Is Hydrogen A Safe Automobile Fuel?

Hydrogen is the potential green fuel of the future but there are some serious safety concerns about its use in automobiles.

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In view of the growing concern over environmental pollution caused by automobile exhausts and continuously depleting petroleum based energy resources, the need to identify and develop alternate environment friendly automotive fuels is on the rise. Researchers across the globe are working on alternatives such as electric cars, hybrids and use of ethanol, natural gas, propane and off course hydrogen.

Hydrogen is being explored aggressively as potential green fuel for the future generations of the car. It is clean, energetic and virtually inexhaustible. However, there are serious safety concerns associated with its burning in cars. In order to reap the benefits of hydrogen in automobiles applications and to create a better image for consumers, technological advances need to be made.

Hydrogen is a fuel and is volatile like most liquid fuels. If an ignition source is available to a proper air fuel mixture, it possesses a tendency to burn along with release of energy. There are two aspects that have raised safety concerns about hydrogen usage in the past. One is the Hindenburg disaster and the other is Hydrogen bomb.

Hindenburg was a hydrogen powered German passenger airship that was destroyed during landing in 1937.However; research indicates that main cause for this incident was not hydrogen combustion. Rather an electric spark due to static charge had caused the explosion. Hydrogen bomb explosion, on the other hand, requires both high temperature and pressure conditions which are unlikely to occur in vehicular applications of hydrogen.

Hydrogen possesses low ignition energycompared to gasoline. The flammable explosive range of hydrogen (4 to 74%) is also wider compared to gasoline (1.4 t0 7.6%). Thus the likelihood of spontaneous combustion of hydrogen under wide range of air fuel mixture conditions is high.

Another safety hazard associated with hydrogen is its low viscosity and thus a greater leakage tendency. Hydrogen is colorless, odorless and its leakage cannot be easily detected. This poses a serious threat as fire preventive and recovery measures cannot be implemented promptly.

The boiling point of hydrogen is -253 degree Celsius. Thus, in some of the applications, hydrogen is stored as a cryogenic liquid. Due to such low storage temperature, contact with liquid or expanding gas may cause irritation and frostbite.

Hydrogen is nontoxic unlike gasoline and diesel fuels and therefore it is not harmful for humans and other living organisms. If spilled it either reacts with oxygen to form water or evaporates to the upper atmosphere within no time. In contrast to this, spills of petroleum based fuels causes a significant damage to environment and natural habitats of animals and plants. Additionally, this takes tremendous cleanup efforts.

If 1.4 % of gasoline is present in the air, it is sufficient to cause a spontaneous combustion. On the other hand, the minimum concentration of hydrogen for combustion to take place is 4 %. Thus gasoline becomes volatile at concentration four times lower than hydrogen. Moreover, hydrogen has a lesser tendency for local congregation and escapes to upper atmosphere almost instantaneously.

Hydrogen is less flammable compared to gasoline. The self ignition temperature of hydrogen (932 degree F) is much higher than that of gasoline (536 degree F) making it less likely to auto ignite. Hydrogen possesses less radiant energy compared to gasoline which means that energy concentration near the flame is less compared to hydrogen.

Hydrogen is expected to be a promising vehicular fuel going forward. Nonetheless, there is some safety threat associated with it. In order to make its use a real success, the potential safety hazards need to be removed through technological development. Also, a positive image of hydrogen fuel needs to be portrayed to enhance its consumer acceptability.

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