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Special Issue "10 Years Energies - Horizon 2028"

A special issue of Energies (ISSN 1996-1073).

Deadline for manuscript submissions: 31 December 2018

Special Issue Editors

Guest Editor
Prof. Dr. Enrico Sciubba

Room 32, Department of Mechanical and Aerospace Engineering, University of Roma Sapienza, Via Eudossiana 18, 00184 Roma, Italy
Website | E-Mail
Phone: +39-06-44585244
Fax: +39 06 44 58 52 49
Interests: turbomachinery CFD; turbulence modelling; exergy analysis of complex systems; engineering applications of AI to thermal conversion processes
Guest Editor
Prof. Dr. Paul Stewart

Institute for Innovation in Sustainable Engineering, University of Derby, Lonsdale House, Derby, DE1 3EE, UK
Website | E-Mail
Interests: complex system simulation, design and optimization; engineering applications of artificial intelligence; advanced control systems; power and energy architectures; electrical machines, drives and systems; energy conversion and storage; remote monitoring and sensing; prognostics and diagnostics; low carbon and low emissions operations
Guest Editor
Prof. Dr. Thomas E. Amidon

Department of Paper and Bioprocess Engineering, College of Environmental Science and Forestry, State University of New York, 1 Forestry Drive, Syracuse, NY 13210, USA
Website | E-Mail
Interests: biorefineries; biofuels; bioenergy; bio-based materials and chemicals; nanocellulose; pulp and paper; pellets; forest and biomass resources; process development; novel bio-based products; cell wall deconstruction; hot water extraction; cellulosic bioproducts; improved fiber-based products; biomass productivity
Guest Editor
Prof. Dr. K.T. Chau

Department of Electrical & Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong
Website | E-Mail
Interests: electric and hybrid vehicles; machines and drives; renewable and clean energies; power electronics
Guest Editor
Prof. Dr. Abdul-Ghani Olabi

School of Engineering and Computing, University of the West of Scotland, Paisley PA1 2BE, UK
Website | E-Mail
Interests: renewable energy; CAD and design; smart materials

Special Issue Information

Dear Colleagues,

Energies (ISSN 1996-1073; CODEN: ENERGA) http://www.mdpi.com/journal/energies) has reached a milestone: it is now 10 years since our journal was launched.

In celebration of this special occasion, the Energies editorial team have decided to publish a special issue called "10 Years of Energies – Horizon 2028". We would like to invite you to contribute a comprehensive review article or an original research paper for peer-review and possible publication. The details for this special issue can be found at:

http://www.mdpi.com/journal/energies/special_issues/A_Decade_of_Horizon_2028

The last ten years of technological and theoretical advancements in Energies have been extraordinary. We now want to look to the future. For example, with the development and application of new materials, Big Data analytics, Industry 4.0, Internet of Things and AI being applied to the Energy sector and its relationship to areas such as electric vehicle design, charging infrastructure and renewable energy networks, we predict the pace of change in the next ten years to be even greater

The purpose of this special issue is to publish a set of articles that typify the very best insightful and influential investigations or theories that will form the foundation of the next ten year’s technological change. We would like to include articles that will form the new benchmark against which other articles are measured; this benchmark is, of course, a moving target as Energies continues to advance to new frontiers. We expect these articles to be widely read and highly influential within the field.

There is no restriction on the subject areas for this special issue. Energies readers and authors are encouraged to send their very best work to be showcased. The key criteria for manuscript acceptance will be novelty and the potential breadth and contribution to the field. Manuscripts with experimental implementation and empirical proofs are also encouraged.

Prof. Dr. Enrico Sciubba
Prof. Dr. Paul Stewart
Prof. Dr. Thomas E. Amidon
Prof. Dr. K.T. Chau
Prof. Dr. Abdul-Ghani Olabi
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

  • Renewables
  • Distribution
  • Electric Transportation
  • Generation
  • Smart Grid
  • Machines and Drives
  • Prognostics and Diagnostics
  • Power Architectures
  • Energy Conversion and Storage
  • Low Carbon

Published Papers (18 papers)

