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Selected Papers from the 10th European Conference on Renewable Energy Systems

A special issue of Sustainability (ISSN 2071-1050). This special issue belongs to the section "Energy Sustainability".

Deadline for manuscript submissions: closed (31 August 2022) | Viewed by 39502

Special Issue Editors

Special Issue Information

Dear Colleagues,

This Special Issue will present the papers selected for the 10th European Conference on Renewable Energy Systems (ECRES2022—ecres.net), which took place in Istanbul, Turkey, through a hybrid format. This international event hosted participants from 59 countries.  

ECRES aims to bring together researchers, engineers, and natural scientists from all over the world that are interested in the advancement of renewable energy systems. Wind, solar, hydrogen, hydro-, geothermal, solar concentrating, fuel cell, energy harvesting, and other energy-related topics are welcome. 

We are open to papers on related topics, including:

  • Energy material production and characterization;
  • Power electronic systems for renewable energy;
  • Conventional energy systems and recovery;
  • Engines and their combustion features;
  • Off-shore and tidal energy systems;
  • Energy statistics and efficiency;
  • Energy transmission systems;
  • Heating/cooling systems;
  • Energy/exergy analysis;
  • Energy efficiency;
  • Wind energy;
  • Solar concentrating system;
  • Photo-voltaic systems and their installation;
  • Energy harvesters;
  • Smart grid;
  • Electrical machines;
  • Hydro-energy plants;
  • Bio-mass systems;
  • Bio-diesel systems;
  • Combustion;
  • Nuclear fusion systems;
  • Hydrogen energy systems;
  • Fuel-cell systems;
  • Efficiency in nuclear plants;
  • Energy education;
  • Energy informatics.

Submissions must have been submitted to the ECRES 2022 conference via the link https://cmt3.research.microsoft.com/ECRES2022 and presented in the conference successfully. Approved papers will be published in the journal.

Prof. Dr. Erol Kurt
Dr. Jose Manuel Lopez-Guede
Guest Editors

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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 submissions that pass pre-check are 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.

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Published Papers (15 papers)

