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Special Issue "Sustainable Energy Systems: From Primary to End-Use"

A special issue of Sustainability (ISSN 2071-1050). This special issue belongs to the section "Sustainable Engineering and Science".

Deadline for manuscript submissions: closed (31 December 2018)

Special Issue Editors

Guest Editor
Prof. João Carlos de Oliveira Matias

GOVCOPP Research Unit; Department of Economics, Management, Industrial Engineering and Tourism (DEGEIT), University of Aveiro, Aveiro, Portugal
E-Mail
Phone: +351 234 370 361 (ext: 23623)
Interests: sustainability; industrial engineering and management; sustainable energy systems; sustainable management systems (quality, maintenance, occupational health and safety); sustainable and lean production; circular economy; technological Innovation
Guest Editor
Dr. Radu Godina

UNIDEMI - Department of Mechanical and Industrial Engineering, Faculty of Science and Technology (FCT), Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
Website 1 | Website 2 | E-Mail
Interests: energy efficiency; electric grids; electric vehicles; transformers; sustainability; model predictive control and quality management systems
Guest Editor
Prof. Dr. Leonel Nunes

Department of Economics, Management, Industrial Engineering and Tourism (DEGEIT),University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
Website | E-Mail
Interests: biomass; biomass energy; biomass supply chains; biomass conversion technologies; sustainability and circular economy

Special Issue Information

Dear Colleagues,

The long-term transformation of the energy industry, from fossil to sustainable energy sources, is one of the central challenges of the 21st century. Such a transition requires many changes on a technical and organizational level. The successful implementation of the energy transition requires not only sufficient generation capacity from renewable energies, but also an efficient, intelligent, decentralized and secure infrastructure for the distribution, storage and use of electricity and heat. The resulting change in the energy industry poses major challenges for small and medium-sized enterprises (SMEs) in particular. On the one hand, this creates great opportunities for the development of new business models, products and processes, on the other hand, a stronger networking of decentralized system components also entails risks, which are due in particular to the increased use of information and communication technology (ICT) and the automation of processes. The goal must therefore be to create solutions for a sustainable energy system that is economically, environmentally and socially viable, while meeting high security requirements.

This Special Issue will focus on sustainable energy systems. On the one hand, several innovative and alternative concepts could be presented, but also the topics of energy policy, circular economy, life cycle assessment and supply chain could play a major role. Models on various temporal and geographical scales could be developed to understand the conditions of technical as well as organizational change. New methods of modeling, which can fulfil technical and physical boundary conditions and nevertheless consider economic environmental and social aspects, could be developed.

Prof. Dr. João Carlos de Oliveira Matias
Dr. Radu Godina
Dr. Leonel Nunes
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. Sustainability is an international peer-reviewed open access semimonthly 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 1700 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

  • Energy Policy
  • Energy Life Cycle Assessment
  • Energy and Circular Economy
  • Energy Technology
  • Energy and Reserve Markets
  • Renewable Energy
  • Renewable Generation Forecasting
  • Distributed Generation
  • Optimization Models
  • Stochastic Models
  • Energy Storage Systems
  • Energy Efficiency in End-Use sectors
  • Electric and Hydrogen Mobility
  • Building Energy Conservation
  • Multi-Energy Systems

Published Papers (18 papers)

