You may be able before long to charge your cell phone by carbo-loading it, if a Virginia Tech team's research pans out. According to a paper published Tuesday in the journal Nature Communications, a group of researchers have found a way to harness the energy in a simple, inexpensive carbohydrate to generate electrical power. The resulting "biobattery" can hold more juice per ounce than similarly sized lithium ion batteries, using only biodegradable compounds.
"Sugar is a perfect energy storage compound in nature," said Virginia Tech biological systems engineer Y.H. Percival Zhang, who led the study. "So it's only logical that we try to harness this natural power in an environmentally friendly way to produce a battery."
Zhang et al's work doesn't necessarily mean you'll be able to top off your electronics by grabbing a sugar packet from the counter in your favorite cafe. The team's biobattery uses a different carbohydrate as its energy source: maltodextrin, a commonly used food additive.
Table sugar, or sucrose, is what the chemists call a "disaccharide": it consists of two saccharide molecules, glucose and fructose, bonded together. Maltodextrin is a polysaccharide, a larger polymer containing anywhere from three to twenty glucose molecules. Maltodextrin combines some of the aspects of both sugar and starch, and is often used in edible items like baked goods and beer to improve texture.
Maltodextrin is also a pretty good delivery system for biologically stored energy, which Zhang's team tapped by using a combination of enzymes not found together in nature to strip electrons from the maltodextrin as the carbohydrate combines with oxygen, creating electricity and water.
Maltodextrin is generally produced from starch through a process called hydrolysis, using enzymes to beak starch's very long chains of glucose down to size. That introduces a potential conflict: starches and sugars are a basic human foodstuff. Widespread adoption of maltodextrin batteries, if the tech proves its worth, might well be one more bit of demand that raises food prices for the world's poorest.
(Probably not coincidentally, Zhang's lab at Virginia Tech published a report on a potential solution to that issue last year, in which his team used a different group of enzymes to break down cellulose, a carbohydrate that's inedible to humans and that's found abundantly in waste plant material, into starch.)
It's premature to worry about your sugar batteries taking food out of the mouths of the hungry: though Zhang says his team's battery might be commercially available in as little as three years, the technology still has to prove itself outside the laboratory. Even if it succeeds, it would take a while for maltodextrin demand to ramp up to levels where it competes with current uses like beer additives.
Nonetheless, an interesting step toward a possible future of running some of our gadgets on biofuels. And if you're worried about food security (as you should be), you can always plant potatoes in your yard and homebrew your own maltodextrin.