Skip to comments.Long-abandoned bacterial fermentation process converts sugar directly to diesel
Posted on 11/07/2012 12:40:41 PM PST by Red Badger
A long-abandoned fermentation process once used to turn starch into explosives can be used to produce renewable diesel fuel to replace the fossil fuels now used in transportation, University of California, Berkeley, scientists have discovered. Campus chemists and chemical engineers teamed up to produce diesel fuel from the products of a bacterial fermentation discovered nearly 100 years ago by the first president of Israel, chemist Chaim Weizmann.
The retooled process produces a mix of products that contain more energy per gallon than ethanol that is used today in transportation fuels and could be commercialized within 5-10 years. While the fuel's cost is still higher than diesel or gasoline made from fossil fuels, the scientists said the process would drastically reduce greenhouse gas emissions from transportation, one of the major contributors to global climate change. "What I am really excited about is that this is a fundamentally different way of taking feedstocks sugar or starch and making all sorts of renewable things, from fuels to commodity chemicals like plastics," said Dean Toste, UC Berkeley professor of chemistry and co-author of a report on the new development that will appear in the Nov. 8 issue of the journal Nature.
The work by Toste, coauthors Harvey Blanch and Douglas Clark, UC Berkeley professors of chemical and biomolecular engineering, and their colleagues was supported by the Energy Biosciences Institute, a collaboration between UC Berkeley, Lawrence Berkeley National Laboratory and the University of Illinois at Urbana Champaign, and funded by the energy firm BP. The late Weizmann's process employs the bacterium Clostridium acetobutylicum to ferment sugars into acetone, butanol and ethanol.
Blanch and Clark developed a way of extracting the acetone and butanol from the fermentation mixture while leaving most of the ethanol behind, while Toste developed a catalyst that converted this ideally-proportioned brew into a mix of long-chain hydrocarbons that resembles the combination of hydrocarbons in diesel fuel. Tests showed that it burned about as well as normal petroleum-based diesel fuel. Ads by Google
"It looks very compatible with diesel, and can be blended like diesel to suit summer or winter driving conditions in different states," said Blanch. The process is versatile enough to use a broad range of renewable starting materials, from corn sugar (glucose) and cane sugar (sucrose) to starch, and would work with non-food feedstocks such as grass, trees or field waste in cellulosic processes.
"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," Toste said.
The fermentation process, dubbed ABE for the three chemicals produced, was discovered by Weizmann around the start of World War I in 1914, and allowed Britain to produce acetone, which was needed to manufacture cordite, used at that time as a military propellant to replace gunpowder. The increased availability and decreased cost of petroleum soon made the process economically uncompetitive, though it was used again as a starting material for synthetic rubber during World War II. The last U.S. factory using the process to produce acetone and butanol closed in 1965.
Nevertheless, Blanch said, the process by which the Clostridium bacteria convert sugar or starch to these three chemicals is very efficient. This led him and his laboratory to investigate ways of separating the fermentation products that would use less energy than the common method of distillation. They discovered that several organic solvents, in particular glyceryl tributyrate (tributyrin), could extract the acetone and butanol from the fermentation broth while not extracting much ethanol. Tributyrin is not toxic to the bacterium and, like oil and water, doesn't mix with the broth. Brought together by the EBI, Blanch and Clark found that Toste had discovered a catalytic process that preferred exactly that proportion of acetone, butanol and ethanol to produce a range of hydrocarbons, primarily ketones, which burn similarly to the alkanes found in diesel.
"The extractive fermentation process uses less than 10 percent of the energy of a conventional distillation to get the butanol and acetone out that is the big energy savings," said Blanch. "And the products go straight into the chemistry in the right ratios, it turns out." The current catalytic process uses palladium and potassium phosphate, but further research is turning up other catalysts that are as effective, but cheaper and longer-lasting, Toste said. The catalysts work by binding ethanol and butanol and converting them to aldehydes, which react with acetone to add more carbon atoms, producing longer hydrocarbons.
