Scientists from the University of Bristol say they have found a way to essentially turn beer into petrol. Although mostly just a demonstration, it has important implications that could help develop sustainable fuels.

Published in the journal Catalysis Science and Technology, the study looked at ways to develop ethanol, which is widely available, into butanol and reduce our reliance on diesel and petrol.

In the US, a common alternative to petrol is bioethanol, which contains up to 10 percent ethanol. However, ethanol is not a great replacement for petrol because it can damage engines. It also has a lower energy density than petrol and mixes too easily with water.

Butanol is more promising, however, and in this study the team found a way to convert ethanol into butanol. As it turned out, beer was a great test study to figure this out.

"Turning beer into petrol was a bit of fun, and something to do with the leftovers of the lab Christmas party, but it has a serious point,” Professor Duncan Wass, whose team led the research, said in a statement

"Beer is actually an excellent model for the mixture of chemicals we would need to use in a real industrial process, so it shows this technology is one step closer to reality."

To convert ethanol into butanol you need a catalyst, a chemical that speeds up and controls a chemical reaction. And their catalyst, composed partly of ruthenium and chlorine, successfully converted the ethanol in beer into butanol, or more specifically isobutanol.

“Isobutanol is an ideal gasoline replacement due to its high energy density, suitable octane number and compatibility with current engine technology,” the team write in their paper.

Showing that this process works means that it could be scaled up to industrial levels. Beer wouldn’t actually be used at a larger scale, but the process by which ethanol would be obtained from fermentation would produce something quite similar to beer, making it a good test subject.

"The alcohol in alcoholic drinks is actually ethanol – exactly the same molecule that we want to convert into butanol as a petrol replacement,” said Professor Wass.

"So alcoholic drinks are an ideal model for industrial ethanol fermentation broths – ethanol for fuel is essentially made using a brewing process.”

It may take a further five years to scale this up, but the results so far are promising. Just don’t start filling your car with beer any time soon.