REVERSIBLE WATER ELECTROLYSIS SYSTEM AND METHOD FOR OPERATING SAME

In a reversible water electrolysis system and a method for operating the reversible water electrolysis system, the reversible water electrolysis system includes a reversible water electrolysis fuel cell, a first heat exchanger, a steam supply passage, a water discharger and a pump. The reversible water electrolysis fuel cell has a hydrogen pole, an air pole and an electrolyte disposed between the hydrogen pole and the air pole. The reversible water electrolysis fuel cell is configured to be operated at one of a water electrolysis mode and a fuel cell mode. The first heat exchanger is configured to exchange a heat between a first exhaust gas exhausted from the hydrogen pole and a hydrogen or a mixed gas including the hydrogen and a steam. The steam supply passage is configured to supply the steam to the hydrogen pole. The water discharger is configured to removing a water from the first exhaust gas. The pump is equipped to a water discharge passage L43 of the water discharge and is configured to pump the water to outside. An operation of the pump is controlled to maintain a pressure difference between an inlet of the hydrogen pole and an inlet of the air pole within a predetermined range.