Scientists making sustainable petrol using beer

The first steps towards making sustainable petrol using beer as a key ingredient.

Bristol scientists turn beer into fuel
Image: Bristol

Contemplating an urgent need for sustainable alternatives to fossil fuels for transportation to replace diesel and petrol, Scientists from the University of Bristol’s School of Chemistry have been working for several years to develop technology that will convert widely-available ethanol into butanol.

One of the most widely used sustainable alternatives to petrol world-wide is bioethanol. But that was also known, ethanol is not an ideal replacement for petrol as it has issues such as lower energy density, it mixes too easily with water and can be fairly corrosive to engines.

Other than ethanol, much better fuel alternative is butanol but this is difficult to make from sustainable sources.

Considering the previous results, the team had to keep in mind that, if this technology is to be scaled up, it needs to work with real ethanol fermentation broths which will contain a lot of water (about 90 percent) and other impurities, so the new technology has to be developed to tolerate that.

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

“So alcoholic drinks are an ideal model for industrial ethanol fermentation broth-ethanol for fuel is essentially made using a brewing process.

“If our technology works with alcoholic drinks (especially beer which is the best model) then it shows it has the potential to be scaled up to make butanol as a petrol replacement on an industrial scale.”

The key finding of this team is that their catalysts will convert beer (or specifically, the ethanol in beer) into butanol.

Catalyst, is the technology used to convert ethanol into butanol as well it is already widely used in the petrochemical industry.

Professor Wass added, “We wouldn’t actually want to use beer on an industrial scale and compete with potential food crops.  

“But there are ways to obtain ethanol for fuel from fermentation that produce something that chemically is very much like beer – so beer is an excellent readily available model to test our technology.”

The next step in terms of application could take as long as five years even if everything went well.

Professor Wass said, “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.  

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.”