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Research

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Open AccessFeature PaperArticle Concurrent Real-Time Estimation of State of Health and Maximum Available Power in Lithium-Sulfur Batteries
Energies 2018, 11(8), 2133; https://doi.org/10.3390/en11082133
Received: 9 July 2018 / Revised: 3 August 2018 / Accepted: 6 August 2018 / Published: 16 August 2018
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Abstract
Lithium-sulfur (Li-S) batteries are an emerging energy storage technology with higher performance than lithium-ion batteries in terms of specific capacity and energy density. However, several scientific and technological gaps need to be filled before Li-S batteries will penetrate the market at a large
[...] Read more.
Lithium-sulfur (Li-S) batteries are an emerging energy storage technology with higher performance than lithium-ion batteries in terms of specific capacity and energy density. However, several scientific and technological gaps need to be filled before Li-S batteries will penetrate the market at a large scale. One such gap, which is tackled in this paper, is represented by the estimation of state-of-health (SOH). Li-S batteries exhibit a complex behaviour due to their inherent mechanisms, which requires a special tailoring of the already literature-available state-of-charge (SOC) and SOH estimation algorithms. In this work, a model of SOH based on capacity fade and power fade has been proposed and incorporated in a state estimator using dual extended Kalman filters has been used to simultaneously estimate Li-S SOC and SOH. The dual extended Kalman filter’s internal estimates of equivalent circuit network parameters have also been used to the estimate maximum available power of the battery at any specified instant. The proposed estimators have been successfully applied to both fresh and aged Li-S pouch cells, showing that they can accurately track accurately the battery SOC, SOH, and power, providing that initial conditions are suitable. However, the estimation of the Li-S battery cells’ capacity fade is shown to be more complex, because the practical available capacity varies highly with the applied current rates and the dynamics of the mission profile. Full article
(This article belongs to the Special Issue 10 Years Energies - Horizon 2028)
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Open AccessArticle The Effect of a Wave Energy Farm Protecting an Aquaculture Installation
Energies 2018, 11(8), 2109; https://doi.org/10.3390/en11082109
Received: 7 July 2018 / Revised: 5 August 2018 / Accepted: 6 August 2018 / Published: 13 August 2018
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Abstract
This paper assesses the impact of a farm of wave energy converters on a nearby offshore aquaculture installation and on the nearshore dynamics. The coastal area targeted is Aguçadoura, located in the north of Portugal, where the world’s first wave farm operated in
[...] Read more.
This paper assesses the impact of a farm of wave energy converters on a nearby offshore aquaculture installation and on the nearshore dynamics. The coastal area targeted is Aguçadoura, located in the north of Portugal, where the world’s first wave farm operated in 2008. The study is focused mainly on the evaluation of the sheltering effect provided by the wave farm to the aquaculture cages. Furthermore, the possible impact on the coastal wave climate of such an energy park is also evaluated. These objectives are accomplished by performing simulations, corresponding to the wave conditions, which are more often encountered in that coastal environment. The SWAN model (Simulating WAves Nearshore) was adopted for this. Various transmission scenarios are considered to account for the impact of different types of wave converter farms on the downwave conditions. The results show that such a wave energy park might have a clear positive impact on the wave conditions fish farm installed downwave and it might also have a beneficial influence on shoreline dynamics from the perspective of coastal protection. Full article
(This article belongs to the Special Issue 10 Years Energies - Horizon 2028)
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Open AccessArticle Site Selection of Hybrid Offshore Wind and Wave Energy Systems in Greece Incorporating Environmental Impact Assessment
Energies 2018, 11(8), 2095; https://doi.org/10.3390/en11082095
Received: 30 June 2018 / Revised: 2 August 2018 / Accepted: 10 August 2018 / Published: 12 August 2018
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Abstract
This paper presents a methodological framework for evaluating marine areas in Greece for the purpose of identifying the most adequate sites for Hybrid Offshore Wind and Wave Energy Systems (HOWiWaES), with special focus on the HOWiWaES’ environmental impact assessment evaluation. Nine evaluation criteria
[...] Read more.
This paper presents a methodological framework for evaluating marine areas in Greece for the purpose of identifying the most adequate sites for Hybrid Offshore Wind and Wave Energy Systems (HOWiWaES), with special focus on the HOWiWaES’ environmental impact assessment evaluation. Nine evaluation criteria that reflect various environmental, economic, technical and socio-political aspects are considered, including Wind Velocity (WV), Wave Energy Potential (WEP), Water Depth (WD), Distance from Shore (DS), Connection to Local Electrical Grid (CLEG), Population Served (PS), Shipping Density (SD), Distance from Ports (DP) and Environmental Performance Value (EPV). Analytical Hierarchy Process (AHP) is performed to hierarchically rank twelve predefined siting alternatives. Questionnaires are used to collect information on pairwise comparisons of the evaluation criteria from a group of stakeholders/experts. Geographic Information Systems (GIS) are used as a metric tool for pairwise comparisons of each siting alternative with respect to the first eight evaluation criteria, while the last criterion is assessed through the development of an innovative environmental impact assessment tool. The results indicate that WV, WEP and EPV present the evaluation criteria with the highest relative significance, while PS, DP and SD correspond to less influencing criteria. The proposed methodology can be easily applied to other countries worldwide for supporting socially accepted siting of HOWiWaES. Full article
