Eco-friendly Energy Resources Research Articles

Challenges and innovative strategies related to synthesis and electrocatalytic/energy storage applications of metal sulfides and its derivatives

Energy is one the most fundamental necessities in daily life which is fulfilled from non-renewable and non-ecofriendly resources that are not only expensive in terms of costs but also depleting with time and causingenvironmental pollution. The quest for the renewable, eco-friendly and economic energy resources is in progression tomitigate the energy demands. In this context, cogent energy alternatives are under investigations to develop innovative strategies based on renewable, affordable and widely available resources. In these perspectives, Metal Sulfides (MS) and their derivatives are sensible, operative and eco-friendly electrocatalysts with ultramodern physiognomies because of extensive durability, porous topography, high surface area, extensive varieties, cost effectiveness, simplicity and chemical functionality. Various synthetic strategies such as hydrothermal, solvothermal and other miscellaneous techniques have been followed to design metal sulfides and their derivatives of countless compositions. The synthesized metal sulfides and their derivatives are favored for electrocatalytic solicitations with characteristic synergetic and plasmonic effects in order to explorehydrogen evolutionreaction (HER), oxygen evolution reaction (OER), overall water splitting (OWS), carbon dioxide reduction ( CO 2 RR ), and super capacitance. Appraising these synthetic strategies and electrocatalytic features, metal sulfides could be influential to attempt new, renewable and eco-friendly energy resources.

Deceleration of the development of city gas connections amidst the covid-19 pandemic in the metropolitan area

The National Energy Policy captured the basis for renewable energy development in Indonesia and also specified a national target for the optimal energy mix. For these fundamental reasons, several unprecedented strategies, blueprints, and collaborations are to be explored in the long term. Apparently, one of the key objectives was to exploit natural gas as the primary and eco-friendly energy resource. This profitable gas was projected to significantly contribute a minimum of 22% of total energy toward enhancing economic growth. Approximately, 10 million city gas connections are required by 2025, in order to achieve the set goals. However, a gap exists between the initially planned city gas connections to the distribution network, and the realization during the Covid-19 pandemic in 2020. This global phenomenon poses a challenge to virtually all economic segments, including energy, as the demand plummeted drastically. Based on Indonesia’s National Energy Policy, the first proposed target was to develop 266,070 gas connections. The project was subsequently adjusted to 127,864. Surprisingly, the realization surpassed the new arrangement by over 6% or was about 135,286. However, the figures obviously comprehended 50.84% of the projects were stalled, contrary to the vision of constructing a minimum of 10 million city gas pipe connections in 2025. This study provided a profound description of the impact of the reduction in abovementioned development on the expected outcome, using the multivariable regression method. The results revealed 96.92% of data from the applied variables were able to describe the developed linear model.

Outstanding Thermoelectric Performance of MCu3X4 (M = V, Nb, Ta; X = S, Se, Te) with Unaffected Band Degeneracy under Pressure

The demand for green energy increases day by day due to environmental concern and thermoelectric (TE) materials are one of the eco-friendly energy resources. Few authors reported high TE performance in TmCu$_3$Ch$_4$, reaching the figure of merit (ZT) above 2 at 1000K, from first-principles calculations neglecting electron-phonon scattering, spin-orbit coupling effect (SOC), and energy-dependent carrier lifetime. Here, thermoelectric transport properties of TmCu$_3$Ch$_4$ are reinvestigated through considering these parameters, and significant discrepancies are found. The ZT of p-type TaCu$_3$Te$_4$ can reach ~3 at 1000K among these compounds due to its low lattice thermal conductivity ($\kappa_l$) (0.38 W m-1 K-1). Interestingly, the value of $\kappa_l$ is reduced to 0.17 W m-1 K-1 through 1 GPa pressure while the power factor is slightly improved due to bandgap reduction, leading to an extraordinary ZT~5.5 at 1000K. Although the substitution of Se causes a slight reduction of $\kappa_l$ to ~0.3 W m-1 K-1, the power factor is reduced significantly due to the dramatic reduction of DOS near Fermi level, which leads to lower the Seebeck coefficient largely and increase electrical conductivity slightly.

DETERMINANTS OF GREENHOUSE GAS EMISSIONS REVISITED: A GLOBAL PERSPECTIVE

This study examines the determinants of emissions for a global sample of 120 countries during the 1995–2012 period using panel data analysis. Specifically, an extended version of the STIRPAT model combined with the EKC was employed to examine the determinants of emissions for the full sample and three subsamples of countries at different income levels. Three proxies for emissions are used, including CO2, N2O and CH4 emissions. The two-step generalized method of moments (GMM) is employed as the estimation technique. The empirical results indicate the evidence of EKC for the global sample and all subgroups of countries for CO2 emissions. On the other hand, U-shaped relationships between income and emissions are found for all three subsamples in the cases of N2O and CH4 emissions. Energy intensity appears to be the major driver of CO2 emissions for all groups of countries as well as for N2O and CH4 emissions for high-income and upper-middle-income countries. The effects of industrialization and urbanization vary across different types of emissions and different income country groups. The global environmental policy should focus on encouraging energy efficiency, enhancing the use of eco-friendly energy resources, as well as incorporating the impacts of industrialization and urbanization on emissions.