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Open AccessArticle Research on Increasing the Performance of Wind Power Plants for Sustainable Development
Sustainability 2019, 11(5), 1266; https://doi.org/10.3390/su11051266
Received: 20 November 2018 / Revised: 8 February 2019 / Accepted: 11 February 2019 / Published: 27 February 2019
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Abstract
A topical issue globally is the development and implementation of renewable energy sources for sustainable development. To meet current requirements, the research in this paper is directed towards finding solutions to increase the performance and efficiency of wind power plants by implementing innovative [...] Read more.
A topical issue globally is the development and implementation of renewable energy sources for sustainable development. To meet current requirements, the research in this paper is directed towards finding solutions to increase the performance and efficiency of wind power plants by implementing innovative solutions for hollow roller bearings developed through the use of sustainable growth programs in the field of green energy. Another solution that has the effect of increasing wind power performance consists of the implementation of a new large-size lubrication system for large-size bearings in wind energy units, which will increase their durability by developing maintenance capabilities. In this research, we will explore the possibility of introducing an innovative automated lubrication system in hollow roller bearings. The main results of the research, the innovative constructive solutions, will lead to important savings by lowering wind farm maintenance costs, increasing the durability of large bearings, and increasing the energy efficiency and yield of the whole system. The expected impact of implementing the solutions found will mainly be in the field of sustainable growth and environmental development. Full article
(This article belongs to the Special Issue Sustainable Energy Systems: From Primary to End-Use)
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Open AccessArticle Thermodynamic Cycle Concepts for High-Efficiency Power Plans. Part A: Public Power Plants 60+
Sustainability 2019, 11(2), 554; https://doi.org/10.3390/su11020554
Received: 24 December 2018 / Revised: 13 January 2019 / Accepted: 17 January 2019 / Published: 21 January 2019
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Abstract
An analysis was carried out for different thermodynamic cycles of power plants with air turbines. Variants with regeneration and different cogeneration systems were considered. In the paper, we propose a new modification of a gas turbine cycle with the combustion chamber at the [...] Read more.
An analysis was carried out for different thermodynamic cycles of power plants with air turbines. Variants with regeneration and different cogeneration systems were considered. In the paper, we propose a new modification of a gas turbine cycle with the combustion chamber at the turbine outlet. A special air by-pass system of the combustor was applied and, in this way, the efficiency of the turbine cycle was increased by a few points. The proposed cycle equipped with a regenerator can provide higher efficiency than a classical gas turbine cycle with a regenerator. The best arrangements of combined air–steam cycles achieved very high values for overall cycle efficiency—that is, higher than 60%. An increase in efficiency to such degree would decrease fuel consumption, contribute to the mitigation of carbon dioxide emissions, and strengthen the sustainability of the region served by the power plant. This increase in efficiency might also contribute to the economic resilience of the area. Full article
(This article belongs to the Special Issue Sustainable Energy Systems: From Primary to End-Use)
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Open AccessArticle Technological Innovation in Biomass Energy for the Sustainable Growth of Textile Industry
Sustainability 2019, 11(2), 528; https://doi.org/10.3390/su11020528
Received: 15 December 2018 / Revised: 14 January 2019 / Accepted: 16 January 2019 / Published: 20 January 2019
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Abstract
The growing increase in world energy consumption favors the search for renewable energy sources. One of the existing options for the growth and sustainable development of such types of sources is through the use of biomass as an input. The employment of biomass [...] Read more.
The growing increase in world energy consumption favors the search for renewable energy sources. One of the existing options for the growth and sustainable development of such types of sources is through the use of biomass as an input. The employment of biomass as solid fuel is widely studied and is no longer a novelty nor presents any difficulty from the technical point of view. It presents, however, logistic obstacles, thus not allowing their direct dissemination in every organization that is willing to replace it as an energy source. Use of biomass can be rewarding due to the fact that it can bring significant economic gains attained due to the steadiness of the biomass price in Portugal. However, the price may rise as predicted in the coming years, although it will be a gradual rising. The main goal of this study was to analyze whether biomass in the case of the Portuguese textile industry can be a viable alternative that separates the possibility of sustainable growth from the lack of competitiveness due to high energy costs. The study showed that biomass can be a reliable, sustainable and permanent energy alternative to more traditional energy sources such as propane gas, naphtha and natural gas for the textile industry. At the same time, it can bring savings of 35% in energy costs related to steam generation. Also, with new technology systems related to the Internet of Things, a better on-time aware of needs, energy production and logistic chain information will be possible. Full article
