The main advantage of the fuel-cell battery is its very long life -- up to four or five times that of conventional dry-cell batteries.

"When the first methanol fuel cell-powered laptops come out in Japan, you'll certainly find the same Japanese products on sale in Europe six months to a year later," a French specialist said, adding that Japanese research was up to three years ahead of the United States and four-five years ahead of Europe.

Japanese car giants Toyota and Honda last year also became the world's first carmakers to start leasing fuel-cell cars, but they are still far from becoming part of everyday life because of their very high cost and the difficulty of transporting hydrogen.

Invented in 1839 by British physicist William Grove, the fuel cell produces electricity by combining hydrogen and oxygen, and its only by-product is harmless water vapour.

US President George W. Bush announced in his February budget he would spend more than 1.7 billion dollars on developing hydrogen as a power source over five years.

An American official, who preferred not to be named, pointed to "tremendous market potential" for portable fuel cells which could be used in electric wheelchairs, illuminated messageboards and signs, medical devices and digital cameras.

"There is a lot of definite market potential. My understanding is that it is certainly picking up in terms of the energy put into it," he said.

The small direct methanol fuel cell for mobile phones and laptop fuel-cell batteries developed by Toshiba and NEC could be commercially available within a couple of years, according to the companies, making the Japanese the first to market this technology.

Toshiba's prototype laptop battery, the world's first, unveiled in March, measures 275 millimetres (11 inches) by 75 millimetres and weighs 900 grams (one pound 13 ounces). It includes a 72-gram cartridge containing 50 cubic centimetres (one-and-a-half fluid ounces) of fuel.

Since then, Toshiba has also come up with the world's smallest fuel-cell battery for mobile gadgets such as telephones and personal digital assistants (organisers).

Genuinely pocket-sized, it has a fuel cartridge holding 25cc of high-concentration methanol, giving a life of 20 hours, roughly six times longer than lithium batteries.

In June NEC unveiled its own prototype fuel-cell battery for a notebook computer, which it aims to put on the market next year, with a model that can run for 40 hours to follow in 2005.

On Wednesday, Hitachi announced it was also working on developing a methanol fuel-cell battery for portable gadgets.

Several American companies including Duracell and Motorola have joined the race to develop small-scale applications, but most of the research effort and funding is directed towards automotive use where the United States and Japan are neck and neck, according to the American official.

But when it comes to the hopes riding on the fuel cell as the answer to global warming and greenhouse gas emissions from combustion engine vehicles and power generation, there are still major hurdles to overcome.

In addition to technical problems, there is a question over the real environmental benefit since most hydrogen is currently produced from natural gas, in a process resulting in carbon dioxide emissions, which contribute to global warming, although less than from a petrol engine.

"Our final goal of hydrogen production is hydrogen from water using renewable energies," said Ken Ichiro Ota, a specialist in the field from the National University of Yokohama.

SPACE.WIRE