Hydrogen Safety
The United States currently produces and safely uses more than nine million metric tons of hydrogen each year, but primarily in a controlled industrial environment. Codes and standards applicable to hydrogen technologies, as well as information on the unique characteristics of hydrogen and its handling, will be essential to achieving the vision of a hydrogen economy.
Hydrogen is odorless, colorless, and tasteless, and thus undetectable by human senses. Like any other fuel, however, including gasoline and natural gas, hydrogen is an energetic substance and must be handled appropriately to ensure safety. The characteristics of hydrogen are different from those of other fuels (just like gasoline differs from natural gas), but it can be used as safely as other common fuels we use today when safety guidelines are observed and the hydrogen user understands its behavior.
Hydrogen has a number of properties that are advantageous with regard to safety. For example, hydrogen is much lighter than air and has a rapid diffusivity (3.8 times faster than natural gas), which means that when released in an open environment, it rises and dilutes quickly into a non-fl ammable concentration. Hydrogen rises at a speed of almost 20 meters per second, twice as fast as helium and six times faster than natural gas. As the lightest and smallest element in the universe, confining hydrogen is very difficult. These properties must be considered when designing structures where hydrogen will be used and stored.
An explosion cannot occur in a tank or any contained location that contains only hydrogen. An oxidizer, such as oxygen, must be present.
There is a low likelihood that hydrogen will explode in open air, due to its tendency to rise quickly. Hydrogen does burn very quickly, however, sometimes making a loud noise that can be mistaken for an explosion. The energy required to initiate combustion of hydrogen is significantly lower than that required for other common fuels, such as natural gas or gasoline. At low concentrations of hydrogen fuel in air, the energy required to initiate combustion is similar to that of other fuels.