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

Deadline for manuscript submissions: closed (31 December 2020) | Viewed by 71830

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Special Issue Editors

Dr. Farooq Sher

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Guest Editor

Department of Engineering, School of Science and Technology, Nottingham Trent University, Nottingham NG11 8NS, UK
Interests: sustainable development; renewable energy technologies; bioenergy; biomass; thermochemical conversion; solar energy; climate change mitigation; hydrogen production; energy optimization; clean fossil fuels; carbon dioxide capture and storage (CCS)
Special Issues, Collections and Topics in MDPI journals

Dr. Oliver Curnick

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Co-Guest Editor

Institute for Future Transport and Cities, Coventry University, Coventry CV1 5FB, UK
Interests: energy storage technologies; fuel cells; power sources; experimental optimization; sustainable environment; renewable energy; catalysis; hydrogen production; low carbon strategies

Dr. Mohammad Tazli Azizan

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Co-Guest Editor

Department of Chemical Engineering, Universiti Teknologi PETRONAS, 32610, Bandar Seri Iskandar, Perak, Malaysia
Interests: sustainability; biofuels; biochemical production; biodiesel; biomass technologies; environmental impact; catalysis; hydrothermal carbonization; sustainable biohydrogen production; environmental management

Special Issue Information

Dear Colleagues,

Research on sustainability has, in the last few decades, been the way that some countries have modernized their energy systems, emission profiles, and low carbon networks in order to respond to the challenges and problems that the world faces regarding global warming and climate change. Sustainability refers to the process of people maintaining homeostasis and balance in a changing environment, in which the exploitation of resources, the direction of investments, the orientation of technological development, and institutional change are all in harmony and enhance both our current and future potential to meet human needs and aspirations. Sustainability is achieved by balancing the species and resources within an environment. To maintain this equilibrium, available resources must not be depleted faster than resources are naturally generated, and natural, renewable resources must only be made use of to the extent that people can continue to rely on their yields in the long term.

In this Special Issue, we aim to provide ground for up-to-date, fruitful, and actionable insights into economic, social, and environmental sustainability. Original research articles and reviews that use conceptual models, analytical frameworks, or empirical studies from critical perspectives and in different contexts will be considered. These perspectives should indicate their potential to bring about actionable insights and fruitful research outcomes. We welcome experimental, theoretical, and empirical contributions that, within the scope of a multidisciplinary approach, may collectively provide a reference for pressing environmental issues and describe the interaction between renewable fuels, CO₂ mitigation, and global warming.

Due to ongoing COVID-19 pandemic across the world, we offer discounts for publications cost for this special issue until 1st July 2020, but only for the papers with high quality.

Dr. Farooq Sher
Dr. Oliver Curnick
Dr. Mohammad Tazli Azizan
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 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.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 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

sustainable and renewable energy sources;
biomass and biofuels;
hydro production and energy storage;
sustainable chemistry and chemical engineering;
wind, solar, hydro, geothermal, nuclear, and bioenergy;
air pollution and climate change;
energy conversion and management;
impact of globalization on local, national, and regional sustainability and stability;
implementation and monitoring of policies for sustainable development;
sustainable education awareness and development;
system analysis methods, including life cycle assessment and management;
sustainable utilization of natural resources, such as land, water, and the atmosphere;
maintenance and preservation of biodiversity in land and aquatic ecosystems
effects of global climate change on development and sustainability;
environmental exposure mitigation strategies.

