Properties and Analysis of Liquid Alternative Fuels II: Alcohols and Ethers

Abstract

The importance of alternative fuels and their share in total energy consumption is constantly growing. The reason is, on the one hand, the saving of the gradually decreasing reserves of fossil fuels and also the effort to gradually reduce the emissions of carbon dioxide and other harmful substances. This article is another in a series of articles focused on an overview of the technical requirements and possibilities for testing alternative fuels. These articles aim to provide an overview of the required properties of individual alternative fuels, an overview of the prescribed analytical tests, and explain their relevance. This article focuses on liquid alternative fuels containing ethanol. Ethanol is currently the most widespread alternative oxygen fuel and, at the same time, also a biofuel. In pure form (E100), ethanol is used only exceptionally. Far more often, it is used as a bio-component of gasoline fuels. This article provides an overview of the technical requirements prescribed by legislation and relevant standards for ethanol for blending into gasoline fuels, and fuels containing ethanol. From ethanol-gasoline blends, E5, E10, and E85 are discussed. In addition, E95 fuel is discussed as well. The article also presents prescribed analytical tests for monitoring the quality of these fuels, or fuel components. Generally, in ethanol fuels or pure ethanol according to EN 15376, the composition is mostly analysed by GC. GC analysis determines the content of main and secondary oxygen components and/or the content of other impurities. In addition, the water content, total acidity, chloride and sulfate content, non-volatile impurities content, and the content of selected metallic and non-metallic elements, especially sulfur, are monitored in these matrices. For fuels intended for combustion in gasoline engines (E5, E10, and E85), important monitored parameters are also vapor pressure, oxidation stability, as well as density and corrosion on copper.