NOVELTY - A fuel cell system comprises a throttle valve (111) established in a flow path of a fuel offgas between a gas-liquid separator (110) and a cathode discharge pipe (107) that restricts a flow rate of the fuel offgas, where a pressure difference in an anode drainpipe causes the fuel offgas and the moisture to flow from an anode drain opening (109) to the gas-liquid separator, and the fuel offgas to flow from the gas-liquid separator to the throttle value.    USE - The fuel cell system is for power generation (claimed).    ADVANTAGE - The fuel cell system does not invite enlargements or complications of construction. Water discharge processing, improvement in fuel consumption, low-cost, and miniaturization of the fuel cell system is achieved, without requiring a scooping device that utilizes the power of the pump, a dilution pump, or a discharge hydrogen processing device. Discharging moisture to the outside of the fuel cell system by scooping up the water prevents flooding of the fuel cell, which stabilizes the performance of fuel cell.    DETAILED DESCRIPTION - A fuel cell system comprises:    (1) a fuel cell (100) that performs power generation by an electrochemical reaction of a fuel gas and an oxidant gas;    (2) a cathode discharge pipe that discharges oxidant offgas generated during power generation from the fuel cell;    (3) an anode drain opening that discharges fuel offgas and moisture generated during power generation from the fuel cell via an anode drainpipe;    (4) a gas-liquid separator that receives the fuel offgas and the moisture from the anode drain opening via the anode drainpipe, and separates fuel gas components and moisture of the fuel offgas; and    (5) a throttle valve established in a flow path of the fuel offgas between the gas-liquid separator and the cathode discharge pipe that restricts a flow rate of the fuel offgas, where a pressure difference in the anode drainpipe causes the fuel offgas and the moisture to flow from the anode drain opening to the gas-liquid separator, and the fuel offgas to flow from the gas-liquid separator to the throttle value.    An INDEPENDENT CLAIM is also included for a method of comprising:    (A) performing power generation by an electrochemical reaction of a fuel gas and an oxidant gas within a fuel cell;    (B) discharging oxidant offgas generated during power generation from the fuel cell via a cathode discharge pipe;    (C) discharging fuel offgas and moisture generated during power generation from the fuel cell with an anode drain opening via an anode drainpipe;    (D) receiving the fuel offgas and the moisture from the anode drain opening via the anode drainpipe, and separating fuel gas components and moisture of the fuel offgas with a gas-liquid separator;    (E) maintaining an opening in a flow path of the fuel offgas between the gas-liquid separator and the cathode discharge pipe with a throttle valve that restricts a flow rate of the fuel offgas; and    (F) establishing a pressure difference in the anode drainpipe that causes the fuel offgas and the moisture to flow from the anode drain opening to the gas-liquid separator, and the fuel offgas to flow from the gas-liquid separator to the throttle value.    DESCRIPTION OF DRAWING(S) - The figure illustrates the structure of a fuel cell system.    Fuel cell (100)    Cathode discharge pipe (107)    Anode drain opening (109)    Gas-liquid separator (110)    Throttle valve (111)