However, due to these different decision variables, optimization objectives and approaches, existing research is significantly different from each other and is difficult to compare without a systematic summary. Therefore, this paper provides an overview of ORC multi-objective research from three perspectives: optimization objective, method and optimization parameters. Based on the classification of different objectives, this work summarizes the involved variables and provides a recommendation for selecting appropriate objectives in different scenarios. For the optimization method, this work compares different approaches and reveals their advantages and disadvantages. Finally, the decision variables are reviewed and classified into four levels. Then the integrated design approach considering “system-process-component-fluid” is proposed and recommended for further development. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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19 pages, 7502 KiB  

Open AccessArticle

Simulation Study on Active Air Flow Distribution Characteristics of Closed Heat Pump Drying System with Waste Heat Recovery

by Hai-Bo Zhao, Kun Wu and Jing-Feng Zhang

Energies 2021, 14(19), 6358; https://0-doi-org.brum.beds.ac.uk/10.3390/en14196358 - 05 Oct 2021

Cited by 1 | Viewed by 1835

Abstract

A tridimensional turbulent flow model is established for a closed heat pump drying system with waste heat recovery to improve the drying air flow characteristics and reduce the energy consumption of air circulation. The active flow distribution mode is introduced to guide air [...] Read more.

A tridimensional turbulent flow model is established for a closed heat pump drying system with waste heat recovery to improve the drying air flow characteristics and reduce the energy consumption of air circulation. The active flow distribution mode is introduced to guide air flowing in the system’s drying cabinet, top air duct, mixing zone, and heat pump. It is found that the wind velocity in the cabinet’s supply channel is greater than that in the return channel, the velocity distribution in the top duct is uneven, and the outlet velocity of the bypass fan is high and a vortex forms. A partition panel added in the top duct and modulating fans in the drying cabinet are proposed to solve these problems. The simulation results show that removing the circulating fan, changing the volume flow of the bypass fan, adopting the alternative operation mode of the bypass fans, reducing the air volume flow of the supply fan, and reducing the total pressure of the fans can improve the dry air velocity uniformity in the drying cabinet and reduce the energy consumption of the fans. This paper analyzes the closed-loop drying air flow characteristics of the active flow distribution system in the heat pump drying system, which lays a foundation for the wind velocity, temperature, and humidity regulating of heat pump drying system with waste heat recovery. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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19 pages, 11985 KiB  

Open AccessArticle

Diagnostics of a Domestic Hot Water Storage Tank under Operating Conditions

by Paweł Obstawski, Monika Janaszek-Mańkowska and Arkadiusz Ratajski

Processes 2021, 9(10), 1771; https://0-doi-org.brum.beds.ac.uk/10.3390/pr9101771 - 02 Oct 2021

Cited by 1 | Viewed by 1802

Abstract

This paper presents a new method for the diagnostics of a hot water storage tank under operating conditions. Depending on the operating point of the tank, the method enables determination of thermal conductivity coefficients of the coil heat exchanger, which allows us to [...] Read more.

This paper presents a new method for the diagnostics of a hot water storage tank under operating conditions. Depending on the operating point of the tank, the method enables determination of thermal conductivity coefficients of the coil heat exchanger, which allows us to determine the intensity of heat transfer between the transfer medium and water in the tank as well as of tank walls, which consequently enables determination of heat losses to the environment. Furthermore, the dynamic properties of the tank may also be determined by applying this method. The advantage of this method is possibility of analyzing changes in the material constants of the coil heat exchanger, tank walls, and dynamic properties of the tank as a function of mass flow of the medium supplying the coil heat exchanger. The possibility of determining coefficients of thermal conductivity as well as the inertia of tank and exchanger, based on temperature measurements acquired in operating conditions is a novelty in this paper. Knowing the variability of material constants and of dynamic properties of the tank as a function of medium flow rate allows multicriteria optimization to be performed which, with a conventional design of the tank, results in a reduction of up to 10% in the time taken to prepare domestic hot water. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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Supplementary material:
Supplementary File 1 (ZIP, 408 KiB)

