Take a look, sounds promising. Here
Booze to Fuel Gadget Batteries
By Louise Knapp
02:00 AM Apr. 02, 2003 PT
Recharging your cell phone might one day become a simple matter of giving it a shot of tequila. A new breed of battery, fueled by alcohol, may become the power source of choice for portable electronics.
The battery is a variation on the biofuel cell. A standard fuel cell works by continuously changing the chemical energy of a fuel and an oxidant to create electrical energy. A biofuel fuel cell uses biological molecules -- in this case, enzymes -- to catalyze this reaction.
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Scientists have experimented with biofuel cells for years, but so far have been unable to engineer any that produce power for more than a few days.
The team behind the new battery has produced a constant current from its biofuel cell that is still going strong after two months. The researchers from Saint Louis University attribute their success to the fuel and to the environment they engineered for the enzymes that create the reaction that produces electricity.
Prior experiments have used methanol, another type of alcohol, as fuel. The Saint Louis team chose ethanol.
"A big advantage is that ethanol is not toxic like methanol, so it is easier to deal with," said team leader and assistant professor of chemistry Shelley Minteer.
Ethanol is also easier to get hold of than methanol -- as long as you're 21.
"You can use any alcohol. You will be able to pour it straight out of the bottle and into your battery," said team member Nick Akers, a graduate student. "We have run it on various types. It didn't like carbonated beer and doesn't seem fond of wine, but any other works fine."
Users won't have to deplete their liquor cabinets to keep their portables powered up, because all it takes is a few drops.
"Once the system is fully optimized, probably one to three drops of alcohol could power your cell phone for a month," Akers said.
Ethanol is also more active than methanol in the presence of enzymes -- the other essential ingredient in the new battery. Enzymes are molecules found in all living things that speed up the body's chemical processes. The Saint Louis team uses them as catalysts inside their biofuel cell.
"The enzymes we use are called dehydrogenase," Akers said. "We chose these because they strip protons from alcohol, and this is the reaction we need to get electricity."
Enzymes are not alive like cells or bacteria, but they have to be active for the biofuel cell to work. Keeping the sensitive catalysts active has caused problems in the past.
"Enzymes are fairly fragile and can be denatured if there are any changes in temperature or in the pH level (acidity or alkalinity)," Minteer said. "Given the proper environment, an enzyme should last for long periods of time. It is creating this environment in a fuel cell that researchers have struggled with for years."
Minteer and her team overcame this conundrum by coating the biofuel cell's electrodes with a polymer that contains tailored micelles, or pores, which provide an ideal microenvironment for the enzymes to thrive.
After two months of producing a constant current with its biofuel cell, the Saint Louis team is optimistic.
"There's no evidence that it is going to stop tomorrow. We don't know yet how long it's going to last. Could be six months," Akers said.
Scott Calabrese Barton, assistant professor in the Department of Chemical Engineering at Columbia University, said the Saint Louis team's test results seemed promising.
"It's a great accomplishment that they were able to turn ethanol into an oxidizer and get a stable current," Barton said.
However, he said the rate of power generated is also an important factor. "If it is low, then it's only suitable for certain applications, like sensors."
Minteer said the team is working on ways to increase their biofuel cell's power density. Currently the team's battery can produce 2 milliwatts of power per effective square centimeter. The average cell phone requires 500 milliwatts to operate.
The team is also looking at ways to produce a battery designed to fit today's portables that can also produce the necessary power output.
"It's like a radiator in car," Akers said. "It's folded, and all those ridges and folds give it a high surface area so the effective surface area becomes tremendously huge. You can do this on a micro scale so that the effective surface area of the electrodes is enormous. This is what we are doing in the designing process."
Akers is confident the team will have a working prototype in a year, and that the finished product will hit store shelves a year later.
