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Special Issue "Sustainable Energy Systems"

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "Sustainable Energy".

Deadline for manuscript submissions: 15 December 2018

Special Issue Editors

Guest Editor
Prof. Nídia Caetano

Laboratory for Process Engineering, Environment, Biotechnology and Energy (LEPABE), Faculty of Engineering, University of Porto (FEUP), R. Dr. Roberto Frias S/N, 4200-465 Porto, Portugal
School of Engineering (ISEP), Polytechnic of Porto, R. Dr. António Bernardino de Almeida 431, 4249-015 Porto, Portugal
Website | E-Mail
Interests: biodiesel; bioethanol; biorefinery; energy storage systems; microalgae biorefineries; sustainable energy systems; waste valorization; wastewater treatment; waste-to-energy
Guest Editor
Dr. Zita Vale

Polytechnic of Porto, Portugal
Website | E-Mail
Interests: demand response; electric vehicles; electricity markets; power systems; smart grids
Guest Editor
Dr. Bo Nørregaard Jørgensen

Center for Energy Informatics, Mærsk Mc-Kinney Møller Institute, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark
E-Mail
Interests: Multi-agent systems; Demand response; Energy flexibility; Multi-objective optimization
Guest Editor
Dr. Carlos Felgueiras

Center for Innovation in Engineering and Industrial Technology (CIETI),Department of Electrical Engineering, School of Engineering (ISEP), Polytechnic of Porto (P.PORTO), Porto, Portugal
Website | E-Mail
Interests: energy quality; energy and buildings; energy and environmental indicators; renewable energy systems; sustainable energy systems

Special Issue Information

Dear Colleagues,

Energy is a crucial resource for nation and society development. Sustainable energy production and use is still a distant target, in spite of all the efforts and advancements achieved so far. Although renewable energy use has been increasing significantly, a large share of the energy currently used around the world is still based on fossil resources (oil and coal).

Renewable energy use brings along technical and business challenges. Geographically distributed by nature, renewables contribute to increasingly distributed generation of electricity. Ensuring the required reliability and efficiency with the spreading of small-scale electricity generation is a huge challenge that must be overcome. Energy storage systems and active participation from the demand side, with efficient use of the available energy, demand flexibility must be intelligently used to compensate for the intermittency of the most attractive renewable energy sources, such as wind and sun.

This Special Issue, therefore, aims to contribute to the “Sustainable Energy Systems” agenda through advanced scientific and multi-disciplinary knowledge, combined to improve energy security and performance.

We therefore invite papers on innovative technical developments, reviews, case studies, analytical, as well as assessments, from different disciplines, which are relevant to “Sustainable Energy Systems”. These include smart grids, renewable energy systems, energy storage systems, life cycle analysis of energy systems, zero energy buildings, electric and hybrid vehicles, financial and economic analysis of energy systems, smart systems, energy management and big data, energy policy, novel energy sources, and renewable-based generation, among others.

Dr. Nídia Caetano
Dr. Zita Vale
Dr. Bo Nørregaard Jørgensen
Dr. Carlos Felgueiras
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • electric and hybrid vehicles
  • energy efficiency
  • energy management and policy
  • energy storage
  • life cycle assessment
  • renewable energy
  • renewable energy systems
  • smart grids
  • waste-to-energy
  • zero energy buildings

Published Papers (10 papers)

