Safer Biofuels through Math

Monday, August 1, 2011 @ 06:08 PM gHale

Using plant-based biofuels instead of gasoline and diesel is crucial to curb climate change. But there are several ways to transform crops to fuel, and some of the methods result in biofuels that are harmful to health as well as nature.

It is possible to predict just how toxic the fuel will become without producing a single drop, according to a new study from the University of Copenhagen. This promises cheaper, faster and above all safer development of alternatives to fossil fuel.

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Among other things the calculations of the computer chemist show that biofuels produced by the wrong synthesis path will decompose to compounds such as health hazardous smog, carcinogenic particles and toxic formaldehyde. But the problem is they had to make the fuel before they could test it. Now there are ways to map out the fuel production via calculations on the computer.

“There is an almost infinite number of different ways to get to these fuels,” said Solvejg Jorgensen, a computational chemist at the Department of Chemistry in Copenhagen. “We can show the least hazardous avenues to follow and we can do that with a series of calculations that take only days.”

Chemically biofuel consists of extremely large molecules. As they degrade during combustion and afterwards in the atmosphere they peel off several different compounds. This was no big surprise. That some compounds are more toxic than others did not come as a revelation either but Jorgensen learned from her calculations there is a huge difference in toxicity depending on how the molecules assemble during production. She also could calculate very precisely the degradation mechanisms for a bio fuel molecule and do it fast.

Solvejg Jorgensen, right, conducted a study that shows using computational chemistry can predict and prevent harmful biofuel production.

Solvejg Jorgensen, right, conducted a study that shows using computational chemistry can predict and prevent harmful biofuel production.

“In order to find the best production method a chemist might have to test thousands of different types of synthesis. They just can’t wait for a method that takes months to predict the degradation mechanisms,” said Jorgensen. “On the other hand: For a chemist who might spend as much as a year trying to get the synthesis right it would be a disaster if their method leads to a toxic result.”

It seems an obvious mission to develop a computational tool that could save thousands of hours in the lab. But Jorgensen wasn’t really all that interested in biofuels. What she really wanted to do was to improve existing theoretical models for the degradation of large molecules in the atmosphere.

To this end she needed some physical analysis to compare to her calculations. Colleagues at the Department of Chemistry had just completed the analysis of two biofuels. One of these would do nicely. But Jorgensen made a mistake. And instead of adding just another piece to a huge puzzle she had laid the foundation for a brand new method.

“I accidentally based my calculations on the wrong molecule, so I had to start over with the right one. This meant I had two different calculations to compare. These should have been almost identical but they were worlds apart. That’s when I knew I was on to something important,” she said.

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