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.

The incident involves a gas booster provided by a manufacturer. This device is used in the experimental platform of the project to raise the pressure in pipelines from 60 to 80 barg (from 6 to 8 MPa), allowing the gas to flow in a close loop. After 5 weeks of operation, a critical gas leakage through the vent port was detected.At the moment of the incident, the compressor was working with a mixture of hydrogen and methane (H2/CH4 blend 20/80 %v/%v). The booster was sent to the manufacturer for inspection and reparation. Severe damage in the seals of the vent port was found.

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.

The company affected manufactures valves and other hydrogen-storage components, equipment tests. It has offers as well a testing laboratory. The accident happened during testing of a hydrogen tank. A dull bang and a huge pressure wave was felt kilometres away. News report massive damage to the test facility, but a very small fire. Still according to the news, the most probable cause emerging from the investigation is the over-pressuring of the tank due to an erroneous connection of a compressed air hose.

A truck-trailer carrying compressed hydrogen cylinders stopped on an autobahn and reported a hydrogen leaking from the cylinders. The highway was immediately closed in both directions. When the fire brigade arrived, the truck had stopped on a hard shoulder, and the driver had al-ready left his vehicle. A pipe was reported to be leaking hydrogen. Fire-fighters closed a valve on the affexted cylinder group to stop the leak.

On a highway, a truck loaded with 400 gas cylinders crashed at night for an undetermined cause against a concrete wall and overturned. It slipped 150 m, before several 200 litre cylinders of hydrogen caught fire and set the truck on fire as well. The police stated that it was a large fire with detonations. The 400 gas cylinders were connected together and many of the cylinders had fallen out of their racks. In order to reduce the danger of further explosions, the fire-brigade cooled the gas cylinders with water for two hours. The highway remained closed for eight hours.

This incident occurred when subcontractor two workers were widening air vents on the roof of a building hosting a tank containing hydrogen chloride solution. This intervention was necessary to to improve hydrogen venting from the tank storage area. The hydrogen gas was a by-product of the chlorine-making process. The two workers were operating an angle grinder, producing sparks which ignited the flammable atmosphere which evidently containing hydrogen. An explosion followed, with one casualty and one injured worker.

At approximately 8:45 a.m. an employee was troubleshooting a thermal chamber, evaluating a Hydrogen on Demand (HOD) unit. The chamber was reported inoperative that morning. Two units were being tested on a work bench and they were connected by an exhaust hose to an HOD inside the test chamber. The gas was not properly exhausted and began to back up into the hose that was attached to the HOD. The employee removed the side panel on the chamber and it exploded while he were standing in front of it. He was killed by the explosion.

[NOTE: One source speak of a hydrogen gasometer, spanish news speak in general of gas, others of ntural gas or coal gas; considering the main product of the factory, it was chosen for this last version, but is is rather doubtful]This incident occurred at a coal gas storage (gasometer) system of a producer of foundry coke. The gasholder was a variable capacity tank, rising in height depending on the amount of gas stored, with a maximum capacity of 24,000 m3.Company sources said that the fire was caused as a result of a spark and a gas leak that was being repaired by the operators.

A 9000 gal (34 m3) LH2 storage tank exploded during repair of the vent stack. Few days before the explosion, the tank had been filled with LH2, but later on the hydrogen released and ignited at the tank pressure control system, damaging the vent stack. To perform the required repairs, the tank had to be emptied. To this purpose the vessel was purged with nitrogen gas to display the LH2 by letting it boiling. However, the pressure inside the vacuum jacket increased because of the opening the vacuum valve. This pressure increase eventually led to the catastrophic tank rupture.