Sustainable Energy Generation Research Articles

(Invited) Slurry of Transition Metal Chalcogenides for Multifaceted Electrochemical Applications: Energy Conversion, Storage, Sensing & Catalysis

Transition metal chalcogenides has been at the center of attraction for materials chemistry for decades owing to their novel and interesting optoelectronic properties that can be tuned with anion composition, coordination and doping. Recently these transition metal chalcogenides have also been explored for energy-related applications with primary focus on sustainable energy conversion. Energy harvesting from solar and water has created ripples in sustainable energy research for the last several decades, complemented by the rise of Hydrogen as a clean fuel. It has become very apparent that hydrogen-on-demand technology needs to be developed to complement the growth of hydrogen fuel economy without adding on to the process cost by storing hydrogen in pressurized tanks or non-reactive framework. In this regard, water electrolysis leading to generation of oxygen and hydrogen, has been one of the most promising routes towards sustainable alternative energy generation and storage without depleting fossil-fuel based natural resources. However, the efficiency and practical feasibility of water electrolysis is limited by the anodic oxygen evolution reaction (OER), which is a kinetically sluggish, electron-intensive uphill reaction and designing efficient catalysts for OER process from earth-abundant resources has been one of the primary concerns for advancing solar water splitting. In the Nath group we have been successful in producing transition metal chalcogenide-based highly efficient OER electrocatalysts which surpasses efficiency of state-of-the-art precious metal oxides by several orders of magnitude. Our main design principle if based on the concept that chalcogenides, specifically, selenides and tellurides will show much better OER catalytic activity due to increasing covalency around the catalytically active transition metal site, compared to the oxides caused by decreasing electronegativity of the anion, which in turn leads to variation of chemical potential around the transition metal center, [e.g. lowering the Ni2+ --> Ni3+ oxidation potential in Ni-based catalysts where Ni3+ is the actually catalytically active species]. Based on such hypothesis, we have synthesized a plethora of transition metal selenides including those based on Ni, Ni-Fe, Co, Ni-Co, Cu, and Cu-Co which show high catalytic efficiency characterized by low onset potential and overpotential at 10 mA/cm2 [Ni3Se2 - 200 - 290 mV; Co7Se8 - 260 mV; FeNi2Se4-NrGO - 170 mV (NrGO - N-doped reduced graphene oxide); NiFe2Se4 - 210 mV; CoNi2Se4 - 190 mV; Ni3Te2 – 180 mV]. In this presentation we will highlight the importance of this increasing covalency in enhancing OER catalytic activity and illustrate with examples recently discovered examples of selenide and telluride compositions ranging from binary chalcogenides (Ni3Se2, NiSe2, NiSe, Cu2Se), to ternary and quaternary mixed metal selenides (Ni-Co-Se, Ni-Fe-Se) as well as seleno-based molecular complex containing NiSe4 tetrahedral core. We will illustrate how the Ni(II) --> Ni(III) oxidation potential is indeed lowered within the chalcogenide coordination compared to the oxide leading to the formation of mixed anionic (hydroxy)chalcogenide surface which enhances surface reactivity through preferential intermediate adsorption. Another aspect that has become more relevant is the electroreduction of atmospheric carbon dioxide into fuel or other value-added chemicals, thereby offering environmental remediation without the need to store large amounts of pressurized CO2. The electrochemical tunability of transition metal chalcogenide surfaces along with their increased lattice covalency has led to development of the concept that some of these compositions can enhance carbon dioxideCO2 reduction. Specifically, we have focused on Cu and Ni-based chalcogenides based on the hypothesis that higher d-electron occupancy of the transition metal within a covalent lattice will lead to better adsorption of intermediate CO on the surface through enhanced metal-to-ligand back-bonding, which in turn leads to longer dwell time and subsequent reduction of the CO to higher carbon content products. The Nath group has recently discovered copper and nickel chalcogenides as highly active electrocatalysts for CO2 reduction to C2 and C3 products with high selectivity. Interestingly it was observed that product composition could be controlled by tuning the applied potential with ethanol and acetic acid forming predominantly at low applied potential while formic acid was obtained exclusively at higher applied potential. Lastly, we will discuss the electrocatalytic activity of the transition metal chalcogenides towards biomolecule conversion enhancing their applicability as biosensors for detecting potentially life-threatening disorders. Detailed studies of the chemical reactivity, electrochemical activity, interfacial chemistry, and functional stability of the transition metal chalcogenides that makes all these applications feasible will be discussed in depth.

