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Gas to Liquids (GTL) diesel has been produced commercially for several years. GTL diesel is known for its excellent properties, including zero aromatics, near zero sulphur and a high cetane number. Most of the GTL diesel produced by commercial plants is utilised as a blend component, especially in blends up to 20%. In these applications, the cold flow properties are potentially less critical, as the cold flow properties of the blend will mostly be determined by the petroleum-derived component. In certain markets, however, it is possible that GTL diesel can be used as a neat diesel, therefore requiring good cold flow properties. An advantage of GTL technology is that the cold flow properties of GTL diesel can be tailored to meet the climatic requirements of a specific geographical area. In the current study, GTL diesel samples with cold flow properties ranging from ‘summer type’ to ‘winter type’ and varying intermediate cold flow qualities were evaluated.

The benefits of blending ethanol into gasoline fuel are well established. Ethanol’s high latent heat of vaporisation and chemical auto-ignition resistance combine in producing significant knock resistance, enabling higher compression ratio and/or higher charge boosting. Its high flame speed characteristics result in shorter burn durations. Its high knock resistance and rapid burning enable ignition phasing optimisation. These factors all improve the efficiency of spark ignition (SI) engines. Current “flex-fuel” vehicles are designed to operate on both conventional gasoline as well as blends containing higher volumes of ethanol and/or methanol, the former being commonly known as E85. The American Society for Testing and Materials ASTM D5798 specification for ethanol fuel blends was adapted in 2011 to prescribe a minimum ethanol content of 51 % with the remainder able to consist of low octane blending streams.

There is a worldwide drive to reduce the dependence on fossil fuels, mainly driven by volatility in the crude oil price, political instability in oil-producing countries and environmental concerns. In several European countries, diesel passenger cars outsell gasoline-powered cars by a significant margin. Common rail diesel injection technology has played a significant role in making diesel engines more acceptable in light-duty applications, given the significantly improved emissions (due to better atomization) and engine noise offered by this technology. These developments have contributed to a renewed interest in alternative diesels like biodiesel and Gas to Liquid (GTL) diesel. Recently, CEN TS 15940:2012 was approved for publication. This specification will enable paraffinic diesel (including GTL diesel) to be sold commercially as a neat fuel or as a blend, containing up to 7% fatty acid methyl ester biodiesel (FAME).