The days of racing to get work done before the notebook battery runs out of juice may soon be over. NEC and two Japanese government-affiliated research institutes have developed a fuel cell for use in mobile devices.

This could mean notebook computer battery life times of several days become commonplace within the next few years.

Fuel cells create electrical energy by electrochemically reacting hydrogen and oxygen to produce water vapor and heat, without combustion. Some fuel cells require pure hydrogen as a fuel source; others can run on methane (natural gas) or other hydrocarbons.

The new fuel cell, announced on Thursday, is the initial result of collaboration between NEC, the Japan Science and Technology and the Institute of Research and Innovation. The cell makes use of carbon nanotubes, a much anticipated raw carbon material being eyed for uses from batteries to microprocessors that was discovered by NEC research fellow Sumio Iijima in 1991.

The experimental battery developed by Iijima's team uses a type of nanotube called a nanohorn, discovered by the team three years ago. They are being used because their horn-like shape and the way they group together mean they have a larger surface area, which makes them better suited for use as a fuel cell electrode.

The new fuel cell has about 10-times the energy capacity of a similar-sized high-density lithium battery, such as those used in notebook computers or portable electronic devices.

The prospect is exciting developers who are finding, as products get more and more complex, that the life of current batteries is becoming a hurdle to packing in greater technology. A recent example is that of 3G (third-generation) mobile telephones, currently on trial in Japan. The full motion video, audio downloading and high-speed data offered by the handsets come at the price of a battery life of less than one hour — something that is infuriating trial users.

Despite its unveiling this week, there is more research to be undertaken before nanotube-based fuel cells can become commercial products. NEC is hoping to commercialise the technology sometime between 2003 and 2005.