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The first part of the current review highlights the evolutionary nuances and research hotspots in the field of nanoparticles in low carbon fuels. Our findings reveal that contribution to the field is largely driven by researchers from Asia, mainly India. Of the three biofuels under review, biodiesel seems to be well studied and developed, whereas studies regarding vegetable oils and alcohols remain relatively scarce. The second part also reviews the application of nanoparticles in biodiesel/vegetable oil/alcohol-based fuels holistically, emphasizing fuel properties and engine characteristics. The current review reveals that the overall characteristics of the low carbon fuel–diesel blends improve under the influence of nanoparticles during combustion in diesel engines. The most important aspect of nanoparticles is that they act as an oxygen buffer that provides additional oxygen molecules in the combustion chamber, promoting complete combustion and lowering unburnt emissions. Moreover, the nanoparticles used for these purposes exhibit excellent catalytic behaviour as a result of their high surface area-to-volume ratio—this leads to a reduction in exhaust pollutants and ensures an efficient and complete combustion. Beyond energy-based indicators, the exergy, economic, environmental, and sustainability aspects of the blends in diesel engines are discussed. It is observed that the performance of the diesel engine fuelled with low carbon fuels according to the second law of efficiency improves under the influence of the nano-additives. Our final part shows that despite the benefits of nanoparticles, humans and animals are under serious threats from the highly toxic nature of nanoparticles. [ABSTRACT FROM AUTHOR]

[Display omitted] • Presence of volatile impurities in sample A resulted in initial degradation at 348 °C. • DAP3 fuel exhibits a higher HRR compared to DAP1 and DAP2 fuels. • DAP3 resulted in an average reduction of ∼17.14% and 21.86% in CO and smoke. • DAP2 fuels emitted lower NOx than DAP1 due to slower oxidation reactions. • DAP1 and DAP2 showed large accumulation and coarse soot in the PM 10 form at ∼83 nm. Most research into the treats of plastic wastes have concentrated mainly on single-exposure pathways or products. These practices fail to acknowledge that the complications of carbon particles from engines are produced not only by diesel but by any plastic oils due to the vast amount of contaminants. With the potential to significantly weaken the impact of contaminants, the present study investigates the effects of dehalogenation and catalytic pyrolysis on plastic waste, as well as the risks associated with plastic oil blends on diesel engine. Different types of washing were conducted to effectively dehalogenate plastic waste. After pretreatment, odor compounds were analyzed using GC–MS. Subsequently, various types of pretreated plastic samples underwent catalytic pyrolysis with a 5:1 ratio of HDPE to Al 2 O 3 ·2SiO 2 ·2H 2 O. Differences in physico-chemical properties and hydrocarbon compounds of oils were determined. Experiments were performed using different fuel blends in a diesel engine under steady-state conditions, and their effects on combustion, emissions, morphology, and size particles were analyzed. The results show that sample B exhibited a lower toxicity level of 1,3-butadiene compared to other samples, while acetone and terpenes represented the second and third-highest emission levels in flakes, respectively. Sample C started to degrade at low temperatures (<300 °C) due to carbon addition from ethyl acetate solvent into the tertiary carbon chain of the flakes. DAP3 fuel achieved a higher reaction due to its degree of unsaturation and lower viscosity, resulting in the formation of smaller fuel droplets at high injection pressure and heat release rate (HRR). Higher emission levels were observed by DAP1 and D100, exceeding the Euro 5/6 standard limits. However, DAP3 fuel resulted in an average reduction of ∼17.14% and 21.86% in CO and smoke emissions, respectively, accompanied by a slight decrease in NOx and HC levels. Conversely, there were inconsistencies in the emission results observed with DAP2. Compared to D100, both DAP1 and DAP2 exhibited a significant accumulation and coarse particles in the PM 10 forms at a peak of ∼83 nm. Whereas the DAP3 showed a smaller mobility Dp with a low nucleation particle peak, which was prone to absorb the unburned HC soot and later change to accumulation mode particles. [ABSTRACT FROM AUTHOR]