(This article belongs to the Special Issue 10 Years Energies - Horizon 2028)
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Open AccessArticle Computational Modeling of Gurney Flaps and Microtabs by POD Method
Energies 2018, 11(8), 2091; https://doi.org/10.3390/en11082091
Received: 6 July 2018 / Revised: 7 August 2018 / Accepted: 10 August 2018 / Published: 11 August 2018
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Abstract
Gurney flaps (GFs) and microtabs (MTs) are two of the most frequently used passive flow control devices on wind turbines. They are small tabs situated close to the airfoil trailing edge and normal to the surface. A study to find the most favorable
[...] Read more.
Gurney flaps (GFs) and microtabs (MTs) are two of the most frequently used passive flow control devices on wind turbines. They are small tabs situated close to the airfoil trailing edge and normal to the surface. A study to find the most favorable dimension and position to improve the aerodynamic performance of an airfoil is presented herein. Firstly, a parametric study of a GF on a S810 airfoil and an MT on a DU91(2)250 airfoil was carried out. To that end, 2D computational fluid dynamic simulations were performed at Re = 106 based on the airfoil chord length and using RANS equations. The GF and MT design parameters resulting from the computational fluid dynamics (CFD) simulations allowed the sizing of these passive flow control devices based on the airfoil’s aerodynamic performance. In both types of flow control devices, the results showed an increase in the lift-to-drag ratio for all angles of attack studied in the current work. Secondly, from the data obtained by means of CFD simulations, a regular function using the proper orthogonal decomposition (POD) was used to build a reduced order method. In both flow control cases (GFs and MTs), the recursive POD method was able to accurately and very quickly reproduce the computational results with very low computational cost. Full article
(This article belongs to the Special Issue 10 Years Energies - Horizon 2028)
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Open AccessArticle Effect of Zonal Hydraulics on Energy Consumption and Boom Structure of a Micro-Excavator
Energies 2018, 11(8), 2088; https://doi.org/10.3390/en11082088
Received: 1 July 2018 / Revised: 6 August 2018 / Accepted: 7 August 2018 / Published: 10 August 2018
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Abstract
This paper investigates the effect of extra weight caused by the Direct Driven Hydraulics (DDH) in a micro-excavator. These projects are investigating the implementation of zonal or decentralized hydraulics for non-road mobile machinery (NRMM) and stationary industrial applications. The benefit of DDH is
[...] Read more.
This paper investigates the effect of extra weight caused by the Direct Driven Hydraulics (DDH) in a micro-excavator. These projects are investigating the implementation of zonal or decentralized hydraulics for non-road mobile machinery (NRMM) and stationary industrial applications. The benefit of DDH is the combination of electric and hydraulic technologies in a compact package compared to conventional hydraulics, which enables a reduction of potential leakage points, flexible tubing, and boosting of the system efficiency due to switching to direct pump control instead of a loss-generating conventional valve-based control. In order to demonstrate these benefits for the excavator case, this paper proposes a system model approach to assess and predict energy consumption of the zonal hydraulics approach implemented with DDH in various working cycles, complemented by a structural analysis. The finite element analysis utilized for this demonstrated that the extra weight and selected location of DDH units do not negatively affect the structure of the excavator. Simulation results demonstrated that the energy consumption is approximately 15% higher with extra weight added by the three DDH units. Although approximately 20% more regeneration energy is produced, taking into account the regeneration energy, the increases in energy consumption are about 12%. Full article
(This article belongs to the Special Issue 10 Years Energies - Horizon 2028)
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Open AccessArticle BiPAD: Binomial Point Process Based Energy-Aware Data Dissemination in Opportunistic D2D Networks
Energies 2018, 11(8), 2073; https://doi.org/10.3390/en11082073
Received: 1 July 2018 / Revised: 3 August 2018 / Accepted: 6 August 2018 / Published: 9 August 2018
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Abstract
In opportunistic device-to-device (D2D) networks, the epidemic routing protocol can be used to optimize the message delivery ratio. However, it has the disadvantage that it causes excessive coverage overlaps and wastes energy in message transmissions because devices are more likely to receive duplicates
[...] Read more.
