The disclosure relates to a fuel cell system comprising a fuel cell stack for providing an electrical power P.sub.stack depending on a power demand, at least one auxiliary unit for operating the fuel cell stack with an electrical power consumption P.sub.aux, at least one consumer with an electrical power request P.sub.use, and a control unit for regulating the power demand as well as a method for controlling such a fuel cell system. It is provided that the control unit is configured to selectively operate the fuel cell system in a first operating mode or in a second operating mode, whereby the fuel cell stack is turned off depending on the operating mode upon the falling below of an optimal efficiency degree operating point P(η.sub.max) of the fuel cell system or a minimum operating point P.sub.min of the fuel cell stack. In particular, at least one auxiliary unit is also turned off in the first operating mode, when the optimal efficiency degree operating point decreases.

A benthic microbial fuel cell comprising: a nonconductive frame having an upper end and a lower end; a plurality of anodes, wherein each anode is a conductive plate having a top section and a bottom edge; a plurality of conductive, threaded rods disposed perpendicularly to the anode plates and configured to secure the top sections of the anodes to the lower end of the frame and to hold the plates in a substantially parallel orientation with respect to each other such that none of the plates are in direct contact with each other; and a plurality of cathodes, wherein each cathode is made of carbon cloth connected to the upper end of the frame.

An air handling system for a fuel cell stack includes a pneumatic storage device disposed downstream from a compressor, a flow control valve system configured to operatively couple an inlet of the pneumatic storage device to an outlet of the compressor and configured to operatively couple an outlet of the pneumatic storage device to an inlet of the fuel cell stack, and a controller configured to, in response to a power demand being greater than a threshold, cause the flow control valve to open to increase a flow rate of air from the pneumatic storage device to the fuel cell stack.

An all mechanically controlled, non-venting pressure control system for liquid hydrogen and liquid oxygen cryogenic tanks that requires no electrical control while managing disparate, non-stoichiometric reactant boil-off rates is provided. The pressure control system allows for the passive and repeatable stoichiometric consumption of hydrogen and oxygen boil-off from cryogenic tanks to form liquid water, while preventing the liquid hydrogen and liquid oxygen cryogenic tanks from overpressurizing and venting to the external environment. More particularly, in response to an overpressure condition in a first reactant reservoir, a backpressure regulator is opened, providing the overpressure first reactant to a fuel cell or other consumer, and providing a pilot signal to open a supply line from a second reactant reservoir to the consumer. Whether the second reactant is supplied from the second reactant reservoir as gas or a liquid is determined based on the pressure within the second reactant reservoir.

A method for diagnosing at least one fuel cell stack of a fuel cell device by way of a fuel cell diagnostic system includes: impressing a sinusoidal first and at least one sinusoidal second AC current into the fuel cell stack; recording a sinusoidal first and second voltage response of the fuel cell stack; evaluating the first voltage response and evaluating the second voltage response by way of an analytical algorithm for a differential impedance analysis; determining a first resistance, a second resistance and a capacitance of the fuel cell stack by specifying an equivalent circuit diagram for the fuel cell stack; and diagnosing the fuel cell stack on the basis of the determined first resistance, the determined second resistance and the determined capacitance, wherein the diagnosis is carried out in real time. A computer-readable storage medium and a fuel cell diagnostic system are also described.

A method for diagnosing at least one fuel cell stack of a fuel cell device by way of a fuel cell diagnostic system includes: impressing a sinusoidal first and at least one sinusoidal second AC current into the fuel cell stack; recording a sinusoidal first and second voltage response of the fuel cell stack; evaluating the first voltage response and evaluating the second voltage response by way of an analytical algorithm for a differential impedance analysis; determining a first resistance, a second resistance and a capacitance of the fuel cell stack by specifying an equivalent circuit diagram for the fuel cell stack; and diagnosing the fuel cell stack on the basis of the determined first resistance, the determined second resistance and the determined capacitance, wherein the diagnosis is carried out in real time. A computer-readable storage medium and a fuel cell diagnostic system are also described.

A fuel cell system has a first boost converter of a fuel cell, a second boost converter of a secondary battery, and a control unit. Output sides of the first boost converter and the second boost converter are connected so as to be the same potential. The control unit is configured to, when detecting failure of the second boost converter, cause input and output sides of the second boost converter to conduct, estimate an open circuit voltage of the secondary battery based on a state of charge, and execute electric power consumption by an accessory that operates by electric power supplied from the fuel cell when determining that the first boost converter is not able to boost the output voltage of the fuel cell to the open circuit voltage, and stops the electric power consumption by the accessory when determining that the first boost converter is able to boost.

A fuel cell system comprising: the fuel cell, the secondary cell and a controller, wherein, when a power generation pretreatment of the fuel cell is carried out, and when there is a request from the fuel cell to run the vehicle by output power of the secondary cell, the controller calculates discharge permission energy of the secondary cell, calculates a running permission delay request time from the discharge permission energy, which is a time necessary from the request to run the vehicle to the permission to run the vehicle, and measures a running permission delay time, which is a time that elapsed from the request to run the vehicle, and wherein, when the running permission delay request time value is smaller than the running permission delay time value, the controller permits the vehicle to run.

A system for generating electricity by pyrolyzing organic materials and feeding the pyrolysis fluid to a battery of fuel-cells. The system includes a pyrolysis reactor receiving organic materials and producing pyrolysis fluid. The fluid pyrolysis is then separated into a plurality of sub-mixtures, each provided via a respective separator output. A plurality of fuel-cell devices for generating electricity using different technologies are each coupled to a respective separator output. A controller controls the pyrolysis reactor, the separator device, and the plurality of fuel-cell devices according to a signal representing a demand for electric power, a signal representing cost of operating at least one of the pyrolysis reactor and the fuel-cell generator, and a signal representing minimum price of electric power.

A fuel cell system and a method for controlling the same may adjust generation of condensate water in a fuel cell by setting relative humidities and temperature and pressure conditions of the fuel cell so as to maintain a constant current density, and may alleviate performance deterioration of the fuel cell during operation by removing an excessive amount of the generated condensate water by injecting a cathode pressure impulse into the fuel cell.