Engineers working on new power systems to obviate the well-known battery problems afflicting mobile devices exhibited at Ceatec this week.

Boffins are developing direct methanol fuel cells (DMFCs), a technology which could one day replace rechargeable batteries for some applications, but work remains to be done.

DMFCs work by generating electricity when methanol mixed with water reacts with air through a thin sheet of plastic called a membrane. Engineers envisage future power cells that can provide power for long periods of time - perhaps enough to keep a laptop computer running all day - and that can be recharged with a simple refill of methanol.

Technology moves forward - slowly

At last year's show both Toshiba and Hitachi were showing prototype rechargers for cell phones based on the technology. Similar prototypes are back this year and the technology has developed enough for the companies to provide a little more technical detail.

Toshiba said its phone recharger can deliver enough energy to recharge a mobile phone battery five times. It is 11 centimetres square and 2cms thick. Hitachi's measures 12-x-7-x-2cms and can power a phone for five hours.

Companies are looking at DMFC-based cell phone rechargers as one of the initial applications for the technology. Japan's leading mobile network operators have said they are working on DMFCs with partners.

Laptops, hard drives, mobiles - and music players

They're also looking to build them into future miniaturised mobile phones to replace the battery. Both companies have prototype DMFC-based mobile phones on display. Toshiba's handset, which is a similar size to a conventional mobile phone, but about twice as thick, will run for about 2.5 times longer than a model powered by a lithium-ion rechargeable battery. Hitachi isn't providing specific details.

At its own booth, Toshiba exhibited several other devices with built-in fuel cells, including two hard-drive and flash-memory-based music players and a laptop computer. Prototype computers are already in the hands of a number of testers and the company is gathering data on their use. The DMFC looks similar to a laptop computer dock and is about the same size. It can power the machine for ten hours.

At least two years to wait

Expect to wait a couple of years to see these technologies in commercial PCs. After long promising to put fuel-cell based laptops on sale this year, both NEC and Toshiba said they are now aiming at 2007, describing regulatory, not technology, problems.

It's not legal to carry methanol on planes, so passengers would be forced to leave their fuel cells at the airport's security checkpoint. If the fuel cell was integrated into the computer or mobile phone then the entire device might have to be deposited every time travellers boarded a plane. International regulators estimate fuel cells won't be cleared for take-off until 2007.

Other companies are also aiming at similar launch schedules. When IBM's Japanese unit and Sanyo said earlier this year that they are working together on DMFC technology they predicted a 2007 or 2008 launch.

The bright side of the delay is that when the first fuel cells do come to market they should be smaller and more compact, thanks to a further two years development.