"To make this work, we had to have the biochemical engineers working hand in hand with the chemists, which means that to develop the process, we had learn each other's language," Clark said. "You don't find that in very many places." Clark noted that diesel produced via this process could initially supply niche markets, such as the military, but that renewable fuel standards in states such as California will eventually make biologically produced diesel financially viable, especially for trucks, trains and other vehicles that need more power than battery alternatives can provide. "Diesel could put Clostridium back in business, helping us to reduce global warming," Clark said. "That is one of the main drivers behind this research."
Journal reference: Nature
UC Berkeley graduate student Zachary Baer works with a fermentation chamber to separate acetone and butanol (top clear layer) from the Clostridium brew at the bottom. The chemicals can be extracted and catalytically altered to make a fuel that burns like diesel. Credit: Robert Sanders
Rest In Peace, old friend, your work is finished.....
As usual, the breakthrough will be access to cheap feed stocks, not process. Even the process such as cellulose to sugar, is not ready.
The algae to fuel process failed when they determined that the algae feedstock needs fertilizer (natural gas) and phosphate which is mined. These inputs exceeded value of output.
Keep frackin while you still can.
Who cares about climate change? What about topsoil and water?
I'll bet these diots call themselves "environmentally conscious."
And again, it’s another ‘food to fuel’ conversion scheme. This process needs so much help you are better off sticking with regular diesel.
Oh, the other thing you need a bunch of is water to make this work. Water stress, of course, isn’t already a bigger problem than access to fuel already is.
I’ll be impressed when they can make either electrical or chemical energy without water, in scale.
Mayor Bloomberg says this conversion of sugar to energy is permissible, so long as it pumped into the vehicle in under-16 ounce servings.
All your corn and wheat are all belongs to us.
You thought it was bad when they used corn for diesel. Just wait until they go after our Crispy Cremes.
Not to worry. If this works as advertised the greenies will kill it. Their goal isn't clean and abundant energy, it is death to capitalism. Period.
Weird. I was just reading about butyl alcohol today.
I’m not a chemist and the article is short on specifics. Am I reading it right that the glyceryl tributyrate (tributyrin) is simply mixed with the fermentation results and then separates out the butanol and acetone from the mixture, leaving the ethanol behind with the bacteria and water?
It sounds like the catalyst part comes aftewards when they try to turn the butanol/acetone into diesel equivalent.
Wouldn’t the butanol by itself be useful as a gasoline replacement?
My (limited) understanding of the ABE process was that it was impractical because the butanol poised the bacteria befor they could generate high amounts of butanol, and then the resulting slurry was mostly water that had to be distilled out (with large energy inputs). It sounds like this tributyrin stuff could make ABE more useful for butanol production.
That will really suck.
Just how do sugar derived hydrocarbons burn cleaner than petroleum derived hydrocarbons? Magic carbon?
How much does sugar cost a pound and how much does diesel cost a pound add to the sugar the cost per pound to turn it into diesel.
Bzzzzzzzzt. You may have passed Chemistry, but you got an F in math.
But if you got a A in Poly-Sci and have an inlaw that is Nancy Pelosi, why son, your a Billionaire!
This nonsense of converting food to fuel has to stop.
That's what was missing from this article. What's the energy of the entire process - from planting and harvesting, delivery, conversion, waste disposal, and end product delivery?
They discovered that ...glyceryl tributyrate...could extract the acetone and butanol from the fermentation broth while not extracting much ethanol. Tributyrin is not toxic to the bacterium and...doesn't mix....
-------------------------------------------------------------- Wouldnt the butanol by itself be useful as a gasoline replacement?
Hummmm..Verry Intresting ...Thanks for the posting
Another foolish green fuel project to turn food into fuel. We already have a process of coal gasification that will turn coal into diesel.
Would that not cause a few strokes among the greenies?
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