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Research

32 pages, 15521 KiB  
Article
Design and Implementation of a MHz Frequency Transformer with a Ferromagnetic Fluid Core
by Erol Kurt and Sude Hatem
Sustainability 2023, 15(1), 23; https://doi.org/10.3390/su15010023 - 20 Dec 2022
Cited by 4 | Viewed by 2082
Abstract
Design and optimization of a magnetic fluid cored transformer are studied for high frequency applications. An easy and cheap fluid core is designed and used to decrease the eddy current and loses, thereby low conducting and paramagnetic features are added. The core exhibits [...] Read more.
Design and optimization of a magnetic fluid cored transformer are studied for high frequency applications. An easy and cheap fluid core is designed and used to decrease the eddy current and loses, thereby low conducting and paramagnetic features are added. The core exhibits both fluid and solid characteristics exerting high frequency modes in the fluid and low current due to the iron powder inside. The finite element analysis simulations are performed via COMSOL Multi-physics package for different mass fractions of iron powder. The maximum peak-to-peak voltage and power are found as 526 mV and 188.8 mW at 12 MHz from the simulations. 3D patterns prove that the magnetic flux and magnetization exhibit turbulence in the core, thereby localized magnetic values indicate an arbitrary attitude for various frequencies. Optimum mass fraction is found as 0.7, which is parallel with experimental results. The transformer operates between 11 MHz and 13.5 MHz optimally. Full article
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17 pages, 3927 KiB  
Article
Methodology of Designing Sealing Systems for Highly Loaded Rotary Machines
by Zidong Yu, Serhii Shevchenko, Mykola Radchenko, Oleksandr Shevchenko and Andrii Radchenko
Sustainability 2022, 14(23), 15828; https://doi.org/10.3390/su142315828 - 28 Nov 2022
Cited by 9 | Viewed by 2458
Abstract
Higher parameters of centrifugal machines are constantly required, such as the pressure of the medium to be sealed and the speed of rotation of the shaft. However, as the parameters increase, it becomes more and more difficult to ensure the effectiveness of sealing. [...] Read more.
Higher parameters of centrifugal machines are constantly required, such as the pressure of the medium to be sealed and the speed of rotation of the shaft. However, as the parameters increase, it becomes more and more difficult to ensure the effectiveness of sealing. In addition, sealing systems affect the overall safety of equipment operation, especially vibration. In order to harmonize the sealing functions and increase the dynamic rigidity of the rotors of centrifugal machines, a method for modeling complex sealing systems has been developed. Non-contact seals are considered as hydrostatic–dynamic bearings that can effectively dampen rotor oscillations. A general approach to the analysis of non-contact seals as automatic control systems and an algorithm for constructing their dynamic characteristics at the design stage were proposed for the first time. Models of “rotor-gap seal”, impulse seal and “rotor–hydraulic face” systems, and seal-supports of a shaftless pump have been studied to assess the effect of these seal systems on the oscillatory characteristics of the rotor. Analytical dependencies are obtained for calculating the dynamic characteristics and stability limits of seals as hydromechanical systems. The directions for improving the safety of operation of critical pumping equipment due to a targeted increase in the rigidity of non-contact seals are determined, which leads to an increase in the vibration resistance of the rotor and the environ-mental safety of centrifugal machines. The paper proposes a method for designing sealing systems based on the configuration of sealing components in order to achieve harmonization between sealing and vibration reliability, taking into account oscillatory processes due to hydrodynamic sealing characteristics. Full article
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15 pages, 5429 KiB  
Article
Cooling Potential of Ship Engine Intake Air Cooling and Its Realization on the Route Line
by Zongming Yang, Roman Radchenko, Mykola Radchenko, Andrii Radchenko and Victoria Kornienko
Sustainability 2022, 14(22), 15058; https://doi.org/10.3390/su142215058 - 14 Nov 2022
Cited by 15 | Viewed by 1967
Abstract
A fuel efficiency of a ship engine increases with cooling inlet air. This might be performed by the chillers, which transform the heat of engine exhaust gas and scavenge air for refrigeration. The effect gained due to cooling depends on the intake air [...] Read more.
A fuel efficiency of a ship engine increases with cooling inlet air. This might be performed by the chillers, which transform the heat of engine exhaust gas and scavenge air for refrigeration. The effect gained due to cooling depends on the intake air temperature drop and the time of engine operation at decreased intake air temperature. Thus, the cooling degree hour (CDH) number, calculated as air temperature depression multiplied by the duration of engine operation at reduced intake air temperature, is used as a primary criterion to estimate the engine fuel efficiency enhancement due to intake air cooling over the ship routes. The engine intake air cooling potential is limited by its value, available according to engine exhaust heat and the efficiency of heat conversion to refrigeration in the chiller, evaluated by the coefficient of performance (COP). Therefore, it should be determined by comparing both the needed and available values of CDH. The ejector chiller (ECh) was chosen for engine exhaust gas heat recovery to refrigeration as the simplest and cheapest, although it has a relatively low COP of about 0.3 to 0.35. However, the ECh generally consists of heat exchanges which are mostly adapted to be placed in free spaces and can be mounted on the transverse and board side bulkheads in the ship engine room. The values of sucked air temperature depression and engine fuel consumption reduction at varying temperatures and humidity of ambient air on the route were evaluated. Full article