[Display omitted] • HC and CO emissions decreases for Hy60 fuels, and increasing NOx with Hy40 fuels. • EC-soot slightly decrease compared to OC at all test fuels. • PAHs and n-alkanes turned out to be more less at higher nanoparticles concentrations. • In-cylinder pressure and HRR improve by 60 ppm hybrid nanoparticles. Due to little industrial use of plastic waste recycling, over 200 million tons are thrown in landfills and more than 15 million tons end up in the ocean every year. This study aimed to investigate the effect of waste plastic pyrolysis oil, n-butanol, hybrid (Al 2 O 3 and TiO 2) nanoparticles, and diesel fuel blends on combustion, gaseous emissions, and toxic particulates from CRDI diesel engine at steady-state mode. Experiments were carried out using different fuel ratios blended with hybrid nanoparticles at 20 ppm, 40 ppm, and 60 ppm through the ultra-sonification process. The most optimal blend was determined by Shannon entropy-weighted TOPSIS and PROMETHEE II, and was verified with the experimental results. The result shows that the overall fuels have a definite outline by naphthalene, which account for ∼42.67% of the total organic compounds. With n-bu15W30Hy60, n-bu20W40Hy40 and n-buW40Hy60 fuels, ∼54.9% significantly reduction was observed with n-alkane emissions. Low PAHs value found in particulate samples might reduce the effect of eyes irritants and cancers. Compared to EC, the variation in OC had unclear trend across all blend fuels, except for n-bu20W40Hy40 which averagely reduce by ∼89.47% across the Hy40 fuels. Reduction in CO and HC emissions were observed with Hy60 fuels, while the NOx of Hy40 tend to increase significantly than that of Hy20 and Hy60 by an average of 0.204 g/kWh and 0.401 g/kWh, respectively. However, almost equal pressure peaks were obtained with nano-fuels and their heat release became faster as the nanoparticles volume elevated. The MCDM results confirmed that significant benefit could be attained when the fuel mixtures are under the influence of nanoparticles at relatively higher concentrations. The short answer for waste plastic is to ban unnecessary uses of plastic, encourage alternative materials or fuels, and cut plastic production. [ABSTRACT FROM AUTHOR]

Due to the growing concerns of emissions from the shipping industry, the International Maritime Organization (IMO) has set strategies to reduce the CO 2 intensity by 40% in 2030 and cut total GHGs emissions by at least 50% by 2050, with 2008 as a baseline. Clean alternative marine fuels are widely recognized and used as a viable solution for reducing ship-related air pollution. Several studies including traditional reviews have been conducted to examine the literature on cleaner alternative marine fuels and their role in decarbonizing the shipping sector. However, these studies fail to unpack the main research actors, evolutionary nuances, and emerging research hotspots in this field. To quantitatively and qualitatively explore this research field, the current study adopts a bibliometric analysis. 583 eligible documents published from 2000 to 2020 were retrieved and merged from the Web of Science Core Collection and Scopus databases, and analyzed with the R-studio bibliometrix package (Biblioshiny). Results revealed that the field is growing significantly at a growth rate of 15.8%, with key contributions to the field originating from the USA. Liquified Natural Gas has been identified as the most researched alternative shipping fuel. However, recent trends show researchers turning their attention towards methanol, ammonia, and hydrogen fuels. By analyzing the frequently used keywords and relevant articles, it became clear that the research community has focused mainly on the potential of different alternative fuels as a replacement to conventional marine fuels to limit the emissions from the shipping sector from an environmental, technical, and economic perspective. The current study offers a basis for future research into the decarbonization of the shipping industry. [Display omitted] • Bibliometric study on clean marine fuels based on Web of Science and Scopus databases. • A growing research field with an annual growth rate of 15.8%. • Key authors, institutions and countries in the field have been identified. • LNG emerged as the most researched alternative shipping fuel. • Research hotspots and trends on clean marine fuels discussed. [ABSTRACT FROM AUTHOR]

