Handling of variable and unpredictable gas composition changes to maximize health and performance of fuel cell systems

A fuel cell system comprising:

• a fuel inlet configured to receive a primary fuel gas from a first fuel source;
• a gas analyzer configured to determine a composition of the primary fuel gas received by the fuel inlet;
• a stack comprising fuel cells configured to generate electricity using the primary fuel gas received from the first fuel source;
• and
• a controller configured to control at least one of a fuel utilization of the stack, 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,
• wherein the controller is further configured:
• to determine a primary fuel gas availability based on the composition of the primary fuel gas determined by the gas analyzer;
• to determine that the fuel availability of the primary fuel gas is below a minimum primary fuel gas availability threshold;
• to control the fuel cell system to generate a blended fuel gas having an increased availability by blending the primary fuel gas with a secondary fuel gas received from a second fuel source, the secondary fuel gas having a known fuel gas availability that is higher than the minimum primary fuel gas availability threshold;
• to adjust a blended fuel gas flow rate, based on the determined primary fuel gas availability, to thereby maintain a predetermined rate at which the blended fuel gas is supplied to the stack;
• and
• to supply the blended fuel gas to the stack.

A fuel cell system comprising:

• a fuel inlet configured to receive a primary fuel gas from a first fuel source;
• a gas analyzer configured to determine a composition of the primary fuel gas received by the fuel inlet;
• a stack comprising fuel cells configured to generate electricity using the primary fuel gas received from the first fuel source and a secondary fuel gas received from a second fuel source with a known fuel availability, the primary fuel gas and the secondary fuel gas forming a blended fuel gas for the stack;
• a controller configured to control at least one of a fuel utilization of the stack, 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 and the secondary fuel gas with the known fuel availability, by controlling a flow rate of the secondary fuel gas to satisfy a minimum blended fuel gas availability threshold;
• a fuel control valve;
• and
• a fuel flow meter,
• wherein the controller is further configured to control generation of the blended fuel gas by performing at least one of the following operations:
• using a closed loop control method to blend an amount of the secondary fuel gas with the primary fuel gas to thereby generate the blended fuel gas having a predetermined minimum blended fuel gas availability or minimum lower heating value;
• using a closed loop control method to control a flow rate of the primary fuel gas, via the fuel control valve and the flow meter, to thereby a maintain a predetermined flow setpoint of the primary fuel gas;
• or
• using an open loop control method to set a first constant flow rate of the primary fuel gas and to set a second constant flow rate of the secondary fuel gas.