In opportunistic device-to-device (D2D) networks, the epidemic routing protocol can be used to optimize the message delivery ratio. However, it has the disadvantage that it causes excessive coverage overlaps and wastes energy in message transmissions because devices are more likely to receive duplicates from neighbors. We therefore propose an efficient data dissemination algorithm that can reduce undesired transmission overlap with little performance degradation in the message delivery ratio. The proposed algorithm allows devices further away than the k-th furthest distance from the source device to forward a message to their neighbors. These relay devices are determined by analysis based on a binomial point process (BPP). Using a set of intensive simulations, we present the resulting network performances with respect to the total number of received messages, the forwarding efficiency and the actual number of relays. In particular, we find the optimal number of relays to achieve almost the same message delivery ratio as the epidemic routing protocol for a given network deployment. Furthermore, the proposed algorithm can achieve almost the same message delivery ratio as the epidemic routing protocol while improving the forwarding efficiency by over 103% when k10. Full article
(This article belongs to the Special Issue 10 Years Energies - Horizon 2028)
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Open AccessArticle A Simple Assessment of Housing Retrofit Policies for the UK: What Should Succeed the Energy Company Obligation?
Energies 2018, 11(8), 2070; https://doi.org/10.3390/en11082070
Received: 30 June 2018 / Revised: 30 July 2018 / Accepted: 1 August 2018 / Published: 8 August 2018
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Abstract
Despite the need for large-scale retrofit of UK housing to meet emissions reduction targets, progress to date has been slow and domestic energy efficiency policies have struggled to accelerate housing retrofit processes. There is a need for housing retrofit policies that overcome key
[...] Read more.
Despite the need for large-scale retrofit of UK housing to meet emissions reduction targets, progress to date has been slow and domestic energy efficiency policies have struggled to accelerate housing retrofit processes. There is a need for housing retrofit policies that overcome key barriers within the retrofit sector while maintaining economic viability for customers, funding organizations, and effectively addressing UK emission reductions and fuel poverty targets. In this study, we use a simple assessment framework to assess three policies (the Variable Council Tax, the Variable Stamp Duty Land Tax, and Green Mortgage) proposed to replace the UK’s current major domestic retrofit programme known as the Energy Company Obligation (ECO). We show that the Variable Council Tax and Green Mortgage proposals have the greatest potential for overcoming the main barriers to retrofit policies while maintaining economic viability and contributing to high-level UK targets. We also show that, while none of the assessed schemes are capable of overcoming all retrofit barriers on their own, a mix of all three policies could address most barriers and provide key benefits such as wide coverage of property markets, operation on existing financial infrastructures, and application of a “carrot-and-stick” approach to incentivize retrofit. Lastly, we indicate that the specific support and protection of fuel-poor households cannot be achieved by a mix of these policies and a complementary scheme focused on fuel-poor households is required. Full article
(This article belongs to the Special Issue 10 Years Energies - Horizon 2028)
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Open AccessFeature PaperArticle Effect of Sodium Chloride and Thiourea on Pollutant Formation during Combustion of Plastics
Energies 2018, 11(8), 2014; https://doi.org/10.3390/en11082014
Received: 10 July 2018 / Revised: 30 July 2018 / Accepted: 31 July 2018 / Published: 2 August 2018
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Abstract
Thermal decomposition of different samples containing a mixture of plastics (polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), and nylon) combined with NaCl and metal oxides (Fe2O3, CuO) was studied under an air atmosphere at 850 °C using a reactor,
[...] Read more.
Thermal decomposition of different samples containing a mixture of plastics (polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), and nylon) combined with NaCl and metal oxides (Fe2O3, CuO) was studied under an air atmosphere at 850 °C using a reactor, followed by analysis of the evolved products. Combustion runs were performed to study how the presence of such compounds influences the production of pollutants. Here, we report the analyses of the emissions of the main gases, as well as volatiles and semivolatiles, including polyaromatic hydrocarbons (PAHs), polychlorinated benzenes and phenols, and polybrominated phenols. Results show that the production of chlorinated pollutants did not increase in the presence of NaCl, but the presence of other metals during the decomposition led to the production of a great amount of pollutants. In this regard, the emission of chlorinated phenols increased from 110 to ca. 250 mg/kg when the sample included a small quantity of a transition metal oxide. Additionally, the presence of an inhibitor—thiourea (TUA)—was tested. Results confirm that adding TUA to the sample reduced these emissions to a considerable extent, with the emission of chlorinated phenols amounting to 65 mg/kg. Full article
(This article belongs to the Special Issue 10 Years Energies - Horizon 2028)
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Open AccessFeature PaperArticle A Practical Formulation for Ex-Ante Scheduling of Energy and Reserve in Renewable-Dominated Power Systems: Case Study of the Iberian Peninsula
Energies 2018, 11(8), 1939; https://doi.org/10.3390/en11081939
Received: 29 June 2018 / Revised: 19 July 2018 / Accepted: 24 July 2018 / Published: 25 July 2018
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Abstract
