IBM's Japanese unit and Sanyo have developed a prototype direct methanol fuel cell (DMFC) for notebook PCs that will probably be available around 2007 or 2008.

IBM is considering endorsing the fuel cell for use in its ThinkPad-branded laptop PCs. Electronics vendors hope that fuel cells will allow portable devices to run for longer without recharging than today's battery technologies.

DMFCs are being developed by a number of companies. They typically work by mixing methanol with air and water to produce electrical power. Only methanol is required as fuel, and the by-products are heat, water and carbon dioxide.

The fuel cell prototype, like others announced by Japanese companies such as Toshiba and NEC, clips on the back of the notebook and wraps around underneath it.

Sanyo's prototype weighs 2kg and can provide about eoght hours of power from a single 8in3 fuel cartridge containing pure methanol, according to Mitsuru Homma, group executive of Sanyo's Power Solutions Group.

The prototype system also contains a slim lithium ion polymer battery, which is built into the base of the unit under the notebook PC, and which is charged by the fuel cell even as the fuel supplies power to the PC.

While the fuel cell by itself supplies a maximum of 12W of power, the combination of the fuel cell with the polymer battery can supply a maximum of 72W – enough to meet the peak power demands of high-end ThinkPads.

Sanyo and IBM call this combination of fuel cell plus battery a hybrid design. They have adopted this approach to overcome DMFC technology's lack of power, the companies said.

Prototypes announced by other Japanese electronics companies generate between 10 watts and 20 watts of power, and developers at these companies are improving designs so that future DMFCs can produce up to about 30 watts.

However, this is still not enough to meet peak power needs of notebook computers running many applications, according to Sanyo.

IBM has been looking for DMFC designs that are durable and powerful, and decided to work with Sanyo on the hybrid design, and Sanyo's approach looks so far to be the most suitable for ThinkPads.

The ThinkPad line was developed in Japan at the Yamato Laboratory, which is part of IBM's PC Division. IBM will continue to work with Sanyo to develop the hybrid system further, and IBM is considering the technology for use with ThinkPads.