(This article belongs to the Special Issue Sustainable Energy Systems: From Primary to End-Use)
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Open AccessArticle The Nexus Concept Integrating Energy and Resource Efficiency for Policy Assessments: A Comparative Approach from Three Cases
Sustainability 2018, 10(12), 4860; https://doi.org/10.3390/su10124860
Received: 27 September 2018 / Revised: 10 December 2018 / Accepted: 14 December 2018 / Published: 19 December 2018
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Abstract
As the world increasingly runs up against physical constraints of energy, land, water, and food, there is a growing role for policy to reduce environmental pressures without adversely affecting increases in prosperity. There is therefore a need for policy makers to understand the [...] Read more.
As the world increasingly runs up against physical constraints of energy, land, water, and food, there is a growing role for policy to reduce environmental pressures without adversely affecting increases in prosperity. There is therefore a need for policy makers to understand the potential trade-offs and/or synergies between the uses of these different resources, i.e., to encompass the water–energy–food–land nexus for policy and decision making, where it is no longer possible to ignore the limitations in land availability and its links to other natural resources. This paper proposes a modelling approach to help to assess various policies from a nexus perspective. The global macro-econometric model (E3ME) explores a low-carbon transition through different sets of energy and climate policies applied at different spatial scales. The limitations of the E3ME model in assessing nexus interactions are discussed. The paper also argues and offers an explanation for why no single traditional or classic model has the potential to cover all parts of the nexus in a satisfactory way, including feedback loops and interactions between nexus components. Other approaches and methodologies suitable for complexity science modelling (e.g., system dynamics modelling) are proposed, providing a possible means to capture the holistic approach of the nexus in policy-making by including causal and feedback loops to the model components. Based on three case studies in Europe, the paper clarifies the different steps (from policy design towards conceptual model) in modelling the nexus linkages and interactions at the national and regional levels. One case study (The Netherlands) considers national low-carbon transitions at national level. Two other case studies (Latvia and southwest UK) focus on how renewable energy may impact the nexus. A framework is proposed for the generic application of quantitative modelling approaches to assess nexus linkages. The value of the nexus concept for the efficient use of resources is demonstrated, and recommendations for policies supporting the nexus are presented. Full article
(This article belongs to the Special Issue Sustainable Energy Systems: From Primary to End-Use)
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Open AccessArticle Valuing Improved Power Supply Reliability for Manufacturing Firms in South Korea: Results from a Choice Experiment Survey
Sustainability 2018, 10(12), 4516; https://doi.org/10.3390/su10124516
Received: 27 September 2018 / Revised: 25 November 2018 / Accepted: 26 November 2018 / Published: 30 November 2018
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Abstract
An outage of electricity may cause considerable economic damage to industrial sectors. Thus, South Korea electricity authorities demand information about the value of improved power supply reliability for the manufacturing sector to implement them in planning electricity supply. This article aims to measure [...] Read more.
An outage of electricity may cause considerable economic damage to industrial sectors. Thus, South Korea electricity authorities demand information about the value of improved power supply reliability for the manufacturing sector to implement them in planning electricity supply. This article aims to measure the value using a specific case of South Korean manufacturing firms. The choice experiment (CE) approach is adopted for this purpose. A nationwide CE survey of 1148 manufacturing firms was undertaken. The firms revealed statistically significant willingness to pay for a decrease in the duration of interruption, avoiding interruption during daytime (9 a.m. to 6 p.m.) rather than off-daytime (6 p.m. to 9 a.m.), and preventing interruption during weekdays rather than weekend. For example, they accepted a 0.02% increase in the electricity bill for reducing one minute of interruption during electricity outage, a 2.98% increase in the electricity bill to avoid interruption during the daytime rather than off-daytime, and a 1.60% increase in electricity bill for preventing interruption during weekdays rather than weekends. However, they put no importance on the season of interruption. These results can be useful for policy-making and decision-making regarding improving electricity supply reliability. Full article
(This article belongs to the Special Issue Sustainable Energy Systems: From Primary to End-Use)
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Open AccessArticle Single-Phase Active Power Harmonics Filter by Op-Amp Circuits and Power Electronics Devices
Sustainability 2018, 10(12), 4406; https://doi.org/10.3390/su10124406
Received: 2 November 2018 / Revised: 19 November 2018 / Accepted: 23 November 2018 / Published: 26 November 2018