Scheduling energy and reserve in power systems with a large number of intermittent units is a challenging problem. Traditionally, the reserve requirements are assigned after clearing the day-ahead energy market using ad hoc rules or solving computationally intense mathematical programming problems to co-optimize
[...] Read more.
Scheduling energy and reserve in power systems with a large number of intermittent units is a challenging problem. Traditionally, the reserve requirements are assigned after clearing the day-ahead energy market using ad hoc rules or solving computationally intense mathematical programming problems to co-optimize energy and reserve. While the former approach often leads to costly oversized reserve provisions, the computational time required by the latter makes it generally incompatible with the daily power system operational practices. This paper proposes an alternative deterministic formulation for computing the energy and reserve scheduling, considering the uncertainty of the demand and the intermittent power production in such a way that the resulting problem requires a lower number of constraints and variables than stochastic programming-based formulations. The performance of the proposed formulation has been compared with respect to two standard stochastic programming formulations in a small-size power system. Finally, a realistic case study based on the Iberian Peninsula power system has been solved and discussed. Full article
(This article belongs to the Special Issue 10 Years Energies - Horizon 2028)
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Open AccessArticle Assessment for the Age-Of-The-Air and Ventilation Efficiency in Confined Outdoor Spaces through Computational Fluid Dynamics Techniques
Energies 2018, 11(8), 1932; https://doi.org/10.3390/en11081932
Received: 29 June 2018 / Revised: 18 July 2018 / Accepted: 19 July 2018 / Published: 24 July 2018
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Abstract
An experimentally validated numerical method for evaluating the suitability of an urban design with regard to its capacity to provide the optimum air quality for its occupants through the confined outdoor spaces is proposed. Eight possible confined outdoor spaces are defined according to
[...] Read more.
An experimentally validated numerical method for evaluating the suitability of an urban design with regard to its capacity to provide the optimum air quality for its occupants through the confined outdoor spaces is proposed. Eight possible confined outdoor spaces are defined according to their position with regard to the built elements, laterally delimited by the envelope surfaces of the neighbouring buildings. This work focuses on the definition of a procedure capable of analysing outdoor air change quality according to the age-of-the-air concept. The obtained results show that the confined outdoor spaces that are exposed to the wind action are more predisposed to reduce the mean age-of-the-air that they contain. For the analysed cases, a considerable improvement of up to 78.68% in the air change quality can be obtained by taking into account wind exposure criteria in relation to its shape and urban density, which is classified for this purpose. Full article
(This article belongs to the Special Issue 10 Years Energies - Horizon 2028)
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Open AccessArticle Indicator-Based Methodology for Assessing EV Charging Infrastructure Using Exploratory Data Analysis
Energies 2018, 11(7), 1869; https://doi.org/10.3390/en11071869
Received: 27 June 2018 / Revised: 13 July 2018 / Accepted: 16 July 2018 / Published: 18 July 2018
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Abstract
Electric vehicle (EV) charging infrastructure rollout is well under way in several power systems, namely North America, Japan, Europe, and China. In order to support EV charging infrastructures design and operation, little attempt has been made to develop indicator-based methods characterising such networks
[...] Read more.
Electric vehicle (EV) charging infrastructure rollout is well under way in several power systems, namely North America, Japan, Europe, and China. In order to support EV charging infrastructures design and operation, little attempt has been made to develop indicator-based methods characterising such networks across different regions. This study defines an assessment methodology, composed by eight indicators, allowing a comparison among EV public charging infrastructures. The proposed indicators capture the following: energy demand from EVs, energy use intensity, charger’s intensity distribution, the use time ratios, energy use ratios, the nearest neighbour distance between chargers and availability, the total service ratio, and the carbon intensity as an environmental impact indicator. We apply the methodology to a dataset from ElaadNL, a reference smart charging provider in The Netherlands, using open source geographic information system (GIS) and R software. The dataset reveals higher energy intensity in six urban areas and that 50% of energy supplied comes from 19.6% of chargers. Correlations of spatial density are strong and nearest neighbouring distances range from 1101 to 9462 m. Use time and energy use ratios are 11.21% and 3.56%. The average carbon intensity is 4.44 gCO2eq/MJ. Finally, the indicators are used to assess the impact of relevant public policies on the EV charging infrastructure use and roll-out. Full article
(This article belongs to the Special Issue 10 Years Energies - Horizon 2028)
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Open AccessArticle A Simple Pseudo-Homogeneous Reversible Kinetic Model for the Esterification of Different Fatty Acids with Methanol in the Presence of Amberlyst-15
Energies 2018, 11(7), 1843; https://doi.org/10.3390/en11071843
