Portable PCs get a fuel cell prototype

Toshiba Corporation has developed a prototype of a small form factor direct methanol fuel cell (DMFC) for portable PCs.

The new fuel cell currently sports an average output of 12W and a maximum output of 20W, and can achieve approximately five hours of operation with a single cartridge of fuel.

Toshiba says that methanol in a fuel cell delivers power most efficiently when it is mixed with water in a 3 to 6% methanol concentration - a concentration requiring a fuel tank that is much too large for use with portable equipment. Toshiba overcame this issue by developing a system that allows a higher concentration of methanol to be diluted by the water produced as a by-product of the power generation process.

This technology allows methanol to be stored at a much higher concentration, and achieves a fuel tank less than 1/10 the size of that required for storing the same volume of methanol in a 3 to 6% concentration. The current prototype operates for approximately five hours on 50cc of high concentration methanol.

In addition, Toshiba developed interface and electronic circuits to control the power supply, sensors to monitor methanol concentration and liquid level and a 'remaining quantity sensor' to tell users when they need to change the methanol fuel cartridge. All these components, and low power liquid and air transmission pumps, are controlled by a small DC-DC converter.

For the cell itself, Toshiba developed a new material that allows smaller cells, allowing for miniaturisation of the cell stacks.

Toshiba has also given the DMFC the same electrodes as found in lithium-ion batteries, allowing it to connect directly to a PC or other portable device in the same way as a lithium-ion battery.

Toshiba will continue development of its DFMC technology, with the aim of product commercialisation in 2004.

The current DMFC will be on display at Toshiba's booth at CeBIT, in Hall 1 6h2.