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Abstract
This paper introduces a new structure for single-phase Active Power Harmonics Filter (APHF) with the simple and low-cost controller to eliminate harmonics and its side effects on low voltage grid. The proposed APHF includes an accurate harmonic detector circuit, amplifier circuit to trap [...] Read more.
This paper introduces a new structure for single-phase Active Power Harmonics Filter (APHF) with the simple and low-cost controller to eliminate harmonics and its side effects on low voltage grid. The proposed APHF includes an accurate harmonic detector circuit, amplifier circuit to trap tiny harmonics, switching driver circuit for precise synchronization, and inverter to create injection current waveform, which is extracted from reference signal. The control circuits are based on electrostatic devices consist of Op-Amp circuits. Fast dynamic, simplicity, low cost, and small size are the main features of Op-Amp circuits that are used in the proposed topology. The aim is removing the all grid harmonic orders in which the proposed APF injects an appropriate current into the grid in parallel way. The proposed control system is smart enough to compensate all range of current harmonics. A prototype is implemented in the power electronics laboratory and it is installed as parallel on a distorted grid by the non-linear load (15 APeak-Peak) to verify the compensating of harmonics. The harmonics are compensated from THD% = 24.48 to THD% = 2.86 and the non-sinusoidal waveform is renovated to sinusoidal waveform by the proposed APHF. The experimental results show a good accurate and high-quality performance. Full article
(This article belongs to the Special Issue Sustainable Energy Systems: From Primary to End-Use)
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Open AccessArticle A Countermeasure for Preventing Flexibility Deficit under High-Level Penetration of Renewable Energies: A Robust Optimization Approach
Sustainability 2018, 10(11), 4159; https://doi.org/10.3390/su10114159
Received: 23 October 2018 / Revised: 6 November 2018 / Accepted: 7 November 2018 / Published: 12 November 2018
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Abstract
An energy paradigm shift has rapidly occurred around the globe. One change has been an increase in the penetration of sustainable energy. However, this can affect the reliability of power systems by increasing variability and uncertainty from the use of renewable resources. To [...] Read more.
An energy paradigm shift has rapidly occurred around the globe. One change has been an increase in the penetration of sustainable energy. However, this can affect the reliability of power systems by increasing variability and uncertainty from the use of renewable resources. To improve the reliability of an energy supply, a power system must have a sufficient amount of flexible resources to prevent a flexibility deficit. This paper proposes a countermeasure for protecting nonnegative flexibility under high-level penetration of renewable energy with robust optimization. The proposed method is divided into three steps: (i) constructing an uncertainty set with the capacity factor of renewable energy, (ii) searching for the initial point of a flexibility deficit, and (iii) calculating the capacity of the energy storage system to avoid such a deficit. In this study, robust optimization is applied to consider the uncertainty of renewable energy, and the results are compared between deterministic and robust approaches. The proposed method is demonstrated on a power system in the Republic of Korea. Full article
(This article belongs to the Special Issue Sustainable Energy Systems: From Primary to End-Use)
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Open AccessArticle Transient Impact Analysis of High Renewable Energy Sources Penetration According to the Future Korean Power Grid Scenario
Sustainability 2018, 10(11), 4140; https://doi.org/10.3390/su10114140
Received: 11 October 2018 / Revised: 3 November 2018 / Accepted: 8 November 2018 / Published: 11 November 2018
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Abstract
Efforts to reduce greenhouse gas emissions constitute a worldwide trend. According to this trend, there are many plans in place for the replacement of conventional electric power plants operating using fossil fuels with renewable energy sources (RESs). Owing to current needs to expand [...] Read more.
Efforts to reduce greenhouse gas emissions constitute a worldwide trend. According to this trend, there are many plans in place for the replacement of conventional electric power plants operating using fossil fuels with renewable energy sources (RESs). Owing to current needs to expand the RES penetration in accordance to a new National power system plan, the importance of RESs is increasing. The RES penetration imposes various impacts on the power system, including transient stability. Furthermore, the fact that they are distributed at multiple locations in the power system is also a factor which makes the transient impact analysis of RESs difficult. In this study, the transient impacts attributed to the penetration of RESs are analyzed and compared with the conventional Korean electric power system. To confirm the impact of the penetration of RESs on transient stability, the effect was analyzed based on a single machine equivalent (SIME) configuration. Simulations were conducted in accordance to the Korean power system by considering the anticipated RES penetration in 2030. The impact of RES on transient stability was provided by a change in CCT by increasing of the RES penetration. Full article
(This article belongs to the Special Issue Sustainable Energy Systems: From Primary to End-Use)
