Methanol is nasty stuff. Careless distillation in many a backwoods still has caused it to blind the imbibers of "alternative" alcoholic drinks. Yet it has its uses, and one of them may be to restore fuel cells to their oft-vaunted role as the power packs of the future--but with a twist. The main role that has been discussed for fuel cells over the past few decades is as replacements for the internal-combustion engine. Their actual use may turn out to be to provide power for portable electronic devices.

That idea has not gone very far, either. But it has provoked another thought. What if it were possible to decompose the methanol without steam, and within the fuel cell itself? And that has, indeed, turned out to be possible. The resulting cells are nowhere near powerful enough to run cars, but they are plenty powerful enough to stand in for small batteries. What is more, they last far longer than batteries and when they do need recharging, it is the work of a moment.

Proton power
In a direct-methanol fuel cell (DMFC) the methanol is oxidised at the anode in the presence of liquid water. The reaction, which requires a catalyst, turns the methanol and water into protons and electrons (in other words, dissociated hydrogen atoms) and carbon dioxide. While the electrons pass along an external circuit as an electric current, the protons diffuse through a membrane to the cathode, where they recombine with the incoming electrons to form hydrogen atoms that react instantly with oxygen to make water. With pleasing symmetry the water is then channelled back to mix with the incoming methanol. Even though DMFCs produce carbon dioxide, the amount is small enough for the cells to count as a much greener technology than batteries. Some companies also think the new cells could be safer than batteries, which can burst into flame if short-circuited.

The efficiency of a DMFC is determined by its membrane. One of the most commonly used sorts is made of Nafion, a polymer developed by DuPont from a variation of Teflon. Nafion, however, can be expensive and it allows some methanol to seep through, which wastes fuel. Researchers are therefore trying to come up with more efficient membranes--and one group, led by Paula Hammond of the Massachusetts Institute of Technology (MIT), appears to have done so.