Industries, especially those related to transportation, have relied extensively on petroleum products for lubrication, raising serious questions about the security of the world energy supply in the future. Observed that the end-products might be released back into the environment, posing major environmental risks. As a result, bio-based products have attracted increasing interest as prospective replacement to mineral-based type due to their important role in resolving the issues of pollution. With renewability and biodegradability as their greatest points, bio-based lubricants have been discovered to offer superior lubricating qualities to those of traditional mineral lubricants but currently have some undesirable qualities that need to be improved based on the literatures. Therefore, this research objective is to showcase the potential of bio-lubricants, both in terms of their environmental benefits and for technical applications, based on studies that have been published over the years. Review of the natural oil's molecular structures, physio-chemical characteristics, and lubricating ability is crucial for the creation and choice of lubricants. Owing to their accessibility in a wide range of characteristics, which are necessary for specific applications, bio-based lubricant is a possible replacement for a variety of applications, according to the primary findings. The results showed that sunflower oil improved in reducing friction and wear by 93.7% and 70.1%; and 77.7% and 74.1%, under TiO2 and SiO2 studied, against base lubricant values of 0.0511 and 11.2414 (mm3), respectively. However, to get beyond some of the restrictions such as poor low temperature and oxidative stability, adequate chemical modification is necessary in solving agglomeration challenges.

The energy crisis and ecological disasters have become a critical problem in recent decades. The human activities through industrial operations increase emissions and other pollutant particulates in the world as a result of steady patronage on fossil feedstock. Several experiments were performed to identify an alternative fuel meeting the rising energy demand. Biomass (bio-fuel) has recently been developed as an economical fuel, environmentally friendly resource, renewable and sustainable fuel. Approximately 350 crop plants were evaluated and some of them could be considered as suitable alternative diesel engine fuels. To increase the bio-fuel quantity globally, apart from crops, other biomaterial sources are considered potential in biofuel production. It was shown that the properties of biofuel combustion are identical to fossil. In the experimental combustion of biodiesel blends, higher ignition pressure and temperature, shorter ignition delay, and higher peak release were recorded. This paper is a literature review on the need for biofuels as a global renewable fuel resource and aims to explain the characteristics of combustion and pollutant formation in the application of biofuels. The study also stated the resources, the use of biogas and its emission impact in flameless combustion mode. With holistic adoption of biomass source of fuel together with the modern conversion techniques, issues from fuel emissions will be mitigated.

The development of diesel engines faces challenging targets to satisfy stringent emissions regulation. To address this issue, the use of alcohol biofuels such as methanol and ethanol has attracted numerous attention due to their physicochemical properties and the possibility to be produced from renewable sources and agricultural waste material. Compared to ethanol, longer carbon alcohol such as butanol has higher energy density and lower latent heat, hygroscopicity, aggressivity, and toxicity. It can also be produced from biomass. Yet, despite its noticeable advantages, the use of butanol in the internal combustion engine is hindered by its low production efficiency. If Acetone-Butanol-Ethanol (ABE) is further distilled and purified, pure butanol and ethanol can be acquired, but this involves an energy-intensive process, thus increasing the production cost of butanol. To solve this problem, the direct use of ABE as a biofuel is considered a promising strategy. The idea of using ABE directly in internal combustion engines is then proposed to solve the economic issue of high butanol production costs. A scoping literature review was performed to screen and filter previously published papers on ABE by identifying knowledge gaps instead of discussing what is already known. Therefore, repeated and almost identical studies were eliminated, thus reporting only the most significant and impactful published papers. In terms of the objective, this article aims to review the progress of ABE as a promising biofuel in regard to the engine performance, combustion, and emission characteristics. Focus is also given to ABE”™s physicochemical properties. Despite their considerable importance, the fuel properties of ABE are rarely discussed. Therefore, this review article intends to analytically discuss the physicochemical properties of ABE in terms of their calorific value, density, kinematic viscosity, and distillation. In general, it is concluded that engine emissions such as NOx and Particulate Matter (PM) could be reduced considerably with the use of ABE. Yet, the BSFC was found to increase due to the relatively lower calorific value and density of ABE blends as opposed to gasoline or diesel fuel, thereby increasing its fuel consumption. In terms of ABE”™s fuel properties, in general, ABE can be used due to its satisfying physicochemical properties. However, it should be noted that the ABE-gasoline/diesel blends are greatly influenced by each of its component ratios (acetone, butanol, ethanol).

The increased energy efficiency of electrified vehicles and their potential to reduce CO₂ emissions through the use of environmentally friendly materials are highlighted as reasons for the shift to electrified vehicles. Brief trends on the development of electric vehicles (EVs) have been discussed, presenting outstanding improvement towards the actualization of the green economy. The state of the art in lubrication has been thoroughly investigated as one of the factors influencing energy efficiency and the lifespan of machine components. As a result, many reports on the effectiveness of specific lubricants in electric vehicle applications have been developed. Good thermal and corrosion-resistant lubricants are necessary because of the emergence of several new tribological difficulties, especially in areas that interact with greater temperatures and currents. To avoid fluidity and frictional problems that may be experienced over its lifetime, a good viscosity level of lubricant was also mentioned as a crucial component in the formulation of EV lubricant. New lubricants are also necessary for the gearbox systems of electric vehicles. Furthermore, battery electric vehicles (BEVs) require a suitable cooling system for the batteries; thus, a compatible nano-fluid is recommended. Sustainable battery cooling options support global energy efficiency and carbon emission reduction while extending the life of EV batteries. The path for future advancements or the creation of the most useful and efficient EV lubricants is provided by this review study.