With eight million of us flying every day and rising, the environmental cost of air travel is a substantial one - in 2012, it was estimated that 2 percent of all carbon emissions were down to aeroplane operations, and that figure is expected to increase in the near future. Against that backdrop, scientists across the world are working on alternative fuels to make air travel a greener form of transport.
A team of researchers from the University of California, Berkeley in the US have come across a novel alternative fuel: sugarcane biomass and waste. The academics say that producing jet diesel from this natural source would substantially reduce greenhouse gas emissions. What's more, because the sugarcane can be grown on marginal, low-yield land, it wouldn't have to replace existing food crops.
"We've identified a new route of chemistry with its source from sugars in sugarcane plus some of the so-called waste material called bagasse," co-author Alexis Bell told Mark Kinver from the BBC. "We show in this paper how we can put these components together to make jet diesel and lubricants."
The process works by using a hot water treatment to remove sugar from the sugarcane, before renewable catalysts (tiny amounts of magnesium oxide and niobium pentoxide) are used to transform the waste into fuel.
Up to this point scientists have struggled to find a viable biofuel to meet the demands of today's high-powered aircraft - there are strict regulations in place in terms of weight, density, lubricity and performance in low temperatures that airlines insist on to keep efficiency at the required levels. But Bell says his new sugarcane fuel meets all of the necessary criteria.
The first commercial flight partly powered by biofuel was back in February 2008, but interest in greener fuel has waned over concerns that the production of the necessary crops would increase strain on worldwide food production. The sugarcane fuel developed by Bell and his colleagues avoids that problem.
"If, for example, we were to use sugar beet instead of sugarcane then there would be a potential conflict over fuel versus food," he says. "By using sugarcane, particularly in Brazil, on land that is not used for agriculture, we escape that conundrum." Bell added that any clearing of ground for sugarcane production would have to be environmentally sound to make the potential benefits worthwhile.
The research, published in the Proceedings of the National Academy of Sciences, has been sponsored by BP and the scientists are now seeking a patent for the innovations they've made. The process may well be used to create lubricants first of all, before becoming part of cleaner jet fuel mixtures.