Hydrogen Safety Basics

Hydrogen, in vast quantities, has been used safely in chemical and metallurgical applications, the food industry, and the space program for many years. Like gasoline and natural gas, hydrogen is a fuel that must be handled appropriately. The characteristics of hydrogen are different (just like gasoline differs from natural gas) and a number of its properties are advantageous with regard to safety. Hydrogen can be used as safely as other common fuels we use today when guidelines are observed.

Properties of Hydrogen

The Lightest and Smallest Element

As the lightest and smallest element in the universe, confining hydrogen is very difficult. Hydrogen is much lighter than air and rises at a speed of almost 20 meters per second—two times faster than helium and six times faster than natural gas—which means that when released, it rises and disperses quickly.

Combustion Only in Presence of Oxidizer

Combustion cannot occur in a tank or any contained location that contains only hydrogen. An oxidizer, such as oxygen, must be present.

Odorless, Colorless, and Tasteless

Hydrogen is odorless, colorless, and tasteless and therefore undetectable by human senses. For these and other reasons, industry designs systems with ventilation and leak detection. Natural gas is also odorless, colorless, and tasteless, but industry adds a sulfur-containing odorant so people can detect it. These odorants are not used with hydrogen, however, because there is no known odorant light enough to "travel with" hydrogen and at the same dispersion rate. Current odorants also contaminate fuel cells, a popular hydrogen application.

High Burn Rate and Low Ignition Energy

Hydrogen burns very quickly. Under optimal combustion conditions, the energy required to initiate hydrogen combustion 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.

Low Radiant Heat

Hydrogen flames have low radiant heat. A hydrogen fire has significantly less radiant heat when compared to a hydrocarbon fire. Since low levels of heat are emitted near a hydrogen flame (the flame itself is just as hot), the risk of secondary fires is lower.

Rapid Dispersion

With the exception of oxygen, any gas can cause asphyxiation in high enough concentrations. In most scenarios, however, because hydrogen rises and disperses so rapidly, it is unlikely to be confined where asphyxiation might otherwise occur.

Non-Toxic and Non-Poisonous

Hydrogen is non-toxic and non-poisonous. It will not contaminate groundwater (it's a gas under normal atmospheric conditions), and a release of hydrogen is not known to contribute to atmospheric pollution or water pollution.

Codes and Standards

Hydrogen codes and standards are being developed to provide the information needed to safely build, maintain, and operate hydrogen and fuel cell systems and facilities, ensure uniformity of safety requirements, and provide local officials and safety inspectors with the information needed to certify hydrogen systems and installations.

Safety Research

Researchers in government, industry, and academia are working to:

Further analyze critical hydrogen behavior data
Develop reliable, inexpensive hydrogen sensor and leak detection technologies
Identify tools and methodologies to support the development of hydrogen codes and standards.