Butanol has significant advantages over ethanol. For one, it has a much higher "energy density" than the weaker ethanol: Butanol has about 90 percent of the energy content of gasoline, compared with about 60 percent for ethanol.

Unlike ethanol, butanol does not mix with water, which means it will not corrode steel pipes and steel storage tanks, the infrastructure of the existing fuel-transportation network. Butanol also is compatible with aluminum vehicular fuel systems and does not need to be mixed with fossil fuels to spark ignition.

It is, the scientists say, a "drop-in" replacement for gasoline.

Making butanol

To make butanol, the researchers intend to use an electrochemical process to release electrons that will be consumed by microbes to convert carbon dioxide into butanol. The result of the process is the alcohol fuel.

Creager, the electrochemist, is researching chemical reactions that generate, store and utilize electricity. Some chemical reactions create electricity spontaneously — the way batteries work. Others need to be given a "push" to do so. The push is a catalyst, which is a substance that starts or speeds up a process. The bacteria will act as a biocatalyst in this process.

Creager's work will focus on creating an environment in which the microbes can live and access the electrons from the electrochemical source.