The accidental hydrogen release occurred when testing the storage system connected to a PEM electrolyzer. The leak test consisted in filling the storage with hydrogen at step-wise increase of pressure. After the step at 3 bar (0.3 MPa), which did not reveal any leak, the storage was pressurised up to 5 bar (0.5 MPa). At that moment a hissing sound occurred from the storage at the outside of the building indicating a leak.

This incident occurred at the electrolyzer of a refuelling station. An employee of the electrolyzers manufacturer was on-site to conduct a reset of the plant power breaker system and to restart gas generation. Whilst putting the system into generation, a loud bang was heard. By reviewing the station CCTV evidence, a cloud of water vapour was seen being emitted from the oxygen vent line of the electrolyzer container. The gas generation system was safely shut down, and an investigation was started to understand the cause and potential impacts.

A fire broke out on the insulating plastic elements of an alkaline electrolyzer in a unit of a chemical plant. The shift saw the smoke from the control room. The first action was to drain the potash into a tank provided for this purpose and to shut down the electrolyzer. The on-call electrician interrupted the electricity. The safety technician brought the fire under control in less than 10 minutes using CO2 extinguishers. After approximately six hours, the unit is restarted.

The incident consisted of a leakage of potassium hydroxide solution (KOH) from an alkaline electrolyzer in a renewable hydrogen production plant. One webpage news reported that smoke formation triggered the fire alarm system. According to the manufacturer, the equipment shut down and automatically went into safety mode in accordance with the integrated safety system.Nobody was injured in the event and there was no damage on the environment.

The incident occurred during the verification operation of a new high pressure hydrogen generator. The electrolysis cell burned down, the pipes of the oxygen circuit burst and the peripheral equipment were scattered all over the facilities. The liquid blown out from the broken pipes and the gas release valve, and glass fragments were scattered within a radius of ten meters. There was no injury. The analysis of the incident (Wada et al., ICHS 2007) assumed as probable initiating cause that titanium electrode in the electrolysis cell was exposed to oxygen and burned.

The hydrogen buffer tanks that exploded were part of an experimental facility experimenting generation of renewable hydrogen from a water electrolyzer coupled to solar panels.The three hydrogen tanks (40 m3 capacity each at pressures of 1,2 MPa one of them and 0,7 MPa the two others) were receiving the hydrogen produced by the electrolyzer. Firefighters said all three tanks were destroyed in the explosion; there was no fire, but the explosion was strong enough to send debris being scattered in an area well over 3,000 square meters.

The explosion occurred at a hydrogen fuel plant mainly serving hydrogen forklift fleets. The explosion damaged several nearby homes and could be felt nearly 10 miles away.Police and firefighters responded and not injury was reported. Several houses in the neighbourhood experienced glass breaking. According to a statement of the company, "...there was no detonation of any on-site storage tanks and no workers were injured."

An explosion and fire occurred at a hydrogen production plant serving the hydrocracker and the diesel hydroteater of a nearby refineryNo injuries were reported among the employees.According to the plant owner, the incident occurred in the collection manifold, also referred to as a collection header or a transfer line, due to the failure of an external carbon steel pipe of the collection manifold.

An explosion occurred a the Lurgi electrolysis unit of a chemical factory. The plant suffered extensive damage and one man died. The electrolysis plant produced hydrogen for process use and oxygen as a waste product by electrolysis of potassium hydroxide solution. The investigation concluded that the explosion probably occurred on the oxygen separating drum into which hydrogen had leaked.

The explosion took place in the hydrogen gasometer. The bell in the gasometer was lifted 15-20 m straight up and cracked. The cover fell down on the pipe bridge besides the gasometer. The cylindrical part of the bell fell down into the gasometer basin. The reason for the explosion was transportation of oxygen into the hydrogen gasometer. This was due to poor drainage, and corresponding overpressure in the oxygen flow line. No persons were injured. The hydrogen gasometer was destroyed, and there was also considerable damage to the 02 and N2 gasometers.