Due to the limited capacity of secondary batteries, the operating period of notebooks is short. A fuel cell (22) in connection with a hydride storage unit allows for significantly longer periods of operation. The arrangement of the fuel cell (22) within a display unit (2) allows for the flexible use of the traditionally two module installation bays (11, 12) of the main unit (1) of a portable computer system. Even if one of the module installation bays is occupied by one of the insertable hydride storage tanks in the form of a module, another module installation bay (12) is available to the user for insertion of drives, such as CD-ROM. The flat arrangement of the fuel cell (22) in the display unit (2) folded open into a vertical position ensures a high efficiency of the fuel cell (22).