18 pages, 3856 KiB  

Open AccessReview

Comparative Life Cycle Assessment of Merging Recycling Methods for Spent Lithium Ion Batteries

by Zhiwen Zhou, Yiming Lai, Qin Peng and Jun Li

Energies 2021, 14(19), 6263; https://0-doi-org.brum.beds.ac.uk/10.3390/en14196263 - 01 Oct 2021

Cited by 16 | Viewed by 3465

Abstract

An urgent demand for recycling spent lithium-ion batteries (LIBs) is expected in the forthcoming years due to the rapid growth of electrical vehicles (EV). To address these issues, various technologies such as the pyrometallurgical and hydrometallurgical method, as well as the newly developed [...] Read more.

An urgent demand for recycling spent lithium-ion batteries (LIBs) is expected in the forthcoming years due to the rapid growth of electrical vehicles (EV). To address these issues, various technologies such as the pyrometallurgical and hydrometallurgical method, as well as the newly developed in-situ roasting reduction (in-situ RR) method were proposed in recent studies. This article firstly provides a brief review on these emerging approaches. Based on the overview, a life cycle impact of these methods for recovering major component from one functional unit (FU) of 1 t spent EV LIBs was estimated. Our results showed that in-situ RR exhibited the lowest energy consumption and greenhouse gas (GHG) emissions of 4833 MJ FU⁻¹ and 1525 kg CO₂-eq FU⁻¹, respectively, which only accounts for ~23% and ~64% of those for the hydrometallurgical method with citric acid leaching. The H₂O₂ production in the regeneration phase mainly contributed the overall impact for in-situ RR. The transportation distance for spent EV LIBs created a great hurdle to the reduction of the life cycle impact if the feedstock was transported by a 3.5–7.5 t lorry. We therefore suggest further optimization of the spatial distribution of the recycling facilities and reduction in the utilization of chemicals. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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19 pages, 4114 KiB  

Open AccessArticle

Catalytic Temperature Effects on Conversion Efficiency of PM_2.5 and Gaseous Emissions from Rice Husk Combustion

by Emmanuel Owoicho Abah, Tofael Ahamed and Ryozo Noguchi

Energies 2021, 14(19), 6131; https://0-doi-org.brum.beds.ac.uk/10.3390/en14196131 - 26 Sep 2021

Cited by 2 | Viewed by 2405

Abstract

Most studies on honeycomb catalysts have been conducted using simulation models and exhaust experiments from automobiles. Very few monolithic catalyst studies have been applied to the agricultural sector, especially the catalyst exhaust system for flue purification from the biomass industry. The importance of [...] Read more.

Most studies on honeycomb catalysts have been conducted using simulation models and exhaust experiments from automobiles. Very few monolithic catalyst studies have been applied to the agricultural sector, especially the catalyst exhaust system for flue purification from the biomass industry. The importance of exhaust gas purification and particulate removal from biomass power plants has become critical for evaluating the performance and environmental sustainability of biomass combustion. This is one of the first studies to investigate the performance of honeycomb catalysts for the oxidation of flue (PM_2.5), (CO), and (SO₂) from a rice husk briquette combustion system. The experimental setup comprised a fixed-bed electric furnace, the catalyst, an aerosol sampler, and a flue gas analyzer. Rice husk (0.1 g/mL density) and rice husk briquettes (0.8 g/mL density), were burned at 600–1000 °C for 3 min. From the results, the catalyst CO conversion rate was 100% at the optimum heated temperatures of 427.4–490.3 °C. At these temperatures, the inhibition effect of the chemisorbed CO was significantly minimized, enhancing the adsorption of oxygen, which reacted with CO to form CO₂. However, SO₂ oxidation was lower than that of CO because platinum-based catalysts are generally more attracted to CO in the presence of oxygen. The emission of PM_2.5 decreased from its uncatalyzed-value (1169.9 mg/m³ and 1572.2 mg/m³) to its catalyzed values (18.9 mg/m³ and 170.1 mg/m³). This is a significant result in ensuring cleaner production of energy from rice husk. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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17 pages, 4078 KiB  