Scalable processing method using waste polystyrene to produce nitrogen-enriched porous carbon for boosting supercapacitor performance

A high-efficiency rational design of a durable material produced from waste materials for sustainable energy generation and storage systems is a formidable challenge. This paper describes the large-scale synthesis of nitrogen-doped porous carbon (PS-C) from waste polystyrene with a short processing time using the thermal plasma method. The as-synthesized PS-C exhibited an electrochemical capacitance of 482 Fg−1 at a current density of 1 Ag−1 and a capacitance retention of 95% at a current density of 6 Ag−1 after 5000 charge–discharge cycles. This reported specific capacitance and cyclic performance are attributed to the morphology, nitrogen doping, and structural integrity resulting from the synergy of the material.

Hydrogen-rich syngas production from biomass in a steam microwave-induced plasma gasification reactor

Substitution of fossil fuels by sustainable practices must be rapidly implemented to mitigate the impacts of climate change. The conversion of biomass into combustible gas is investigated in a microwave-induced plasma reactor using pure steam as the plasma working gas for the first time. The optimum results are achieved at the highest forward microwave power of 6 kW with biomass carbon conversion efficiency over 98% and complete biomass energy recovery in syngas. Unreacted steam is simply condensed out, leading to the production of a syngas with low inert dilution and high calorific value in the range 10.5–12 MJ/Nm3. The syngas produced is rich in hydrogen, exceeding 60% by volume. The proposed process could aid in the transition to a carbon neutral economy as it has the potential to efficiently convert biomass to syngas that can be used for the sustainable generation of fuels, chemicals and energy.

Energy Harvesting on Airport Pavements: State-of-the-Art

Society is dependent on transport systems, not only to meet its daily needs with short journeys but also to meet their arising needs with longer distances. The ability to connect remote regions and the trip duration makes the aircraft a mode of transport for distant travel. However, it impacts greenhouse gas production. The survey for new ways to reduce greenhouse gas emissions emerges from the contribution of energy harvesting systems. Energy harvesting technology has been presenting prosperous solutions and applications in road pavements. Due to the similarity between road pavements, this paper addresses state-of-the-art technologies for airport pavements and road pavements, aiming to analyze which ones can be developed for application in airport pavements. An analysis is presented not only for the density, efficiency, and energy generation, but also for each energy harvesting technology’s implementation and technology readiness level. The photovoltaic technology, to be incorporated into airport pavements, will allow sustainable energy generation dependent on the airport location. The hydraulic/pneumatic technology, to be incorporated into the airport pavements, will generate electrical energy based on aircraft movement.

A circular economy model for fossil fuel sustainable decisions based on MADM techniques

Fossil fuels as the primary energy source create career opportunities, provide industries with vital raw material and energy resources, have harmful emissions to the environment and are also related to finite natural resources. They rely on them as the main source of energy supply is unsustainable. Sustainability assessment tools may be useful in developing a more sustainable scenario. However, the resiliency of nature is not taken into account in this linear assessment. The detrimental effect of these fuels on the environment during their life cycle would suggest transitioning from cradle-to-grave to the cradle-to-cradle lifecycle viewpoint. This study implements the Circular Economic (CE) in fossil fuel development to minimize the unsustainable effects and ensure the environment’s resiliency. In this context, three different fossil fuels are assessed based on the CE model’s proposed lifecycle phases to find out the most sustainable fossil fuel option. A case study is carried out in an industrial location with high-level decision-makers. CE criteria are evaluated based on the E-SWARA method to ensure the assessment’s reliability at this critical step. Next, a novel MCDM method, MARCOS, is applied to this study. Based on the results, gas is the most sustainable energy generation plant in the intended region.

Hybrid Nanocomposite Thin Films for Photovoltaic Applications: A Review.

