Fuel cell technology for laptop has drawn one step close with the publication by a standards group of requirements for the technology.

The new guidelines from the Mobile PC Extended Battery Life Working Group, which includes Intel and STMicroelectronics, should help speed the development of longer lasting power sources for laptops. Their development is widely seen as vital to the growth of Wi-Fi and other wireless Internet technologies.

The development of wireless power supplies has lagged mobile Internet efforts. Batteries still last only a few hours in notebook computers before needing a recharge, while fuel cell systems could last for days, the group says. An Intel spokeswoman also made it clear that the company sees the fuel cell research as important for its Centrino wireless chipset.

Intel's popular chip package has fueled a surge in laptop sales in recent years and popularised the use of the wireless Web in coffee shops, airports, and other places outside the office and home.

The guidelines will help developers of fuel cells for mobile devices, like Millennium Cell and Tekion Solutions, by outlining key technical requirements for fuel cells to work well inside a mobile PC.

Fuel cells operate differently than batteries. One of the troublesome aspects of using fuel cells in mobile PCs is they provide a steady supply of power, whereas power demand in notebook computers is very uneven, driven by bursts of power demand as different parts of the notebook, like the DVD drive or hard drive, are tapped for use, the group said. The stored charge of a battery matches this kind of uneven power demand, but fuel cells need careful management.

Batteries also require fewer supporting components inside a mobile PC, the group said. A fuel-cell system includes the fuel cell itself, as well as supporting systems similar to a car engine, like a fuel pump, cooling system, and a starter battery.

The guidelines cover these issues as well as electrical, mechanical, control, thermal, environmental and regulatory aspects of fuel cell designs for mobile PCs, including those made for use inside a device, and external fuel cells.