Biomass waste can be characterized to identify its use in bio-energy production. This study aimed to characterize Mbwazirume peel (MP) and Nakyinyika peel (NP) biomass using various analyses such as proximate and ultimate, TGA, FT-IR, AAS, and SEM-EDS. This was in order to assess their suitability for bio-energy application in Uganda. Results indicate that MP biomass shows higher VM 69.988%, FC 13.582%, ash content 5.825%, and HHV 18.28 MJ-kg−1, and shows lower moisture content 10.605%, nitrogen (N) 5.78%, oxygen (O) 46.74% and sulfur 0.30%. The decomposition of hemicellulose mainly takes place at 100–250 °C, cellulose at 300–500 °C, and lignin at 500 °C and above. The spectrometer results exhibit various functional groups which are related to C C, OH, C O, and C–O–C. The heavy metals (HMs) results for both samples indicate that Cu, Cd and Pb were low, and Zn was high. These toxics may not affect the environment due to their low amount of eco-toxicity and bioavailability. The SEM images show the presence of starch granules and irregular particles with heterogeneous morphology. This might justify the occurrence of high cellulose content due to additional restrictions on molecular motion. During the EDS analysis, the elements found in both ash residues were ordered as follows: O > K > C > Cl > Mg > P for MP, and K > Cl > Mg > P > Al for NP. All these properties proved that MP biomass is more suitable as a potential application for bio-energy. Image 1 • Pyrolysis behavior obtained reveals the three distinct regions. • The HMs results indicate that the Cu, Cd and Pb were low, and Zn was high. • High cellulose content occurs due to additional restrictions on molecular motion. • The micrographs show the presence of starch granules and irregular particles. • White spots were observed during EDS which are elements from different categories. [ABSTRACT FROM AUTHOR]

With rapid industrialization, rising fossil fuel consumption, and environmental concerns, developing clean and green energy is an inescapable option. Hydrogen has emerged as a significant potential energy carrier and a viable future replacement fuel for fossil fuels due to its renewable and pollution-free properties. Previous review papers have significantly contributed to the body of literature on the various technologies for producing hydrogen by revealing key insights into their working principles and conditions, as well as the economic and environmental aspects. In addition, they also highlighted the potential pathways to enable the application of these technologies in the context of carbon neutrality. However, these studies have not broken down the evolutionary patterns and developmental progress of either fossil fuel-based or renewable energy-based technologies used to produce hydrogen. In addition, the currently available literature does not contain the most recent research that focuses on the evolution and life cycle of each technology category from a chronological point of view. The key drivers, countries/regions, and their contributions to the field's development have received little attention. As a result, it is critical to monitor technological advances in hydrogen energy production and investigate the key enablers of these advancements. Against this backdrop, the current study employs patent analysis tools to achieve four primary goals: (1) to track the development trends in the field of hydrogen production from 2000 to 2019; (2) to identify and compare the recent development trends in the last five years according to the feedstock, i.e., fossil fuel, water, and biomass-based technologies; (3) to predict the technology life cycle of the two main groups of hydrogen production technologies (fossil and renewable); (4) to identify and compare the key drivers of hydrogen production technologies from a statistical standpoint. The findings of the study may aid in identifying technical prospects in the field of fossil and renewable-based hydrogen production, and decision-makers may use them as a reference in developing a strategic plan for future technological growth. • Patent review on hydrogen production technologies from 2000 to 2019. • Japan, US, China are the leading countries in the field. • Recent developments are focused on renewable energy-based technologies especially water. • Technology maturity rate of renewable-based technologies is about 57%. • R&D expenditure strongly promotes hydrogen production innovations. [ABSTRACT FROM AUTHOR]

