A service providing mobile unit 1 comprised of a frame 2 forming a ring shape about a horizontal axis, movement-use wheels 4, 5 attached to the bottom part of the frame 2, a hydrogen storage tank insert pan 10 formed inside the frame 2, and a fuel cell 40 arranged inside the frame 2. Hydrogen is supplied to the fuel cell 40 from a replaceable hydrogen storage tank 20 inserted into the hydrogen storage tank insert part 10. A service providing space 3 having a ring-shaped inner circumference surface of the frame 2 as its outer edges is formed by the frame 2, and power can be supplied from the fuel cell 40 to a service providing unit installed inside the service providing space 3.

A redox flow battery system includes an anolyte having a first ionic species in solution; a catholyte having a second ionic species in solution, where the redox flow battery system is configured to reduce the first ionic species in the anolyte and oxidize the second ionic species in the catholyte during charging; a first electrode in contact with the anolyte, where the first electrode includes channels for collection of particles of reduced metallic impurities in the anolyte; a second electrode in contact with the catholyte; and a separator separating the anolyte from the catholyte. A method of reducing metallic impurities in an anolyte of a redox flow battery system includes reducing the metallic impurities in the anolyte; collecting particles of the reduced metallic impurities; and removing the collected particles using a cleaning solution.

A system for estimating a concentration of hydrogen in a fuel cell is provided. The system includes a hydrogen supply line supplying the hydrogen to the fuel cell and a time measurement sensor measuring a time duration from a point in time when an operation of the fuel cell ends to a point in time when the fuel cell restarts. A controller estimates an amount of air introduced into the fuel cell during the time duration using the measured time duration and estimates a concentration of hydrogen in the hydrogen supply line at the time of restarting the fuel cell based on the measured time duration and the estimated amount of introduced air.

Methods of determining concentrations and/or amounts of redox-active elements at each valence state in an electrolyte solution of a redox flow battery are provided. Once determined, the concentrations and/or amounts of the redox-active elements at each valence state can be used to determine side-reactions, make chemical adjustments, periodically monitor battery capacity, adjust performance, or to otherwise determine a baseline concentration of the redox-active ions for any purpose.

A fuel cell system includes a branch flow passage that branches from a supply pipe disposed outside an inner surface of a wall portion of a case enclosing a fuel cell stack, the branch flow passage communicating with the inside of the case. The outlet end of the branch flow passage is provided at a position lower than a ventilation hole in the installed state of the fuel cell system.

A fuel cell system is disclosed, which includes an anode recirculation loop comprising a fuel cell stack for generating power, a flowmeter for measuring a fuel flow rate of a fuel provided into the anode recirculation loop, a current measuring device for measuring a current drawn from the fuel cell stack, a recycle ratio measuring device for measuring a recycle ratio in the anode recirculation loop, and a processor for estimating a fuel utilization of the fuel cell stack based on the measured fuel flow rate, the measured current and the measured recycle ratio. Methods for operating the fuel cell system are also disclosed.

Provided is a method of operating a fuel cell system equipped with a fuel cell stack, a liquid hydrogen storage unit configured to store liquid hydrogen, a boil-off gas recovery unit configured to recover boil-off gas generated from the liquid hydrogen storage unit, and a hydrogen concentration estimation unit configured to estimate the hydrogen concentration at a hydrogen electrode in the fuel cell stack in a standby state, the method including: in a case in which a hydrogen concentration at a hydrogen electrode in the fuel cell stack in a standby state has become less than a predetermined value, supplying boil-off gas recovered by the boil-off gas recovery unit to the hydrogen electrode in the fuel cell stack.

A system and method for controlling a fuel cell system. An anode tail gas oxidizer (ATO) receives air and fuel exhaust streams from one or more fuel cell stacks of the fuel cell system. The one or more fuel cell stacks provide current to one or more loads. An ATO temperature signal is used to control at least one of a fuel inlet flow to the one or more fuel cell stacks or the current provided to the one or more loads.

A fuel cell hydrogen supply fault diagnosis system is provided. The system includes multiple fuel tanks that store hydrogen therein to supply the hydrogen and a fuel tank valve disposed at each of the fuel tanks and configured to be opened or closed to supply or shut off the hydrogen of the fuel tanks. A pressure sensor measures pressure in a fuel supply line that extends from each of the multiple fuel tanks to be integrally connected to a fuel cell stack. A supply amount estimator then estimates a supply amount of hydrogen supplied to the fuel cell stack and a consumption amount estimator estimates a consumption amount of hydrogen consumed in a reaction in the fuel cell stack or discharged therefrom. A fault detector then detects a hydrogen supply state.

A method of determining hydrogen deficiency of a fuel cell having a plurality of cell groups includes a reference value storage step of storing, as a reference value, a value of impedance in a state where hydrogen-off gas is discharged from the fuel cell and hydrogen gas and oxidant gas are supplied, a measured value calculation step of calculating a measured value of impedance based on a voltage of the cell groups and a current of the fuel cell, a corrected value calculation step of calculating a corrected value of impedance by correcting the measured value based on the reference value, and a determination step of determining that hydrogen deficiency occurs in a case where the corrected value exceeds a predetermined threshold.