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The diesel engine process including fuel injection, fuel spray, air and fuel mixing, ignition and combustion which influences its performance and emission characteristics. The fuel injection and fuel spray are important process as they are directly related to the quality of fuel which results into fluctuating the ignition and combustion characteristics. Ignition in a diesel engine occurs at the edge of the spray depending on the in-cylinder pressure and temperature. Experiments were conducted on a modified dual-fuel diesel engine (3.5 kW power) with fuel additives, diesel and hydrogen (gaseous fuel) at a stable speed of 1500 rpm. Spray behavior and ignition delay were analyzed to determine the impact of fuel additives in neat diesel combined with hydrogen. Additionally, for dual-fuel Cases, the ignition delay correlations provided for diesel engines have been modified as per the experimental results. The injection velocity was maximized with a 15–25% hydrogen substitution range because the fuel density was reduced to a minimum, but it was decreased with the addition of fuel additives. The SMD for hydrogen with neat diesel and diesel with fuel additives both increased up to 20% hydrogen substitution, whereas for higher hydrogen substitution, the Sauter mean diameter decreased. It was found that the addition of fuel additives in diesel resulted into an increased fuel injection velocity (3.3%) with reduced sauter mean diameter of 3.4% while with the lower substitution of H 2 (15%), a maximum increment of 32% in the injection velocity was seen as compared with neat diesel operation. With 15% hydrogen substitution, the change in pressure and density of diesel along with fuel additives accommodated the optimum spray penetration equivalent to neat diesel. In all Cases of hydrogen substitution, the experimental and theoretical values obtained for the chemical ignition delay were found to be consistent with one another except for 35% H 2 showing a maximum deviation of 0.2%. • Addition of fuel additives with higher hydrogen reduced the chemical delay. • TID reduced up to 25% hydrogen, increased with higher hydrogen substitution. • Injection velocity was found optimum in the range of 15–25% hydrogen substitution. • Spray penetration and sauter diameter increased up to 20% hydrogen substitution. [ABSTRACT FROM AUTHOR]

The present study is focused on the combustion behavior, performance and emissions of a modified diesel engine working on dual fuel mode with hydrogen as a gaseous fuel by the inclusion of tri-ethylene glycol mono methyl ether and alumina nanoparticles as fuel additives. The inclusion of tri-ethylene glycol mono methyl ether, alumina and hydrogen separately and simultaneously improved the net heat release with reduced cylinder pressure at high loads as compared with neat diesel. The brake thermal efficiency increased by 22.5% and 11.6% by the inclusion of tri-ethylene glycol mono methyl ether and hydrogen respectively at 50% load, when combined together, it was improved remarkably by 28.15%. The addition of alumina was responsible for a slight reduction in NO x formation at all loads, while it was incremented by hydrogen enrichment at the highest load as compared to pure diesel. The CO formation was incremented by the addition of alumina, while the CO 2 and HC formations were reduced up to 50% load, increased at 70% load. The CO, CO 2 , HC and smoke opacity were reduced with TGME and hydrogen enrichment, while the NO x formation was reduced up to 50% load, then increased at the higher load. • The H 2 enrichment incremented NHR by 21.7% at 356°CA. • A minimum ID of 11°CA was observed in case of D + TGME @5%. • BTE increased by 28.15% at a load of 50% for D + TGME @5% +H 2@35%. • For D + TGME @5% , combustion efficiency improved by 10.4%. • The HC formation was reduced by 21.8% for D + TGME @5% at 50% load. [ABSTRACT FROM AUTHOR]

The utilization of hydrogen as a gaseous fuel in CI engines in dual fuel mode, has gained significant interest due to its clean-burning nature, high energy share, and higher availability in nature. In this experimental study, hydrogen was used as a secondary fuel along with tri-ethylene glycol mono methyl ether (TGME) as a fuel additive in diesel to investigate the effects on the engine performances and emissions using a modified duel fuel diesel engine (power of 3.5 kW at 1500 rpm). It revealed that addition of hydrogen (30–35%) enhanced the brake thermal efficiency of the engine at each load conditions, but in accordance it also reduces with the lower hydrogen (15–25%). Reduction in oxides of nitrogen was observed with the hydrogen insertion up to 50% load while carbon mono oxide, carbon dioxide and un-burnt hydrocarbon were significantly reduced at entire load conditions. Further, the addition of fuel additive (TGME) enhanced the brake thermal efficiency at each loads. A reduced ignition delay was also observed by the inclusion of TGME and hydrogen due to pre-ignition of the fresh charge. Moreover, this study concluded that addition of 1% fuel additive in diesel with 25% of hydrogen at 30% load, performance and emissions were optimum. • Addition of TGME with higher H 2 enhanced the BTE at entire loads. • NO x reduced up to 50% loads with TGME, increased at highest load. • CO and HC emission at all loads reduced with 5% TGME and 35% H 2. • Use of 1% TGME with 25% H 2 at all loads, BTE and emissions were optimum. [ABSTRACT FROM AUTHOR]