Received: 14 June 2018 / Revised: 3 July 2018 / Accepted: 12 July 2018 / Published: 13 July 2018
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Abstract
Fatty acid esterification with alcohols is a crucial step in biodiesel synthesis. Biodiesel consists of long-chain alkyl esters that derive from the transesterification or hydro-esterification of the triglycerides that are contained in vegetable oils. In the first route, the esterification of the free
[...] Read more.
Fatty acid esterification with alcohols is a crucial step in biodiesel synthesis. Biodiesel consists of long-chain alkyl esters that derive from the transesterification or hydro-esterification of the triglycerides that are contained in vegetable oils. In the first route, the esterification of the free fatty acids is an important pretreatment of the feed; in the second, it is the main reaction of the industrial process. Knowledge of appropriate kinetic models for the catalytic esterification of fatty acids with alcohols is critical in the design of biodiesel synthesis processes. In this work, the kinetic behavior of the reversible esterification of lauric, myristic, palmitic and stearic acid, which are the most common saturated fatty acids that are contained in triglyceride feedstocks for biodiesel, with methanol at different temperatures (70–150 °C) and molar ratios of the reactants (1:1–1:2–1:5) was investigated in a batch laboratory basket reactor both in the presence and absence of Amberlyst-15 as the catalyst. Results obtained with Amberlyst-15 were fitted through a ready-to-use pseudo-homogeneous reversible model suitable for process design. The kinetic model was compared with that obtained in a previous work with niobium oxide as the catalyst. With respect to the results that were obtained with niobium oxide, the influence of the chain length of the acid on the kinetic behavior was strongly reduced in the presence of Amberlyst-15. This phenomenon was ascribed to a different catalytic mechanism. Full article
(This article belongs to the Special Issue 10 Years Energies - Horizon 2028)
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Open AccessArticle Energy Revolution for Our Common Future: An Evaluation of the Emerging International Renewable Energy Law
Energies 2018, 11(7), 1769; https://doi.org/10.3390/en11071769
Received: 15 May 2018 / Revised: 25 June 2018 / Accepted: 26 June 2018 / Published: 5 July 2018
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Abstract
Climate change poses profound threats to the Earth and its people. Its mitigation, therefore, demands common but differentiated actions with comprehensive and coordinated approach. The global community has pledged to mitigate various greenhouse gases in some international soft law instruments. Exploitation of renewables
[...] Read more.
Climate change poses profound threats to the Earth and its people. Its mitigation, therefore, demands common but differentiated actions with comprehensive and coordinated approach. The global community has pledged to mitigate various greenhouse gases in some international soft law instruments. Exploitation of renewables to generate energy and produce electricity is simultaneously suggested for the last couple of decades as a viable alternative in mitigating climate change. This gets momentum with the adoption of the historical and universally ratified Paris Agreement in 2016 where energy is placed at the heart of the Agreement. Energy, where renewable energy is a branch, is generally regulated and governed domestically and so, international legal regime is still evolving in this regard. In the absence of any specific and direct international instrument on energy and renewable energy, published literatures have considered this topic from different directions ranging from climate change to the principle of national sovereignty, economic, trade and investment issues. In this backdrop, this paper aims to introduce various renewable sources, prospects and challenges in their promotion that may help to mitigate the adverse effects of climate change. Relevant international law provisions have been evaluated, performances of the relevant regional and international organizations active in this sector are highlighted and some of the disputes in this area considered in international forums are duly addressed. It is revealed that strong political will of the global community in fulfilling their commitments made so far in different international forums is the key to transforming the world into a better one for the future generation. Full article
(This article belongs to the Special Issue 10 Years Energies - Horizon 2028)
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Open AccessArticle Nuclear Energy Development in Bangladesh: A Study of Opportunities and Challenges
Energies 2018, 11(7), 1672; https://doi.org/10.3390/en11071672
Received: 30 May 2018 / Revised: 7 June 2018 / Accepted: 25 June 2018 / Published: 27 June 2018
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Abstract
It is a challenging task for Bangladesh to meet its increasing demand of energy while its economy is rapidly growing. Though prices of oil, coal, and fossil fuels around the world have been volatile, the price trend in Bangladesh demonstrates a persistent rise
[...] Read more.
