A fuel cell system and a method and apparatus for starting a fuel cell stack

The invention concerns fuel cell systems and methods for converting chemical energy of a fuel containing hydrogen into electricity. According to the invention, a fuel cell stack is provided having at least one anode and one cathode separated by a proton-exchange membrane. A fuel transport circuit feeds fuel to the fuel cell stack, and a temperature control system is adapted to control the temperature of the fuel cell stack by circulating a coolant medium through said fuel cell stack. The temperature control system includes a pump for circulating the coolant medium, a heater unit connected to a coolant transport circuit for heating the coolant with a PTC heater, a heat radiation unit connected to the coolant transport circuit for removing excess heat, and a temperature sensor. In response to a startup condition of the fuel cell stack, a controller is adapted to read a temperature signal indicative of the fuel cell stack temperature, to bypass the heat radiation unit, if the fuel cell stack temperature is below a first predetermined value, and to connect electric power generated by said fuel cell stack to be started-up to said PTC heater.