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22 pages, 3719 KiB  
Article
Scenario Analysis of a Coal Reduction Share in the Power Generation in Bosnia and Herzegovina until 2050
by Azrudin Husika, Nurin Zecevic, Ilham Numic and Ejub Dzaferovic
Sustainability 2022, 14(21), 13751; https://doi.org/10.3390/su142113751 - 24 Oct 2022
Cited by 7 | Viewed by 2289
Abstract
This paper is effectively a scenario analysis of the energy system of Bosnia and Herzegovina (BiH) from the perspective of the possible future reduction of greenhouse gas (GHG) emissions in the power generation sector, with the aim to become climate neutral by 2050, [...] Read more.
This paper is effectively a scenario analysis of the energy system of Bosnia and Herzegovina (BiH) from the perspective of the possible future reduction of greenhouse gas (GHG) emissions in the power generation sector, with the aim to become climate neutral by 2050, in compliance with the Green Agenda for the Western Balkan. According to the data from 2016, the share of power generation in the total GHG emissions in BiH was approximately 50%. By using the LEAP (Long-range Energy Alternatives Planning) energy model, two scenarios—the “gradual transition scenario” and the “climate neutral” scenario—have been analyzed for the period 2018–2050, and each scenario included decarbonization measures such as the extensive use of Renewable Energy Sources (RES). Unlike the climate neutral scenario, the gradual transition scenario includes the replacement of certain parts of the old, currently-in-operation Coal-fired Power Plants (CFPPs) with the new CFPP, which is more efficient. In the climate-neutral scenario, that part of the existing CFPPs is replaced by a mix of RESs. The results from the first scenario suggest that the share of CFPPs in electricity generation has gradually decreased from 69.3% to 16.3% in 2050, and CO2 emissions from the power generation sector in 2050 will be 2.2 million tons—roughly 83.5% less than in 2014. According to the second scenario, the emphasis is strongly on the growth and promotion of RESs, which have significantly taken over the roles of major producers of electricity, encouraging the low-carbon development of BiH. Analysis results show that, in 2050, there will be no CO2 emissions from power generation. It can be concluded that specifically designed energy models for the optimization of capacities and CO2 emissions through convergence towards RESs could be an optimistic and promising option for BiH to become climate neutral while meeting increasing energy demands. The results show the required RES capacities needed for achieving climate-neutral power generation by 2050, with the current rate level of power generation. Based on the results, RES investment needs can be estimated. Overall, the results of the scenarios can be used for the strategic planning of the power generation sector in BiH until 2050. Full article
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16 pages, 17629 KiB  
Article
Analysis of Wind Turbine Distances Using a Novel Techno-Spatial Approach in Complex Wind Farm Terrains
by Bukurije Hoxha, Igor K. Shesho and Risto V. Filkoski
Sustainability 2022, 14(20), 13688; https://doi.org/10.3390/su142013688 - 21 Oct 2022
Cited by 7 | Viewed by 1992
Abstract
Among the current challenges facing the energy sector is finding environmentally friendly and high-performance forms of energy generation. One such form of energy generation is from the wind. In addition to the fluctuations that cause changes in the generated energy, another factor that [...] Read more.
Among the current challenges facing the energy sector is finding environmentally friendly and high-performance forms of energy generation. One such form of energy generation is from the wind. In addition to the fluctuations that cause changes in the generated energy, another factor that significantly affects the overall efficiency of wind farms is the distance between the turbines. In that context, a distance of at least three diameters (3D) onwards is necessary to enable a stable operation. This is more difficult to implement for mountainous terrain due to the terrain configuration’s influence, the turbine units’ positioning, and the mutual influence resulting from their position in the area under consideration. This work investigates the interdependence of the terrain features, the placement of ten turbines in different scenarios, and the impact on the overall efficiency of the wind farm. The place where the wind farm is considered is in Koznica, a mountainous area near Prishtina. An analysis has been carried out for two-diameter (2D), three-diameter (3D), and five-diameter (5D) turbine blade spacing for turbines with a rated power of 3.4 MW. The study considers placement in the following forms: Arc, I, L, M, and V. The results show that for 2D distance layout, the capacity factors for Arc, I, L, M, and V placements have the values: 32.9%, 29.8%, 31.1%, 30.6%, and 37.1%. For the 3D distance, according to these scenarios, the capacity factor values are: 29.9%, 30.8%, 30.4%, 29.3%, and 35.6%. For the longest distance, 5D, the capacity factor values are: 28.9%, 29.9%, 29.4%, 27.6%, and 30.6%. The value of the capacity factor for an optimal layout; is achieved at 39.3%. Full article