Published Papers (11 papers)

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Editorial

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4 pages, 191 KiB

Open AccessEditorial

Sustainable Conversion of Renewable Energy Sources

by Farooq Sher, Oliver Curnick and Mohammad Tazli Azizan

Sustainability 2021, 13(5), 2940; https://0-doi-org.brum.beds.ac.uk/10.3390/su13052940 - 08 Mar 2021

Cited by 35 | Viewed by 3741

Abstract

Global energy requirements are rising tremendously because of increasing urbanization and the human population. In the last few centuries, the consumption of fossil fuels has caused increased emissions of greenhouse gases resulting in environmental concerns like global warming, climatic change, and biodiversity loss. As a result, progress in sustainable energy has become the centre of attention in climatic change agenda and economic growth. Until now, various methods of renewable energy production have been extensively studied such as geothermal energy, wind energy, and solar energy. In addition to this, the utilization of biofuels from different sustainable sources are also being considered to reduce greenhouses gas emissions. New approaches and developments are still required for the creation of more sustainable, efficient, and affordable renewable energy systems and for the mitigation of global environmental threats. This special issue aims to advance novel developments in the sustainable conversion of renewable energy, providing up to date, fruitful, and actionable insights into economic, social, and environmental sustainability and includes original research articles and reviews to describe the interaction between renewable fuels, CO2 mitigation, and global warming. Full article

(This article belongs to the Special Issue Sustainable Conversion of Renewable Energy Sources)

Research

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27 pages, 8977 KiB

Open AccessArticle

Modeling and Application of Controllers for a Photovoltaic Inverter for Operation in a Microgrid

by Rubén Ortega, Víctor H. García, Adrián L. García-García, Jaime J. Rodriguez, Virgilio Vásquez and Julio C. Sosa-Savedra

Sustainability 2021, 13(9), 5115; https://0-doi-org.brum.beds.ac.uk/10.3390/su13095115 - 03 May 2021

Cited by 5 | Viewed by 2103

Abstract

The penetration of renewable energies in the context of distributed generation represents challenges such as maintaining the reliability and stability of the system and considering the random behavior proper of generation and consumption. In this context, microgrids make it possible to manage effectively the generation and consumption of this energy, incorporating, electronic power converters, energy storage systems, and hierarchical control schemes. This paper presents the modeling, design, and application of controllers for a photovoltaic inverter operating in island mode. For this application, the photovoltaic inverter regulates the inverter output voltage via two control configurations implemented to follow the voltage reference imposed by the scheme droop. The first control scheme is configured with a two-degrees-of-freedom controller plus a repetitive controller. In this configuration, the repetitive controller is implemented in the direct loop. The second scheme is configured with an integral proportional controller—proportional controller plus a resonant controller. This configuration is formed by an integral proportional control in the direct loop plus a resonant controller and a proportional controller in the feedback loop. Both control configurations are implemented to improve the inverter disturbance rejection capability when it feeds both linear and non-linear local loads. In addition, these configurations allow the parallel connection of inverters with good performance, using a droop scheme that allows the parallel connection of converters. The tests are carried out by means of simulations using PSIMTM, which shows that, with the implemented controllers, the total harmonic distortion of the inverter output is below 5%, as recommended by the IEEE 519-1992 standard. Full article

(This article belongs to the Special Issue Sustainable Conversion of Renewable Energy Sources)

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30 pages, 4305 KiB

Open AccessEditor’s ChoiceArticle

Optimized Physical Properties of Electrochromic Smart Windows to Reduce Cooling and Heating Loads of Office Buildings

by Jae-Hyang Kim, Jongin Hong and Seung-Hoon Han

Sustainability 2021, 13(4), 1815; https://0-doi-org.brum.beds.ac.uk/10.3390/su13041815 - 08 Feb 2021

Cited by 10 | Viewed by 2298

Abstract

The concept of smart windows that can change the properties of windows and doors in response to external stimuli has recently been introduced. Smart windows provide superior energy savings and control of indoor environments. This concept can advance sustainable architecture, and it will make it possible to connect with the fourth industry, which has developed recently. However, unlike the relevant hardware, is advancing rapidly, research on methods of adjusting smart windows is slow. Therefore, in this study, an analysis of energy use over time was conducted on electrochromic windows, one of the main types of smart windows. Through this analysis, the optimal properties of electrochromic smart windows were identified, and an operation schedule was created. In addition, energy saving rates were derived through a comparison with existing architectural windows. Full article