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Research

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Open AccessArticle Consequences of the National Energy Strategy in the Mexican Energy System: Analyzing Strategic Indicators with an Optimization Energy Model
Energies 2018, 11(10), 2837; https://doi.org/10.3390/en11102837 (registering DOI)
Received: 28 August 2018 / Revised: 16 October 2018 / Accepted: 16 October 2018 / Published: 20 October 2018
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Abstract
This paper presents an approach to the assessment of the Mexican energy system’s evolution under the climate and energy objectives set by the National Climate Change Strategy using an energy optimization model. Some strategic indicators have been chosen to analyze the performance of
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This paper presents an approach to the assessment of the Mexican energy system’s evolution under the climate and energy objectives set by the National Climate Change Strategy using an energy optimization model. Some strategic indicators have been chosen to analyze the performance of three integration elements: sustainability, efficiency, and energy security. Two scenarios have been defined in the medium and long-term: the business as usual scenario, with no energy or climate targets, and the National Climate Change Strategy scenario, where clean energy technologies and CO2 emissions objectives are considered. The aim of this work is the analysis of some of those strategic indicators’ evolution using the EUROfusion Times Model. Results show that reaching the strategy targets leads to improvements in the integration elements in the medium and long term. Besides, meeting the CO2 emission limits is achievable in terms of technologies and resources availability but at a high cost, while clean technologies targets are met with no extra costs even in the business as usual scenario. Full article
(This article belongs to the Special Issue Sustainable Energy Systems)
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Open AccessFeature PaperArticle Circular Statistics Applied to the Study of the Solar Radiation Potential of Rooftops in a Medium-Sized City
Energies 2018, 11(10), 2813; https://doi.org/10.3390/en11102813
Received: 15 September 2018 / Revised: 12 October 2018 / Accepted: 16 October 2018 / Published: 18 October 2018
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Abstract
Solar energy constitutes one of the most effective alternative energy sources for combating climate change. However, the solar potential in a city can vary depending on the urban morphology. The purpose of this paper is to perform a directional statistical analysis of the
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Solar energy constitutes one of the most effective alternative energy sources for combating climate change. However, the solar potential in a city can vary depending on the urban morphology. The purpose of this paper is to perform a directional statistical analysis of the distribution of the monthly solar potential of rooftops in the city of Cáceres, Spain, in relation to the orientations and slopes of the rooftops. Two residential areas, one in the city center and one on the outskirts of the city, and an industrial zone, all of which exhibit different urban morphologies, have been evaluated. Statistics have been assessed in consideration of the orientation and slope values of the rooftops as circular data, and the radiation values as linear data. The three dissimilar urban morphologies result in different solar potential values, and the monthly disaggregation of the data enables the ability to detect the differences existing in the solar potential between each zone, during each month. The proposed analysis could also be extrapolated to urban planning for the design of more sustainable cities to face the challenges associated with climate change. Full article
(This article belongs to the Special Issue Sustainable Energy Systems)
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Open AccessArticle Heat Removal Factor in Flat Plate Solar Collectors: Indoor Test Method
Energies 2018, 11(10), 2783; https://doi.org/10.3390/en11102783
Received: 9 August 2018 / Revised: 20 September 2018 / Accepted: 4 October 2018 / Published: 17 October 2018
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Abstract
This paper presents a couple of methods to evaluate the heat removal factor FR of flat plate solar collectors, as well as a parametric study of the FR against the tilt angle β, and (TiTa
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This paper presents a couple of methods to evaluate the heat removal factor FR of flat plate solar collectors, as well as a parametric study of the FR against the tilt angle β, and (TiTa)/G, and its effects on the a0-factor (FRτα) and the a1-factor (FRULmin). The proposed methods were based on indoor flow calorimetry. The first method considers the ratio of the actual useful heat to the maximum useful heat. The second takes into account the slopes of the family of efficiency curves (FRULmin) according to ANSI/ASHRAE 93-2010, and the minimum overall heat loss coefficient, ULmin. In both methods, a feedback temperature control at collector inclinations from horizontal to vertical allows the inlet temperature and the emulating of the solar radiation to be established by electrical heating. The performance of the methods was determined in terms of the uncertainty of the FR. Method 1 allowed a three-fold improved precision compared to Method 2; however, this implied a more detailed experimental setup. According to the first method, the effects of the tilt angle β, and the (TiTa)/G, on the a0-factor were considerable, since FR is directly proportional to the a0-factor. The changes in (TiTa)/G caused an average change in FR of 32% The FR shows almost linear behavior for inclinations from horizontal to vertical with a 14.5% change. The effects of β on the a1-factor were not considerable, due to the compensation between the increase in FR and the decrease in ULmin as β increased. Full article
(This article belongs to the Special Issue Sustainable Energy Systems)
