TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Component: The system further comprises:(1) a return mechanism that returns methanol aqueous solution discharged from the anode fluid channel to the methanol aqueous solution container;(2) a variable resistor;(3) a resist that detects a current flowing into the variable resistor from the power generating unit;(4) a voltage detection mechanism that detects a voltage of the power generating unit when the current flows in the variable resistor;(5) a liquid supply mechanism that supplies methanol aqueous solution to the anode fluid channel;(6) an air supply mechanism that supplies air to the cathode fluid channel;(7) an auxiliary power source that drives the air supply mechanism and the liquid supply mechanism;(8) a changeover mechanism that changes over between the auxiliary power source and the power generating unit on the basis of the voltage of the power generating unit;(9) a memory that stores information about an amount of methanol aqueous solution to be supplied in the power generating unit and information about an amount of air to be supplied in the power generating unit; and(10) a fuel tank that stores a fuel containing methanol.The characteristic-measuring mechanism measures current and voltage of the power generating unit by changing over resistors with different values connected in parallel.It comprises a load; a switch connected in series to the load and controlled to be opened or closed by a control signal subjected to pulse width modulation varying in the on/off time; the resistor; and the voltage detection mechanism.The auxiliary power source comprises a secondary battery that is charged when the electric power by the power generating unit is supplied in the external load or that is charged by the power generating unit at the time of end of power generation.The fuel cartridge comprises a memory that stores at least a concentration of the methanol aqueous solution; a spare fuel tank that stores a fuel to be replenished in the fuel tank; and a harmful substance trap that traps harmful substances in a gas in the fuel tank. The memory is fixed in the fuel cartridge.The trap includes a trap material container having a gas exhaust port, a gas diffusion passage that is formed in the trap material, a gas diffusion hole opened in a wall of the gas diffusion passage, and a harmful substance trap material filled in a space between the inner side of the trap material container and the wall of the gas diffusion passage.