Special Issue "Adoption of Renewable Energy Technologies (RETs) to Achieve Sustainability"

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

Deadline for manuscript submissions: 30 November 2021.

Special Issue Editors

Prof. Dr. Gholamhassan Najafi
E-Mail Website
Guest Editor
Biosystems Engineering Department, Tarbiat Modares University (TMU), Tehran 1411713116, Iran
Interests: renewable energies; sustainability; IC engines—fuels and combustion; machine design and FEM methods
Special Issues and Collections in MDPI journals
Dr. Shiva Gorjian
E-Mail Website
Guest Editor
Biosystems Engineering Department, Tarbiat Modares University (TMU), Tehran 1411713116, Iran
Interests: renewable energy technologies; solar thermal; photovoltaics; photovoltaic-thermal; solar concentrators; solar-powered desalination; solar-powered greenhouses; energy storage

Special Issue Information

Dear Colleagues,

The International Renewable Energy Agency (IRENA) has claimed that the energy sector contributes nearly two-thirds of global greenhouse gas (GHG) emissions. In this regard, alteration of the global energy system, with a specific focus on the adoption of renewable energy technologies (RETs), is becoming crucial. This transformation entails the involvement of all social levels in both the public and private sectors. The rapid adoption of renewable energy strategies along with improved energy efficiency would result in at least a 90% reduction in energy-related carbon dioxide (CO2) emissions.

Energy sustainability has many dimensions, including both production and utilization as well as the way in which they can be connected to sustainable development. The concept of sustainability also consists of three distinct aspects of economic, environmental, and social sustainability. Due to the rapid global consumption rate of conventional energy sources, several initiatives are underway all over the world to replace them with alternative energy sources. Renewable energies and sustainable development are both known as highly debated topics. Renewable energies can be harnessed economically and in an environmentally friendly manner to produce heat, electricity, and fuels. Along with the declining costs of renewable energy technologies, the economic opportunities for the employment of renewable technologies are globally increasing. Therefore, targets of both reducing GHG emissions and fostering more sustainability would be both an opportunity and a societal priority.

This Special Issue is a platform to motivate prominent researchers to share the latest developments in renewable energy systems and policy and address issues of novelty and scientific relevance in the design, assessment, and improvement of these technologies for a more sustainable future. In this regard, authors worldwide are invited to contribute their full-length, peer-review-ready papers on the following topics:

  • Renewable energy technologies;
  • Renewable energy applications;
  • Renewable energy policy, management, and governance;
  • Technical innovations and economic feasibility;
  • Case studies encompassing renewable energies and sustainable development.

Prof. Dr. Gholamhassan Najafi
Dr. Shiva Gorjian
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 1900 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

  • renewable energy
  • sustainable development
  • modeling and optimization
  • agriculture
  • industry
  • policy

Published Papers (4 papers)