The population explosion and rapid economic development has led to tremendous increase in the per capita use of fossil fuel energy resulting in major environmental consequences. To tackle these significant energy and environmental concerns, semiconductor photocatalysis is viewed as a promising environmentally friendly and sustainable solution. The photocatalytic hydrogen evolution utilizes solar energy into clean hydrogen energy which makes it green, environmentally friendly and effective technique to meet energy demands. This process requires workable catalysts to reach a significant reaction rate because of their multiple electrons and multiple proton nature. Among various visible light active photocatalytic materials, metal molybdates have been reported as emerging class of materials owing to their outstanding features as stable crystal structure, photo-corrosion inhibition, high redox efficiency, low cost and toxicity and suitable band structure. The present research provides an extensive review of the most recent advances and new insights into the utilization of metal molybdates in photocatalytic clean energy production and environment challenges. This review article summarizes the recent progresses in advanced strategies applied in metal molybdate based photocatalysts to enhance the photocatalytic performance. The advanced strategies are categorized as control over morphology and surface modification, doping of heteroatom, co-catalyst loading, noble metal deposition and construction of heterojunction, which are devoted to photocatalytic H 2 production and CO 2 reduction and to overcome the fast recombination of charge carriers and increasing the light absorption capacity. The fabrication strategies of metal molybdates and based materials are discussed in detail, as well as their usage as catalysts for H 2 evolution and CO 2 reduction have been analysed. Metal molybdates are promising photocatalysts for addressing present environmental issues, and this work paves the way for future photocatalytic research and development, which may assist in the development of highly effective photocatalysts for sustainable energy needs. [Display omitted] • Metal molybdates as photocatalysts-Structure and properties. • Introduced the synthetic routes: Effect on properties and photocatalytic performance. • Discussed strategies to improve the photocatalytic potential of metal molybdates. • Application for superior hydrogen evolution and CO 2 conversion-Recent advances. • Fundamentals and bottlenecks along with future prospects are discussed. [ABSTRACT FROM AUTHOR]

Fast depleting fossil fuel and its associated negative impacts on environment and climate change raising concern over clean fuel and sustainability. Thus, in line scientific community are thinking to have alternative fuels like hydrogen, natural gas, syngas, and biofuels. Furthermore, hydrogen gas is superior among alternative fuels due to its renewable nature, zero emissions, and generate large content of energy during combustion. Researcher cites on various biological methods like bio photolysis of water, dark fermentation, photo-fermentation, and microbial electrolysis cell. However, biohydrogen production from wastewater as substrate is becoming popular due to less energy intensive and sustainable way to fulfil the future energy demands. With rapid increase in industrialization and urbanization will further increase wastewater generation globally. Hence, wastewaters could have huge potential for the green hydrogen production which ultimately provides clean energy, and the low-cost wastewater treatment. Literature reveals that wastewater from various industries like citric acid, cheese whey, paper mill, rice mill, beverage, cassava starch processing, palm oil, starch processing, pharmaceutical, food processing, distillery, and sugar industry have been utilized for biohydrogen production. Hence, the present review is focused on various wastewaters based green hydrogen production which have overall positive impacts on social, economic, and environment for the future generation. [ABSTRACT FROM AUTHOR]