Open AccessArticle

Solar-Powered Thermoelectric-Based Cooling and Heating System for Building Applications: A Parametric Study

by Mohadeseh Seyednezhad and Hamidreza Najafi

Energies 2021, 14(17), 5573; https://0-doi-org.brum.beds.ac.uk/10.3390/en14175573 - 06 Sep 2021

Cited by 7 | Viewed by 4006

Abstract

Thermoelectric (TE) based cooling and heating systems offer significant advantages over conventional vapor compression systems including no need for refrigeration or major moving parts, high controllability, and scalability. The purpose of the present study is to provide an energy and economic assessment of [...] Read more.

Thermoelectric (TE) based cooling and heating systems offer significant advantages over conventional vapor compression systems including no need for refrigeration or major moving parts, high controllability, and scalability. The purpose of the present study is to provide an energy and economic assessment of the performance of a TE-based radiant cooling and heating system for building applications. It is considered that TE modules are integrated in the ceiling to lower/increase the ceiling temperature through the Peltier effect during the hot/cold season to provide thermal comfort for the occupants via radiation and convection. The study explores the possibility of using rooftop PV panels to produce electricity required for the operation of TE modules. An actual office building located in Melbourne, FL, USA is considered for a test study, and the hourly cooling and heating loads of the building are calculated through building energy simulation in eQuest. Various operating conditions, including different input voltages and temperature gradient across TE modules, are considered, and the system is sized to properly address the year-around cooling/heating demand. It is shown that a nominal cooling capacity of 112.8 W and a nominal PV capacity of 31.35 W per unit area of the building is required to achieve the target goal when the system operates at the optimal condition. An economic analysis is also performed, and estimated cost, as well as potential savings, are calculated for each operating condition. The optimal operating condition with minimum cost is selected accordingly. The results demonstrated that the initial cost of the proposed system is considerably higher than conventional heating/cooling systems. However, the system offers other benefits that can potentially make it an attractive option for building cooling/heating applications. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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20 pages, 12946 KiB  

Open AccessArticle

Coupled Interactions Analysis of a Floating Tidal Current Power Station in Uniform Flow

by Chao Hu, Chenxuan Tang, Chenyang Yuwen and Yong Ma

J. Mar. Sci. Eng. 2021, 9(9), 958; https://0-doi-org.brum.beds.ac.uk/10.3390/jmse9090958 - 03 Sep 2021

Cited by 2 | Viewed by 2169

Abstract

For a floating tidal current power station moored in the sea, the mutual interactions between the carrier and the turbine are pretty complex. Current simulation methods based on potential flow theory could not consider the complicated viscous effects between the carrier motion and [...] Read more.

For a floating tidal current power station moored in the sea, the mutual interactions between the carrier and the turbine are pretty complex. Current simulation methods based on potential flow theory could not consider the complicated viscous effects between the carrier motion and rotor rotation. To accurately account for the viscous effect, developing a different numerical simulation method based on computational fluid dynamics is necessary. This paper deals with a moored FTCPS (floating tidal current power station) with 6-degree-of-freedom motion in uniform flow based on dynamic fluid body interactions (DFBI) method. Results showed that the blockage effect caused by the columns would increase the average power output of the turbine, while the power output fluctuation also increased. When the carrier is individually moored in the sea, the motion response of the carrier is pretty small, and the carrier is obviously trimming by the bow. However, when the turbine is mounted on the carrier, the carrier motion response is simple harmonic. The motion response frequency of the carrier is in relation to the rotation frequency of the turbine. Full article

(This article belongs to the Topic Sustainable Energy Technology)

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