In the current study, low carbon alcohols (methanol and ethanol) have been blended into marine heavy fuel oil (HFO) at 10–50 vol% alcohol in the presence of microbial (Rhamnolipid) and synthetic (Span 80) surfactants. The ternary systems were subjected to three different temperatures, i.e., 25, 45, and 55 °C. The investigated areas included (1) the comparative solubilizing ability between the two distinct surfactant types, (2) the viscosity adjustment of the resulting ternary system, and their sulfur content. Results show that the biosurfactants have strong solubilizing power than their synthetic counterparts. Also, as the ratio of low carbon alcohol in the ternary system increases, the stability worsens, requiring more surfactants to promote miscibility. For instance, At 30% and 50% methanol content for 25 °C , the amount of Span 80 needed by these systems to become a kinetically stable solution was 2.83 mL and 4.65 mL, corresponding to 36.14 vol% and 48.16 vol%, respectively. For the same base systems, the corresponding requirement of Rhamnolipid was 0.87 mL (14.82 vol%) and 1.53 mL (23.43 vol%), respectively. In general, solubility in ethanol-containing systems was much easier to achieve upon adding surfactants than in methanol's. Rhamnolipid and the low carbon alcohols positively decreased the viscosity of HFO, hence reducing the cost of its preheating. Results from this study show that at a minimum of 20 vol% methanol and 25 vol% ethanol (when Rhamnolipid is the surfactant and system temperature is as low as 25 °C), ship owners could take advantage of this fuel blend by significantly reducing or eliminating fuel preheating costs. When the concentration of HFO in the ternary system did not exceed 60 vol%, the blend could meet the global sulfur content limit (0.5%); hence the need for exhaust abatement technologies could be avoided if the operation is outside the emission control areas. Results of the current study address some of the key issues raised in the combustion of HFO in the shipping sector. [Display omitted] [ABSTRACT FROM AUTHOR]

Production of potential pigments using the bacterial source can be an important area of research to disclose its possible value in diverse industrial applications. Soil samples from various terrestrial, rhizosphere, and forest habitats were collected from Karnataka, and pigment-producing actinomycetes were recovered. In the present investigation, 25 strains were isolated using starch casein agar medium; further, phenotypic, biochemical, and morphological and the 16S rRNA gene sequence studies have suggested that the strain belonged to the Streptomyces species, strain BJZ10, an actinomycetes. With higher production of pigments, starch casein broth medium was used, and the extraction of actinobacterial pigments was done by exclusively using methanol solvent. The pigment was characterized by UV-visible spectroscopy; absorption spectra range from 220 to 250 nm. The FTIR characterization was carried out, and the spectrum obtained for the strain BJZ10 indicated alkane, alkyls, alkynes, alcohols, esters, and sulfate functional groups. Antibacterial activity of the pigments was tested against Bacillus cereus (Gram-positive) and Escherichia coli (Gram-negative), and significant results were compared. The present study revealed the brown pigment synthesized by Streptomyces sp. strain BJZ10, known for its potential antimicrobial activity. [ABSTRACT FROM AUTHOR]

The rapid rise in global oil prices, the scarcity of petroleum sources, and environmental concerns have all created severe issues. As a result of the country's rapid expansion and financial affluence, Malaysia's energy consumption has skyrocketed. Biodiesel and solar power are currently two of the most popular alternatives to fossil fuels in Malaysia. These two types of renewable energy sources appear to be viable options because of their abundant availability together with environmental and performance competence to highly polluting and fast depleting fossil fuels. The purpose of adopting renewable technology is to expand the nation's accessibility to a reliable and secure power supply. The current review article investigates nonconventional energy sources added with nanosized metal particles called as nanomaterials including biodiesel and solar, as well as readily available renewable energy options. Concerning the nation's energy policy agenda, the sources of energy demand are also investigated. The article evaluates Malaysia's existing position in renewable energy industries, such as biodiesel and solar, as well as the impact of nanomaterials. This review article discusses biodiesel production, applications, and government policies in Malaysia, as well as biodiesel consumption and recent developments in the bioenergy sector, such as biodiesel property modifications utilizing nanoparticle additions. In addition, the current review study examines the scope of solar energy, different photovoltaic concentrators, types of solar energy harvesting systems, photovoltaic electricity potential in Malaysia, and the experimental setup of solar flat plate collectors (FPC) with nanotechnology. [ABSTRACT FROM AUTHOR]

