Beer Makes a Better Biofuel Ethanol

At Cornell, researchers are turning beer into biofuel.

It’s not the beer that’s good to drink — but fermentation broth, which is chemically identical to the imbibing beer, from which the fuel ethanol is produced.

Using a mixed bag of microbes for specific chemical reactions, biological engineers have designed a process for upgrading ethanol into something even better — caproic acid, a carboxylic acid that’s a versatile fuel precursor. If scaled up, their process could integrate seamlessly into already-established ethanol production lines.

Largus Angenent, associate professor of biological and environmental engineering, led the study, which was published online June 13 by the Royal Society of Chemistry journal Energy and Environmental Science. The journal has promoted it as a "hot paper."

Ethanol is already a widely used biofuel, but it is expensive to produce because it is water soluble and requires distillation — an energy-intensive industrial process.

Usually made from corn in the United States, ethanol is produced in large reactors to ferment: enzymes convert cornstarch to sugar, and yeast converts the sugar to ethanol. Chemically identical to beer (and called that in the industry), the broth is not palatable — drinkable beer has had the yeast filtered out, for starters.