Environment

Resurrected process converts sugar directly into diesel

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Graduate student Zachary Baer works with a fermentation chamber to separate acetone and butanol (clear top layer) from the fermented brew at the bottom (Photo: Robert Sanders, UC Berkeley)
The clear liquid at the top of the vial extracts the acetone and butanol, separating the chemicals from the fermenting brew while protecting the bacteria, which are killed by high concentrations of the chemicals (Photo: Robert Sanders, UC Berkeley)
Graduate student Zachary Baer works with a fermentation chamber to separate acetone and butanol (clear top layer) from the fermented brew at the bottom (Photo: Robert Sanders, UC Berkeley)

Researchers at the Energy Biosciences Institute (EBI) are generating bio fuels from renewable sources, such as sugar and starch, using a process that could be commercialized in as little as five to ten years. Although the fuels are currently more expensive to produce than those made from petroleum, they contain more energy per gallon than ethanol and the researchers say that, if adopted, could help to cut greenhouse gas emissions from transportation.

The process begins with a bacterial fermentation process first developed by chemist Chaim Weizmann back during the first world war, which results in a mixture of acetone, butanol, and ethanol. Weizmann, who became the first President of Israel in 1949, is considered the father of industrial fermentation as he used the bacterium Clostridium acetobutylicum to produce acetone. This was in turn used in the manufacture of cordite, which was used by the Allies as a replacement for gunpowder as an explosive propellant.

The EBI researchers discovered that organic solvents could distill acetone and butanol using just ten percent of the energy normally required. The process leaves most of the ethanol behind and the resulting mixture has the right ratio to be easily converted into fuel resembling petroleum-based diesel using a catalytic process. Tests carried out by the team showed the fuel burned about as well as normal petroleum-based diesel fuel.

“It looks very compatible with diesel, and can be blended like diesel to suit summer or winter driving conditions in different states,” said Harvey Blanch, a professor of chemical and biomolecular engineering.

The clear liquid at the top of the vial extracts the acetone and butanol, separating the chemicals from the fermenting brew while protecting the bacteria, which are killed by high concentrations of the chemicals (Photo: Robert Sanders, UC Berkeley)

The catalytic process, which uses palladium and potassium phosphate, converts the chemicals into hydrocarbons. “You can tune the size of your hydrocarbons based on the reaction conditions to produce the lighter hydrocarbons typical of gasoline, or the longer-chain hydrocarbons in diesel, or the branched chain hydrocarbons in jet fuel,” explained Dean Toste, a professor of chemistry who developed the catalyst. The resulting chemicals can also be turned into plastics.

The researchers have already found alternative catalysts that are cheaper but just as effective, nudging the process closer towards commercial viability. BP pledged US$500 million dollars in funding to the EBI, a joint initiative between UC Berkeley, the Lawrence Berkeley National Laboratory, and the University of Illinois at Urbana-Champaign, where the discovery was made.

The team's work is described in a paper published in a recent issue of the journal Nature.

Source: UC Berkeley News Center

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12 comments
Joel Detrow
So this stuff is between ethanol and gasoline in terms of energy density, but the process can be tailored to produce stuff that's more like jet fuel or diesel? Seems pretty darn interesting. Maybe when we start to run out of oil, we'll use this. But by that time, either electrons will have surpassed and replaced liquid fuel, or the higher cost of producing liquid fuel will balance out with the much greater efficiency of these future vehicles.
RJB
Once again I feel that something is missing here.
If growers move from food production to the bio-materials required for this process the result will be soaring food prices and in poorer countries, famine and starvation.
These processes can only be viable if they use waste products and do not compete with the increasing demands for food.
Julian Skinner
This is sugar we are talking about, not real food.
chidrbmt
Yes but would more sugar be grown instead of food crops because of higher profits. We have seen huge areas of the Amazon and other areas cleared for growing sugar cane and palm oil for bio-fuel. As much of the corn crop is used for this Fed. gov't. subsidized, expensive joke that does drive up food costs for all,including the poor in this world.
Slowburn
re; Julian Skinner
what crops will be used to produce the sugar? In the USofA we make ethanol to be mixed with gas from corn and the price of tortillas went up in Mexico and elsewhere.
Using farmland to produce motor fuel is stupid.
Mick Perger
So is drilling for Coal Seam Gas in the farmlands of the World .
Joel Detrow
If we were to create a form of zoophytic plankton that produces excess amounts of sugar from photosynthesis (which will be child's play in just a few years), we could grow them out in the middle of the ocean - massive production capacity and no competition from land-based farming.
While we're at it, we can also grow algae out there as feedstock for cattle, and free up enough land-farming capacity to feed another 6 billion people (my basis? Enough food is grown annually to feed 11 billion people, but more than half of it goes to feeding animals). Since it would be zoophytic plankton, this technique would also sequester a significant amount of carbon from the atmosphere (ocean-going plankton already produce 2/3 of the atmosphere's oxygen).
nutcase
Depending on who you believe, obesity is a bigger problem than starvation. Millions of tons of perfectly good food are dumped every year. Seems to me most cases of famine are caused by fat people stealing from the starving people. Food marketing is a sickening business!
Will, the tink
If you can tune the size of the hydrocarbons to be like gasoline, diesel, and jet fuel, that's great! That makes it a pretty versatile base product but when he goes on to mention it could be used to make plastics as well, that is excellent! Now we can speed up the rate we are covering the oceans of the world! I would rather hear we have developed efficient ways to harvest the flotsam and turn it back into usable petroleum.
Fusiontek
Algae is already being used in Spain to grow fuel in areas which would not be suitable for farmland and which does not use food crops. They can grow it in the desert away from farmland and turn it into regular gasoline which has the highest energy density of all commonly used liquid fuels for cars.
An experimental plant in the US says they can create oil to refine into gasoline using this renewable method for about $85 per barrel which at todays prices is competitive with oil drilled and pumped from the ground.