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14 pages, 4497 KiB  
Article
A Hydrogen-Fueled Micro Gas Turbine Unit for Carbon-Free Heat and Power Generation
by Reyhaneh Banihabib and Mohsen Assadi
Sustainability 2022, 14(20), 13305; https://doi.org/10.3390/su142013305 - 16 Oct 2022
Cited by 21 | Viewed by 5279
Abstract
The energy transition with transformation into predominantly renewable sources requires technology development to secure power production at all times, despite the intermittent nature of the renewables. Micro gas turbines (MGTs) are small heat and power generation units with fast startup and load-following capability [...] Read more.
The energy transition with transformation into predominantly renewable sources requires technology development to secure power production at all times, despite the intermittent nature of the renewables. Micro gas turbines (MGTs) are small heat and power generation units with fast startup and load-following capability and are thereby suitable backup for the future’s decentralized power generation systems. Due to MGTs’ fuel flexibility, a range of fuels from high-heat to low-heat content could be utilized, with different greenhouse gas generation. Developing micro gas turbines that can operate with carbon-free fuels will guarantee carbon-free power production with zero CO2 emission and will contribute to the alleviation of the global warming problem. In this paper, the redevelopment of a standard 100-kW micro gas turbine to run with methane/hydrogen blended fuel is presented. Enabling micro gas turbines to run with hydrogen blended fuels has been pursued by researchers for decades. The first micro gas turbine running with pure hydrogen was developed in Stavanger, Norway, and launched in May 2022. This was achieved through a collaboration between the University of Stavanger (UiS) and the German Aerospace Centre (DLR). This paper provides an overview of the project and reports the experimental results from the engine operating with methane/hydrogen blended fuel, with various hydrogen content up to 100%. During the development process, the MGT’s original combustor was replaced with an innovative design to deal with the challenges of burning hydrogen. The fuel train was replaced with a mixing unit, new fuel valves, and an additional controller that enables the required energy input to maintain the maximum power output, independent of the fuel blend specification. This paper presents the test rig setup and the preliminary results of the test campaign, which verifies the capability of the MGT unit to support intermittent renewable generation with minimum greenhouse gas production. Results from the MGT operating with blended methane/hydrogen fuel are provided in the paper. The hydrogen content varied from 50% to 100% (volume-based) and power outputs between 35kW to 100kW were tested. The modifications of the engine, mainly the new combustor, fuel train, valve settings, and controller, resulted in a stable operation of the MGT with NOx emissions below the allowed limits. Running the engine with pure hydrogen at full load has resulted in less than 25 ppm of NOx emissions, with zero carbon-based greenhouse gas production. Full article
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22 pages, 978 KiB  
Article
Democracy, Economic Development and Low-Carbon Energy: When and Why Does Democratization Promote Energy Transition?
by Zeynep Clulow and David M. Reiner
Sustainability 2022, 14(20), 13213; https://doi.org/10.3390/su142013213 - 14 Oct 2022
Cited by 9 | Viewed by 4976
Abstract
Despite the growing consensus surrounding the need to decarbonise power for meeting an increasingly ambitious temperature target as set by the 2015 Paris Agreement, the share of low-carbon energy sources in the overall energy mix has varied significantly across countries and over time. [...] Read more.
Despite the growing consensus surrounding the need to decarbonise power for meeting an increasingly ambitious temperature target as set by the 2015 Paris Agreement, the share of low-carbon energy sources in the overall energy mix has varied significantly across countries and over time. We evaluate the influence of democracy on clean energy transition by studying national solar, wind, hydro and nuclear energy shares of total energy use for electricity generation from 1980 to 2020. Using data from the Varieties of Democracy, Freedom House and Polity IV democracy indices, International Energy Agency Extended Energy Balances and Summary Statistics and World Bank World Development Indicators, we conduct a large-N study of the emissions levels of 135 countries. This article develops existing understandings about the relationship between democracy and energy transition by employing a more sophisticated—hierarchical—research design to determine whether: (i) democracy continues to be an important driver of low-carbon energy use once country-level clustering is accounted for, (ii) fluctuations in the democratic attributes of domestic political regimes have uniform effects across countries and (iii), if so, economic development plays a role in shaping the effect of democracy within individual countries. The results suggest that, even after controlling for country-level clustering and other putative drivers of energy portfolios, democracy has a significant effect on the low-carbon energy sources examined in this article. A second-order regression of the country-specific democracy effects estimated by our hierarchical model provides robust evidence that economic development plays an important role in shaping the effect of democracy within individual countries: Strikingly, democratic spells (of increased democratic institutions and processes) in advanced economies tend to inhibit solar, wind and hydro energy, but promote nuclear energy use, while, in contrast, having the opposite effects (promoting solar, wind and hydro and inhibiting nuclear shares) in developing countries. Full article