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Open AccessArticle A Sketch of Bolivia’s Potential Low-Carbon Power System Configurations. The Case of Applying Carbon Taxation and Lowering Financing Costs
Energies 2018, 11(10), 2738; https://doi.org/10.3390/en11102738
Received: 22 August 2018 / Revised: 28 September 2018 / Accepted: 8 October 2018 / Published: 12 October 2018
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Abstract
This paper considers hypothetical options for the transformation of the Bolivian power generation system to one that emits less carbon dioxide. Specifically, it evaluates the influence of the weighted average cost of capital (WACC) on marginal abatement cost curves (MACC) when applying carbon
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This paper considers hypothetical options for the transformation of the Bolivian power generation system to one that emits less carbon dioxide. Specifically, it evaluates the influence of the weighted average cost of capital (WACC) on marginal abatement cost curves (MACC) when applying carbon taxation to the power sector. The study is illustrated with a bottom-up least-cost optimization model. Projections of key parameters influence the shape of MACCs and the underlying technology configurations. These are reported. Results from our study (and the set of assumptions on which they are based) are country-specific. Nonetheless, the methodology can be replicated to other case studies to provide insights into the role carbon taxes and lowering finance costs might play in reducing emissions. Full article
(This article belongs to the Special Issue Sustainable Energy Systems)
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Open AccessFeature PaperArticle Performance Evaluation of a PID-Controlled Synchronous Buck Converter Based Battery Charging Controller for Solar-Powered Lighting System in a Fishing Trawler
Energies 2018, 11(10), 2722; https://doi.org/10.3390/en11102722
Received: 28 September 2018 / Revised: 1 October 2018 / Accepted: 2 October 2018 / Published: 11 October 2018
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Abstract
A Proportional-Integral-Derivative (PID)-controlled synchronous buck converter (SBC)-based battery charging system was designed to charge a lead-acid cell battery using commercially available Photovoltaic (PV) panel. The proposed system was installed aboard a fishing trawler to power its electrical system replacing the conventional system, which
[...] Read more.
A Proportional-Integral-Derivative (PID)-controlled synchronous buck converter (SBC)-based battery charging system was designed to charge a lead-acid cell battery using commercially available Photovoltaic (PV) panel. The proposed system was installed aboard a fishing trawler to power its electrical system replacing the conventional system, which uses a diesel generator and a few kerosene lamps for lighting purposes. A PID algorithm instead of traditional Maximum power point tracker (MPPT) is used in the proposed system since the charging process of the battery requires a maximum current instead of maximum power. The proposed control algorithm is compared with the popular MPPT technique Perturb and Observation (P&O) to validate its dynamic performance at different solar irradiance levels using MATLAB/Simulink®. The simulation and the experimental results have demonstrated that the dynamic response of the proposed algorithm is significantly improved by considering higher charging current, the capability to charge the battery at low irradiance, high stability, and lower cost. Finally, a successful 15-day field trial was conducted at sea using the proposed system, and a maximum charging current output of 6.5 A was achieved by the SBC during noon time; it was sufficient to charge a 12 V, 100 Ah battery, with a state of charge (SoC) of 33%, at a voltage charging rate of +0.3 V/h. Full article
(This article belongs to the Special Issue Sustainable Energy Systems)
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Open AccessArticle High Performances Design of a Six-Phase Synchronous Reluctance Motor Using Multi-Objective Optimization with Altered Bee Colony Optimization and Taguchi Method
Energies 2018, 11(10), 2716; https://doi.org/10.3390/en11102716
Received: 24 August 2018 / Revised: 13 September 2018 / Accepted: 10 October 2018 / Published: 11 October 2018
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Abstract
A two-step optimal design with multi-objective functions by using two kinds of optimization methods for a six-phase synchronous reluctance motor is applied in a centrifugal compressor to achieve minimum cost, lower torque ripple, maximum efficiency and higher power factor. In the first-step procedure,
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A two-step optimal design with multi-objective functions by using two kinds of optimization methods for a six-phase synchronous reluctance motor is applied in a centrifugal compressor to achieve minimum cost, lower torque ripple, maximum efficiency and higher power factor. In the first-step procedure, the optimal design with multi-objective functions by use of the altered bee colony optimization (BCO) and the Taguchi method combined with finite element analysis (FEA) is used for optimizing the barrier shape and size in the rotor to reduce torque ripple, raise power factor, maximum efficiency and raise output torque. In the second-step procedure, the optimal design with multi-objective functions by means of the altered BCO and the Taguchi method combined with FEA is applied for optimizing the geometry of stator to reduce manufacturing cost, stator iron weight and stator winding weight. Finally, some experimental results show the effectiveness of the proposed techniques. Full article
(This article belongs to the Special Issue Sustainable Energy Systems)
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Open AccessArticle Correlation Analysis between Wind Speed/Voltage Clusters and Oscillation Modes of Doubly-Fed Induction Generators
Energies 2018, 11(9), 2370; https://doi.org/10.3390/en11092370
Received: 13 August 2018 / Revised: 28 August 2018 / Accepted: 5 September 2018 / Published: 8 September 2018