Continuing growth in global energy consumption and the growing concerns regarding climate change and environmental pollution are the strongest drivers of renewable energy deployment. Solar energy is the most abundant and cleanest renewable energy source available. Nowadays, photovoltaic technologies can be regarded as viable pathways to provide sustainable energy generation, the achievement attained in designing nanomaterials with tunable properties and the progress made in the production processes having a major impact in their development. Solar cells involving hybrid nanocomposite layers have, lately, received extensive research attention due to the possibility to combine the advantages derived from the properties of both components: flexibility and processability from the organic part and stability and optoelectronics features from the inorganic part. Thus, this review provides a synopsis on hybrid solar cells developed in the last decade which involve composite layers deposited by spin-coating, the most used deposition method, and matrix-assisted pulsed laser evaporation, a relatively new deposition technique. The overview is focused on the hybrid nanocomposite films that can use conducting polymers and metal phthalocyanines as p-type materials, fullerene derivatives and non-fullerene compounds as n-type materials, and semiconductor nanostructures based on metal oxide, chalcogenides, and silicon. A survey regarding the influence of various factors on the hybrid solar cell efficiency is given in order to identify new strategies for enhancing the device performance in the upcoming years.

Defining the cost of water impact for thermoelectric power generation

Thermal power plants use large amounts of water, mainly for cooling purposes. Over a long operational period, power-plant cooling can have a large impact on the water source: elevated temperatures of return flows alter the local physical and chemical properties of the water (i.e., quality impact), while water consumption reduces the available water reserves for future and down-stream uses (i.e., Quantity impact). The vulnerability of the energy sector to water availability is an important problem and measures to confront or mitigate this challenge have not yet been adopted. Here, a novel, straightforward methodology to calculate the cost of water impact caused by coal and natural-gas (combined-cycle) plants with once-through and wet-recirculating cooling systems is developed. The goal is to internalize systemic costs related to water use impacts and thereby incentivize more sustainable energy generation practices. The impact is calculated here as a theoretical feedback on the plant’s operational costs, since altered water properties will eventually lead to malfunction or part-load operation. The main parameter affecting the cost of water impact is found to be the temperature rise of the cooling water in the condenser. In plants with once-through cooling systems, the quantity and quality impacts of water use are of a comparable magnitude. The cost of water impacts in facilities with wet-recirculating cooling systems, on the other hand, is determined only by their quantity impact on water resources. Overall, recirculating systems result in a significantly lower water cost when compared to once-through systems. Furthermore, an approximately three times higher cost of water impact is calculated for coal plants in comparison to natural gas plants, which clearly demonstrates the importance of operational efficiency on the water use of power plants.

A Novel FCS-MPC Method of Multi-Level APF Is Proposed to Improve the Power Quality in Renewable Energy Generation Connected to the Grid

When photovoltaic, wind, energy storage batteries, and other new forms of energy are connected to the grid, power electronic converters are needed, and there are a lot of nonlinear devices in the grid. The characteristics of sustainable energy generation determine the variability and intermittency, which will produce harmonic components. Active power filters (APF) are commonly used in industry for harmonic compensation, so it is of great significance to control APF quickly and effectively. The multi-objective, single-factor, multistep finite control set model predictive control (FCS-MPC) of an APF proposed in this paper is suitable for a multi-objective, multi-level converter control. This method is applied to the three-level APF structure, which changes the traditional three-level FCS-MPC control method. The traditional three-level FCS-MPC includes four control objectives, stable control of the DC-side voltage, power grid harmonic currents generated under non-linear loads, and balance of the capacitor voltage on the DC side when switching frequency. This method uses the redundant switching state of the three-level structure to achieve the voltage balance of the two capacitors on the DC side, which reduces the difficulty of target optimisation caused by the selection of weight factors. Based on the multi-step prediction, power feedback control is added on the DC side to increase the DC side’s reaction speed, eliminate the influence of uncertainty, and realise better dynamic performance. According to the simulation results, we can observe that the proposed method has good followability, can compensate for the harmonics of the power grid, reduces the harmonic content to less than 5%, and can balance the DC-side capacitor voltage.

