Chemists at the University of Bristol in England have taken the first steps toward making sustainable gasoline using beer as a key ingredient.
Of course, they wouldn’t want to convert beer to fuel on an industrial basis. But in developing technology to replace ethanol, which is typically blended with gasoline in the U.S., beer is ideal, they say.
Ethanol isn’t an ideal replacement for gasoline: It has a lower energy density, it mixes too easily with water and it can be fairly corrosive to engines.
A much better fuel alternative is butanol but this is difficult to make from sustainable sources.
Scientists from the University of Bristol’s School of Chemistry have been working for several years to develop technology to convert widely-available ethanol into butanol.
This has already been demonstrated in laboratory conditions with pure, dry ethanol but, if this technology is to be scaled up, it needs to work with real ethanol fermentation broths.
These contain about 90% water and other impurities, so the new technology has to be developed to tolerate that.
“The alcohol in alcoholic drinks is actually ethanol – exactly the same molecule that we want to convert into butanol as a petrol replacement,” Prof. Duncan Wass, whose team led the research, said.
“So alcoholic drinks are an ideal model for industrial ethanol fermentation broths – 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 technology used to convert ethanol into butanol is called a catalyst – these are chemicals which can speed up and control a chemical reaction and are already widely used in the petrochemical industry.
The Bristol team’s key finding is that their catalysts will convert beer (or specifically, the ethanol in beer) into butanol.
In demonstrating that catalysts work with a ‘real’ ethanol mixture, the team has demonstrated a key step in scaling this technology up to industrial application.
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.”
Another advantage of this approach is that it is quite similar to many existing petrochemical processes.
The next step in terms of application is to build this larger scale process and, based on previous processes, this could take as long as five years even if everything went well. From a scientific point of view, the team are now trying to understand what makes their catalysts so successful.
“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,” Wass said. “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.”