Production of potential pigments using the bacterial source can be an important area of research to disclose its possible value in diverse industrial applications. Soil samples from various terrestrial, rhizosphere, and forest habitats were collected from Karnataka, and pigment-producing actinomycetes were recovered. In the present investigation, 25 strains were isolated using starch casein agar medium; further, phenotypic, biochemical, and morphological and the 16S rRNA gene sequence studies have suggested that the strain belonged to the Streptomyces species, strain BJZ10, an actinomycetes. With higher production of pigments, starch casein broth medium was used, and the extraction of actinobacterial pigments was done by exclusively using methanol solvent. The pigment was characterized by UV-visible spectroscopy; absorption spectra range from 220 to 250 nm. The FTIR characterization was carried out, and the spectrum obtained for the strain BJZ10 indicated alkane, alkyls, alkynes, alcohols, esters, and sulfate functional groups. Antibacterial activity of the pigments was tested against Bacillus cereus (Gram-positive) and Escherichia coli (Gram-negative), and significant results were compared. The present study revealed the brown pigment synthesized by Streptomyces sp. strain BJZ10, known for its potential antimicrobial activity. [ABSTRACT FROM AUTHOR]

The rapid rise in global oil prices, the scarcity of petroleum sources, and environmental concerns have all created severe issues. As a result of the country's rapid expansion and financial affluence, Malaysia's energy consumption has skyrocketed. Biodiesel and solar power are currently two of the most popular alternatives to fossil fuels in Malaysia. These two types of renewable energy sources appear to be viable options because of their abundant availability together with environmental and performance competence to highly polluting and fast depleting fossil fuels. The purpose of adopting renewable technology is to expand the nation's accessibility to a reliable and secure power supply. The current review article investigates nonconventional energy sources added with nanosized metal particles called as nanomaterials including biodiesel and solar, as well as readily available renewable energy options. Concerning the nation's energy policy agenda, the sources of energy demand are also investigated. The article evaluates Malaysia's existing position in renewable energy industries, such as biodiesel and solar, as well as the impact of nanomaterials. This review article discusses biodiesel production, applications, and government policies in Malaysia, as well as biodiesel consumption and recent developments in the bioenergy sector, such as biodiesel property modifications utilizing nanoparticle additions. In addition, the current review study examines the scope of solar energy, different photovoltaic concentrators, types of solar energy harvesting systems, photovoltaic electricity potential in Malaysia, and the experimental setup of solar flat plate collectors (FPC) with nanotechnology. [ABSTRACT FROM AUTHOR]

Currently, the vehicle industry is confronted with issues such as the depletion of fossil resources, an increase in crude oil costs, and stricter emission regulatory standards. In this scenario, the use of viable alternatives to diesel as a fuel is necessary. This study discusses the combined effects of injection time and exhaust gas recirculation (EGR) on neat algal biodiesel-powered diesel engines. The transesterification technique was used to extract algal oil methyl ester (AOME), and the majority of the fuel qualities of AOME were quite comparable to diesel. The practicality of neat AOME for diesel engines operating at varied injection timings such as 19º BTDC, 23º BTDC, and 27º BTDC was investigated. The results of the tests revealed that advanced injection timing has a 3.02% higher BTE than standard fuel injection timing at maximum load for the AOME. Compared to other injection timings at full load, the neat AOME at 27º BTDC has better combustion characteristics and lower exhaust emissions. At full load, however, NOx emissions were higher. NOx emission was reduced by 35.24% when AOME was burned at 27º BTDC combined with 10% exhaust gas recirculation (EGR) compared to 27º BTDC without EGR. [ABSTRACT FROM AUTHOR]