Assessment of ligninolytic bacterial consortium for the degradation of azo dye with electricity generation in a dual-chambered microbial fuel cell

The contribution of microorganisms toward sustainable energy generation, bioremediation and other industrial applications is incredible though a large part of it remains untapped and unexplored. Microbial Fuel Cells (MFCs) serve a promising technology for renewable energy generation through the oxidation of biodegradable organic stuff in the presence of electro-genic bacteria. Well suited applications of MFC are simultaneous wastewater treatment and electricity production. The present study aimed to find a potential dye decolorizing ligninolytic bacterial consortium for the degradation of azo dye mixture with the generation of electricity in a dual-chambered microbial fuel cell. In the present study, the bacterial consortium WGC-D was investigated for its ability to produce electricity with the degradation of azo direct dye mixture. For this, a dual-chambered microbial fuel cell was assembled. The bacterial consortium WGC-D was inoculated in the anode chamber and the MFC was operated for 7 days. UV–visible and FTIR spectral studies fortified the biodegradation mechanism of dye components by the consortium. GCMS study revealed the biotransformation of dye molecules to various smaller molecules during the degradation process. The MFC generated up to 673 mV during the operation period which revealed the electro-genic nature of the bacterial consortium. The bacterial biofilm formation on carbon cloth anode was observed by FESEM analysis. The cyclic voltammetric study confirmed the extracellular electron transfer (EET) by the consortium to the anode.

Development of environment friendly water-based self-rechargeable battery

There is a growing demand for the development of sustainable electrical energy generation devices with a high energy-to-price ratio. On the other hand, industrial waste, such as fly ash is a hazard to environmental pollution. However, here for the first time, water-based self-rechargeable batteries have been fabricated by using bio-waste (golden shower tree bark ash (TBA)), a rural pollutant (cow dung ash), and industrial pollutant (coal fly ash). The TBA-based battery, out of all three batteries, shows the highest open-circuit voltage of ∼1.48 V and a specific capacity of 183 mAhg−1. Further, the TBA based cell has retained ∼97% columbic efficiency even after 2000 cycles. It has been found that pH of TBA ash is the highest, i.e. ∼12 in presences of tap water and it is found that the TBA ash is composed of a large number of metal oxides. The materials present in the ash powder have generated oxides and hydroxides ions which have, in turn, caused the generation of the potential difference between the two electrodes. The fabricated devices are portable and can power up a large number of electronic gadgets, including light-emitting diodes (LEDs). It is envisioned that this work may open the door to the development of sustainable, environment-friendly, and low-cost bio-waste ash-based self-rechargeable energy devices in future.

Advanced Two-Dimensional Heterojunction Photocatalysts of Stoichiometric and Non-Stoichiometric Bismuth Oxyhalides with Graphitic Carbon Nitride for Sustainable Energy and Environmental Applications

Semiconductor-based photocatalysis has been identified as an encouraging approach for solving the two main challenging problems, viz., remedying our polluted environment and the generation of sustainable chemical energy. Stoichiometric and non-stoichiometric bismuth oxyhalides (BiOX and BixOyXz where X = Cl, Br, and I) are a relatively new class of semiconductors that have attracted considerable interest for photocatalysis applications due to attributes, viz., high stability, suitable band structure, modifiable energy bandgap and two-dimensional layered structure capable of generating an internal electric field. Recently, the construction of heterojunction photocatalysts, especially 2D/2D systems, has convincingly drawn momentous attention practicably owing to the productive influence of having two dissimilar layered semiconductors in face-to-face contact with each other. This review has systematically summarized the recent progress on the 2D/2D heterojunction constructed between BiOX/BixOyXz with graphitic carbon nitride (g-C3N4). The band structure of individual components, various fabrication methods, different strategies developed for improving the photocatalytic performance and their applications in the degradation of various organic contaminants, hydrogen (H2) evolution, carbon dioxide (CO2) reduction, nitrogen (N2) fixation and the organic synthesis of clean chemicals are summarized. The perspectives and plausible opportunities for developing high performance BiOX/BixOyXz-g-C3N4 heterojunction photocatalysts are also discussed.