It is a challenging task for Bangladesh to meet its increasing demand of energy while its economy is rapidly growing. Though prices of oil, coal, and fossil fuels around the world have been volatile, the price trend in Bangladesh demonstrates a persistent rise in the immediate past. This is further exacerbated by depleting reserves of natural gas. Cumulatively, these two effects heighten Bangladesh’s energy needs. Bangladesh presently mitigates her energy requirements predominantly through natural gas, supplemented by a handful of coal and furnace oil plants. Consequently, due to scarcity of natural gas, oil and coal resources, nuclear power surfaces as a palatable strategic option for Bangladesh’s future development agenda. However, a successful nuclear power program entails an extensive infrastructure. Just like the other nuclear energy-producing countries, Bangladesh also face challenges to safeguard the health and security of nuclear reactors, the proper management for nuclear waste treatment and the security concerns over the safe usage of nuclear materials. Additionally, the development of nuclear energy is also bewildered because of the complex nature of fission technology, lack of efficient human resources, and non-existence of proper legal instruments to guide safe nuclear power production. Moreover, the further challenges include the questions, for example: whether the nuclear power plant project is supported by the mass people or not? What are the strategies for nuclear waste disposal? Whether the recent initiatives for nuclear energy production is necessary or the country should more concern with renewable sources? This paper evaluates the nuclear energy development in Bangladesh. It operates under qualitative methodological framework and utilises secondary sources for analysis. We advance several recommendations in this paper to remedy the highlighted issues: (1) creating a comprehensive legal and regulatory system; (2) fortifying home-based technology of nuclear development and simultaneously localising of foreign-based technology; (3) reducing the cost of nuclear energy production; (4) fast-tracking the procedure of efficient development of nuclear technology; (5) accelerating the procedure of switching to more efficient reactor and nuclear fuel cycle, and (6) conducting effective profile-raising activities to generate greater awareness and spur common acceptance. Full article
(This article belongs to the Special Issue 10 Years Energies - Horizon 2028)
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Open AccessArticle The Influence of Imports and Exports on the Evolution of Greenhouse Gas Emissions: The Case for the European Union
Energies 2018, 11(7), 1644; https://doi.org/10.3390/en11071644
Received: 1 June 2018 / Revised: 18 June 2018 / Accepted: 22 June 2018 / Published: 24 June 2018
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Abstract
Part of a country’s emissions are caused by producing goods for export to other countries, while a country’s own needs also generate emissions in other parts of the world that are associated with the products they import. Our interest was to evaluate the
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Part of a country’s emissions are caused by producing goods for export to other countries, while a country’s own needs also generate emissions in other parts of the world that are associated with the products they import. Our interest was to evaluate the influence of imports and exports of goods and services on greenhouse gas (GHG) emissions in a data panel composed of 30 countries over 21 years. We included as control variables the gross domestic product per capita, employment, an indicator of the economic crisis and a non-linear trend and inferences were performed using a Bayesian framework. The results showed that it was the exports and imports of goods, rather than services, that were related to CO2-equivalent levels. Exports and imports of goods were very inelastic, albeit less so in the case of the index. In summary, the more a country imports, the higher their GHG emission levels are. However, it is important to point out that when employment rates are higher more energy is consumed and GHG emissions are greater. In richer countries, GDP per capita is the factor that best explains why their emissions are so high. Full article
(This article belongs to the Special Issue 10 Years Energies - Horizon 2028)
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Open AccessArticle Design, Fabrication, and Performance Test of a 100-W Helical-Blade Vertical-Axis Wind Turbine at Low Tip-Speed Ratio
Energies 2018, 11(6), 1517; https://doi.org/10.3390/en11061517
Received: 6 May 2018 / Revised: 1 June 2018 / Accepted: 7 June 2018 / Published: 11 June 2018
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Abstract
A 100-W helical-blade vertical-axis wind turbine was designed, manufactured, and tested in a wind tunnel. A relatively low tip-speed ratio of 1.1 was targeted for usage in an urban environment at a rated wind speed of 9 m/s and a rotational speed of
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A 100-W helical-blade vertical-axis wind turbine was designed, manufactured, and tested in a wind tunnel. A relatively low tip-speed ratio of 1.1 was targeted for usage in an urban environment at a rated wind speed of 9 m/s and a rotational speed of 170 rpm. The basic dimensions were determined through a momentum-based design method according to the IEC 61400-2 protocol. The power output was estimated by a mathematical model that takes into account the aerodynamic performance of the NACA0018 blade shape. The lift and drag of the blade with respect to the angle of attack during rotation were calculated using 2D computational fluid dynamics (CFD) simulation to take into account stall region. The average power output calculated by the model was 108.34 W, which satisfies the target output of 100 W. The manufactured wind turbine was tested in a large closed-circuit wind tunnel, and the power outputs were measured for given wind speeds. At the design condition, the measured power output was 114.7 W, which is 5.9% higher than that of the mathematical model. This result validates the proposed design method and power estimation by the mathematical model. Full article
(This article belongs to the Special Issue 10 Years Energies - Horizon 2028)
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Review

