Provided is a method of operating an electrolysis apparatus that can inhibit electrode degradation under a variable power supply. The method of operating an electrolysis apparatus includes: an energization step in which electrolysis of electrolyte is performed in an anode compartment including an anode and a cathode compartment including a cathode that are partitioned from each other by a membrane; a suspension step in which electrolysis of electrolyte in the anode compartment and the cathode compartment is suspended; and a discharge step of, in the suspension step, electrically connecting an electrolyzer of the electrolysis apparatus to an external load and adjusting a cell voltage to 0.1 V or less in 5 hours or less.

There are provided an electrolyzer gasket, which can accommodate and hold a separator inside an electrolyzer by a simple handling, can more surely prevent leakage of an electrolyte and an electrolytically generated gas from the inside of the electrolyzer, can keep the separator in such a state that the separator is held at a position that is in contact with one of electrodes and is located along the electrode and therefore can suppress damage of the separator and makes it possible to use the separator stably for a long period of time, and an electrolyzer. An electrolyzer gasket including a picture-frame-shaped thin-plate-like frame having a first surface being in contact with an anode metal frame and a second surface being in contact with a cathode metal frame, wherein the gasket has a structure in which a notch having a difference in level of approximately the same thickness as the thickness of the separator, the notch obtained by thinly scraping off, in a uniform thickness, a region including the edge on the anode chamber side or the cathode chamber side, is formed on any one of the first surface and the second surface, and the edge part of the separator is accommodated and held in the notch, and an electrolyzer using the electrolyzer gasket.

A method for controlling a hydrogen generation system includes controlling the potentials of an electrode for oxygen generation and an electrode for hydrogen generation included in an electrolyzer so that the potential change is smaller in the electrode for oxygen generation or the electrode for hydrogen generation having a larger deterioration rate than in the electrode having a smaller deterioration rate.

A method for controlling a hydrogen generation system includes controlling the potentials of an electrode for oxygen generation and an electrode for hydrogen generation included in an electrolyzer so that the potential change is smaller in the electrode for oxygen generation or the electrode for hydrogen generation having a larger deterioration rate than in the electrode having a smaller deterioration rate.

A membrane-electrode-gasket assembly for alkaline water electrolysis, the assembly including: a separating membrane having first and second membrane faces; a first electrode arranged in contact with the first membrane face; and an insulating gasket holding the membrane and the electrode as one body, the gasket including: first and second faces for contacting with anode- and cathode-side frames respectively; a slit part opening toward an inner side of the gasket and receiving the entire peripheries of the membrane and the electrode; first and second parts facing with each other across the slit part; and a continuous part arranged on an outer periphery side of the slit part, uniting the first and second parts into one body, and sealing an outer periphery end of the slit part, wherein the first and second parts sandwich therebetween to hold the entire peripheries of the membrane and the electrode received in the slit part into one body.

An anode-side half cell for an electrochemical cell of an electrolytic apparatus for carbon dioxide electrolysis and/or carbon monoxide electrolysis, having a separator in the form of a diaphragm, which has an anode-side separator surface and a cathode-side separator surface opposite the anode-side separator surface; a catalyst layer, which has a first catalyst surface and a second catalyst surface opposite the first catalyst surface, the first catalyst surface facing the anode-side separator surface; and a fluid-permeable anode plate, which has a first anode surface, the first anode surface facing the second catalyst surface.

An anode-side half cell for an electrochemical cell of an electrolytic apparatus for carbon dioxide electrolysis and/or carbon monoxide electrolysis, having a separator in the form of a diaphragm, which has an anode-side separator surface and a cathode-side separator surface opposite the anode-side separator surface; a catalyst layer, which has a first catalyst surface and a second catalyst surface opposite the first catalyst surface, the first catalyst surface facing the anode-side separator surface; and a fluid-permeable anode plate, which has a first anode surface, the first anode surface facing the second catalyst surface.

Methods and systems related to the field of electrolyzers are disclosed. An electrolyzer assembly is disclosed which includes a stack of cells, a plurality of polar plates in the stack of cells, a plurality of flow fields between the plurality of polar plates, a conduit fluidly connecting flow fields in the plurality of flow fields, an electrically conductive fluid in the conduit, a plurality of insulating layers arranged between a conductive surface of the plurality of flow fields and the conduit, and a plurality of openings in the plurality of insulating layers providing a plurality of fluid connections between the conduit and the plurality of flow fields.

Methods and systems related to the field of electrolyzers are disclosed. An electrolyzer assembly is disclosed which includes a stack of cells, a plurality of polar plates in the stack of cells, a plurality of flow fields between the plurality of polar plates, a conduit fluidly connecting flow fields in the plurality of flow fields, an electrically conductive fluid in the conduit, a plurality of insulating layers arranged between a conductive surface of the plurality of flow fields and the conduit, and a plurality of openings in the plurality of insulating layers providing a plurality of fluid connections between the conduit and the plurality of flow fields.

A method of producing hydrogen using a water electrolysis system comprising at least an electrolyzer and a purifier for removing oxygen in a hydrogen gas generated in the electrolyzer. The method includes controlling a concentration of oxygen in a hydrogen gas to be introduced to the purifier to be constantly less than 0.5 volume % when the electrolyzer is operated at least under a current density of 0.5 kA/m.sup.2 or greater; and further controlling Ob/Oa to be less than 10.0, where Oa represents the concentration of oxygen in the hydrogen gas to be introduced to the purifier when the electrolyzer is operated under a current density of 2.0 kA/m.sup.2, and Ob represents the concentration of oxygen in the hydrogen gas to be introduced to the purifier when the electrolyzer is operated under a current density of 0.2 kA/m.sup.2.