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Abstract
Potential machine-grid interactions caused by large-scale wind farms have drawn much attention in recent years. Previous work has been done by analyzing the small–signal modeling of doubly-fed induction generators (DFIGs) to obtain the oscillation modes. This paper, by making use of the metered
[...] Read more.
Potential machine-grid interactions caused by large-scale wind farms have drawn much attention in recent years. Previous work has been done by analyzing the small–signal modeling of doubly-fed induction generators (DFIGs) to obtain the oscillation modes. This paper, by making use of the metered power data of wind generating sets, studies the correlation between oscillation modes of the DFIG system and influence factors which includes wind speed and grid voltage. After the metered data is segmented, the Prony algorithm is used to analyze the oscillation modes contained in the active power. Then, the relevant oscillation modes are extracted in accordance with the small-signal analysis results. Meanwhile, data segments are clustered according to wind speed and grid voltage. The Apriori algorithm is finally used to discuss the association rules. By training the mass of data of wind generating sets, the inevitable association rules between oscillation modes and influence factors can be mined. Therefore, the prediction of oscillation modes can be achieved based on the rules. The results show that the clustering number quite affects the association rules. When the optimal cluster number is adopted, part of the wind speed/voltage clusters can analyze the certain oscillation modes. The predicted results are quite consistent with the practical data. Full article
(This article belongs to the Special Issue Sustainable Energy Systems)
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Open AccessArticle Scrutinising the Gap between the Expected and Actual Deployment of Carbon Capture and Storage—A Bibliometric Analysis
Energies 2018, 11(9), 2319; https://doi.org/10.3390/en11092319
Received: 29 July 2018 / Revised: 24 August 2018 / Accepted: 28 August 2018 / Published: 3 September 2018
Cited by 1 | PDF Full-text (2232 KB) | HTML Full-text | XML Full-text
Abstract
For many years, carbon capture and storage (CCS) has been discussed as a technology that may make a significant contribution to achieving major reductions in greenhouse gas emissions. At present, however, only two large-scale power plants capture a total of 2.4 Mt CO
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For many years, carbon capture and storage (CCS) has been discussed as a technology that may make a significant contribution to achieving major reductions in greenhouse gas emissions. At present, however, only two large-scale power plants capture a total of 2.4 Mt CO2/a. Several reasons are identified for this mismatch between expectations and realised deployment. Applying bibliographic coupling, the research front of CCS, understood to be published peer-reviewed papers, is explored to scrutinise whether the current research is sufficient to meet these problems. The analysis reveals that research is dominated by technical research (69%). Only 31% of papers address non-technical issues, particularly exploring public perception, policy, and regulation, providing a broader view on CCS implementation on the regional or national level, or using assessment frameworks. This shows that the research is advancing and attempting to meet the outlined problems, which are mainly non-technology related. In addition to strengthening this research, the proportion of papers that adopt a holistic approach may be increased in a bid to meet the challenges involved in transforming a complex energy system. It may also be useful to include a broad variety of stakeholders in research so as to provide a more resilient development of CCS deployment strategies. Full article
(This article belongs to the Special Issue Sustainable Energy Systems)
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Open AccessArticle Variable Parameters for a Single Exponential Model of Photovoltaic Modules in Crystalline-Silicon
Energies 2018, 11(8), 2138; https://doi.org/10.3390/en11082138
Received: 18 July 2018 / Revised: 8 August 2018 / Accepted: 13 August 2018 / Published: 16 August 2018
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Abstract
The correct approximation of parallel resistance (Rp) and series resistance (Rs) poses a major challenge for the single diode model of the photovoltaic module (PV). The bottleneck behind the limited accuracy of the model is the static
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The correct approximation of parallel resistance (Rp) and series resistance (Rs) poses a major challenge for the single diode model of the photovoltaic module (PV). The bottleneck behind the limited accuracy of the model is the static estimation of resistive parameters. This means that Rp and Rs, once estimated, usually remain constant for the entire operating range of the same weather condition, as well as for other conditions. Another contributing factor is the availability of only standard test condition (STC) data in the manufacturer’s datasheet. This paper proposes a single-diode model with dynamic relations of Rp and Rs. The relations not only vary the resistive parameters for constant/distinct weather conditions but also provide a non-iterative solution. Initially, appropriate software is used to extract the data of current-voltage (I-V) curves from the manufacturer’s datasheet. By using these raw data and simple statistical concepts, the relations for Rp and Rs are designed. Finally, it is proved through root mean square error (RMSE) analysis that the proposed model holds a one-tenth advantage over numerous recently proposed models. Simultaneously, it is low complex, iteration-free (0 to voltage in maximum power point Vmpp range), and requires less computation time to trace the I-V curve. Full article
(This article belongs to the Special Issue Sustainable Energy Systems)
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Review

