A number of other companies are developing similar fuel cells, which promise to power electronics ten times longer than the lithium-ion batteries currently in use.
Also, users will be able to keep operating their computers by replacing the fuel cartridge or refilling with methanol fuel, instead of recharging the battery.
NEC initially plans to introduce a computer with a fuel-cell system able to run for five consecutive hours on a single cartridge of methanol fuel, but also plans to make a PC within two years that can run continuously for as long as 40 hours.
Fuel cells produce electricity without generating pollutants, through an electrochemical reaction that uses oxygen and hydrogen.
Japanese companies are shaping up to be pioneers in fuel-cell technology. NEC rival Toshiba Corp. said in March it developed the world's first prototype of a methanol-type fuel cell system to run notebook PCs. It also plans to commercialize its product in 2004.
Among other leading Japanese micro fuel cell developers are Sony Corp. (SNE), Casio Computer Co. and Hitachi Ltd.