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Open AccessArticle A Scenario Analysis of Solar Photovoltaic Grid Parity in the Maldives: The Case of Malahini Resort
Sustainability 2018, 10(11), 4045; https://doi.org/10.3390/su10114045
Received: 10 October 2018 / Revised: 31 October 2018 / Accepted: 2 November 2018 / Published: 5 November 2018
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Abstract
The Maldives, one of the Small Island Developing States (SIDS) with great solar potential, is keen to promote renewable energy systems to reduce its heavy reliance on imported diesel for power generation. However, adopting renewable energy systems is still burdensome for the Maldives [...] Read more.
The Maldives, one of the Small Island Developing States (SIDS) with great solar potential, is keen to promote renewable energy systems to reduce its heavy reliance on imported diesel for power generation. However, adopting renewable energy systems is still burdensome for the Maldives not only because of its high initial costs and insufficient financial resources but also because of a lack of understanding about whether the deployment of a renewable system is economically feasible. Therefore, the concept of grid parity is explored as an important concept in this paper to examine the possible timeframe for reaching it. A distinctive feature of the paper is that the paper used actual cost and technical information to analyze the levelized cost of energy (LCOEs) of the independent renewable system in a remote island and examined its timeframe for reaching the grid parity condition. Based on economic and technical information from a project for replacing existing diesel generator to photovoltaic (PV) with energy storage system (ESS) in Kuda Bandos Island in the Maldives, the paper considers three different system configurations and evaluates which configuration could result in the most optimal off-grid energy systems in this remote island. With sensitivity analysis on various uncertainties, the paper shows the range of the levelized costs of energy and the periods required for reaching grid parity for deploying solar photovoltaics and ESSs in Kuda Bandos Island, Maldives. The result indicates that the photovoltaic system is an economically feasible option for the resort, and that grid parity can be reached within the project lifetime. However, the result shows that the use of advanced ESSs is still an expensive option and would not be economically reasonable. Full article
(This article belongs to the Special Issue Sustainable Energy Systems: From Primary to End-Use)
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Open AccessArticle Long-Term Decision on Wind Investment with Considering Different Load Ranges of Power Plant for Sustainable Electricity Energy Market
Sustainability 2018, 10(10), 3811; https://doi.org/10.3390/su10103811
Received: 23 September 2018 / Revised: 10 October 2018 / Accepted: 15 October 2018 / Published: 22 October 2018
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Abstract
The aim of this paper is to provide a bi-level model for the expansion planning on wind investment while considering different load ranges of power plants in power systems at a multi-stage horizon. Different technologies include base load units, such as thermal and [...] Read more.
The aim of this paper is to provide a bi-level model for the expansion planning on wind investment while considering different load ranges of power plants in power systems at a multi-stage horizon. Different technologies include base load units, such as thermal and water units, and peak load units such as gas turbine. In this model, subsidies are considered as a means to encourage investment in wind turbines. In order that the uncertainties related to demand and the wind turbine can be taken into consideration, these effects are modelled using a variety of scenarios. In addition, the load demand is characterized by a certain number of demand blocks. The first-level relates to the issue of investment in different load ranges of power plants with a view to maximizing the investment profit whilst the second level is related to the market-clearing where the priority is to maximize the social welfare benefits. The bi-level optimization problem is then converted to a dynamic stochastic mathematical algorithm with equilibrium constraint (MPEC) and represented as a mixed integer linear program (MILP) after linearization. The proposed framework is examined on a real transmission network. Simulation results confirm that the proposed framework can be a useful tool for analyzing the investments different load ranges of power plants on long-term strategic decision-making. Full article
(This article belongs to the Special Issue Sustainable Energy Systems: From Primary to End-Use)
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Open AccessArticle Hybrid Neural Fuzzy Design-Based Rotational Speed Control of a Tidal Stream Generator Plant
Sustainability 2018, 10(10), 3746; https://doi.org/10.3390/su10103746
Received: 20 August 2018 / Revised: 8 October 2018 / Accepted: 12 October 2018 / Published: 17 October 2018
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Abstract
Artificial Intelligence techniques have shown outstanding results for solving many tasks in a wide variety of research areas. Its excellent capabilities for the purpose of robust pattern recognition which make them suitable for many complex renewable energy systems. In this context, the Simulation [...] Read more.
