A method of operating a fuel cell system includes characterizing the fuel or fuels being provided into the fuel cell system, characterizing the oxidizing gas or gases being provided into the fuel cell system, and calculating at least one of the steam:carbon ratio, fuel utilization and oxidizing gas utilization based on the step of characterization.

A fire suppression system for producing oxygen-depleted air includes a fuel cell stack formed from a plurality of fuel cells for providing power to an associated load, and a controller coupled to the plurality of fuel cells, wherein the controller is configured to regulate current output from the plurality of fuel cells to maintain a prescribed percentage level of oxygen depleted air in an exhaust stream of the plurality of fuel cells. Further, a method for maintaining an updated polarization curve for a fuel cell includes commanding step-and-hold air flow commands and associated electrical current limit commands to the fuel cell system. Upon the fuel cell reaching each successive step-and-hold steady state condition, electrical current and voltage pairs are stored and plotted to form the real-time polarization curve. Upon characterizing the fuel cell polarization curve, a maximum power line is projected at the knee of the polarization curve, above which point the system is not permitted to operate without augmentation from the battery storage device. A maximum fuel cell power capability is continually prognosticated during run-time and is used to maximize operational robustness.

In various aspects, systems and methods are provided for integration of molten carbonate fuel cells with a Fischer-Tropsch synthesis process. The molten carbonate fuel cells can be integrated with a Fischer-Tropsch synthesis process in various manners, including providing synthesis gas for use in producing hydrocarbonaceous carbons. Additionally, integration of molten carbonate fuel cells with a Fischer-Tropsch synthesis process can facilitate further processing of vent streams or secondary product streams generated during the synthesis process.

In various aspects, systems and methods are provided for integration of molten carbonate fuel cells with a Fischer-Tropsch synthesis process. The molten carbonate fuel cells can be integrated with a Fischer-Tropsch synthesis process in various manners, including providing synthesis gas for use in producing hydrocarbonaceous carbons. Additionally, integration of molten carbonate fuel cells with a Fischer-Tropsch synthesis process can facilitate further processing of vent streams or secondary product streams generated during the synthesis process.

A fuel cell includes a cathode side and an anode side. An oxidant gas is fed to the cathode side. In the cathode side, an oxidant exhaust gas is generated by using the oxidant gas. A fuel gas is fed to the anode side. In the anode side, a fuel exhaust gas is generated by using the fuel gas. The oxidant exhaust gas and the fuel exhaust gas are discharged from an outlet of a mixed exhaust gas discharge pipe as a mixed exhaust gas. The dilution apparatus is connected to the outlet of the mixed exhaust gas discharge pipe. The dilution apparatus includes a stirring chamber and an opening. The stirring chamber communicates with the mixed exhaust gas discharge pipe and expands from the outlet of the mixed exhaust gas discharge pipe. The opening is provided in the stirring chamber to take in air.

Systems and methods are provided for using molten carbonate fuel cells (MCFCs) to reduce, minimize, and/or avoid CO.sub.2 emissions in a marine vessel environment. The systems and methods can include operation of MCFCs on a marine vessel under high fuel utilization conditions in order to provide power and capture CO.sub.2. The high fuel utilization conditions can allow for mitigation of CO.sub.2 over extended periods of time in spite of the challenges of performing CO.sub.2 mitigation in a potentially isolated environment such as a marine vessel. Additionally, the high fuel utilization can also reduce or minimize exhaust of fuels, such as methane, to the environment.

Captured carbon dioxide is converted into ultra-high purity hydrocarbons, particularly methane. A gas stream containing carbon dioxide is fed to a reactor containing both sorbent and catalyst, until the sorbent portions are substantially saturated with carbon dioxide; non-sorbed species are removed from the first reactor via vacuum and/or purge cycles with high-purity gas; hydrogen gas is introduced to the first reactor to a pressure above ambient; reactor temperature is raised to facilitate desorption of carbon dioxide; and the carbon dioxide is catalytically transformed with the hydrogen gas into methane by recirculating the gas through the reactor. Carbon dioxide adsorption and desorption occur within the sorbent portions, while methanation takes place on the catalytic portions assisted by the sorbent at a temperature substantially consistent with the desorption. Downstream upgrading steps may remove or reduce impurities to produce ultra-high purity methane for chemical vapor deposition or other processes.

The present invention provides a solid oxide fuel cell system capable of preventing excess temperature rises while increasing overall energy efficiency. The present invention is a solid oxide fuel cell system, including: a fuel cell module, a fuel supply device, a heat storing material, and a controller which, based on power demand, increases the fuel utilization rate when output power is high and to lower it when output power is low, and changes the electrical power actually output at a delay after changing the fuel supply amount. The controller has a stored heat estimating circuit for estimating the surplus heat based on fuel supply and on power output at a delay relative thereto. When a utilizable amount of surplus heat is accumulated in the heat storage material, the fuel supply is reduced so that the fuel utilization rate increases relative to the same electrical power.

Systems and methods are provided for capturing CO.sub.2 from a combustion source using molten carbonate fuel cells (MCFCs). At least a portion of the anode exhaust can be recycled for use as part of anode input stream. This can allow for a reduction in the amount of fuel cell area required for separating CO.sub.2 from the combustion source exhaust and/or modifications in how the fuel cells can be operated.

The present disclosure is directed to a fuel cell system for generating oxygen depleted air. The fuel cell system may include a fuel cell having an anode, a cathode, and an electrolyte positioned between the anode and the cathode. The cathode may be configured to receive an air flow and discharge an oxygen depleted air flow. The fuel cell system may further include a sensor configured to generate a first signal indicative of a presence of hydrogen in the oxygen depleted air flow and a controller in communication with the sensor and the fuel cell. The controller may be configured to detect the presence of hydrogen in the oxygen depleted air flow based on the first signal, and in response to detecting the presence of hydrogen in the oxygen depleted air flow, selectively cause a current density of the fuel cell to decrease and/or increase a flow rate of the air flow to the cathode.