ANALYSIS AND OPTIMIZATION OF VAPOR ABSORPTION GENERATOR-HEAT EXCHANGER USING KERN METHOD AND CFD

The growing demand for new and eco-friendly energy resources has raised the need of sustainable sources or renewable energy for use in present era. A vapor absorption refrigeration system (VARS or VAS) is a closed loop refrigeration system which requires low heat for its functioning and, it is therefore, considered an eco-friendly solution. Since, generator is the main component of VAS which can significantly influence the efficacy of overall system, the current paper involves modeling and thermal analysis of generator using Computational Fluid Dynamics (CFD). The objective of this study is to optimize the heat transfer by changing baffle spacing of generator heat exchanger, running on a single effect LiBr/ water absorption cycle. For this purpose, hot water driven generator of 1ton capacity is taken. The simulation results of CFD were validated by comparing them with theoretical results. The overall design estimation and design technique that follows Birmingham Wire Gauge (BWG) and Tubular Exchangers Manufacturers Association (TEMA) standard are considered in this study. It was found from the analysis that the design model with smallest baffle spacing has the highest heat transfer coefficient. On reducing the baffle spacing from 137mm to 101mm, an increment of 48% in overall heat transfer coefficient was observed. Likewise, an increase in velocity by 36% and drop in static pressure by 27% were seen. Similar trend was observed in the theoretical results.

Energy Priority Estimation Model for Quantitative Analysis of Potential Bioethanol Feedstock

Conventional energy sources depletion, energy insecurity, fluctuating petroleum prices and global climate change have driven countries worldwide to consider alternative and renewable energy options. The use of biofuel such as bioethanol is as an option over conventional petroleum and important for the development of sustainable and eco-friendly energy resources. However, bioethanol manufactured from various biomass resources is different in terms of its processing stages and the need for extra pre-treatments. This study aims to suggest the most feasible biomass resource for bioethanol generation by using Analytical Hierarchy Process (AHP), one of the multi-criteria decision-making methods based on priority estimation model. Among biomass resources, the issue of selecting the most feasible resource is evaluated, using numerous criteria influencing the biomass selection which are chosen through Focus Group Discussion (FGD) with experts in the biomass research field. Out of the five selected biomass resources, sugarcane is preferable as a bioethanol feedstock with an overall priority of 31.69%, followed by palm oil residues (overall priority= 23.51%), compared to corn (overall priority= 22.59%), rice straws (overall priority= 13.53%) and sugar beet (overall priority= 8.67%). Sugarcane is claimed to be the most feasible bioethanol feedstock due to its high availability over years, high energy ratio, high cellulose and hemicellulose content. Although sugarcane takes a longer time to grow, it is easier to be planted and harvested with the help of developed machineries. However, an ideal bioethanol-producing feedstock should not be food crops. Thus, as a suggestion for future research, more factors to determine the potential and suitability of the crops should be considered.

Improvement of photobiological hydrogen production by suspended and immobilized cells of the N2-fixing cyanobacterium Fischerella muscicola TISTR 8215

To develop H2 photoproduction by using the N2-fixing cyanobacterium Fischerella muscicola TISTR 8215, a novel strain isolated from soil in Thailand, the factors affecting H2 production were investigated in this study. Enhanced H2 production in suspension culture was obtained when adapting the cells under N2-fixing condition (modified AA medium) with continuous illumination of 250 μmol photons m−2 s−1 under aerobic condition for 24 h, followed by further incubation under anaerobic condition for 9 h for production phase. The maximum H2 production rate was 38.5 μmol mg−1 chl a h−1. Low concentration of Fe2+ and Mo6+, essential elements for nitrogenase, enhanced H2 production. The enhanced H2 production was accompanied by the upregulation of nifD. On the other hand, an increased hupL transcript level was observed when there was a decrease of H2 production. In cells immobilization, 1.5% (w/v) agar-immobilized cells had a 23-fold increase in maximum H2 yield compared with that using free cell suspension at the same cell concentration, i.e., 7.48 mmol H2 L−1 by immobilized cells and 0.32 mmol H2 L−1 by suspended cells. Moreover, cell immobilization in agar could prolong H2 production up to 108 h. This study underlines the strategies toward enhanced and sustained H2 production from cyanobacteria. Furthermore, it will pave the way for large-scale production of biohydrogen to be used as an eco-friendly energy resource.

