Environmental concerns and the rising cost of crude oil have incentivised the search for alternative aviation fuels. However, any potential alternatives must be thoroughly characterised and tested. In this investigation nine potential biofuels derived from sustainable sources were tested for their compatibility with Jet A-1 aviation kerosene. The fuels chosen were n-butanol, n-hexanol, butyl levulinate, butyl butyrate, ethyl octanoate, methyl linolenate, farnesene, ethyl cyclohexane and limonene. Viscosities were determined between-30 and 40 °C and were observed to increase with decreasing temperature roughly in accordance with ideal fluid behaviour. Cloud point temperatures of all samples were tested and all fuels except n-butanol and methyl linolenate were found to be below the specification maximum. Flash points of all fuels apart from pure and blends of ethyl cyclohexane and n-butanol were found to be greater than 38 °C, the minimum threshold specified in the standard. Of all the samples only the hydrocarbon fuels met the required energy content minimum with energy content decreasing with increasing oxygen content. The effect of each fuel on the range vs. the payload, relative to Jet A-1 was determined using a simplified model in order to ascertain likely impact of adoption upon airline operations. Only limonene fulfilled all the requirements of an alternative aviation fuel, though butyl butyrate and ethyl octanoate were acceptable except for the reduced energy density.

Biorefineries have been established since the 1980s for biofuel production, and there has been a switch lately from first to second generation feedstocks in order to avoid the food versus fuel dilemma. To a lesser extent, many opportunities have been investigated for producing chemicals from biomass using by-products of the present biorefineries, simple waste streams. Current facilities apply intensive pre-treatments to deal with single substrate types such as carbohydrates. However, most organic streams such as municipal solid waste or algal blooms present a high complexity and variable mixture of molecules, which makes specific compound production and separation difficult. Here we focus on flexible anaerobic fermentation and hydrothermal processes that can treat complex biomass as a whole to obtain a range of products within an integrated biorefinery concept.

In this investigation ozonolysis in the presence of ethanol was used to depolymerise lignin, resulting in a low conversion of oxygenated aromatics over short reaction times, or a range of saturated esters over 24 h. Short chain oxygenates can be used as fuel additives, displacing a percentage of a hydrocarbon fuel while leading to improvement in some of the fuel properties. The utility of the resulting bio-oils was therefore assessed by blending with a range of fuels. Guaiacol, a potential antioxidant, was formed over short reaction times and was found to be completely miscible with low-sulphur petrol (ULSP), diesel, aviation kerosene and rapeseed methyl ester. The mainly aliphatic proportion of the bio-oil produced over 24 h could be blended with the fuels replacing a maximum of 12-17 wt.% of the hydrocarbon fuel.

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Benzaldehyde lyase (BAL) results in an efficient biocatalyst for the umpolung carboligation of furfural, HMF, and mixtures therein.