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Open AccessReview A Review on Recent Advances and Future Trends of Transformerless Inverter Structures for Single-Phase Grid-Connected Photovoltaic Systems
Energies 2018, 11(8), 1968; https://doi.org/10.3390/en11081968
Received: 6 July 2018 / Revised: 23 July 2018 / Accepted: 24 July 2018 / Published: 28 July 2018
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Abstract
°CThe research significance of various scientific aspects of photovoltaic (PV) systems has increased over the past decade. Grid-tied inverters the vital elements for the effective interface of Renewable Energy Resources (RER) and utility in the distributed generation system. Currently, Single-Phase Transformerless Grid-Connected Photovoltaic
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°CThe research significance of various scientific aspects of photovoltaic (PV) systems has increased over the past decade. Grid-tied inverters the vital elements for the effective interface of Renewable Energy Resources (RER) and utility in the distributed generation system. Currently, Single-Phase Transformerless Grid-Connected Photovoltaic (SPTG-CPV) inverters (1–10 kW) are undergoing further developments, with new designs, and interest of the solar market. In comparison to the transformer (TR) Galvanic Isolation (GI)-based inverters, its advantageous features are lower cost, lighter weight, smaller volume, higher efficiency, and less complexity. In this paper, a review of SPTG-CPV inverters has been carried out. The basic operational principles of all SPTG-CPV inverters are presented in details for positive, negative, and zero cycles. A comprehensive analysis of each topology has been deliberated. A comparative assessment is also performed based on weaknesses, strengths, component ratings, efficiency, total harmonic distortion (THD), semiconductor device losses, and leakage current of various SPTG-CPV inverters schemes. Typical PV inverter structures and control schemes for grid connected three-phase system and single-phase systems are also discussed, described, and reviewed. Comparison of various industrial grids-connected PV inverters is also performed. Loss analysis is also performed for various topologies at 1 kW. Selection of appropriate topologies for their particular application is thoroughly presented. Then, discussion and forthcoming progress are emphasized. Lastly, the conclusions are presented. More than 100 research publications on the topic of SPTG-CPV inverter topologies, configurations, and control schematics along with the recent developments are thoroughly reviewed and classified for quick reference. Full article
(This article belongs to the Special Issue 10 Years Energies - Horizon 2028)
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Open AccessReview Voltage Correction Factors for Air-Insulated Transmission Lines Operating in High-Altitude Regions to Limit Corona Activity: A Review
Energies 2018, 11(7), 1908; https://doi.org/10.3390/en11071908
Received: 30 June 2018 / Revised: 17 July 2018 / Accepted: 19 July 2018 / Published: 21 July 2018
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Abstract
Nowadays there are several transmission lines projected to be operating in high-altitude regions. It is well known that the installation altitude has an impact on the dielectric behavior of air-insulated systems. As a result, atmospheric and voltage correction factors must be applied in
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Nowadays there are several transmission lines projected to be operating in high-altitude regions. It is well known that the installation altitude has an impact on the dielectric behavior of air-insulated systems. As a result, atmospheric and voltage correction factors must be applied in air-insulated transmission systems operating in high-altitude conditions. This paper performs an exhaustive literature review, including state-of-the-art research papers and International Standards of the available correction factors to limit corona activity and ensure proper performance when planning air-insulated transmission lines intended for high-altitude areas. It has been found that there are substantial differences among the various correction methods, differences that are more evident at higher altitudes. Most high-voltage standards were not conceived to test samples to be installed in high-altitude regions and, therefore, most high-voltage laboratories are not ready to face this issue, since more detailed information is required. It is proposed to conduct more research on this topic so that the atmospheric corrections and altitude correction factors found in the current International Standards can be updated and/or modified so that high-voltage components to be installed in high-altitude regions can be tested with more accuracy, taking into account their insulation structure. Full article
(This article belongs to the Special Issue 10 Years Energies - Horizon 2028)
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