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Traditionally, hydrogen has been used extensively in the petrochemical and chemical industries and in smaller quantities in the electronics, steel-producing, glass-making, and food hydrogenation industries. In energy applications, the only significant use of hydrogen has appeared in space exploration. This is about to change, given the promise that hydrogen brings as an efficient energy carrier and an energetic fuel with minimal environmental impact. Systems are being developed that produce hydrogen from primary energy sources such as sunlight, wind power, biomass, hydro and fossil fuels, for use in energy applications for home and office heating, generation of electricity, and transportation.
The use of hydrogen as an energy carrier is conditioned by cost, technical factors related to its production, transport and usage; and of course safety factors. The problems that hydrogen can create for people and equipment are due to its chemical and physical characteristics which are different from other gaseous fuels widely used on the market, such as methane.
Unlike other gases, hydrogen can damage the physical and mechanical properties of metals due to embrittlement: hydrogen atoms can dissolve in metal lattice and accumulate in disturbed lattice regions, thus impairing the main mechanical characteristics.
If hydrogen is used in large quantities as an energy carrier, it may need to be stored in such places as distribution stations, containers inside cars, etc., with a consequent possible accumulation in closed or poorly ventilated environments.
A hydrogen?air mixture can support deflagration when the fuel volumetric concentration is within the flammability range: from 4% to 75% of hydrogen.
The perception of hydrogen as being a particularly dangerous gas comes from public fear; people believe such gas to be highly explosive (many cite the vivid images of the Hindenburg ablaze, or the 1986 Challenger catastrophe, or the hydrogen bomb). In reality, these highly publicized explosions have little or no bearing on the level of safety of hydrogen in the car or home.
The safe use of hydrogen as a fuel is a primary goal for the whole world. A key element in the safe use of hydrogen is understanding its unique safety-related properties and that there are acceptable engineering approaches to controlling the risks associated with the use of hydrogen. This lecture describes the hazards associated with the use and presence of hydrogen, discusses the properties of hydrogen relevant to safety, and provides a general discussion of approaches taken to mitigate hydrogen hazards.
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