Wastewater treatment and energy production by microbial fuel cells

The increasing demands of efficient and sustainable energy generation methods from waste products have taken a giant leap in the last century, and especially in the previous two decades. Wastewater treatment has also been a much-researched topic in recent years owing to the exponential increase in effluent-laden wastewater from industries, the agricultural sector and food sector, and its effects on the environment. There have been plenty of wastewater treatment techniques over the years, but most of them lack in terms of cost-effectiveness, durability, and energy recovery rates. Microbial fuel cells can prove to be of great use to tackle both of these issues in one go, as they perform bioelectrochemical processes on organic biodegradable compounds to oxidize them to generate power which can be harnessed by various means. This article explains the aim, construction, mechanism, and application of microbial fuel cells; the economic and scientific challenges that they face in the future; and microbial fuel cell (MFC) hybrid systems which make use of MFCs combined with other useful technologies for greater aims and better efficiencies. It overall discusses the various ways in which MFCs outperform other wastewater treatment technologies by significantly decreasing sludge production and being environment-friendly, and also some limitations and drawbacks that MFCs face owing to the fact that they are relatively newer technologies and still require decades of modifications until they reach excellent output rates. MFCs are known not only for wastewater treatment but also for contaminant removal, heavy metal removal, biohydrogen production, applications in biosensors, etc., as also discussed in this article.

MXenes: Emerging 2D materials for hydrogen storage

Abstract The generation of sustainable energy has become a priority issue to properly maintain the sustainability of humankind. To meet the future global energy demands, the efficient generation of clean and renewable energy like hydrogen has become the need of the hour. Currently, hydrogen is being used either as a compressed gas in high-pressure tanks or in liquefied form in tanks. However, these storage technologies have safety issues, making the solid-state storage approach an attractive alternative option. In this context, the potential of light-weight high-performance solid-state materials like MXenes (a few-atoms-thick layers of transition metal carbides, nitrides, or carbonitrides) allow reversible hydrogen storage. The Ti2C MXene has shown a maximum hydrogen adsorption capacity up to 8.6 wt%, which is far higher than the gravimetric capacity of metal-based complex hydrides (~5.5 wt%) as set by U.S. DOE (2015). Hydrogen storage performance was also evaluated in other MXenes like Ti3C2, Cr2C, Ti2N, and their composites. Despite their great potential, the utility of MXenes in hydrogen storage applications has not been explored to its full extent. In this review, a detailed discussion is provided on state of art applications of MXene-based materials for hydrogen storage along with their challenges and future outlook.

Hybridization of solar photovoltaic and biogas system: Experimental, economic and environmental analysis

The coupling of renewable energy systems has proven to be advantageous in achieving sustainable and reliable energy generation. In this study, the techno-economic and environmental assessment of a hybrid 1 kW solar photovoltaic (PV) plant (having battery backup) and a 3.5 kVA biogas fueled (BF) generator was investigated. The hybrid system was subjected to constant load conditions from 20% to 80% of the rated power conditioning unit (PCU), and energy shared by the combined systems was investigated. At lower loads, the photovoltaic system was sufficient to meet the demand. Whereas at higher loads, energy share from the biogas system was required for meeting the load demand. Economic analysis over a project lifetime of 25 years revealed a high positive net present value of $1562.15 with a Levelized cost of the energy value of $0.21/kWh for the hybrid system. A comparative financial analysis for the standalone solar photovoltaic system was also performed using the system advisor model (SAM). System advisor model analysis resulted in a positive net present value of $306.45 and a Levelized cost of the energy value of $0.15/kWh. The environmental analysis revealed net CO2 mitigation of 104.59 Tons, equivalent to an earned carbon credit of $2090.31 from the hybrid system.

Selective Synthesis of Bismuth or Bismuth Selenide Nanosheets from a Metal Organic Precursor: Investigation of their Catalytic Performance for Water Splitting.