Artificial Intelligence techniques have shown outstanding results for solving many tasks in a wide variety of research areas. Its excellent capabilities for the purpose of robust pattern recognition which make them suitable for many complex renewable energy systems. In this context, the Simulation of Tidal Turbine in a Digital Environment seeks to make the tidal turbines competitive by driving up the extracted power associated with an adequate control. An increment in power extraction can only be archived by improved understanding of the behaviors of key components of the turbine power-train (blades, pitch-control, bearings, seals, gearboxes, generators and power-electronics). Whilst many of these components are used in wind turbines, the loading regime for a tidal turbine is quite different. This article presents a novel hybrid Neural Fuzzy design to control turbine power-trains with the objective of accurately deriving and improving the generated power. In addition, the proposed control scheme constitutes a basis for optimizing the turbine control approaches to maximize the output power production. Two study cases based on two realistic tidal sites are presented to test these control strategies. The simulation results prove the effectiveness of the investigated schemes, which present an improved power extraction capability and an effective reference tracking against disturbance. Full article
(This article belongs to the Special Issue Sustainable Energy Systems: From Primary to End-Use)
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Open AccessArticle Energy Life-Cycle Assessment of Fruit Products—Case Study of Beira Interior’s Peach (Portugal)
Sustainability 2018, 10(10), 3530; https://doi.org/10.3390/su10103530
Received: 8 August 2018 / Revised: 24 September 2018 / Accepted: 26 September 2018 / Published: 1 October 2018
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Abstract
Currently, there is a growing demand for cleaner and sustainable technologies due to environmental issues. In this sense, there is a necessity to manage the assessment of production processes and the rationalization of energy consumption. In this study, an Energy Life-Cycle Assessment (ELCA) [...] Read more.
Currently, there is a growing demand for cleaner and sustainable technologies due to environmental issues. In this sense, there is a necessity to manage the assessment of production processes and the rationalization of energy consumption. In this study, an Energy Life-Cycle Assessment (ELCA) was carried out through energy efficiency indicators, directed to the characterization and renewability of the peach production system life-cycle in the Portuguese region of Beira Interior. The study intends to investigate the non-renewable energy inputs from fossil fuels, as well as the emissions resulting from machinery. In addition, warehouse energy inputs are analyzed, mainly cooling systems of refrigerated chambers where fruits are preserved. This analysis aims to find opportunities for technological, environmental and best practices improvements. Test scenarios were analyzed and revealing soil groundcover maintenance is the operation with the largest impact in the energy consumption of the production process (3176 MJ·ha−1). In the post-harvest processes, the energy consumption largest impact is given by the warehouse’s operations (35,700 MJ·ha−1), followed by transportation (6180 MJ·ha−1). Concerning the emissions resulting from the fuels consumption, the largest impact is due to the plantation machinery and the transportation from warehouse to retailers. Full article
(This article belongs to the Special Issue Sustainable Energy Systems: From Primary to End-Use)
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Open AccessArticle Evaluation of the Physical, Chemical and Thermal Properties of Portuguese Maritime Pine Biomass
Sustainability 2018, 10(8), 2877; https://doi.org/10.3390/su10082877
Received: 30 July 2018 / Revised: 8 August 2018 / Accepted: 9 August 2018 / Published: 13 August 2018
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Abstract
A characterisation of Pinus pinaster Aiton. (Maritime Pine) woody biomass and ashes is presented in this study. Physical, thermal and chemical analysis, including density, moisture content, calorific value, proximate and ultimate analysis, were carried out. The fuel Energy Density (Ed) and [...] Read more.
A characterisation of Pinus pinaster Aiton. (Maritime Pine) woody biomass and ashes is presented in this study. Physical, thermal and chemical analysis, including density, moisture content, calorific value, proximate and ultimate analysis, were carried out. The fuel Energy Density (Ed) and the Fuelwood Value Index (FVI) were assessed by ranking the fuelwood quality. Furthermore, the determination of the ash metal elementals was performed. The results from this study indicated, for Pinus pinaster biomass tree components, carbon content ranging from 46.5 to 49.3%, nitrogen content from 0.13 to 1.18%, sulphur content from 0.056 to 0.148% and hydrogen content around 6–7%. The ash content in the tree components ranged from 0.22 to 1.92%. The average higher heating value (HHV) was higher for pine needles (21.61 MJ·kg−1). The Ed of 8.9 GJ·m−3 confirm the good potential of Pinus pinaster biomass tree components as fuel. The FVI ranked the wood stem (4658) and top (2861.8) as a better fuelwood and pine needles (394.2) as inferior quality. The chemical composition of the ashes revealed that the elemental contents are below the national and most European countries legislation guidelines for the employment of ash as a fertiliser. Full article
(This article belongs to the Special Issue Sustainable Energy Systems: From Primary to End-Use)
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Open AccessArticle Integrated Model of Economic Generation System Expansion Plan for the Stable Operation of a Power Plant and the Response of Future Electricity Power Demand
Sustainability 2018, 10(7), 2417; https://doi.org/10.3390/su10072417
Received: 6 June 2018 / Revised: 2 July 2018 / Accepted: 3 July 2018 / Published: 11 July 2018
