Biofuel Cell Could Replace Rechargeable Batteries

Scientists at Saint Louis University have invented a gadget fit for a James Bond movie. Imagine 007 sauntering up to the bar, ordering his trademark martini and, before taking a sip, topping off his cell phone with a few drops of alcohol to recharge the battery.

Researchers at Saint Louis University have developed a new biofuel cell - a battery that runs off of alcohol and enzymes - that could replace the rechargeable batteries found in everything from laptops to Palm Pilots. Instead of plugging into a fixed power outlet and waiting for a recharge, these new "batteries" may last up to a full month after they are charged instantly with a few milliliters of alcohol.

The new findings were presented today in New Orleans at the national meeting of the American Chemical Society, the world's largest scientific society.

Scientists have studied biofuel cells for nearly half a century, but the technology has not advanced to the point of practical use. Unlike batteries, which use expensive metals to catalyze the power-producing reaction, these cells use enzymes - molecules found in all living things that speed up the body's chemical processes.

"The only items consumed in a biofuel cell is the fuel and oxygen from air," said Shelley Minteer, Ph.D., a professor of chemistry at Saint Louis University who presented the research. "Given the proper environment, an enzyme should last for a very long time."

But finding that proper environment has been the problem. Enzymes are extremely sensitive to changes in pH and temperature, and even slight departures from ideal conditions can lead to inactivation of the enzymes, producing a short supply of power.

For years, scientists have struggled with creating just the right environment for this idea to really work. Saint Louis University researchers have overcome this major hurdle.

Minteer and her colleagues coated the electrodes of the fuel cell with a special material that has created the ideal environment for these enzymes to thrive and produce a surprising amount of long-lasting power. Other biofuel cells have only lasted a few days.

"With proper optimization, our biofuel cells could last up to a month without recharging, which means you wouldn't have to recharge a cell phone for 30 days," Minteer said.

Most other biofuel cells have used a type of alcohol known as methanol as a fuel, but Saint Louis University researchers chose a different kind known as ethanol because of its higher activity in the presence of enzymes. Ethanol is abundant and cheap to make, relying on the well-established corn industry for its production. Additionally, methanol is toxic to humans. The use of ethanol is what will allow consumers to recharge their cell phone with gin if they are in a pinch.

Minteer and her colleagues are focusing on small-scale applications, with prototypes no bigger than five square centimeters - about the size of a postage stamp. Researchers have tested 30 to 50 of the ethanol cells with a number of different fuels. They've had success with vodka, gin, white wine and flat beer.

The Saint Louis University team currently is pursing a patent for their work and recently received the very first Technology Transfer Proof-of-Concept Award from the University's Technology Transfer Office. While consumer applications may be few years off, Minteer said, "these results show that biofuel technology can work in the real world and truly would benefit consumers."

Saint Louis University is a Jesuit, Catholic university ranked among the top research institutions in the nation. The University fosters the intellectual and character development of 11,000 students on campuses in St. Louis and Madrid, Spain. Founded in 1818, it is the oldest university west of the Mississippi and the second oldest Jesuit university in the United States. Through teaching, research, health care and community service, Saint Louis University is the place where knowledge touches lives. Learn more about SLU at www.slu.edu.