Hydrogen Accident & Safety

In the previous decades, severe accidents have happened involving hydrogen utilized in industrial and other applications. One of them is Hindenburg accident (1937). The accident occurred at Lakehurst, New Jersey, on May 6, 1937 and was for many years under investigation to identify the reasons that caused the ignition of the hydrogen gas used for buoyancy of the giant airship “Hindenburg”.

In that accident, the ignition of hydrogen proceeded rapidly to fire toward the tail section of the craft. The fire was almost simultaneously succeeded by an explosion that engulfed the 240 t craft causing it to crash onto the ground killing 36 people. The overall results indicated that the outer shell and the paint of the airship were flammable and could be ignited from electrical sparks. Indeed, prevailing atmospheric conditions at the time the accident occurred could generate considerable electrostatic discharge activity on the airship.

Today, the memory of the Hindenburg accident is fading, and as the safety record of hydrogen—based on its safe use in space exploration and in industry—becomes more widely known, it is also becoming accepted as a safe means of storing chemical energy.

This trend has been further encouraged by the lessons learned from accidents, such as the one that occurred in 2008 on Interstate 84 in Connecticut, where a trailer truck carrying hydrogen plunged down the embankment. If the truck had carried gasoline, we know what would have happened—a huge fireball. However, because hydrogen does not form pools on the ground, but rather escapes into the atmosphere, there was no fire and no injuries were caused by the hydrogen. Nevertheless, the wide use of hydrogen as an energy carrier will result in its use by laypersons necessitating different safety regulations and technologies that are now under development.

One of the major issues affecting the acceptance of hydrogen for public use is the safety of hydrogen installations (production and storage units) as well as its applications (i.e., as vehicle fuel or home use). The hazards associated with the use of hydrogen can be characterized as physiological (frostbite and asphyxiation), physical (embrittlement and component failures), and chemical (burning or explosion), the primary hazard being inadvertently producing a flammable or explosive mixture with air

From the safety point of view, the following are the most important properties of hydrogen when compared to other conventional fuels: When released, hydrogen quickly diffuses (3.8 times faster than natural gas) into a non-flammable concentration. It also rises 6 times faster than natural gas at a speed of almost 45 mph (20m/s). When it burns, due to the absence

of carbon and the presence of heat absorbing water vapor, the fire produces much less radiant heat than a hydrocarbon fire. This reduces the risk of secondary fires. If only hydrogen is present, an explosion cannot occur. An oxidizer, such as oxygen, must be present in a concentration of at least 10% pure oxygen or 41% air. Hydrogen can be explosive at concentrations of 18.3% to 59% while gasoline can present a more dangerous potential, because it can explode at much lower concentrations, 1.1% to 3.3%.