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10 pages, 467 KiB  
Article
Intentions to Charge Electric Vehicles Using Vehicle-to-Grid Technology among People with Different Motivations to Save Energy
by Zbigniew Bohdanowicz, Jarosław Kowalski and Cezary Biele
Sustainability 2022, 14(19), 12681; https://doi.org/10.3390/su141912681 - 5 Oct 2022
Cited by 8 | Viewed by 1771
Abstract
This article presents the results of a quantitative survey conducted on 4000 electric energy consumers in Spain, France, Italy, and Denmark. The results demonstrate differences in the effects of additional remuneration for using vehicle-to-grid (V2G) stations, depending on users’ reasons for saving electricity. [...] Read more.
This article presents the results of a quantitative survey conducted on 4000 electric energy consumers in Spain, France, Italy, and Denmark. The results demonstrate differences in the effects of additional remuneration for using vehicle-to-grid (V2G) stations, depending on users’ reasons for saving electricity. Individuals with extrinsic financial motivations are sensitive to such incentives; the higher the remuneration is, the more willingness they demonstrate to use V2G. Although individuals with intrinsic (the desire to control spending) and ecological (caring for the environment) motivations are also interested in using V2G, no relationship can be observed between the sizes of the rewards and individuals’ desire to use the technology. Users are similarly encouraged by low (an extra 2.5% of energy for free) and high (an extra 20%) rewards. In contrast, individuals who display intrinsic general modesty (willingness to not waste things) motivations may even be discouraged: the higher the reward, the less interest they demonstrate in V2G. The article illustrates how different types of motivation can affect users’ interest in the innovative V2G concept, as well as underlining the importance of constructing intrinsic and altruistic motivations in the process of education. Full article
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14 pages, 3159 KiB  
Article
Selection of Renewables for Economic Regions with Diverse Conditions: The Case of Azerbaijan
by Mahammad Nuriyev, Jeyhun Mammadov, Aziz Nuriyev and Joshgun Mammadov
Sustainability 2022, 14(19), 12548; https://doi.org/10.3390/su141912548 - 2 Oct 2022
Cited by 3 | Viewed by 2586
Abstract
The objective of this paper is to study the specifics of the selection of renewables for regions of Azerbaijan with diverse conditions. Information is obtained through the analysis of the regions’ conditions and experts’ opinions. Analysis reveals that geographical position, diversity of natural [...] Read more.
The objective of this paper is to study the specifics of the selection of renewables for regions of Azerbaijan with diverse conditions. Information is obtained through the analysis of the regions’ conditions and experts’ opinions. Analysis reveals that geographical position, diversity of natural resources, and a variety of other factors of the five economic regions of the country require subdivision of these regions in the selection of renewables. Given that the selection of renewables is a multi-criteria decision-making (MCDM) task under a high degree of uncertainty, Z-number-based models have been developed, and Z-extension of the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) method has been used. Solutions have been derived based on direct calculations with Z-numbers. In this paper, results obtained for two regions are presented. In the case of one region, for the first part (mountains and foothill) of the Karabakh economic region, renewables are ranked as hydro, solar, and wind. For the second part (plain), the ranking is as follows: solar, hydro, and wind. For the Guba-Khachmaz economic region, the rankings of renewables for parts of the region are also different: the wind is preferable for the seaside, and solar is more appropriate for the foothills. Results show that in the case of uneven distribution of renewables and significant differences in factors influencing decision-making, it is necessary to subdivide economic regions and use different models for the selection of renewables. Full article
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14 pages, 1070 KiB  
Article
Harnessing Residual Biomass as a Renewable Energy Source in Colombia: A Potential Gasification Scenario
by Claudia Patricia Pérez-Rodríguez, Luis Alberto Ríos, Carmen Sofía Duarte González, Andres Montaña and Catalina García-Marroquín
Sustainability 2022, 14(19), 12537; https://doi.org/10.3390/su141912537 - 1 Oct 2022
Cited by 4 | Viewed by 3371
Abstract
Currently, developing new or more efficient ways of producing bioenergy has caused governments from around the world to formulate compromises. These compromises translate, on a national scale, into government policies and strategies that aim to decarbonize the energy matrix of each country. The [...] Read more.
