Air-independent propulsion fuel cell system

A fuel cell system comprising:

• a fuel cell comprising an anode, a cathode, and an electrolyte membrane, wherein the anode and the cathode face each other across the electrolyte membrane, and the fuel cell is configured to generate power using a fuel and an oxidizing agent;
• a first supply path configured to supply the fuel to the anode;
• a first circulation path configured to supply unreacted fuel discharged from the anode to the first supply path;
• a second supply path configured to supply the oxidizing agent to the cathode, wherein the oxidizing agent comprises oxygen and nitrogen;
• a second circulation path configured to supply unreacted oxidizing agent discharged from the cathode to the second supply path;
• a third path configured to supply at least a portion of the unreacted fuel from the first circulation path to the second circulation path;
• a hydrogen separator in the third path and configured to separate and remove at least a portion of hydrogen from the unreacted fuel;
• a first chamber configured to supply the oxidizing agent to the second supply path;
• and
• a reuse path connecting the hydrogen separator to the first circulation path.

A method of operating a fuel cell system with a fuel cell including an anode, a cathode, and an electrolyte membrane, in which the anode and the cathode face each other across the electrolyte membrane, the method comprises:

• supplying a fuel to the anode through a first supply path;
• circulating unreacted fuel from the anode to the first supply path through a first circulation path;
• supplying an oxidizing agent to the cathode through a second supply path;
• circulating unreacted oxidizing agent from the cathode to the second supply path through a second circulation path;
• and
• supplying at least a portion of the unreacted fuel from the second circulation path to a third path which connects the second circulation path and the first circulation path.