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Feature Papers in Sustainable Energy

A topical collection in Energies (ISSN 1996-1073). This collection belongs to the section "A: Sustainable Energy".

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Editor


grade E-Mail Website
Collection Editor
1. Department of Sustainable and Renewable Energy Engineering, University of Sharjah, Sharjah P.O. Box 27272, United Arab Emirates
2. Mechanical Engineering and Design, School of Engineering and Applied Science, Aston University, Aston Triangle, Birmingham B4 7ET, UK
Interests: renewable energy; energy storage systems, sustainability; CAD and design; smart materials
Special Issues, Collections and Topics in MDPI journals

Topical Collection Information

Dear Colleagues,

We are delighted to invite you to contribute a research or review paper for this Topical Collection on hybrid renewable energy and energy storage systems. The Collection Editor and main topics are presented below:

  • Renewable Energy Systems;
  • Solar Energy;
  • Wind Energy;
  • Marine and Hydro Energy;
  • Geothermal Energy;
  • Biomass;
  • Hydrogen and Fuel Cell;
  • Energy Storage Systems

Prof. Dr. Abdul-Ghani Olabi
Collection Editor

Keywords

  • Renewable Energy Systems
  • Solar Energy
  • Wind Energy
  • Marine and Hydro Energy
  • Geothermal Energy
  • Biomass
  • Hydrogen and Fuel Cell
  • Energy Storage Systems

Published Papers (6 papers)

2022

Jump to: 2021, 2020

35 pages, 7660 KiB  
Review
The Role of Electrification in the Decarbonization of the Energy Sector in Portugal
by Fernando Martins, Pedro Moura and Aníbal T. de Almeida
Energies 2022, 15(5), 1759; https://doi.org/10.3390/en15051759 - 26 Feb 2022
Cited by 19 | Viewed by 4429
Abstract
Climate change already affects all inhabited regions of the world, with human influence contributing to many observed changes in climate extremes and to mitigate this trend, important decisions have been taken by different world organizations and countries to achieve global net-zero emissions. At [...] Read more.
Climate change already affects all inhabited regions of the world, with human influence contributing to many observed changes in climate extremes and to mitigate this trend, important decisions have been taken by different world organizations and countries to achieve global net-zero emissions. At the European Union level (EU27 countries), two of the main pillars for achieving carbon neutrality are: (1) The “Energy Efficiency First principle” in the formulation of energy policy and in taking relevant investment decisions and (2) the electrification of the energy sector, supported by generating electricity through endogenous renewable energy sources. In this context, a comprehensive review was carried out on what has been developed by the scientific community and main international energy organizations on the electrification of the energy sector. Additionally, with the purpose of better understanding the state of the art of a country regarding the decarbonization process, the Portuguese energy vectors were identified in terms of which ones can and should be electrified by 2050, based on the data available from Eurostat (2019). Portugal is a country highly dependent on imported energy (78%), where the largest energy vector is from oil and petroleum products (68%) mostly used in the transport sector, where the electrification of the sector will be increased gradually until 2050. However, other decarbonized solutions, such as biofuels and synthetic (green) fuels cannot be ruled out and should be the subject of future work and considered for the decarbonization goals to be achieved in 2050. The main conclusions reflect that there is still a long way to go, much like the rest of the world, as it is necessary to electrify the equivalent to almost all the energy presently imported by Portugal, a tough challenge considering the need for its generation to be decarbonized. In this context, energy efficiency must play an equivalently important role to significantly reduce current energy demand, leading to more cost-effective and resilient energy services. Full article
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2021