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Research

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Article
Study on the Influence of EGR on the Combustion Performance of Biofuel Diesel at Different Ambient Simulated Pressures
Sustainability 2021, 13(14), 7862; https://doi.org/10.3390/su13147862 - 14 Jul 2021
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Abstract
In order to explore the influence of EGR at different altitudes on the performance of biofuel diesel engines, a comparative experimental study is conducted with the biodiesel–ethanol–diesel B15E5 (biodiesel with 15% volume fraction, ethanol with 5% volume fraction and diesel with 80% volume [...] Read more.
In order to explore the influence of EGR at different altitudes on the performance of biofuel diesel engines, a comparative experimental study is conducted with the biodiesel–ethanol–diesel B15E5 (biodiesel with 15% volume fraction, ethanol with 5% volume fraction and diesel with 80% volume fraction) mixed fuel at different EGR rate and different atmospheric pressure. The experimental results show that diesel engine power performance and economy goes up with the increase of atmospheric pressure, and it decreases with the increase of EGR rate. At 2200 rpm, the improvement range of medium and high diesel engine load is 1.5–6.8%, and that of 1800 rpm is 2.8–11.7%. At the same atmospheric pressure, with the increase of EGR rate, the power and economy turn worse. The peak combustion pressure and heat release rate both increased with the increase of the atmospheric pressure at full load. At the same atmospheric pressure, peak combustion pressure and peak heat release rate fall with the increase of EGR rate. At part load, firstly, smoke emissions fall with the increase of the load and then rise. As the atmospheric pressure goes up, the smoke emissions show a downward trend, with a decline of 6.6–40%, while the NOx emissions show a rising trend, with an increase of 1.2–8.5%. At the same atmospheric pressure, the smoke emission increase with the increase of EGR rate by 9–12.5%, and the NOx emissions increase with the decrease of EGR rate by 2.5–6.8%. The HC and CO Emissions decrease with the increase of atmospheric pressure. HC emission decreases by 9.3–19.1%, and CO emission decreases by 2.9–16.6%. At the same atmospheric pressure, the HC emission decreases with the increase of the EGR rate by 3.3–4.5% at medium and high loads, and the CO emission increases with the EGR rate by 3.1–4.5%. Full article
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Article
Experimental and Theoretical Analysis of Energy Efficiency in a Flat Plate Solar Collector Using Monolayer Graphene Nanofluids
Sustainability 2021, 13(10), 5416; https://doi.org/10.3390/su13105416 - 12 May 2021
Viewed by 453
Abstract
Flat-plate solar collectors are one of the cleanest and most efficient heating systems available. Studies on the presence of covalently functionalized graphene (Gr) suspended in distilled water as operating fluids inside an indoor flat-plate solar collector (FPSC) were experimentally and theoretically performed. These [...] Read more.
Flat-plate solar collectors are one of the cleanest and most efficient heating systems available. Studies on the presence of covalently functionalized graphene (Gr) suspended in distilled water as operating fluids inside an indoor flat-plate solar collector (FPSC) were experimentally and theoretically performed. These examinations were conducted under different testing conditions namely 0.025 wt.%, 0.05 wt.%, 0.075 wt.%, and 0.1 wt.%, 0.5, 1, and 1.5 kg/min, 30, 40, and 50 °C, and 500, 750, and 1000 W/m2. Various techniques were used to characterize the functionalized nanofluids’ stability and morphological properties namely UV/Vis spectrophotometry, EDX analysis with a Scanning Electron Microscope (SEM), zeta potential, and nanoparticle size. The results showed that the collected heat improved as the percentage of GrNPs and the fluid mass flow rates increased, although it decreased as the reduced temperature coefficient increased, whereas the maximum increase in collector efficiency at higher concentration was 13% and 12.5% compared with distilled water at 0.025 kg/s. Finally, a new correlation was developed for the base fluid and nanofluids’ thermal efficiency as a function of dropped temperature parameter and weight concentration with 2.758% and 4.232% maximum deviations. Full article
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Article
The Influence of Diesel–Ethanol Fuel Blends on Performance Parameters and Exhaust Emissions: Experimental Investigation and Multi-Objective Optimization of a Diesel Engine
Sustainability 2021, 13(10), 5379; https://doi.org/10.3390/su13105379 - 11 May 2021
Viewed by 440
Abstract
Compression combustion engines are a source of air pollutants such as HC and Co, but are still widely used throughout the world. The use of renewable fuels such as ethanol, which is a low-carbon fuel, can reduce the emission of these harmful gases [...] Read more.
Compression combustion engines are a source of air pollutants such as HC and Co, but are still widely used throughout the world. The use of renewable fuels such as ethanol, which is a low-carbon fuel, can reduce the emission of these harmful gases from the engine. A fundamental analysis is proposed in this research to experimentally examine the emission characteristics of diesel–ethanol fuel blends. Furthermore, a multi-objective genetic algorithm (e-MOGA) was developed based on the experimental data obtained to fine the most effective or Pareto set of engine emission and performance optimization solutions. So, the optimization problem had two inputs and seven objectives. For this purpose, input variables for the search space were S (rpm) varied in the range of (1600–2000) and E (%) varied in the range of (0–12). These design variables were chosen to be varied in a prespecified range with a lower and upper band as same as experimental conditions. A diesel engine using (DE2, DE4, DE6, DE8, DE10, and DE12) diesel–ethanol fuel blends, at the various speed of 1600 to 2000 rpm, was utilized for the experiment. The findings showed that the use of diesel–ethanol fuel blends decreased the concentration of CO and HC emissions by 3.2–30.6% and 7.01–16.25%, respectively, due to the high oxygen content of ethanol. As opposed to CO and HC emissions, the NOx concentration showed an increase of 7.5–19.6%. This increase was attributed to the high combustion quality in the combustion chamber, which resulted in a higher combustion chamber temperature. The optimization results confirmed that the shape of the Pareto front obtained from multi-objective ϵ-Pareto optimization could be convex, concave, or a combination of both. A new parameter was introduced as emission index or EI for selection of the best solution among the Pareto set of solutions. This parameter had a minimum value of 4.61. The variables levels for this optimum solution were as follows: engine speed = 1977 rpm, ethanol blend ratio = 10%, CO = 0.27%, CO2 = 6.81%, HC = 3 ppm, NOx = 1573 ppm, SFC = 239 g/kW·h, P = 56 kW, and T = 269.9 N·m. The EI index had a maximum value of 8.26. Conclusively, we can say that the optimization algorithm was successful in minimizing emission index for all ethanol blend ratios, especially at higher engine speeds. Full article
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Review

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Review
Recent Advancements in Technical Design and Thermal Performance Enhancement of Solar Greenhouse Dryers
Sustainability 2021, 13(13), 7025; https://doi.org/10.3390/su13137025 - 22 Jun 2021
Viewed by 630
Abstract
The food industry is responsible for supplying the food demand of the ever-increasing global population. The food chain is one of the major contributors to greenhouse gas (GHG) emissions, and global food waste accounts for one-third of produced food. A solution to this [...] Read more.
The food industry is responsible for supplying the food demand of the ever-increasing global population. The food chain is one of the major contributors to greenhouse gas (GHG) emissions, and global food waste accounts for one-third of produced food. A solution to this problem is preserving crops, vegetables, and fruits with the help of an ancient method of sun drying. For drying agricultural and marine products, several types of dryers are also being developed. However, they require a large amount of energy supplied conventionally from pollutant energy sources. The environmental concerns and depletion risks of fossil fuels persuade researchers and developers to seek alternative solutions. To perform drying applications, sustainable solar power may be effective because it is highly accessible in most regions of the world. Greenhouse dryers (GHDs) are simple facilities that can provide large capacities for drying agricultural products. This study reviews the integration of GHDs with different solar technologies, including photovoltaic (PV), photovoltaic-thermal (PVT), and solar thermal collectors. Additionally, the integration of solar-assisted greenhouse dryers (SGHDs) with heat pumps and thermal energy storage (TES) units, as well as their hybrid configuration considering integration with other renewable energy sources, is investigated to improve their thermal performance. In this regard, this review presents and discusses the most recent advances in this field. Additionally, the economic analysis of SGHDs is presented as a key factor to make these sustainable facilities commercially available. Full article
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