(This article belongs to the Special Issue Sustainable Conversion of Renewable Energy Sources)

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20 pages, 2476 KiB

Open AccessArticle

Optimization Issues of a Hammer Mill Working Process Using Statistical Modelling

by Gigel Paraschiv, Georgiana Moiceanu, Gheorghe Voicu, Mihai Chitoiu, Petru Cardei, Mirela Nicoleta Dinca and Paula Tudor

Sustainability 2021, 13(2), 973; https://0-doi-org.brum.beds.ac.uk/10.3390/su13020973 - 19 Jan 2021

Cited by 9 | Viewed by 5888

Abstract

Our paper presents the hammer mill working process optimization problem destined for milling energetic biomass (MiscanthusGiganteus and Salix Viminalis). For the study, functional and constructive parameters of the hammer mill were taken into consideration in order to reduce the specific energy consumption. The energy consumption dependency on the mill rotor spinning frequency and on the sieve orifices in use, as well as on the material feeding flow, in correlation with the vegetal biomass milling degree was the focus of the analysis. For obtaining this the hammer mill was successively equipped with 4 different types of hammers that grind the energetic biomass, which had a certain humidity content and an initial degree of reduction ratio of the material. In order to start the optimization process of hammer mill working process, 12 parameters were defined. The objective functions which minimize hammer mill energy consumption and maximize the milled material percentage with a certain specific granulation were established. The results obtained can serve as the basis for choosing the optimal working, constructive, and functional parameters of hammer mills in this field, and for a better design of future hammer mills. Full article

(This article belongs to the Special Issue Sustainable Conversion of Renewable Energy Sources)

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15 pages, 2760 KiB

Open AccessArticle

Solution Combustion Synthesis of Transparent Conducting Thin Films for Sustainable Photovoltaic Applications

by Sana Ullah, Rita Branquinho, Tiago Mateus, Rodrigo Martins, Elvira Fortunato, Tahir Rasheed and Farooq Sher

Sustainability 2020, 12(24), 10423; https://0-doi-org.brum.beds.ac.uk/10.3390/su122410423 - 13 Dec 2020

Cited by 12 | Viewed by 2616

Abstract

Sunlight is arguably the most promising continuous and cheap alternative sustainable energy source available at almost all living places of the human world. Photovoltaics (PV) is a process of direct conversion of sunlight into electricity and has become a technology of choice for sustainable production of cleaner and safer energy. The solar cell is the main component of any PV technology and transparent conducting oxides (TCO) comprising wide band gap semiconductors are an essential component of every PV technology. In this research, transparent conducting thin films were prepared by solution combustion synthesis of metal oxide nitrates wherein the use of indium is substituted or reduced. Individual 0.5 M indium, gallium and zinc oxide source solutions were mixed in ratios of 1:9 and 9:1 to obtain precursor solutions. Indium-rich IZO (A1), zinc-rich IZO (B1), gallium-rich GZO (C1) and zinc-rich GZO (D1) thin films were prepared through spin coating deposition. In the case of A1 and B1 thin films, electrical resistivity obtained was 3.4 × 10⁻³ Ω-cm and 7.9 × 10⁻³ Ω-cm, respectively. While C1 films remained insulating, D1 films showed an electrical resistivity of 1.3 × 10⁻² Ω-cm. The optical transmittance remained more than 80% in visible for all films. Films with necessary transparent conducting properties were applied in an all solution-processed solar cell device and then characterized. The efficiency of 1.66%, 2.17%, and 0.77% was obtained for A1, B1, and D1 TCOs, respectively, while 6.88% was obtained using commercial fluorine doped SnO₂: (FTO) TCO. The results are encouraging for the preparation of indium-free TCOs towards solution-processed thin-film photovoltaic devices. It is also observed that better filtration of precursor solutions and improving surface roughness would further reduce sheet resistance and improve solar cell efficiency. Full article