Jump to: 2022, 2020

20 pages, 10568 KiB  
Article
Performance Analysis of TiO2-Modified Co/MgAl2O4 Catalyst for Dry Reforming of Methane in a Fixed Bed Reactor for Syngas (H2, CO) Production
by Arslan Mazhar, Asif Hussain Khoja, Abul Kalam Azad, Faisal Mushtaq, Salman Raza Naqvi, Sehar Shakir, Muhammad Hassan, Rabia Liaquat and Mustafa Anwar
Energies 2021, 14(11), 3347; https://doi.org/10.3390/en14113347 - 7 Jun 2021
Cited by 21 | Viewed by 4098
Abstract
Co/TiO2–MgAl2O4 was investigated in a fixed bed reactor for the dry reforming of methane (DRM) process. Co/TiO2–MgAl2O4 was prepared by modified co-precipitation, followed by the hydrothermal method. The active metal Co was loaded [...] Read more.
Co/TiO2–MgAl2O4 was investigated in a fixed bed reactor for the dry reforming of methane (DRM) process. Co/TiO2–MgAl2O4 was prepared by modified co-precipitation, followed by the hydrothermal method. The active metal Co was loaded via the wetness impregnation method. The prepared catalyst was characterized by XRD, SEM, TGA, and FTIR. The performance of Co/TiO2–MgAl2O4 for the DRM process was investigated in a reactor with a temperature of 750 °C, a feed ratio (CO2/CH4) of 1, a catalyst loading of 0.5 g, and a feed flow rate of 20 mL min−1. The effect of support interaction with metal and the composite were studied for catalytic activity, the composite showing significantly improved results. Moreover, among the tested Co loadings, 5 wt% Co over the TiO2–MgAl2O4 composite shows the best catalytic performance. The 5%Co/TiO2–MgAl2O4 improved the CH4 and CO2 conversion by up to 70% and 80%, respectively, while the selectivity of H2 and CO improved to 43% and 46.5%, respectively. The achieved H2/CO ratio of 0.9 was due to the excess amount of CO produced because of the higher conversion rate of CO2 and the surface carbon reaction with oxygen species. Furthermore, in a time on stream (TOS) test, the catalyst exhibited 75 h of stability with significant catalytic activity. Catalyst potential lies in catalyst stability and performance results, thus encouraging the further investigation and use of the catalyst for the long-run DRM process. Full article
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34 pages, 11067 KiB  
Review
Selection Guidelines for Wind Energy Technologies
by A. G. Olabi, Tabbi Wilberforce, Khaled Elsaid, Tareq Salameh, Enas Taha Sayed, Khaled Saleh Husain and Mohammad Ali Abdelkareem
Energies 2021, 14(11), 3244; https://doi.org/10.3390/en14113244 - 2 Jun 2021
Cited by 72 | Viewed by 7853
Abstract
The building block of all economies across the world is subject to the medium in which energy is harnessed. Renewable energy is currently one of the recommended substitutes for fossil fuels due to its environmentally friendly nature. Wind energy, which is considered as [...] Read more.
The building block of all economies across the world is subject to the medium in which energy is harnessed. Renewable energy is currently one of the recommended substitutes for fossil fuels due to its environmentally friendly nature. Wind energy, which is considered as one of the promising renewable energy forms, has gained lots of attention in the last few decades due to its sustainability as well as viability. This review presents a detailed investigation into this technology as well as factors impeding its commercialization. General selection guidelines for the available wind turbine technologies are presented. Prospects of various components associated with wind energy conversion systems are thoroughly discussed with their limitations equally captured in this report. The need for further optimization techniques in terms of design and materials used for the development of each component is highlighted. Full article
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33 pages, 11791 KiB  
Review
Critical Review of Flywheel Energy Storage System
by Abdul Ghani Olabi, Tabbi Wilberforce, Mohammad Ali Abdelkareem and Mohamad Ramadan
Energies 2021, 14(8), 2159; https://doi.org/10.3390/en14082159 - 13 Apr 2021
Cited by 122 | Viewed by 23333
Abstract
This review presents a detailed summary of the latest technologies used in flywheel energy storage systems (FESS). This paper covers the types of technologies and systems employed within FESS, the range of materials used in the production of FESS, and the reasons for [...] Read more.
This review presents a detailed summary of the latest technologies used in flywheel energy storage systems (FESS). This paper covers the types of technologies and systems employed within FESS, the range of materials used in the production of FESS, and the reasons for the use of these materials. Furthermore, this paper provides an overview of the types of uses of FESS, covering vehicles and the transport industry, grid leveling and power storage for domestic and industrial electricity providers, their use in motorsport, and applications for space, satellites, and spacecraft. Different types of machines for flywheel energy storage systems are also discussed. This serves to analyse which implementations reduce the cost of permanent magnet synchronous machines. As well as this, further investigations need to be carried out to determine the ideal temperature range of operation. Induction machines are currently stoutly designed with lower manufacturing cost, making them unsuitable for high-speed operations. Brushless direct current machines, the Homolar machines, and permanent magnet synchronous machines should also be considered for future research activities to improve their performance in a flywheel energy storage system. An active magnetic bearing can also be used alongside mechanical bearings to reduce the control systems’ complications, thereby making the entire system cost-effective. Full article
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2020