Factors affecting the stability of perovskite solar cells: a comprehensive review

Accelerated depletion of fossil fuel, energy demands, and pollution force us to choose renewable and eco-friendly energy resources. Solar cells are considered as an efficient replacement for fossil fuel. In the family of solar cells, silicon-based solar cells and perovskite solar cells (PSC) have displayed significant power conversion efficiency (PCE). Perovskites have been investigated extensively over the past two decades, due to their advantageous properties, such as high absorption coefficient, efficient carrier mobility, long charge diffusion length, and direct bandgap. These features make PSC a prospective candidate to replace silicon in solar cells. By 2018, PSC achieved an encouraging PCE of 23.3%. However, low stability and toxicity have retarded the commercialization of PSC. With the aim of assisting junior researchers, we consider the latest achievements in this domain and review the field from a stability and performance perspective. We emphasize recent developments and methodologies to overcome drawbacks concerning stability and toxicity.

Quantitative priority estimation model for evaluation of various non-edible plant oils as potential biodiesel feedstock

Energy security, fluctuating petroleum prices, resource depletion issues and global climate change have driven countries to consider adding alternative and renewable energy options to their conventional energy share. The use of biofuel such as non-edible oils-based biodiesel is as an option over conventional diesel and could be important for the development of a sustainable and eco-friendly energy resource. The aim of the present study was to select the most feasible non-edible plant oil as biodiesel feedstock by using Analytic Hierarchy Process (AHP), one of the multi-criteria decision making methods based on priority estimation model. Among various non-edible plant oils which are widely available in the South-East-Asian region, selection of the most feasible plant oil was evaluated based on seven criteria; seed oil yield, oil yield, free fatty acid (FFA) content, cold filter plugging point, oxidation stability, easiness to grow in marginal land, and availability in tropical areas. The obtained results from priority determination showed that nyamplung was the most efficient feedstock of biodiesel for the industry with the criteria weightage of 0.180. It was followed by kemiri sunan (2 nd order) having weightage of 0.164, physic nut 0.150 (3 rd order), indian beech 0.107(4 th order), indian milkweed 0.095(5 th order), lead 0.092 (6 th order), kapok 0.076 (7 th order), cassia 0.049 (8 th order), soursop 0.043 (9 th order) and monkey pod 0.043 (10 th order). This study highlights an insight into multi-criteria decision making technique to assess the feasible plant oil for biodiesel production that could aid decision-making in the industry and policy development, particularly for the South-East-Asian region.

Design approach of a density-driven solar water heater system

Energy conservation continues to play a crucial role in social and economic development. With the remarkable increase in oil prices and exploring solutions for the replacement of fossil fuels, an ecofriendly energy resource has become the priority among more and more people. Keeping the intension for reducing the global warming impact and looking for alternative clean source of energy, solar energy applications such as solar thermal systems, solar water heating and cooling are becoming energy-efficient designs. One of the widely used applications of solar energy is solar water heating systems. Low-cost solar water heaters can cover the domestic needs for water in the range of 100–200 l per day. Solar water heating systems are generally more efficient and advantageous in hot areas. However, the application of solar water heating is still a challenge in winter and sub-zero conditions, having low solar irradiance. In such conditions, solar water heating system cannot produce enough energy, which drives a need for evaluating system component design and improves its performance during low ambient conditions. In this study, detailed design methods for solar water heater components are discussed for cold regions like North Dakota, USA. The type of system chosen in this study is natural circulation-based solar water heating system. The study will also compare the experimental data with previously conducted numerical analysis.

Self-assembled dopamine nanolayers wrapped carbon nanotubes as carbon-carbon bi-functional nanocatalyst for highly efficient oxygen reduction reaction and antiviral drug monitoring

Oxygen reduction reaction (ORR) catalysts are the heart of eco-friendly energy resources particularly low temperature fuel cells. Although valuable efforts have been devoted to synthesize high performance catalysts for ORR, considerable challenges are extremely desirable in the development of energy technologies. Herein, we report a simple self-polymerization method to build a thin film of dopamine along the tubular nanostructures of multi-walled carbon nanotubes (CNT) in a weak alkaline solution. The dopamine@CNT hybrid (denoted as DA@CNT) reveals an enhanced electrocatalytic activity towards ORR with highly positive onset potential and cathodic current as a result of their outstanding features of longitudinal mesoporous structure, high surface area, and ornamentation of DA layers with nitrogen moieties, which enable fast electron transport and fully exposed electroactive sites. Impressively, the as-obtained hybrid afford remarkable electrochemical durability for prolonged test time of 60,000 s compared to benchmark Pt/C (20 wt%) catalyst. Furthermore, the developed DA@CNT electrode was successfully applied to access the quality of antiviral drug named Valacyclovir (VCR). The DA@CNT electrode shows enhanced sensing performance in terms of large linear range (3–75 nM), low limit of detection (2.55 nM) than CNT based electrode, indicating the effectiveness of the DA coating. Interestingly, the synergetic effect of nanostructured DA and CNT can significantly boost the electronic configuration and exposure level of active species for ORR and biomolecule recognition. Therefore, the existing carbon-based porous electrocatalyst may find numerous translational applications as attractive alternative to noble metals in polymer electrolyte membrane fuel cells and quality control assessment of pharmaceutical and therapeutic drugs.

