A system for capturing carbon dioxide in flue gas includes a fuel cell assembly including at least one fuel cell including a cathode portion configured to receive, as cathode inlet gas, the flue gas generated by the flue gas generating device or a derivative thereof, and to output cathode exhaust gas and an anode portion configure to receive an anode inlet gas and to output anode exhaust gas, a fuel cell assembly voltage monitor configured to measure a voltage across the fuel cell assembly, and a controller configured to receive the measured voltage across the fuel cell assembly from the fuel cell assembly voltage monitor, determine an estimated carbon dioxide utilization of the fuel cell assembly based on the measured voltage across the fuel cell assembly, and reduce the carbon dioxide utilization of the fuel cell assembly when the determined estimated carbon dioxide utilization is above a predetermined threshold utilization.

Methods and apparatus for detecting electrical short circuits in fuel cell stacks are provided. The methods involve supplying a reactant and an inert gas to a fuel cell stack and measuring the open circuit voltage of fuel cell assemblies in the fuel cell stack. The sensitivity of the methods can be adjusted to detect an electrical short circuit having a resistance at or below a particular threshold short-circuit resistance value, by using a suitable reactant concentration in the method. The methods can include determining a set-point reactant concentration that can be used to detect an electrical short circuit having a resistance at or below a particular threshold short-circuit resistance value.

Methods and apparatus for detecting electrical short circuits in fuel cell stacks are provided. The methods involve supplying a reactant and an inert gas to a fuel cell stack and measuring the open circuit voltage of fuel cell assemblies in the fuel cell stack. The sensitivity of the methods can be adjusted to detect an electrical short circuit having a resistance at or below a particular threshold short-circuit resistance value, by using a suitable reactant concentration in the method. The methods can include determining a set-point reactant concentration that can be used to detect an electrical short circuit having a resistance at or below a particular threshold short-circuit resistance value.

A disclosed fuel cell system includes a fuel inlet that receives a fuel gas from a fuel source, a gas analyzer that determines a composition of the fuel gas received by the fuel inlet, and a stack including fuel cells that generate electricity using the fuel gas received from the fuel source. The fuel cell system further includes a controller that controls at least one of a fuel utilization of the stack, a current generated by the stack, or a voltage generated by the stack, based on the composition of the primary fuel gas determined by the gas analyzer. The controller may control the fuel cell system by increasing or decreasing a fuel flow rate to thereby increase or decrease the voltage generated by the stack to maintain a predetermined target voltage or to maintain a predetermined rate at which usable fuel is supplied to the stack based on composition.

A redox flow battery system includes a redox flow battery that has a redox flow cell and a supply/storage system. The supply/storage system has first and second electrolytes for circulation through the redox flow cell. At least the first electrolyte is a liquid electrolyte that has electrochemically active species with multiple, reversible oxidation states. A secondary cell is operable to monitor concentration of one or more of the electrochemically active species. The secondary cell has a counter electrode, a flow passage that connects the counter electrode with the redox flow battery to receive the first or second electrolyte, a working electrode, and a separator. The working electrode is isolated from receiving the electrochemically active species of the first and second electrolytes except for a transport passage connecting the flow passage and the working electrode. The transport passage limits movement of the electrochemically active species to the working electrode.

An exemplary fuel cell ship is a fuel cell ship for propelling a hull by using electric power supplied from a fuel cell that generates electric power through an electrochemical reaction of fuel, and includes a compartment including an emission source of the fuel and a first detector arranged in the compartment to detect the fuel. If the first detector detects that a concentration of the fuel in the compartment is equal to or greater than a first threshold value, a power supply to a non-explosion-proof device in the compartment is stopped.

A fuel cell ship includes a cooling system that cools a fuel cell. The cooling system includes a cooling medium tank that accommodates a cooling medium, a cooling medium circulation pipe that circulates the cooling medium between the fuel cell and the cooling medium tank, a cooling tank internal gas detector installed in the cooling medium tank, a cooling tank internal gas discharge pipe connected to the cooling medium tank, and a cooling tank internal gas discharge valve installed in the cooling tank internal gas discharge pipe. The fuel cell ship includes a control unit that controls opening and closing of the cooling tank internal gas discharge valve. The control unit opens the cooling tank internal gas discharge valve when the cooling tank internal gas detector detects that the concentration of the fuel gas in the cooling medium tank is equal to or greater than a specified value determined in advance.

A fuel cell ship includes a propulsion device that generates propulsive force on a hull by electric power, an electric power supply unit that supplies the electric power to the propulsion device, and a degradation rate control unit that adjusts a degradation rate. The electric power supply unit includes a plurality of fuel cells that generate electric power by an electrochemical reaction of fuel and at least one storage battery.

A fuel cell ship includes a fuel cell that generates electric power by an electrochemical reaction of fuel, a propulsion device that generates propulsive force on a hull by electric power supplied from the fuel cell, a fuel supply pipe through which the fuel is supplied from a fuel tank housing the fuel to the fuel cell, a duct compartment that houses a part of the fuel supply pipe, a vent pipe that communicates with the duct compartment, and a fuel filling port that serves as an inlet for filling the fuel tank with the fuel. The fuel filling port is provided in the duct compartment.

This invention provides a system and a method for safe production of electrolyte at required concentration on site on demand where occasionally only water is needed to be filled up. The system includes two main units: a saturated electrolyte unit and a diluted electrolyte unit.