Alcohol powers fuel cell

Researchers from Saint Louis University have developed a fuel cell that uses enzymes rather than metal and can be recharged by adding a few milliliters of alcohol. Enzymes commonly speed up chemical reactions in living cells.

In the biofuel cell, the enzymes convert ethanol to acetaldehyde, removing a proton in the process. The proton is then added to nicotinimide adenine dinucleotide. The fuel cell's electrode strips the proton back off to produce electricity.

Key to the method is a polymer membrane modified with ammonium salts to increase the size of the membrane's pores and reduce its acidity. When enzymes are added to the membrane, they become trapped in the pores, which provide them with a stable environment.

Enzymes in the researchers' prototypes remained active for several weeks. Given the proper environment, enzymes theoretically last forever, according to the researchers.

Biofuel cells could eventually be used as a replacement for any rechargeable power source, including laptop and PDA batteries, according to the researchers.

Biofuel cells could be applied practically in five to ten years, according to the researchers. The work was presented at the 225th national meeting of the American Chemical Society in New Orleans on March 27, 2003.