Jump to: 2022, 2021

23 pages, 5577 KiB  
Article
Enhancing the Economic Viability of Anaerobic Digestion by Exploiting the Whole Biomass of Mango Waste and Its Residues after Digestion
by R. Alrefai, A.M. Alrefai, K.Y. Benyounis and J. Stokes
Energies 2020, 13(24), 6683; https://doi.org/10.3390/en13246683 - 17 Dec 2020
Cited by 1 | Viewed by 2312
Abstract
A significant expansion of anaerobic digestion (AD) processes would certainly result in a reduction in the current dependence on fossil fuels. The operational costs, the large amounts of digestate generated and the expenses of dealing with it and the volatility of the fuel [...] Read more.
A significant expansion of anaerobic digestion (AD) processes would certainly result in a reduction in the current dependence on fossil fuels. The operational costs, the large amounts of digestate generated and the expenses of dealing with it and the volatility of the fuel indexes represent major environmental and economical challenges to the diffusion of AD. Increasing the bio-products of AD could possibly help in increasing its profitability and limit these challenges. This study investigates the influence of mango starch and seed coats on the biogas produced from mango waste. To overcome the environmental challenges, the digestate was tested and its bio-fertiliser potential proven. The study reached the conclusion that the effect of the starch on the AD biogas of mango waste is low while the effect of the seed coats is quite high. This finding supports further investigations to evaluate the effect of the production of mango starch and seed coat-based products on the profitability of AD. The highest energy balance achieved was 65% at 32 °C, 3.93 g-VS organic concentration and 37% sludge concentration, which yielded a maximum CH4 yield of 62.5%. This finding encourages the application of gate fees for accepting bio-waste, which may help in overcoming its economic challenges. Full article
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28 pages, 4200 KiB  
Article
Stochastic Fractal Search Optimization Algorithm Based Global MPPT for Triple-Junction Photovoltaic Solar System
by Hegazy Rezk and Ahmed Fathy
Energies 2020, 13(18), 4971; https://doi.org/10.3390/en13184971 - 22 Sep 2020
Cited by 5 | Viewed by 2199
Abstract
A significant growth in PV (photovoltaic) system installations have been observed during the last decade. The PV array has a nonlinear output characteristic because of weather intermittency. Partial shading is an environmental phenomenon that causes multiple peaks in the power curve and has [...] Read more.
A significant growth in PV (photovoltaic) system installations have been observed during the last decade. The PV array has a nonlinear output characteristic because of weather intermittency. Partial shading is an environmental phenomenon that causes multiple peaks in the power curve and has a negative effect on the efficiency of the conventional maximum power point tracking (MPPT) methods. This tends to have a substantial effect on the overall performance of the PV system. Therefore, to enhance the performance of the PV system under shading conditions, the global MPPT technique is mandatory to force the PV system to operate close to the global maximum. In this paper, for the first time, a stochastic fractal search (SFS) optimization algorithm is applied to solve the dilemma of tracking the global power of PV system based triple-junction solar cells under shading conditions. SFS has been nominated because it can converge to the best solution at a fast rate. Moreover, balance between exploration and exploitation phases is one of its main advantages. Therefore, the SFS algorithm has been selected to extract the global maximum power point (MPP) under partial shading conditions. To prove the superiority of the proposed global MPPT–SFS based tracker, several shading scenarios have been considered. The idea of changing the shading scenario is to change the position of the global MPP. The obtained results are compared with common optimizers: Antlion Optimizer (ALO), Cuckoo Search (CS), Flower Pollination Algorithm (FPA), Firefly-Algorithm (FA), Invasive-Weed-Optimization (IWO), JAYA and Gravitational Search Algorithm (GSA). The results of comparison confirmed the effectiveness and robustness of the proposed global MPPT–SFS based tracker over ALO, CS, FPA, FA, IWO, JAYA, and GSA. Full article
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