Renewables, Shale Gas and Gas Import- Striking a Balance for India

India's primary energy basket is heavily weight in favour of coal, oil and gas (92%) and balance 8% renewables, hydro and nuclear. The eco-friendly energy resources like natural gas and renewables (wind & solar) account only for 9% and 2%. The long term energy demand forecast also suggests contribution of coal, oil and gas to slide down to 87%. The Natural gas demand though on increase but the consumption is constrained due to limited domestic production and inadequacy of LNG import facilities. Considering the huge import bill on oil, gas and coal imports ($150 billion, Kelkar 2013) and the ever increasing concern for environment, the eco-friendly non-conventional resources as shale gas are getting preference. This paper examines the potential contribution from Shale Gas to meet the energy demand to fuel the economic growth of India

ENGLISH

Electrical energy is provided worldwide by cable or overhead transmission lines. However, power systems are still needed to locations which are isolated or far from electrical energy suppliers. Renewable energy resources in micro-grid power systems are interesting topics of recent research as environmental pollution and scarcity of energy resources come to the fore. Moreover, power systems which have renewable sources of energy are becoming popular need of green energy. A micro-grid electricity power system on a local scale usually using renewable source of energy satisfies both problem of isolation and power quality, benefits not available from conventional utility grid system, but also serves a customer with multiple load locations.In this present situation the development of intelligent system that integrate Eco-friendly energy resources such as wind, photovoltaic system, and fuel cell for green energy and cost effectiveness under different environment condition.

Oxidative Stress Is a Mediator for Increased Lipid Accumulation in a Newly Isolated Dunaliella salina Strain

Green algae offer sustainable, clean and eco-friendly energy resource. However, production efficiency needs to be improved. Increasing cellular lipid levels by nitrogen depletion is one of the most studied strategies. Despite this, the underlying physiological and biochemical mechanisms of this response have not been well defined. Algae species adapted to hypersaline conditions can be cultivated in salty waters which are not useful for agriculture or consumption. Due to their inherent extreme cultivation conditions, use of hypersaline algae species is better suited for avoiding culture contamination issues. In this study, we identified a new halophilic Dunaliella salina strain by using 18S ribosomal RNA gene sequencing. We found that growth and biomass productivities of this strain were directly related to nitrogen levels, as the highest biomass concentration under 0.05 mM or 5 mM nitrogen regimes were 495 mg/l and 1409 mg/l, respectively. We also confirmed that nitrogen limitation increased cellular lipid content up to 35% under 0.05 mM nitrogen concentration. In order to gain insight into the mechanisms of this phenomenon, we applied fluorometric, flow cytometric and spectrophotometric methods to measure oxidative stress and enzymatic defence mechanisms. Under nitrogen depleted cultivation conditions, we observed increased lipid peroxidation by measuring an important oxidative stress marker, malondialdehyde and enhanced activation of catalase, ascorbate peroxidase and superoxide dismutase antioxidant enzymes. These observations indicated that oxidative stress is accompanied by increased lipid content in the green alga. In addition, we also showed that at optimum cultivation conditions, inducing oxidative stress by application of exogenous H2O2 leads to increased cellular lipid content up to 44% when compared with non-treated control groups. Our results support that oxidative stress and lipid overproduction are linked. Importantly, these results also suggest that oxidative stress mediates lipid accumulation. Understanding such relationships may provide guidance for efficient production of algal biodiesels.

Characterization of Photoelectrochemical Properties of SiC as a Water Splitting Material

Hydrogen energy attracts attention as an eco-friendly energy resource. The water splitting by semiconductor materials can generate hydrogen without CO2 emission. However, the hydrogen conversion efficiency using conventional materials is not high enough, or the materials corrode easily even if they show high efficiency. On the other hand, silicon carbide (SiC) is expected to be a water splitting material showing high conversion efficiency without corrosion. In this study, we characterized band edge potentials for 4H-, 6H- and 3C-SiC, and we revealed that they are capable of water splitting. We also estimated conversion efficiencies by photocurrent measurements in electrolytes for bulk 4H- and 6H-SiC.