Green hydrogen, a carbon-neutral fuel, has the potential to reduce atmospheric greenhouse gas and plays a vital role in mitigating climate change. Its potential is immense in renewable-rich Asian economies, however, its production is yet to start with key factors such as safety parameters, resources, proper government incentives, and public acceptability affecting its optimal generation. This study employs three multi-criteria decision-making approach like analytic hierarchy process (AHP), decision-making trial and evaluation laboratory (DEMATEL), and Fuzzy-AHP followed by the sensitivity analysis to identify and prioritize the robustness of the five primary potentials (social, political, economic, technical, and environmental). Subsequently, categorized into 22 sub-potentials of green hydrogen and ideal renewable resource for the sustainable development objective of India. The results of the DEMATEL analysis suggest that the social is the key predictor and the last one is Technical. The Fuzzy-TOPSIS method suggests that solar is the best renewable energy resource followed by wind, small hydro, and biomass energy. Hence, the government's intervention and robust policy frameworks are required to increase its production with special emphasis on cost considering solar energy. The finding of this study will guide the governments, energy sector players, producers, environmental advocacy groups, and users to make a strategic decision regarding the choice of the most viable source of renewable energy to achieve the targets of sustainable development Goals (SDGs-7). • Potentials for Green Hydrogen (GH) in India. • Source of Renewable energy for Green Hydrogen production. • Integrated framework for prioritizing the GH potentials. [ABSTRACT FROM AUTHOR]

Electrolytic hydrogen produced from wind and solar energy is considered a long-term option for multi-sectoral decarbonization. The study objective is to develop a framework for assessing country-level hydrogen technical potential from wind and solar energy. We apply locational suitability and zonal statistical analyses methods in a geographic information system-based environment to derive granular insights on non-captive technically exploitable hydrogen potential in high-resource locations. Seven setback factors were considered for locational suitability, and integrated with modules developed for evaluating the wind and solar resource penetration from open-source theoretical renewable resource geospatial data and electricity-to-hydrogen conversion analyses. The technique applied in this study would be a relevant contribution to determining national and regional-wide electrolytic hydrogen production potentials in other jurisdictions with requisite adjustments to data and technical constraints. The results from the case study country, Canada – a major hydrogen-producing country – show that the technical hydrogen potentials from wind and solar energy are approximately 1,897 and 448 million metric tonnes per year, respectively, at least 6.3 times greater than global hydrogen demand in 2019. When we integrated locational data on enabling infrastructure, we discovered that the lack of access to power transmission lines in low-population-density areas of the country significantly reduces the exploitable wind- and solar-based hydrogen potential by over 80% and 6%, respectively. The findings of this study show that in the absence of spatial data on infrastructural constraints, the exploitable hydrogen potential in a jurisdiction can be overestimated, leading to improper guidance for policy and decision-makers. • A framework is developed to determine the H 2 technical potential from solar and wind. • The framework combines locational suitability and zonal statistical analysis in GIS. • A case study analysis was conducted for Canada. • Solar- and wind-based H 2 technical potential is 448 and 1898 Mt/year, respectively. • Low access to enabling infrastructure limits the exploitable potential by over 26%. [ABSTRACT FROM AUTHOR]

The worldwide energy demand is steadily increasing and estimated to be doubled by the year 2050 due to a continuous hike in economies and population. A large part of the global energy requirement procures using traditional energy sources such as fossil fuels, which are non-renewable. Also, their excessive consumption imparts negative impacts on the environment by CO 2 , and CO emissions, which constantly increase the average global temperature. Therefore, the need for a more reliable, sustainable, inexpensive, renewable and environmentally-friendly form of energy is imperative. From these perspectives, hydrogen energy is emerging as one of the most promising alternatives to overcome rising energy demand with a zero-carbon footprint. Herein, various layered double hydroxides (LDH) nanocomposite owing to their attractive physicochemical properties and synergistic effect with other materials in the field of hydrogen production are reviewed. Why the class of LDHs materials is critical and their ideographic properties which make them promising materials in the field of water splitting via photocatalysis and electrocatalysis are also discussed. The synthetic methods of LDHs based nanocomposites fabrication are summarized. Various challenges and strategies from the viewpoint of a different method of hydrogen production through LDHs are reported. Additionally, multiple techniques like surface plasmon resonance (SPR), heterojunction formation, and doping with co-catalyst to increase the efficiency for photocatalytic hydrogen production are also presented. Hopefully, this review will help the readers explore highly efficient, inexpensive and stable LDH catalysts toward photocatalytic water splitting. • Current issues related with energy requirements and green energy sources. • Recent advancements in LDH based electrocatalysts and photocatalysts for water splitting. • Challenges in conventional photocatalysts based water splitting. • Strategies to enhance photocatalytic hydrogen evolution and oxygen evolution reactions. [ABSTRACT FROM AUTHOR]