TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Components: A cooling fan (20) for cooling the fuel cell stack when the system driving is stopped is installed at the fuel cell stack. The heating unit comprises a hydrogen combustor (22) installed at the fuel supplying line and the air supplying line for heating fuel and air supplied to the fuel cell stack by using hydrogen generated from the fuel cell stack as a heating source. It may comprise a fuel kit installed at the fuel tank for heating fuel by using heat generated when fuel power is mixed with water stored in the fuel tank. The purge unit comprises a fuel recollecting line (48) connected between the fuel cell stack and the fuel tank for recollecting fuel discharged from the fuel cell stack into the fuel tank; and a recycling pump (46) installed at the fuel recollecting line for returning fuel remaining at each system to the fuel tank through the fuel recollecting line when a system driving is stopped. It comprises a fuel pump (28) installed at the fuel supplying line for pumping fuel; and a controller for returning fuel remaining at each system to the fuel tank by reversely driving the fuel pump when a system driving is stopped. It comprises a purge line connected between the fuel supplying line and the air supplying line and a three-way valve installed at a part where the purge line and the fuel supplying line are connected to each other. The purge line returns remaining fuel to the fuel tank by injecting air into the anode when a system driving is stopped. A power source of a battery drives the fuel cell system. Preferred Method: A battery is charged when a temperature of the fuel cell stack is higher than a set temperature in the electricity generating step.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Materials: The fuel kit comprises sodium hydroxide (NaOH) and boron hydride (BH3) powder as fuel powder.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Materials: The fuel kit comprises sodium hydroxide (NaOH) and boron hydride (BH3) powder as fuel powder.