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Biodiesel is an alternative to fossil fuels for diesel engines, yet actual biofuel properties need to be tuned to comply with fuel standards. In particular, fuel stability is required for efficiency and commercial use. Fuel stability varies with the nature and proportion of chemical functional groups of biodiesel. Optimum oxidation stability is required because degradation by oxidation gives products that compromise fuel properties and impair fuel quality and engine performance. For instance, oxidation induces the formation of short-chain corrosive acids and deposits. Here, we review techniques to improve the oxidation stability of biodiesel. For instance, stability is improved by additives such as antioxidants. Factors influencing oxidation stability include composition of fatty acids, acid content, peroxide content, iodine content, viscosity, insoluble impurities, external conditions, and storage material. Antioxidants reduce lipid peroxidation at the beginning of the chain reaction and increase the onset temperatures. [ABSTRACT FROM AUTHOR]

Processing biodiesel from non-edible sources of feedstock seems to be thriving in recent years. It also has also gathered more attention than in the past, mainly because the biodiesel product is renewable and emits lower pollution compared to fossil fuels. Researchers have started their work on various kinds of biodiesel product, especially from a non-edible feedstock. Non-edible feedstocks such as Ceiba pentandra show great potential in the production of biodiesel, especially in the Southeast Asia region because the plants seem to be abundant in that region. Ceiba pentandra, also known as the Kapok tree, produces hundreds of pods with a length of 15 cm (5.9 in) and diameter 2–5 cm (1–2 in). The pods consist of seeds and fluff in the surrounding areas inside the pod, which itself contains yellowish fibre, a mixture of cellulose and lignin. The seeds of Ceiba pentandra can be used as feedstock for biodiesel production. The study for Ceiba pentandra will involve techno-economic, as well as a sensitivity analysis. Moreover, the study also shows that the techno-economic analysis of a biodiesel processing plant for 50 ktons Ceiba pentandra with a life span of 20 years is around $701 million with 3.7 years of the payback period. Besides that, this study also shows the differences in operating cost and oil conversion yield, which has the least impact on running cost. By improving the conversion processes continuously and by increasing the operational efficiency, the cost of production will decrease. In addition, the study also explains the differences of final price biodiesel and diesel fossil fuel, both showing dissimilar scenarios subsidy and taxation. Biodiesel has a subsidy of $0.10/L and $0.18/L with a total tax exemption of 15%. The value was obtained from the latest subsidy cost and diesel in Malaysia. Finally, further research is needed in order to fully utilize the use of Ceiba pentandra as one of the non-edible sources of biodiesel. [ABSTRACT FROM AUTHOR]

Nowadays, increased interest among the scientific community to explore the Calophyllum inophyllum as alternative fuels for diesel engines is observed. This research is about using mixed Calophyllum inophyllum-palm oil biodiesel production and evaluation that biodiesel in a diesel engine. The Calophyllum inophyllum–palm oil methyl ester (CPME) is processed using the following procedure: (1) the crude Calophyllum inophyllum and palm oils are mixed at the same ratio of 50:50 volume %, (2) degumming, (3) acid-catalysed esterification, (4) purification, and (5) alkaline-catalysed transesterification. The results are indeed encouraging which satisfy the international standards, CPME shows the high heating value (37.9 MJ/kg) but lower kinematic viscosity (4.50 mm2/s) due to change the fatty acid methyl ester (FAME) composition compared to Calophyllum inophyllum methyl ester (CIME). The average results show that the blended fuels have higher Brake Specific Fuel Consumption (BSFC) and NOx emissions, lower Brake Thermal Efficiency (BTE), along with CO and HC emissions than diesel fuel over the entire range of speeds. Among the blends, CPME5 offered better performance compared to other fuels. It can be recommended that the CPME blend has great potential as an alternative fuel because of its excellent characteristics, better performance, and less harmful emission than CIME blends. [ABSTRACT FROM AUTHOR]