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Renewable substitutes for transportation fuels have had an important role in the recent years. Hydrotreated vegetable oils (HVO) are produced from two stage hydrotreating process of vegetable oils. The second stage of this hydroteating process is used to convert normal paraffins to isoparaffins in order to improve cold flow properties of these fuels. As this stage is a high energy consuming process, it is of interest to investigate the characteristics and the usability of the first stage of hydrotreatment of lipids. This paper examines the properties of alternative fuel derived from the hydrotreatment of used cooking oil (UCO). Used cooking oil is a difficult feedstock for biodiesel production. The hydrotreating of UCO converts triglycerides mainly into normal paraffins within the diesel fuel range. The hydrotreated UCO (HUCO) has an excellent cetane number and cetane index (>90), but very poor cold flow properties.

In accordance to the current environmental policy of the European Union by 2020, 10% of the transport fuel in every country comes from renewable sources such as biofuels. One of the most popular biofuels, (bio) ethanol is a probable suitable candidate for addition in diesel fuel because of its cleaner combustion and the ability to reduce emissions of gaseous pollutants. However, its use presents some important problems, attributed mainly to its incompatibility with diesel fuel during mixing due to the difference in the polarity. For this reason, substances that act as stabilizers of these mixtures are used, one of the most suitable being butanol. This substance is compatible with diesel fuel and ethanol, acting as a chemical bridge between the two, but also exhibits positive combustion behavior, as it is also an oxygenate that can be produced from renewable sources as well. The aim of this work was to investigate the behavior of diesel-ethanol mixtures using butanol as co-solvent.

FAME is the most common renewable component of conventional automotive diesel. Despite the advantages, biodiesel is more susceptible to oxidative deterioration and due to its chemical composition as well as its higher affinity to water, is considered to be a favorable substrate for microorganisms. On the other hand, apart from biodiesel, alcohols are considered to be promising substitutes to conventional diesel fuel because they can offer higher oxygen concentration leading to better combustion characteristics and lower exhaust emissions. More specifically, n-butanol is a renewable alcohol demonstrating better blending capabilities and properties when it is added to diesel fuel, as its composition is closer to conventional fuel, when compared ethanol to for example. Taking into consideration the alleged disinfectant properties of alcohols, it would be interesting to examine also the microbial stability of blends containing n-butanol in various concentrations.