Abstract: A water electrolysis system includes a water electrolysis apparatus, a gas-liquid separating apparatus, a hydrogen supply line, a water level detector, and a current regulator. The water electrolysis apparatus is to electrolyze water to generate oxygen and high-pressure hydrogen having a higher pressure than a pressure of the oxygen. The gas-liquid separating apparatus is disposed upstream of the water electrolysis apparatus in a gravitational direction to separate moisture contained in the high-pressure hydrogen. The hydrogen supply line is to supply the high-pressure hydrogen discharged from the water electrolysis apparatus to the gas-liquid separating apparatus. The water level detector is configured to detect a water level in the gas-liquid separating apparatus. The current regulator is configured to regulate a current to be applied to the water electrolysis apparatus based on the water level detected by the water level detector in the gas-liquid separating apparatus.

Abstract: A water electrolysis system includes a water electrolysis apparatus, a low-pressure gas-liquid separator, a high-pressure gas-liquid separator, water pipe, and a decompression water supply device. The high-pressure gas-liquid separator separates the hydrogen received from a cathode of the water electrolysis apparatus and permeation water that has permeated from the anode. The water pipe connects the high-pressure gas-liquid separator and the low-pressure gas-liquid separator and is used for returning the water from the high-pressure gas-liquid separator to the low-pressure gas-liquid separator. The decompression water supply device is arranged at the water pipe and is to decompress the water discharged from the high-pressure gas-liquid separator.

Abstract: A high-pressure water electrolysis apparatus includes a plurality of unit cells each having an anode separator, a cathode separator, and a membrane electrode assembly which is sandwiched between the anode separator and the cathode separator. The membrane electrode assembly includes a solid polymer electrolyte membrane, and an anode current collector and a cathode current collector which are disposed respectively on opposite sides of the solid polymer electrolyte membrane. An electrically-conductive member is interposed between the cathode separator and disc springs and between a plate member and the cathode current collector so as to integrally extend from a region between the cathode separator and the disc springs to a region between the plate member and the cathode current collector. The electrically-conductive member includes an electrically-conductive path which electrically connects the cathode separator with the cathode current collector.

Abstract: A water electrolysis system includes a high-pressure water electrolysis apparatus, a water circulation apparatus and a vapor-liquid separation apparatus. The high-pressure water electrolysis apparatus generates oxygen and hydrogen The hydrogen has a pressure higher than a pressure of the oxygen. The water circulation apparatus circulates water to the high-pressure water electrolysis apparatus. The vapor-liquid separation apparatus separates a gas component discharged from an anode side of the high-pressure water electrolysis apparatus from the water in the water circulation apparatus. The vapor-liquid separation apparatus includes a reservoir, a blower and a movable wall. The movable wall is disposed in the reservoir. The movable wall is vertically movable in accordance with a water level in the reservoir and allows the gas component to pass therethrough.

Abstract: Each unit cell of a water electrolysis apparatus includes a pair of an anode separator and a cathode separator and a membrane electrode assembly interposed between the pair of separators. The anode separator has a first flow field to which water is supplied, and the cathode separator has a second flow field for producing high-pressure hydrogen through electrolysis of the water. A second seal groove for receiving a second seal member is disposed annularly around the second flow field. A pressure-releasing chamber is disposed outwardly of the second seal groove, is capable of communicating with the second seal groove and communicates with the outside through a depressurizing channel.

Abstract: Each unit cell of a water electrolysis apparatus includes a pair of an anode separator and a cathode separator and a membrane electrode assembly interposed between the pair of separators. The anode separator has a first seal groove extending annularly around an anode current collector, a first seal member being disposed in the first seal groove. The cathode separator has a second seal groove extending annularly around a cathode current collector, a second seal member being disposed in the second seal groove. The first seal groove and the second seal groove are located across the solid polymer electrolyte membrane from each other respectively at different positions with respect to a stacking direction of the separators.

Abstract: A water electrolysis apparatus is formed by stacking a plurality of unit cells. Each unit cell includes a membrane electrode assembly, and an anode separator and a cathode separator which sandwich the membrane electrode assembly therebetween. The anode separator has a plurality of inlet joint channels in fluid communication with a water supply passage, and a plurality of outlet joint channels in fluid communication with a discharge passage. The water supply passage has an inner wall surface at which the inlet joint channels are open, and an outer wall surface which faces the inner wall surface, the inner wall surface and the outer wall surface jointly forming an opening of an oblong cross-sectional shape.

Abstract: A water electrolysis apparatus includes an anode separator having a water flow field held in fluid communication with a water supply passage and a discharge passage. The water flow field includes a plurality of water channels, an arcuate inlet buffer, and an arcuate outlet buffer. The water channels have respective ends connected to the arcuate inlet buffer through respective inlet joint channels. The inlet joint channels are oriented at an angle of 90 degrees or greater with respect to respective tangential lines at the ends of the inlet joint channels which are connected to the arcuate inlet buffer.

Abstract: A water electrolysis system has a water electrolysis apparatus for electrolyzing pure water, thereby producing hydrogen, a water storage apparatus for separating between oxygen and residual water discharged from the water electrolysis apparatus, thereby storing the water, a water circulation apparatus for circulating the water stored in the water storage apparatus through the water electrolysis apparatus, and a water supply apparatus for supplying the pure water prepared from city water to the water storage apparatus. An inlet is formed at one end of a return pipe to introduce the oxygen and the residual water discharged from the water electrolysis apparatus into a tank, and the position of the inlet is determined such that the inlet is constantly opened in the water stored in the tank.

Abstract: A hydrogen electrolysis apparatus includes a stack of unit cells each having a membrane electrode assembly sandwiched between an anode separator and a cathode separator. The anode separator has a first flow field which is supplied with water, and the cathode separator has a second flow field which produces high-pressure hydrogen through an electrolysis of the water. The cathode separator also has a first seal groove defined therein which extends around the second flow field and a first seal member inserted in the first seal groove. The first seal groove and the second flow field are held in fluid communication with each other through passageways. The passageways keep the first seal groove and the second flow field in direct fluid communication with each other in bypassing relation to the boundary between the cathode separator and a solid polymer electrolyte membrane.

Abstract: A unit cell of an electrolysis apparatus includes a membrane electrode assembly sandwiched between an anode separator and a cathode separator. The membrane electrode assembly includes a solid polymer electrolyte membrane, an anode current collector disposed on one side of the solid polymer electrolyte membrane and held against the anode separator, and a cathode current collector disposed on the other side of the solid polymer electrolyte membrane and held against the cathode separator. A protective sheet having a number of through holes defined therein is interposed between the anode current collector and the solid polymer electrolyte membrane.