A Japanese company unveiled a breakthrough fuel cell for mobile computers based on so-called 'solid methanol' technology.

Kurita Water Industries claims that the technology solves the safety issues that have previously prevented widespread adoption of this volatile material as a power source.

Methanol fuel cells promise to give notebook PCs and mobile phones battery life measured in days or even weeks.

Companies including Toshiba, IBM and Sanyo are already experimenting with them in laptops and other products, but the material is highly toxic, flammable and can even cause explosions in confined spaces.

However, by combining the methanol with another, as yet undisclosed, compound Kurita claims to have created a safe methanol fuel cell. The methanol compound can be stored as powder or can be fashioned into a variety of shapes.

Getting the methanol out of the solid form is simple, according to the manufacturer, and can be achieved by simply adding water.

Kurita's mystery compound captures the methanol within a molecular lattice, and releases it on contact with water. Because the holding compound is unchanged by this process, according to the company, it can be recharged with methanol and reused.

The technology is an offshoot of Kurita's work in water treatment. The company realised that the compounds it was using to absorb environmental impurities from water could also store them.

It said it is also looking at the possibility of storing hydrogen, also used to power fuel cells, in the same way.

Kurita plans to demonstrate a prototype solid methanol fuel cell for mobile phones at the New Earth 2005 environmental technology exhibition, which begins today in Osaka, Japan. Kurita expects to make the technology available in the market by 2007.

However, by that time, it may have some competition. Japan's aviation authorities reportedly plan to relax their restrictions on liquid methanol in order to allow fuel cell devices on board aircraft. A Kurita spokesman did not respond to a request for comments today.

While improvements in the capacity of conventional battery technology have been very slow in recent years, fuel cells already offer five to 10 times the power-to-weight ratio of lithium ion batteries - the most powerful in common use.

Methanol fuel cells are notable for their low operating temperature, which makes them particularly suitable for handheld devices, but are seen as less useful for heavy-duty applications, such as vehicles, because of their low peak power output.