Can cars run on sugar?

Hydrogen-powered fuel-cell technology is certainly one of the alternative fuel technologies on the lips of everyone these days, from the DOE and President Bush—whose 2007 budget included a 46% spending increase for developing hydrogen technology research—to the local mechanic, and right down to the casual driver. But there are a number of obstacles blocking mainstream adoption–not the least of which is cost. However, researchers at Virginia Tech’s Oak Ridge National Laboratory (ORNL) and the University of Georgia believe a teaspoon of sugar could make the prices go down.

Using synthetic biology approaches, Professor Y.H. Percival Zhang, Barbara R. Evans, and Jonathan R. Mielenz of ORNL, and Robert C. Hopkins and Michael W.W. Adams of the University of Georgia, are using a combination of 13 enzymes never found together in nature to completely convert polysaccharides (sugar carbohydrates) and water into hydrogen, when and where that form of energy is needed.

“In nature, most hydrogen is produced from anaerobic fermentation,” said Zhang. “But hydrogen, along with acetic acid, is a co-product and the hydrogen yield is pretty low–only four molecules per molecule of glucose. In our process, hydrogen is the main product and hydrogen yields are three-times higher, and the likely production costs are low–about $1 per pound of hydrogen.”

Researchers believe the ingredients could be mixed in a car’s fuel tank. A car with an approximately 12-gallon tank could hold 27 kg of starch, which is the equivalent of 4 kg of hydrogen. The range would be more than 300 miles, Zhang estimates. One kilogram of starch will produce the same energy output as 1.12 kg (0.38 gallons) of gasoline.

“The next R&D step will be to increase reaction rates and reduce enzyme costs,” Zhang said. “We envision that in the future we will drive vehicles powered by carbohydrate, or energy stored in solid carbohydrate form, with hydrogen production from carbohydrate and water, and electricity production via hydrogen-fuel cells.”

Ralph Raiola

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