Although PC vendors are eager to breathe new life into their aging systems, at least one highly anticipated technology may not hit the mainstream as soon as hoped.Micro fuel cell technology has been aggressively touted as a convenient and easily renewable power source. Fuel cells generate electricity through a chemical reaction between oxygen and a fuel such as hydrogen or methanol, and they can power a notebook for up to 40 hours. Yet it\u2019s unlikely that large numbers of users will be "filling up" notebook PCs, PDAs and other mobile devices anytime soon. Adoption roadblocks include fuel cell size, the lack of a universal standard, customer education issues, and safety and security concerns as users would be bringing devices containing volatile fluids into buildings and onto airplanes and other vehicles.All of these drawbacks have made many notebook vendors skeptical about fuel cell technology. "Fuel cells are not likely to be relevant for mainstream notebooks for several years," says Jay Parker, notebook products manager for Dell. He believes it will be hard to change notebook users\u2019 ingrained habits. "Customers will need to become acclimated to refueling rather than recharging," he says. However, Dell is continuing to evaluate various fuel cell technologies, notes Parker.Howard Locker, chief architect of IBM\u2019s PC division, says fuel cells will never become popular because users will have to pay for each refill. "Today, when you charge a battery, it\u2019s free," he says. "Folks are already at nine hours on a battery, so how much better does it need to get?" Locker\u2019s opinion of fuel cell technology: "It\u2019s a nonstarter."Yet two notebook makers are undeterred and plan to push ahead with fuel cell technology. NEC has announced it will start selling fuel cell-equipped notebooks by the end of 2004, and Toshiba says it will follow the same path in 2005.