(This article belongs to the Special Issue Sustainable Conversion of Renewable Energy Sources)

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13 pages, 8445 KiB

Open AccessArticle

An Experimental Investigation on Tribological Behaviour of Tire-Derived Pyrolysis Oil Blended with Biodiesel Fuel

by Haseeb Yaqoob, Yew Heng Teoh, Muhammad Ahmad Jamil, Tahir Rasheed and Farooq Sher

Sustainability 2020, 12(23), 9975; https://0-doi-org.brum.beds.ac.uk/10.3390/su12239975 - 29 Nov 2020

Cited by 35 | Viewed by 3193

Abstract

The demand for alternative fuels has risen in recent years due to the economic and environmental consequences of conventional fuels. In addition to engine characteristics, i.e., performance, combustion, and emission the lubricity of the considered fuel is an important parameter for its selection. This experimental study shows the tribological performance of the tire pyrolysis oil by using the four-ball tester. Waste tire pyrolysis oil was purified by using the distillation process. The experiment was conducted over 300 s at 40, 50, 63, and 80 kg load, 1800 rpm constant speed, and 27 °C temperature of all fuels on the ASTM D2266 standard. The tribological performance of the tire pyrolysis oil was compared with the BT10 (biodiesel 90%–tire pyrolysis oil 10%) and BT20 (biodiesel 80%–tire pyrolysis oil 20%) and biodiesel. The optical microscope is used to measure the wear scar diameter and then it is examined through a scanning electron microscope. In terms of greater load-carrying capacity, tire pyrolysis oil shows better anti-wear behaviour compared to biodiesel fuel. The wear scar diameter of BT10, BT20, and tire pyrolysis oil was 23.99%, 8.37%, and 32.62%, respectively, lower than the biodiesel fuel at 80 kg load. The SEM micrographs revealed that tire pyrolysis oil and BT10 displayed lower wear as compared to counterparts. Finally, it is concluded that BT10 is the most suitable fuel in terms of tribological performance. Full article

(This article belongs to the Special Issue Sustainable Conversion of Renewable Energy Sources)

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16 pages, 1803 KiB

Open AccessArticle

Drivers and Barriers for Efficient Energy Management Practices in Energy-Intensive Industries: A Case-Study of Iron and Steel Sector

by Iftikhar Ahmad, Muhammad Salman Arif, Izzat Iqbal Cheema, Patrik Thollander and Masroor Ahmed Khan

Sustainability 2020, 12(18), 7703; https://0-doi-org.brum.beds.ac.uk/10.3390/su12187703 - 17 Sep 2020

Cited by 13 | Viewed by 3685

Abstract

The two major reasons behind the world’s energy crisis are losses in energy transmission and less efficient energy use at sinks. The former flaw can be catered by changing the entire energy transmission system which requires investment and planning on a large scale, whereas the later deficiency can be overcome through proper management of energy utilizing systems. Energy-intensive industries have a substantial share in energy consumption and equally high energy saving potentials if they adopt some integrated and improved energy efficiency. This study investigates the energy management systems in the iron and steel sector of Pakistan, and compare it with findings of similar work in Sweden, Bangladesh, and Ghana. A systematic questionnaire was circulated in the iron and steel sector across the country and afterward the collected data was analyzed to find major barriers and drivers for efficient energy management practices. In addition, questions on non-energy benefits and information sources relevant to the energy efficiency were also part of the questionnaire. Cost reduction resulting from lowered energy use was rated as the most important driver for applying energy-efficient operation. On the other hand, the cost of production disruption was considered among high-level barriers to the implementation of improved energy efficiency. An increase in the life-time of equipment was labeled as the top non-energy benefits. Company peers and seminars/conferences were referred as the best information sources related to energy efficiency. The outcome of the study will be helpful to the decision-maker in the industry, as well as the government levels. Full article

(This article belongs to the Special Issue Sustainable Conversion of Renewable Energy Sources)

