A jet fuelled by methane gas generated from farmyard waste has made the shortlist of a global competition to design the aircraft of the future.
The Fly Your Ideas competition is run by aircraft manufacturer Airbus and comes with a £25,500 prize for the winning entry.
The idea to fuel plane with cow dung was submitted by the Australian Team CliMA in the engineering students' competition.
This isn't the first time that cattle waste has been used to power machinery. It's already used to fuel farm vehicles in the US. The manure is stored in tanks and powerful methane gas is trapped to generate fuel.
If it catches on, there certainly won't be any shortage of this kind of fuel. One cow can make up to 30 gallons of manure a day, which could translate to up to 70 gallons of fuel a year.
In flight terms, a 3,500-mile flight from London to New York uses around 17,500 gallons of fuel - the equivalent of 1,000 cows' worth of dung generated over three months.
The CLiMA team estimates that the gassy solution could cut CO2 emissions by up to 97 per cent.
According to londonlovesbusiness.com the other innovative entries in the competition included a jet that ran on passengers' body heat, a plane powered on rechargeable batteries, a plane made from shape-shifting materials that reduced noise and floating luggage on a bed of air for faster access.
An Airbus spokesman told The Sun: "Though the idea that cows could provide the fuel to fly you from London to New York - or that noise reduction could be achieved through shape-shifting engines - may seem far-fetched, the existence of these concepts could be not too far away."
Charles Champion, Airbus's executive vice president of engineering, said that the aviation industry needed: "A constant source of fresh and inventive ideas from the innovators of today and those of tomorrow."
"These future-focused and disruptive concepts prove that engineering isn't just about technical skills - it's about having an innovative mindset and creative approach."
Poo isn't the only strange substance that has been touted as the next big thing in plane fuel. In February, a pilot attempted to fly the 10,500-mile trip from Sydney to London using fuel produced entirely from plastic waste in February.
Would you fly on a plane powered by poo or do you think it sounds like a load of cock and bull?
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