Scientists turn beer into fuel

December 6, 2017
Credit: CC0 Public Domain

Chemists at the University of Bristol have made the first steps towards making sustainable petrol using beer as a key ingredient.

It is commonly accepted that there is an urgent need for sustainable alternatives to fossil fuels for transportation to replace diesel and .

One of the most widely used sustainable alternatives to petrol world-wide is bioethanol - in the United States gasoline is typically sold as a blend with up to 10 percent .

It is also know that 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.

A much better fuel alternative is 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 that will 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 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 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 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 have 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.

Professor Wass said: "Turning 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."

The study is published in Catalysis Science & Technology.

Explore further: Cost-saving measure to upgrade ethanol to butanol—a better alternative to gasoline

More information: Katy J. Pellow et al. Towards the upgrading of fermentation broths to advanced biofuels: a water tolerant catalyst for the conversion of ethanol to isobutanol, Catal. Sci. Technol. (2017). DOI: 10.1039/C7CY01553D

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3 / 5 (1) Dec 06, 2017
What wooses! That there was ANY beer leftover from their xmas party.
not rated yet Dec 06, 2017
These are chemists: BYOB may mean 'Bring Your Own Barrel'...
3.5 / 5 (2) Dec 06, 2017
This is great. Since you dont buy beer you only rent it, beer is a renewable resource and a possible source of zero-point energy.
not rated yet Dec 07, 2017
I'm all for sustainable energy sources.. But using BEER ! That's a red line!!
not rated yet Dec 07, 2017
Converting the ethanol into butanol greatly reduces the energy necessary to separate it from the water, because it's less soluble.

The main problem of ethanol as fuel is not its corrosive properties or poor energy density, but the large amount of energy required to make it. About 75% of the energy contents of a barrel of ethanol is actually from fossil fuels, as they are the cheapest way to run the farm equipment and then the brewery/distillery.

5 / 5 (1) Dec 07, 2017
I'm all for sustainable energy sources.. But using BEER ! That's a red line!!

I dunno. I could name a number of beers that would be better off as fuels.

But seriously: That this process is feasible is not in doubt. That it is economical in any way is something that needs to be investigated. Alcoholic beverages aren't generated 'for free'. Even though the microbes themselves aren't paid there's quite a bit of input in terms of environmental controls and time. There needs to be a throughput calculation how much fuel can be generated given x amount of factory space and y amount of time to see if this makes any sense in the real world.
not rated yet Dec 07, 2017
There needs to be a throughput calculation how much fuel can be generated given x amount of factory space and y amount of time to see if this makes any sense in the real world.

For ethanol it is already known that the EROEI of the process, with fossil fuels being largely the input, is around 1.3 - 2 except where exceptional conditions exist such as sugar cane in Brazil where the cost is slash-and-burn agriculture in the jungle instead of chemically fertilized farms.

The conversion to butanol necessarily involves some loss of efficiency, but it greatly reduces the cost of separating the fuel from the raw stock.
not rated yet Dec 07, 2017
E,, perhaps I am misunderstanding your comment. "but it greatly reduces the cost of separating the fuel from the raw stock."

Have you factored in the energy/environmental/ tansportation/development/ROI/tech construction costs of producing the raw stock?

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