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16 pages, 3166 KiB

Open AccessArticle

Slow-Release Urea Prills Developed Using Organic and Inorganic Blends in Fluidized Bed Coater and Their Effect on Spinach Productivity

by Bilal Beig, Muhammad Bilal Khan Niazi, Zaib Jahan, Erum Pervaiz, Ghulam Abbas Shah, Midrar Ul Haq, Mazhar Iqbal Zafar and Munir Zia

Sustainability 2020, 12(15), 5944; https://0-doi-org.brum.beds.ac.uk/10.3390/su12155944 - 23 Jul 2020

Cited by 33 | Viewed by 5424

Abstract

The application of urea-based fertilizers in developing countries has gained significant momentum over time. urea usage is to meet demand and supply gap of food resources as world population is increasing at a fast pace. urea contains largest content of nitrogen (46%) among all the solid nitrogenous fertilizers. However, main drawback of urea is its higher dissolution rate. After soil application, most of urea nitrogen is lost through a leaching, runoff, nitrification-denitrification and ammonia volatilization. To tackle urea related environmental pollution, development of slow-release urea fertilizer is a need of the hour and this would also increase product use efficiency in terms of crop productivity and its N uptake. We studied the usage of polymeric materials in combination with inorganic substances like sulfur and plaster of Paris as effective and biodegradable coating substances for urea prills. For coating on urea prills, fluidized bed coater was used whereas paraffin wax and molasses were used as binding agents. The urea was coated with four different formulations, i.e., C-1: PVA 5% + plaster of Paris 10% + sulfur 5% + paraffin wax 2%, C-2: PVA 5% + starch 10% + sulfur 5% + paraffin wax 2%, C-3: gelatin 5% + plaster of Paris 10% + sulfur 5% + paraffin wax 2% and C-4: PVA 5% + starch 10% + sulfur 5% + paraffin wax 2.5% + molasses 2.5%. Each formulation along with uncoated urea prills (C-0) were evaluated for characterization and N release kinetics. All the formulations along with uncoated urea were applied to spinach crop in pot experiment. A control (No N: untreated) was also kept. Spinach biomass yield and N uptake were determined. The formulation C-1 yielded highest urea-N release efficiency and spinach N uptake of6.87% and 1.93 g N/pot, respectively. Themodified Schwarz and Sinclair formula gave the excellent representation of release of nutrient-N from coated urea prills. It is concluded that coating urea prills with organic and inorganic blends is better option to slow down N release kinetics and improve spinach productivity. Therefore, by using coated fertilizers, farmers can improve agro-environmental value of urea, worldwide. Full article

(This article belongs to the Special Issue Sustainable Conversion of Renewable Energy Sources)

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20 pages, 4349 KiB

Open AccessArticle

Modeling Viscosity and Density of Ethanol-Diesel-Biodiesel Ternary Blends for Sustainable Environment

by Luqman Razzaq, Muhammad Farooq, M. A. Mujtaba, Farooq Sher, Muhammad Farhan, Muhammad Tahir Hassan, Manzoore Elahi M. Soudagar, A. E. Atabani, M. A. Kalam and Muhammad Imran

Sustainability 2020, 12(12), 5186; https://0-doi-org.brum.beds.ac.uk/10.3390/su12125186 - 25 Jun 2020

Cited by 77 | Viewed by 5476

Abstract

Rapid depletion in fossil fuels, inflation in petroleum prices, and rising energy demand have forced towards alternative transport fuels. Among these alternative fuels, diesel-ethanol and diesel-biodiesel blends gain the most attention due to their quality characteristics and environmentally friendly nature. The viscosity and density of these biodiesel blends are slightly higher than diesel, which is a significant barrier to the commercialization of biodiesel. In this study, the density and viscosity of 30 different ternary biodiesel blends was investigated at 15 °С and 40 °С, respectively. Different density and viscosity models were developed and tested on biodiesel blends soured from different feedstock’s including palm, coconut, soybean, mustard, and calophyllum oils. The prognostic ability and precisions of these developed models was assessed statistically using Absolute Percentage Error (APE) and Mean Absolute Percentage Error (MAPE). The MAPE of 0.045% and 0.085% for density model and 1.85%, 1.41%, 3.48% and 2.27%, 1.85%, 3.50% for viscosity models were obtained on % volume and % mass basis. These developed correlations are useful for ternary biodiesel blends where alcohols are the part of biodiesel blends. The modeled values of densities and viscosities of ternary blends were significantly comparable with the measured densities and viscosities, which are feasible to avoid the harm of vehicles’ operability. Full article