Methanol is a very promising clean alternative fuel, and the study on pure methanol spray flames has not been found before to authors' knowledge. In this study, the flame structure, soot formation, and combustion stability of spray flame for methanol and conventional fuels were investigated at the ambient pressure of 4 MPa and the ambient temperature of 950 K by the means of optical phenomenology, theoretical analysis and chemical kinetic simulations. Optical images reveal that the methanol spray auto-ignition location and the established steady lifted flame is away from the injector nozzle compared to that of isooctane and n-heptane. The results of the RGB two-color method show that the KL factor in the methanol spray flame is only 0.04–0.05, which is one twentieth of n-heptane and isooctane. The combustion stability of methanol increases with increasing injection mass. Methanol spray flame is the most unstable which is 13.33% and 151.58% less than that of the spray flame of isooctane and n-heptane respectively. In chemical kinetic simulations, the appropriate region for methanol high temperature reactions is outside the relative dense region. The residence time of the rich mixture is short and may not come into contact with the supporting peripheral hot product pool, which leads to poor combustion stability. • Methanol spray flames are mainly yellowish in color. • The combustion stability of methanol increases with increasing injection mass. • The steady methanol flame is away from the nozzle compared to that of iso-octane and n-heptane. • The soot content of methanol flames is much lower. • Methanol spray flames are less stable than iso-octane and n-heptane. [ABSTRACT FROM AUTHOR]

One of the main setbacks to electric vehicles (EVs) adoption relates to the unavailability of the required charging stations across a jurisdiction. In addition, drawing the required energy of the EVs from a fossil fuel-dominated grid does not only minimize the cleaner benefits of EVs but also puts enormous pressure on an already stressed grid network in electricity-deficient regions like Sub-Saharan Africa (SSA). Hence, in the current study, six different 100% hybrid renewable energy systems based on powerplants of solar, wind, and biomass have been proposed for meeting the energy needs of 70 and 30 battery and fuel cell electric vehicles, respectively using Ghana as a case study. With the aid of HOMER Pro software and multicriteria decision-making tools, the hybrid system, biogas generator-photovoltaic emerged as the most feasible of the six proposed solutions from a technical, economic, and environmental standpoint. This winning system produces 3.9 GWh/yr and 55.6 tonnes/yr of electricity and hydrogen, respectively. The NPC, LCOE, LCOH, and payback period was recorded as $6.53 million, $0.52/kWh, $9.09/kg and ∼8 years, respectively. Approximately, 4 tonnes of GHG emissions are produced by the HRECS each year, and the amount of CO 2 emissions avoided from replacing 100 gasoline vehicles with the proposed EVs has been obtained as 460 tons/yr. With the aid of sensitivity analysis, it became apparent that the feasibility of the proposed systems could improve with improvement in components' efficiencies and lifetime, and reduction in unit costs. The current work has several contributions to the sustainable development goals (7, 8, 11, 13), and could aid in accelerating EV penetration in SSA. [Display omitted] • A hybrid RE standalone HRECS for EVs in Ghana. • Investigation by HOMER and CRITIC-PROMETHEE II methods. • PV + Biogas generator presents most feasible results for HRECS. • Break-even Grid Extension Distance investigated. • Standalone vrs grid-connectivity analysis. [ABSTRACT FROM AUTHOR]

A recent publication of two independently performed studies investigating a very similar topic of green shipping, applying very similar methods (bibliometric analysis) on very similar data sets (scientific databases) provides an opportunity for an unbiased analysis of what factors can impact the outcome of one's research. This discussion paper reviews and compares the two following papers: • Ampah, J.D., Yusuf, A.A., Afrane, S., Jin, C., Liu, H., 2021. Reviewing two decades of cleaner alternative marine fuels: Towards IMO's decarbonization of the maritime transport sector. J. Clean. Prod. 320, 128871. https://doi.org/10.1016/j.jclepro.2021.128871 • Kołakowski, P., Gil, M., Wróbel, K., Ho, Y., 2021. State of play in technology and legal framework of alternative marine fuels and renewable energy systems: a bibliometric analysis. Marit. Policy Manag. https://doi.org/10.1080/03088839.2021.1969460 This paper aims to conclude on the insights arising from both papers concerning their different methodological peculiarities. • Commentary on two independent bibliometric studies on alternative fuels for shipping. • Similarities and differences of both studies discussed. • Current commentary offers key insights into the use of bibliometric analysis. [ABSTRACT FROM AUTHOR]