Currently, developing new or more efficient ways of producing bioenergy has caused governments from around the world to formulate compromises. These compromises translate, on a national scale, into government policies and strategies that aim to decarbonize the energy matrix of each country. The first step for efficient development is the quantification and energy-potential characterization of the available biomass. Using this framework, this study establishes the energy potential of the residual biomass produced by agricultural, agro-industrial, and forestry processes in Colombia, with gasification being the selected transformation technology. For this purpose, data from primary and secondary sources were analyzed. Next, some biomasses were prioritized according to their availability and physicochemical properties. Then, the theoretical energy potential of the total biomass produced in these productive sectors was estimated by using its physicochemical properties. The technical biomass–energy potential of the country (204.8–235.3 PJ) was estimated by considering the current level of unused biomass and evaluating the logistics and conditioning requirements of the gasification process, while accounting for the peaks and off-peaks of production in the country. Thus, if all the biomasses were processed in a gasification plant (22.2–24.0% efficiency), as proposed in this study, then the installed capacity—if the plant-use factor was 85%—would range between 1696.7–2111.3 MW. The results of the present research were validated by representatives of unions, companies, and government entities. Full article
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25 pages, 8006 KiB  
Article
Dual-Level Voltage Bipolar Thermal Energy Harvesting System from Solar Radiation in Malaysia
by Muhammad Nazri Rejab, Omar Mohd Faizan Marwah, Muhammad Akmal Johar and Mohamed Najib Ribuan
Sustainability 2022, 14(19), 12521; https://doi.org/10.3390/su141912521 - 30 Sep 2022
Viewed by 1923
Abstract
Harvesting energy from solar radiation in Malaysia attracts the attention of researchers to utilize the potential by ongoing improvement. Roofing material with low albedo absorbs the heat, that can then be harvested using a thermoelectric generator. Previous research only measured the open-circuit voltage [...] Read more.
Harvesting energy from solar radiation in Malaysia attracts the attention of researchers to utilize the potential by ongoing improvement. Roofing material with low albedo absorbs the heat, that can then be harvested using a thermoelectric generator. Previous research only measured the open-circuit voltage with different thermoelectric generator configurations. Low power output limits the potential to be utilized. The low output power can be increased using a DC converter. However, the converter must be tuned concerning low- and high-voltage levels, bipolar, and the maximum power point tracking. Therefore, this paper presents a dual-level voltage bipolar (DLVB) thermal energy harvesting system. The circuit is tested at constant and various time intervals to evaluate the system’s functionality and performance. Experiment results show that the proposed harvesting system can boost from 0.6 and 1.6 V to achieve the optimum level. The mean efficiency of the harvesting circuit obtains 91.92% at various time intervals. Further, the field test result obtains output power from 1.45 to 66.1 mW, with the mean efficiency range of 89.62% to 92.98%. Furthermore, recommendations are listed for future research. Full article
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15 pages, 1051 KiB  
Article
Wave Energy Potential of the Coast of El Hierro Island for the Exploitation of a Wave Energy Converter (WEC)
by Isidro Padrón, Manuel Damián García, Graciliano Nicolás Marichal and Deivis Avila
Sustainability 2022, 14(19), 12139; https://doi.org/10.3390/su141912139 - 25 Sep 2022
Cited by 5 | Viewed by 1784
Abstract
In this paper, we studied the territorial, technical, and economic conditions for the potential installation of a wave energy converter plant (WEC) connected to the small power grid of the island of El Hierro (Canary Islands). To define the best location, the non-directional [...] Read more.
In this paper, we studied the territorial, technical, and economic conditions for the potential installation of a wave energy converter plant (WEC) connected to the small power grid of the island of El Hierro (Canary Islands). To define the best location, the non-directional gross energy potential at the selected points was computed from long series of data of deep-water waves, propagated up to the coast using coefficients of refraction and shoaling calculated for the bathymetry of the island. The study concludes that the best location is the northeastern coast of the island “Llanos Blancos”, where the gross energy potential for the non-directional oscillating water column (OWC) plant used as a reference is 265.40 MWh/m per year. The methodology proposed in the work uses light computing means and affordable data series and is easily extrapolated by industry practitioners to other regions, particularly oceanic insular regions subject to waves potentially from any direction. Full article
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21 pages, 8178 KiB  
Article
Research of Exhaust Gas Boiler Heat Exchange Surfaces with Reduced Corrosion When Water-Fuel Emulsion Combustion
by Zongming Yang, Victoria Kornienko, Mykola Radchenko, Andrii Radchenko and Roman Radchenko
Sustainability 2022, 14(19), 11927; https://doi.org/10.3390/su141911927 - 21 Sep 2022
Cited by 17 | Viewed by 2118
Abstract
The application of water-fuel emulsion (WFE) in internal combustion engines enables to reduce the consumption of sulfurous fuel oils, thereby protecting the environment from emissions of sulfur and nitrogen oxides, as well revealing a great potential for the heat utilization of exhaust gases. [...] Read more.