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Abstract
The current study aims to establish an optimal Generation System Expansion Plan that can satisfy the increasing electricity demand while maintaining operational elements and the stability of the energy supply. The architecture is composed of plan-level and operation-level models, which are basically based [...] Read more.
The current study aims to establish an optimal Generation System Expansion Plan that can satisfy the increasing electricity demand while maintaining operational elements and the stability of the energy supply. The architecture is composed of plan-level and operation-level models, which are basically based on optimization. In the first step, we estimated future power demand data through time series analysis. In addition, power plant data were defined and verified data were collected. In the next step, the previous Generation System Expansion Plan methodology was used to deduce a feasible solution and construction costs that satisfy the reserve rate. In the third step, mixed integer programming (MIP)-based power generation system operation plan methodology was used to deduce numbers on the operation of power generation system. In addition, power plants with similar characteristics were grouped to reduce the calculation complexity of unit commitment. In the last step, a feasible solution for the duration of the plan (deduced in Stage II) and operations and maintenance cost information were combined to produce the optimal solution that minimizes the total cost. Experiments were conducted to demonstrate the proposed integrated generation system expansion planning architecture for establishing the optimal generation system expansion planning. This study has academic implications for the establishment of optimal power plant expansion plans to meet future increasing power demand while maintaining operational considerations and supply stability. The effectiveness of the proposed methodology is also illustrated through comparison and verification with the National Plan for Electricity Supply and Demand. Full article
(This article belongs to the Special Issue Sustainable Energy Systems: From Primary to End-Use)
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Open AccessArticle An Integrated Multi-Criteria Decision Making Model and AHP Weighting Uncertainty Analysis for Sustainability Assessment of Coal-Fired Power Units
Sustainability 2018, 10(6), 1700; https://doi.org/10.3390/su10061700
Received: 3 April 2018 / Revised: 12 May 2018 / Accepted: 18 May 2018 / Published: 23 May 2018
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Abstract
The transformation of the power generation industry from coal-based to more sustainable energy sources is an irreversible trend. In China, the coal-fired power plant, as the main electric power supply facility at present, needs to know its own sustainability level to face the [...] Read more.
The transformation of the power generation industry from coal-based to more sustainable energy sources is an irreversible trend. In China, the coal-fired power plant, as the main electric power supply facility at present, needs to know its own sustainability level to face the future competition. A hybrid multi-criteria decision making (MCDM) model is proposed in this paper to assess the sustainability levels of the existing Chinese coal-fired power units. The areal grey relational analysis (AGRA) method is involved in the hybrid model, and a combined weighting method is used to determine the priorities of the criteria. The combining weight fuses the fuzzy rough set (FRS) and entropy objective weighting method together with the analytic hierarchy process (AHP) subjective weighting method by game theory. Moreover, an AHP weighting uncertainty analysis using Monte Carlo (MC) simulation is introduced to measure the uncertainty of the results, and a 95 percent confidence interval (CI) is defined as the uncertainty measurement of the alternatives. A case study about eight coal-fired power units is carried out with a criteria system, which contains five aspects in an operational perspective, such as the flexibility, economic, environmental, reliability and technical criterion. The sustainability assessment is performed at the unit level, and the results give a priority rank of the eight alternatives; additionally, the uncertainty analysis supplies the extra information from a statistical perspective. This work expands a novel hybrid MCDM method to the sustainability assessment of the power generation systems, and it may be a benefit to the energy enterprises in assessing the sustainability at the unit level and enhance its ability in future sustainable development. Full article
(This article belongs to the Special Issue Sustainable Energy Systems: From Primary to End-Use)
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Open AccessArticle The Facilitation of a Sustainable Power System: A Practice from Data-Driven Enhanced Boiler Control
Sustainability 2018, 10(4), 1112; https://doi.org/10.3390/su10041112
Received: 10 March 2018 / Revised: 4 April 2018 / Accepted: 4 April 2018 / Published: 8 April 2018
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Abstract
An increasing penetration of renewable energy may bring significant challenges to a power system due to its inherent intermittency. To achieve a sustainable future for renewable energy, a conventional power plant is required to be able to change its power output rapidly for [...] Read more.