The development of cost-effective, functional materials that can be efficiently used for sustainable energy generation is highly desirable. Herein, a new molecular precursor of bismuth (tris(selenobenzoato)bismuth(III), [Bi(SeOCPh)3]), has been used to prepare selectively Bi or Bi2Se3 nanosheets via a colloidal route by the judicious control of the reaction parameters. The Bi formation mechanism was investigated, and it was observed that the trioctylphosphine (TOP) plays a crucial role in the formation of Bi. Employing the vapor deposition method resulted in the formation of exclusively Bi2Se3 films at different temperatures. The synthesized nanomaterials and films were characterized by p-XRD, TEM, Raman, SEM, EDX, AFM, XPS, and UV–vis spectroscopy. A minimum sheet thickness of 3.6 nm (i.e., a thickness of 8–9 layers) was observed for bismuth, whereas a thickness of 4 nm (i.e., a thickness of 4 layers) was observed for Bi2Se3 nanosheets. XPS showed surface oxidation of both materials and indicated an uncapped surface of Bi, whereas Bi2Se3 had a capping layer of oleylamine, resulting in reduced surface oxidation. The potential of Bi and Bi2Se3 nanosheets was tested for overall water-splitting application. The OER and HER catalytic performances of Bi2Se3 indicate overpotentials of 385 mV at 10 mA cm–2 and 220 mV, with Tafel slopes of 122 and 178 mV dec–1, respectively. In comparison, Bi showed a much lower OER activity (506 mV at 10 mA cm–2) but a slightly better HER (214 mV at 10 mA cm–2) performance. Similarly, Bi2Se3 nanosheets were observed to exhibit cathodic photocurrent in photoelectrocatalytic activity, which indicated their p-type behavior.

Photoferroelectric perovskite solar cells: Principles, advances and insights

• The structure and property of ferroelectric perovskite are introduced to provide a knowledge for understanding the PPSCs. • Basic aspects of PPSCs are described including the device architecture, working principle and characterization. • The recent advances in PPSCs are discussed, focusing on oxide and halide perovskite materials. • Some strategies are envisioned for developing efficient PPSCs. This review mainly reported photoferroelectric materials including oxide and halide perovskites, and their recent advances in solar cells. The device architecture, working principle and characterization are described, and some strategies are envisioned for developing efficient photoferroelectric perovskite solar cells. Increasing environmental crises caused by exploring and using fossil fuels have compelled human being to develop innovative technologies to utilize renewable and sustainable energy sources. For this purpose, photovoltaic conversion of solar energy into electricity with solar cells is a promising and attracting way in that solar energy is clean and inexhaustible. Nowadays, the bottleneck in the application of solar cells on a large scale to sustainable energy generation still lies in lacking an efficient, stable and low-cost materials system for photon-to-electricity conversion. Perovskite materials are a class of materials widely applied in solar cells. Many evidences showed that the perovskite materials have both ferroelectric and photovoltaic properties, offering a special system called photoferroelectric materials. A built-in electric field established in these materials due to the ferroelectric property is more helpful for the separation of e-h pairs and enhancing the power conversion efficiency during photovoltaic process in solar cells. Here, we review the recent photoferroelectric perovskite solar cells (PPSCs). After giving a brief description of the structure and property of photoferroelectric perovskite materials, the device structures, working principles and characterization of PPSCs are introduced, followed by the state-of-the-art advances and the insights for the PPSCs based on oxide and halide perovskite materials. Finally, the main challenges in developing efficient PPSCs are discussed.

Enhancement of Low Voltage Ride Through Capability of Doubly Fed Induction Generator Based Wind Turbine Using Fuzzy Logic Controller

Combined impact of environmental issues and policies of utilities has led to generation of clean and sustainable energy. Solar and wind energies are prominent and can provide bulk amount of electrical energy. Vast number of resources and more electrical energy density are attractive features of wind energy. Generation of bulk amount of wind energy especially offshore wind energy is attracting utilities to incline towards wind energy. Variable speed wind energy conversion systems employing Doubly fed induction generators offers several advantages such as maximum power generation and independent control of active and reactive powers. Doubly fed induction generator-based wind energy system became the first choice of power system operators due to its low-cost power electronic convertors. Stringent grid codes adopted by various countries made Low voltage ride through a serious problem for electric utilities as well as DFIG manufacturers. Many researchers tried to address the problem of low voltage ride through. In initial stages, crowbar circuits were used. Later Low voltage ride through was addressed using additional hardware such as STATCOM. Artificial intelligent controllers were used to minimize the effect of ride through. A comprehensive review, of different issues allied with low voltage ride through of doubly fed induction generator-based wind energy conversion system is presented in this article.

