November 17, 2006

Ethanol Batteries

High-energy cocktails

Many cell phone users, including myself, have had the frustrating experience of needing to make a call just as our phone battery loses it charge; unless you’ve brought your phone charger or a spare battery with you, you’re out of luck for the moment. Imagine the same situation happening while you are out at a bar or restaurant, but this time you are able to recharge your phone easily and quickly, needing no special equipment. Instead, you take a thimbleful of the cocktail or wine in front of you, pour it into a special fuel cartridge on your phone, and end up with enough of a charge to last you for the next month.

While this technology is not yet available, a team of researchers at Saint Louis University in St. Louis, Missouri, with the backing of the company they founded, is working to make it a reality. Once their invention, known as Stabilized Enzyme Biofuel Cells (or SEBC), is fully developed and tested, consumers will not only have a more convenient way to keep their cell phones and laptops charged, but will be protecting the environment at the same time.

Fuel for Thought
As part of the search for renewable and less environmentally damaging sources of energy, scientists have begun developing alternatives to traditional batteries, which rely on heavy metals and toxic chemicals to create an electrical charge. Along with the problem of recycling these batteries safely, there is also a need to improve on their relatively poor efficiency and the limited number of times they can be recharged.

Scientists are looking at an alternative to traditional batteries called biofuel cells. Biofuel cells use the energy released during the chemical reaction between hydrogen and oxygen, which produces water, to generate electricity. Some biofuel cells use pure hydrogen as a fuel, although it is not ideal since it can be explosive. Fuels that can be catalyzed to produce hydrogen, such as alcohols made from the fermentation of corn (namely, methanol and ethanol), provide a more stable source of energy.

However, scientists have run into difficulty using these alcohols as well; the enzymes needed to remove hydrogen from the fuel are notoriously finicky. They don’t respond well to changes in temperature or pH level, and can become inactive after a short period of time. One approach to this problem was to bind the enzymes to the battery electrode to make them more stable, but there was still a limit to how long the enzymes stayed active.

Enzyme in the Membrane
Looking at this issue, a research team at Saint Louis University, headed by Assistant Professor of Chemistry Dr. Shelley Minteer, developed a way to keep the enzymes active longer. They created a polymer with a neutral pH that has special pores small enough to trap enzymes, but large enough for alcohol to pass through them. They applied this polymer to the battery electrode, essentially creating a membrane, like those found in cells, in which the enzymes became embedded. They discovered that the enzymes fared much better in this environment, and could last for a few months, instead of a few days.

Upon further experimentation, Dr. Minteer and her colleagues created batteries that have a lifetime of two years, and can be run on various types of alcohol, including vodka, gin, white wine, and flat beer. In 2002, Dr. Minteer and graduate student Nick Akers filed a patent for the SEBC, and in late 2003, founded Akermin Inc., a company that will capitalize on the technology once it is fully developed.

Although this research has so far been limited to batteries for small electronics, in the future it could have an impact on how larger machines, including vehicles, are powered; because both the enzymes and the biofuel can be grown and processed as needed, the SEBC could provide an invaluable alternative to non-renewable energy sources. Who knows: one day you might order “one more for the road”—not for yourself, but for your car. —Morgen Jahnke

More Information about Ethanol Batteries…

Thanks to reader Matt Eliason for suggesting today’s topic!

Dr. Shelley Minteer was interviewed about her work on the April 15, 2006 episode of The Science Show on ABC Radio National.

Dr. Minteer’s official bio is on the Saint Louis University Web site.

Read about Akermin Inc. on their official Web site, or in the St. Louis Business Journal here or here.

cover art

You can purchase Dr. Minteer’s book Alcoholic Fuels from Amazon.com or the C.H.I.P.S Web site.

For further information about biofuel cells, go to the New Scientist Web site or the Science Blog.