The application of water-fuel emulsion (WFE) in internal combustion engines enables to reduce the consumption of sulfurous fuel oils, thereby protecting the environment from emissions of sulfur and nitrogen oxides, as well revealing a great potential for the heat utilization of exhaust gases. The efficiency of utilization of exhaust gas heat in exhaust boilers (EGB) depends on their temperature at the outlet of EGB, id est. the depth of heat utilization. Exhaust gas temperature is limited by the rate of low-temperature corrosion (LTC), which reaches a level of 1.2 mm/year at the wall temperature of about 110 °C for the condensing heat exchange surfaces (HES) and reduces the reliability of the HES operation. Therefore, decreasing the corrosion rate of condensing HES at wall temperature below 110 °C to an acceptable level (about 0.2 mm/year) when undergoing WFE combustion will make it possible to reduce the exhaust gas temperature and, consequently, increase the efficiency of EGB and fuel saving during the operation of the ship power plant. The aim of the research is to assess improvements to the reliability, durability and efficient operation of condensing HES in marine EGB undergoing WFE combustion in a diesel engine based on experimental studies of the LTC process. A special experimental setup was developed for investigation. The use of WFE with a decreased wall temperature of HES below 80 to 70 °C would improve the reliability of the EGB along the accepted service life, increase the lifetime of the HES metal by almost six times as well as the overhaul period, and reduce the cost of repairing condensing HES. Furthermore, due to the reducing corrosion rate under WFE combustion, the application of low-temperature condensing HES makes it possible to enhance the efficiency of deeper exhaust gas heat utilization and provide sustainable efficient operation of a diesel engine plant on the whole at a safe thermal and environmentally friendly level. Full article
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12 pages, 2591 KiB  
Article
SOS-Based Nonlinear Observer Design for Simultaneous State and Disturbance Estimation Designed for a PMSM Model
by Artun Sel, Bilgehan Sel, Umit Coskun and Cosku Kasnakoglu
Sustainability 2022, 14(17), 10650; https://doi.org/10.3390/su141710650 - 26 Aug 2022
Cited by 4 | Viewed by 1531
Abstract
In this study, a type of nonlinear observer design is studied for a class of nonlinear systems. For the construction of the nonlinear observer, SOS-based optimization tools are utilized, which for some nonlinear dynamical systems have the advantage of transforming the problem into [...] Read more.
In this study, a type of nonlinear observer design is studied for a class of nonlinear systems. For the construction of the nonlinear observer, SOS-based optimization tools are utilized, which for some nonlinear dynamical systems have the advantage of transforming the problem into a more tractable one. The general problem of nonlinear observer design is translated into an SOS polynomial optimization which can be turned into an SDP problem. For a study problem, simultaneous state and disturbance estimation is considered, a cascaded nonlinear observer using a certain parameterization is constructed, and computation techniques are discussed. Cascade nonlinear observer structure is a design strategy that decomposes the problem into its components resulting in dimension reduction. In this paper, SOS-based methods using the cascade design technique are represented, and a simultaneous state and disturbance signal online estimation algorithm is constructed. The method with its smaller components is given in detail, the efficacy of the method is demonstrated by means of numerical simulations performed in MATLAB, and the observer is designed using numerical optimization tools YALMIP, MOSEK, and PENLAB. Full article
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14 pages, 5072 KiB  
Article
Study of Lead-Free Perovskite Photoelectric Devices with TiO2 as a Buffer Layer
by Rade Tomov and Mariya Aleksandrova
Sustainability 2022, 14(16), 10043; https://doi.org/10.3390/su141610043 - 13 Aug 2022
Viewed by 1819
Abstract
In this work, a titanium oxide buffer layer was explored as a possible buffer electron transporting layer (ETL) with iodine-tin-based perovskite material for enhancement of a thin-film lead-free perovskite solar cell. The open-circuit voltage of the device was used as an indicator for [...] Read more.
In this work, a titanium oxide buffer layer was explored as a possible buffer electron transporting layer (ETL) with iodine-tin-based perovskite material for enhancement of a thin-film lead-free perovskite solar cell. The open-circuit voltage of the device was used as an indicator for the interface energy barrier’s change with the thickness of the TiO2. The buffer and photoabsorbing layers were deposited by vacuum reactive sputtering and a low-temperature ion-assisted process from a confocal sintered source, respectively, allowing precise tuning of the film properties and reproducibility of the solar cell behavior. The surface roughness of the buffer layers was investigated by atomic force microscopy and together with the measured absorbance spectra conclusions about the optical losses in the device were made. It was found that the highest voltage was generated from the structure with 75 nm-thick ETL. The electrical behavior of the cell with this buffer layer was additionally studied by impedance measurements. Small interface capacitance and contact resistance were obtained and considered suitable for photodetector fabrication. The practical applicability of the structure with a dual function of self-powered photodetection was demonstrated by the measurement of the response time. Full article
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