(This article belongs to the Special Issue Sustainable Conversion of Renewable Energy Sources)

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Review

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23 pages, 10975 KiB

Open AccessReview

Ionic Liquids Roles and Perspectives in Electrolyte for Dye-Sensitized Solar Cells

by Ruwaida Asyikin Abu Talip, Wan Zaireen Nisa Yahya and Mohamad Azmi Bustam

Sustainability 2020, 12(18), 7598; https://0-doi-org.brum.beds.ac.uk/10.3390/su12187598 - 15 Sep 2020

Cited by 42 | Viewed by 3513

Abstract

Exploration of renewable energy, such as solar energy, is imminent not only to cater to the escalating energy demand but also to address the uprising environmental issues due to heavy usage of non-renewable fossil fuel. The dye-sensitized solar cells (DSSCs) which are considered as the third-generation solar cells, have a huge potential to be commercialized due to their low cost, simplicity in fabrication, and promising photon-to-electrical energy conversion efficiency. Nevertheless, a high cell efficiency can only be achieved when an organic solvent is incorporated into the formulation of the electrolyte, which is prone to evaporation and leakage. As a result, DSSCs become unsuitable for long-run usage due to thermal instability in the electrolyte. The early intention of incorporating ionic liquids (ILs) into the electrolyte was to curb the abovementioned problem and to enable the DSSCs to function as a sustainable energy device. As such, this article briefly reviews how ILs have been incorporated into the electrolyte formulation and the extent of how the ILs can affect the cell efficiency in various electrolyte states. The role of the ILs in a range of electrolytes is also highlighted. This sheds light on the true purpose of introducing ILs into DSSC electrolyte, which is to enhance the ionicity of the electrolyte. Full article

(This article belongs to the Special Issue Sustainable Conversion of Renewable Energy Sources)

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31 pages, 5249 KiB

Open AccessReview

A Critical Review of Sustainable Energy Policies for the Promotion of Renewable Energy Sources

by Yuehong Lu, Zafar A. Khan, Manuel S. Alvarez-Alvarado, Yang Zhang, Zhijia Huang and Muhammad Imran

Sustainability 2020, 12(12), 5078; https://0-doi-org.brum.beds.ac.uk/10.3390/su12125078 - 22 Jun 2020

Cited by 186 | Viewed by 31560

Abstract

Meeting the rising energy demand and limiting its environmental impact are the two intertwined issues faced in the 21st century. Governments in different countries have been engaged in developing regulations and related policies to encourage environment friendly renewable energy generation along with conservation strategies and technological innovations. It is important to develop sustainable energy policies and provide relevant and suitable policy recommendations for end-users. This study presents a review on sustainable energy policy for promotion of renewable energy by introducing the development history of energy policy in five countries, i.e., the United States, Germany, the United Kingdom, Denmark and China. A survey of the articles aimed at promoting the development of sustainable energy policies and their modelling is carried out. It is observed that energy-efficiency standard is one of the most popular strategy for building energy saving, which is dynamic and renewed based on the current available technologies. Feed-in-tariff has been widely applied to encourage the application of renewable energy, which is demonstrated successfully in different countries. Building energy performance certification schemes should be enhanced in terms of reliable database system and information transparency to pave the way for future net-zero energy building and smart cities. Full article

(This article belongs to the Special Issue Sustainable Conversion of Renewable Energy Sources)

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