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Open AccessReview Frosting Phenomenon and Frost-Free Technology of Outdoor Air Heat Exchanger for an Air-Source Heat Pump System in China: An Analysis and Review
Energies 2018, 11(10), 2642; https://doi.org/10.3390/en11102642
Received: 18 August 2018 / Revised: 19 September 2018 / Accepted: 30 September 2018 / Published: 3 October 2018
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Abstract
Frost layer on the outdoor air heat exchanger surface in an air-source heat pump (ASHP) can decrease the system coefficient of performance (COP). Although the common defrosting and anti-frosting methods can improve the COP, the periodic defrosting not only reduces the system energy
[...] Read more.
Frost layer on the outdoor air heat exchanger surface in an air-source heat pump (ASHP) can decrease the system coefficient of performance (COP). Although the common defrosting and anti-frosting methods can improve the COP, the periodic defrosting not only reduces the system energy efficiency but also deteriorates the indoor environment. To solve these problems, it is necessary to clearly understand the frosting phenomenon and to achieve the system frost-free operation. This paper focused firstly on the analyses of frosting pathways and frosting maps. Followed by summarizing the characteristics of frost-free technologies. And then the performances of two types of frost-free ASHP (FFASHP) systems were reviewed, and the exergy and economic analysis of a FFASHP heating system were carried out. Finally, the existing problems related to the FFASHP technologies were proposed. Results show that the existing frosting maps need to be further improved. The FFASHP systems can not only achieve continuous frost-free operation but reduce operating cost. And the total COP of the FFASHP heating system is approximately 30–64% higher than that of the conventional ASHP system under the same frosting conditions. However, the investment cost of the FFASHP system increases, and its reliability also needs further field test in a wider frosting environment. In the future, combined with a new frosting map, the control strategy for the FFASHP system should be optimized. Full article
(This article belongs to the Special Issue Sustainable Energy Systems)
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