The cell is not designed to replace batteries in mobile devices, but instead it is intended to provide an alternative power source to charge batteries, providing greater freedom for mobile gear users, said a Toshiba spokesman.

The portable cell that fits into the palm of the hand weighs 130 grams. With fuel cartridge, it measures 100-mm by 60-mm by 30-mm. It generates an average output of 1-watt for 20 hours. One cartridge can charge the lithium ion battery in a cellphone about six times, according to Toshiba.

Toshiba announced a prototype fuel cell system for notebook PCs in March. The prototype featured a dilution system that utilizes the water produced as a by-product of the power generation process to dilute methanol fuel to the desired concentration. This eliminates the needs to carry diluted methanol.

The fuel cell realizes the most efficient power generation with a 3 percent to 6 percent concentration of methanol. The dilution system uses almost a 100 percent concentration of methanol, which means a fuel tank meansures only one- tenth as big as the tank that stores thin fuel liquid.

The prototype fuel cell will be demonstrated at CEATEC JAPAN 2003 to be held in Makuhari near Tokyo October 7 to 11.