Contemporary climate challenges and energy security issues once again demonstrate that the transition to alternative motor fuels is a key and priority task for ensuring sustainable development in European Union countries, as well as in Ukraine. This review provides a comparative analysis of the physical, chemical, and performance properties of biodiesel fuels derived from 17 lipid-based feedstocks, including vegetable oils, animal fats, food industry waste, and microalgae. This study investigates the influence of fatty acid composition and transesterification alcohol type on key fuel properties, including density, viscosity, cetane number, pour point, heat value, and flash point. The results show that biodiesel fuels with a high content of saturated fatty acids exhibit higher cetane numbers and energy content, while biodiesel fuels with a high content of unsaturated fatty acids possess improved viscosity and cold flow properties. Camelina, rapeseed, and used cooking oil are identified as being particularly promising feedstocks based on their performance and availability in the European and Ukrainian dimensions. These findings are supported by a SWOT analysis and cost–benefit comparison, providing practical insights into the feasibility and scalability of biodiesel production pathways.

The growing demand for sustainable and environmentally friendly fuels and the increasing need to diversify energy sources have stimulated significant research in the field of renewable motor fuels. Despite the progress made, there is still a need to expand the feedstocks, optimize technological pathways, and, in particular, conduct comprehensive studies of the compatibility of renewable components with traditional fuels. In light of the above, the authors propose optimizing the properties of renewable fuels by using new vegetable oils and alcohols for their synthesis. The work is focused on studying the basic physical–chemical properties of fatty acid esters and assessing the possibility of using them as renewable components of motor fuels. Renewable components were obtained via the esterification of selected plant oils (rapeseed oil, camelina oil, palm kernel oil, and coconut oil) with different alcohols (ethanol and isobutanol) with further vacuum distillation of esters. The influence of the structure and composition of renewable components on their physical–chemical properties was studied and substantiated. It shows how the carbon number distribution and double bonds in fatty acid radicals influence the properties of renewable components. The paper shows the impact of the type and structure of alcohol used for esterification on the properties of studied products. The regularities in the change in properties of renewable components depending on the composition of oils and alcohols are explained and substantiated from the point of view of physical chemistry and the basics of forces of intermolecular interactions. Renewable components were compared to the properties of conventional motor fuels (diesel fuel and jet fuel). Based on the level of component compatibility with petroleum fuels, recommendations for replacing or blending petroleum fuels with renewable components were proposed.

Synthesis of Camelina oil ethyl esters as components of jet fuels

Acid value is one of the key technical characteristic of vegetable oils and oleochemicals, obtaining on its basis. The existing standard methods of acid value measurement are relatively complicated and have some disadvantages. There are including utilization of the significant amounts of solvents, throwing out as wastes, and necessity in special equipment for determination. Also, a special issue is visual indication of the equivalence point of indicator transfer from acid to alkali form for intensive colored oils’ samples. Visual indication of the color transfer of phenol-phthalein as indicator (from colorless to pink) is quite difficult. The color transfer of thymolphthalein (from yellow to green) in such condition is not determined. Using of alkali blue 6B is complicated by the necessity of use ethanol and aromatic compounds mixture. In current work the rapid and simple method of acid value determination was proposed. It consists in alkali-acid titration of the sample by sodium butoxide solution in n-butanol with bromothymol blue, n-butanol is also using as solvent. The method was tested on 3 series of the mixtures of the refined sunflower oil and free fatty acids (distilled fatty acids of sunflower and rapeseed oils and chemical grade oleic acid). The fatty acid content in tested mixtures was in range 1-50 % wt. Some disadvantages of traditional methods, such as the necessity of mixed solvents’ and relatively complicated laboratory equipment use, titration in a hot state, effect of temperature changes in the laboratory and difficulties with visual indication of color transfer, were overcame. Proposed method requires only the simplest laboratory glassware (conic flasks, non-calibrated pipettes, hermetically sealed glass vessels for titrant) and technical laboratory scales (weighting accuracy ±0.01 g). The method allows to determine the acid value in wide range of samples, including the samples with intense coloration. The relatively high accuracy of acid value determination was shown. The method sensitivity is 0.02-0.10 mg KOH/g. The time for analyze is enough short (about 5-15 minutes).