Researchers synthesise aviation fuel from sugarcane
Researchers at the University of California, working collaboratively with a number of Berkeley-based biotechnology institutions, have published a report outlining a new process to synthesise aviation fuel and lubricants from sugarcane.
The new method, which is detailed in the report ‘Novel pathways for fuels and lubricants from biomass optimized using life-cycle greenhouse gas assessment’, involves the conversion of sugars in sugarcane to ketones using a combination of chemical and biocatalytic processes, and then processing them to produce condensates suitable to be used as jet fuels.
According to the study, this strategy produces a new class of compounds that could achieve net-cycle greenhouse gas savings of up to 81 per cent compared to traditional aviation fuels. Serious questions remain over the provenance and sustainability of the sugarcane, however, as it is expected it will be grown in Brazil and could require land use changes in the Amazon River basin.
The report’s authors claim that the development of biofuels to replace conventional jet fuels is of particular importance due to a lack of available renewable alternatives, and the ‘unique’ standards that aviation fuel must meet to be viable.
Speaking to the BBC, co-author of the study Professor Alexis Bell explained the three main challenges involved in the production of aviation fuels compared to other fuels: the need to have no oxygen content as “you'd like to pack in as much energy in the form of burnable fuel as possible”; the need for the right boiling point distribution and lubricity, “which means it does not cause excessive wear of the turbine components; and the need for “a very low pour point” to ensure fuel does not “gel up on you” when flying in cold temperatures in the stratosphere.
He added: "What we have developed meets all of those criteria."
‘Food versus fuel’
Although biofuels were originally considered an environmentally-friendly fuel source, feelings surrounding the development of biofuels have been mixed due to the potential negative impacts on biodiversity, indigenous land rights and food security.
First-generation biofuels (those made from crops specifically grown to be made into fuel, as would be the case with the jet fuel made from sugar cane) are increasingly considered unsustainable, with the European Union recently capping the use of first generation, crop-based biofuels for transport purposes to six per cent by 2020.
The researchers claim that they can grow the requisite sugar cane on land in the Amazon River basin that is not currently used for agriculture, though Bell acknowledged to the BBC that clearing any land of scrubs and trees to plant sugar cane will result in a “big pulse of CO2” being released into the atmosphere.
Elsewhere in the search for sustainable jet biofuel, British Airways and bioenergy company Solena are building the ‘world’s first’ waste-to-jet-fuel facility in Thurrock, which will allegedly use ‘waste biomass, which does not compete with food crops or require indirect land use change’.
The full report detailing the new method of making jet fuel from sugarcane is available from the Proceedings of the National Academy of Science of the United States of America (PNSA).