6. Environmental, safety and regulatory aspects

From an environmental point of view, hydrogen, as long as it is not confined, behaves neutrally in the atmosphere, with no chemical action and therefore harmless, despite the fact that it is the most energetic constituent per unit mass. Being very light (14 times lighter than air), it rises rapidly in the atmosphere before combining chemically with oxygen molecules to form water molecules.

In the presence of air, hydrogen can, in certain proportions and under certain conditions, cause an explosion, which explains the fear it provokes. This risk was initially associated with the spectacular accident involving the Hindenburg airship in the USA in May 1937 (36 deaths out of the 100 occupants), although it was later proved that hydrogen had nothing to do with the accident, which was caused by the impact of a thunderbolt on the highly flammable balloon structure! Had...