Alcohol gives new life to thirsty portables

Radical new battery technology promises much more power for portable devices, according to NEC and Sony. Both companies are developing fuel cells that turn methanol directly into electricity and could have many times the capacity of current lithium-ion batteries.

Although the basic physics is not new, both companies have turned to nanotechnology to overcome some of the problems that have stopped fuel cells becoming consumer products. The basic innovation is the use of recently discovered forms of carbon, called fullerenes, where the atoms form a geometric mesh that can be formed into different shapes.

NEC developed its design in conjunction with the Japan Science and Technology Corporation and the Institute of Research and Innovation. It uses nanohorns, fullerene sheets rolled into microscopic cones, incorporating platinum atoms to catalyse the electrochemical reaction that rips methanol apart. Such cells are around 20 percent more efficient than existing fuel cells, says NEC, and can have ten times higher power per weight ratios than lithium-ion at a comparable cost. The company predicts this could give mobile phones and laptops many weeks of operation between recharging, and expects to be in production between 2003 and 2005 in time for the higher power demands of next-generation devices.

Sony has yet to say when it expects to commercialise its technology, which uses a similar complex carbon structure. Unlike earlier designs that required high temperatures to work, the company says, electrodes using fullerenes are effective for the range of temperatures encountered by personal portable devices. They also exhibit a far smaller lag between demand and supply; while other fuel cells take many seconds to generate power, fullerene technology kicks in within one to two seconds.

Both companies have yet to sort out practical issues such as the recharging mechanism: unlike current batteries, fuel cells are replenished by injecting fresh methanol. However, the technology promises to be particularly green: the products of the cell are electricity, water and carbon dioxide, and methanol, like most small alcohol molecules, is notoriously easy to produce.

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