An increasing penetration of renewable energy may bring significant challenges to a power system due to its inherent intermittency. To achieve a sustainable future for renewable energy, a conventional power plant is required to be able to change its power output rapidly for a grid balance purpose. However, the rapid power change may result in the boiler operating in a dangerous manner. To this end, this paper aims to improve boiler control performance via a data-driven control strategy, namely Active Disturbance Rejection Control (ADRC). For practical implementation, a tuning method is developed for ADRC controller parameters to maximize its potential in controlling a boiler operating in different conditions. Based on a Monte Carlo simulation, a Probabilistic Robustness (PR) index is subsequently formulated to represent the controller’s sensitivity to the varying conditions. The stability region of the ADRC controller is depicted to provide the search space in which the optimal group of parameters is searched for based on the PR index. Illustrative simulations are performed to verify the efficacy of the proposed method. Finally, the proposed method is experimentally applied to a boiler’s secondary air control system successfully. The results of the field application show that the proposed ADRC based on PR can ensure the expected control performance even though it works in a wider range of operating conditions. The field application depicts a promising future for the ADRC controller as an alternative solution in the power industry to integrate more renewable energy into the power grid. Full article
(This article belongs to the Special Issue Sustainable Energy Systems: From Primary to End-Use)
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Open AccessFeature PaperReview Future Perspectives of Biomass Torrefaction: Review of the Current State-Of-The-Art and Research Development
Sustainability 2018, 10(7), 2323; https://doi.org/10.3390/su10072323
Received: 31 May 2018 / Revised: 28 June 2018 / Accepted: 4 July 2018 / Published: 5 July 2018
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Abstract
The growing search for alternative energy sources is not only due to the present shortage of non-renewable energy sources, but also due to their negative environmental impacts. Therefore, a lot of attention is drawn to the use of biomass as a renewable energy [...] Read more.
The growing search for alternative energy sources is not only due to the present shortage of non-renewable energy sources, but also due to their negative environmental impacts. Therefore, a lot of attention is drawn to the use of biomass as a renewable energy source. However, using biomass in its natural state has not proven to be an efficient technique, giving rise to a wide range of processing treatments that enhance the properties of biomass as an energy source. Torrefaction is a thermal process that enhances the properties of biomass through its thermal decomposition at temperatures between 200 and 300 °C. The torrefaction process is defined by several parameters, which also have impacts on the final quality of the torrefied biomass. The final quality is measured by considering parameters, such as humidity, heating value (HV), and grindability. Studies have focused on maximizing the torrefied biomass’ quality using the best possible combination for the different parameters. The main objective of this article is to present new information regarding the conventional torrefaction process, as well as study the innovative techniques that have been in development for the improvement of the torrefied biomass qualities. With this study, conclusions were made regarding the importance of torrefaction in the energy field, after considering the economic status of this renewable resource. The importance of the torrefaction parameters on the final properties of torrefied biomass was also highly considered, as well as the importance of the reactor scales for the definition of ideal protocols. Full article
(This article belongs to the Special Issue Sustainable Energy Systems: From Primary to End-Use)
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Open AccessTechnical Note Day-Ahead Forecasting of Hourly Photovoltaic Power Based on Robust Multilayer Perception
Sustainability 2018, 10(12), 4863; https://doi.org/10.3390/su10124863
Received: 13 November 2018 / Revised: 11 December 2018 / Accepted: 14 December 2018 / Published: 19 December 2018
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Abstract
Photovoltaic (PV) modules convert renewable and sustainable solar energy into electricity. However, the uncertainty of PV power production brings challenges for the grid operation. To facilitate the management and scheduling of PV power plants, forecasting is an essential technique. In this paper, a [...] Read more.
Photovoltaic (PV) modules convert renewable and sustainable solar energy into electricity. However, the uncertainty of PV power production brings challenges for the grid operation. To facilitate the management and scheduling of PV power plants, forecasting is an essential technique. In this paper, a robust multilayer perception (MLP) neural network was developed for day-ahead forecasting of hourly PV power. A generic MLP is usually trained by minimizing the mean squared loss. The mean squared error is sensitive to a few particularly large errors that can lead to a poor estimator. To tackle the problem, the pseudo-Huber loss function, which combines the best properties of squared loss and absolute loss, was adopted in this paper. The effectiveness and efficiency of the proposed method was verified by benchmarking against a generic MLP network with real PV data. Numerical experiments illustrated that the proposed method performed better than the generic MLP network in terms of root mean squared error (RMSE) and mean absolute error (MAE). Full article
(This article belongs to the Special Issue Sustainable Energy Systems: From Primary to End-Use)
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