A sustainable cross-efficiency DEA model for international MSW-to-biofuel supply chain design

Fossil fuels, as the primary source of the energy supply in today’s global society, are being depleted much faster than expected and are raising serious environmental and social concerns for contemporary societies. To deal with issues, a global movement towards the generation of sustainable renewable energy is underway. One of the most promising sources of renewable energy alternatives is the use of municipal solid waste, as a biomass source since it does not endanger food security and considerably the biomass made by municipal solid waste will enable the appropriate management of the waste and help cities to be sustainable. The supply chain of converting the municipal solid waste to bioenergy is a challenging issue that have attracted the attention of academic and industrial research. In this direction, a three-echelon mathematical model is developed to design MSW-to-biofuel supply chain network. This supply network is a global network; hence, the international supply chain-related issues and the disruption in the raw material supply have also been studied. Identifying appropriate potential locations to site facilities is a challenge faced in the municipal solid waste-to-biofuel supply chain models. To achieve goal, in this research, the use has been made of a proposed sustainable cross-efficiency DEA model which is an effective ranking method, especially for finding potential points. To deal with sustainability, the social and environmental indicators have also been presented in the form of some criteria in this DEA method. In addition, effort has been made to improve the ecological indicators of the supply chain design in line with the sustainable development as an objective function. Finally, in order to validate the proposed model, a case study with real data is presented.

Enhanced solar-light-driven photocatalytic and photoelectrochemical properties of zinc tungsten oxide nanorods anchored on bismuth tungsten oxide nanoflakes

At present, sustainable water supply and energy generation are the most important challenges faced by humankind globally. Thus, it is crucial to progress ecological techniques for sustainable removal of organic pollutants from wastewater and generation of hydrogen as an alternative to fossil fuels. In this study, zinc tungsten oxide (ZnWO4) nanorods, bismuth tungsten oxide (Bi2WO6) nanoflakes, and Bi2WO6/ZnWO4 (BO–ZO) nanocomposites were prepared via a simple hydrothermal approach. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, diffuse reflectance spectroscopy, and electrochemical analyses were conducted to confirm the formation of the BO–ZO heterostructure. The structural and morphological analyses revealed that the ZnWO4 nanorods were moderately dispersed on the Bi2WO6 nanoflakes. The bandgap tuning of BO–ZO nanocomposite confirmed the establishment of the heterostructure with band bending properties. The BO–ZO nanocomposite could degrade 99.52% of methylene blue (MB) within 60 min upon solar-light illumination. The photoelectrochemical (PEC) measurement results showed that the BO–ZO nanocomposite showed low charge-transfer resistance and high photocurrent response with good stability. The BO–ZO photoanode showed a low charge-transfer resistance of 35.33 Ω and high photocurrent density of 0.1779 mA/cm2 in comparison with Ag/AgCl in a 0.1 M Na2SO3 electrolyte under solar-light illumination. The MB photocatalytic degradation and PEC water oxidation mechanisms of the nanocomposite were investigated.

Use of DEMATEL and COPRAS method to select best alternative fuel for control of impact of greenhouse gas emissions

Generation of energy is a vital process for sustenance of human life. Quality of human life is undoubtedly linked to the efficient generation and use of energy. The choice of alternative fuels is of the utmost significance due to the decline of fossil fuel reserves and their effect on global warming. One of the most important areas of research all over the world is the generation and distribution of sustainable energy. There are, in fact, many sustainable fuel resources. In this study, we describe the problem of selecting alternate fuel using novel types of hesitant multi criteria decision-making equation methods. The considered fuel systems are Electricity, natural gas, biodiesel, ethanol, and propane. In the selection of alternative fuels, quantity, quality of performance, cost, and efficiency among others, have to be taken into account. The alternatives selected should, for example, increase the speed of buses, and provide for greater mileage while and not affecting the environment. Here, the DEMATEL (Decision Making Trial and Evaluation Laboratory Model) method is used to determine the weights of the criteria and the COPRAS (Complex Proportional Assessment) method is used to calculate the ranking of the alternatives. The main objective of this research paper is to select the best alternative, based on environmental safety, CO2 emission level, technical cost, and fuel cost. Thus a better alternative is selected with the selected alternatives and criteria. The results of this research are summarized as follows. These are natural gas ( R2 ) > propane ( R5 ) > biodiesel ( R3 ) > electricity ( R1 ) > ethanol (R4 ). The numeric values of these selected alternatives are R2=1>R5=0.5215>R3=0.4904>R1=0.4887>R4=0.3299.