Helium vs. Hydrogen in Airships: Safety, Usage, and Future Prospects

Introduction

When considering the use of gases in airships for lift and buoyancy, helium is most commonly chosen over hydrogen, despite hydrogen being more buoyant due to its lighter molecular weight. This article explores the reasons behind this choice, including safety, regulations, availability, and performance considerations.

Why Helium Over Hydrogen

The primary reason for using helium in airships is safety. Helium is non-flammable and non-toxic, making it a safer alternative to hydrogen, which is highly flammable and can form explosive mixtures with air.

Flammability Concerns

Hydrogen's flammability poses significant risks, as seen in the Hindenburg disaster in 1937. In this incident, a hydrogen-filled airship caught fire, highlighting the dangers of using flammable gases in large, public transport vehicles. In contrast, helium does not burn, making it inherently safer in case of a leak or accidental ignition.

Safety Regulations and Standards

Air transport regulations have shifted towards helium primarily due to safety considerations. The use of non-flammable gases like helium ensures the safety of passengers and crew in the event of an accident. This shift in regulations makes helium a preferred choice for airship operators.

Availability and Cost

While hydrogen is more buoyant, it is less readily available and more expensive to produce. Advances in helium extraction and production have made it more cost-effective in the long run. Helium is also more readily available, making it a practical choice for airship operators who need reliable, safe, and easy-to-handle gas for their operations.

Performance and Practical Considerations

Hydrogen does provide slightly better lift due to its lower molecular weight. However, the safety benefits of helium often outweigh this advantage, especially for airships. Helium still offers sufficient lift, making it a practical choice for most airship applications.

The Hindenburg Disaster: A Misunderstood Tragedy

It is often cited that the Hindenburg disaster is one of the main reasons helium is preferred in airships. However, a closer look at the incident reveals that it was the skin of the airship that caused most of the ignition, not the hydrogen itself.

Reality vs. Popular Belief

While some hydrogen did burn, most of it leaked away as soon as a hole developed. If the skin of the Hindenburg had been made from a non-combustible material, the disaster could have been avoided. Instead, the skin was sealed with a highly flammable substance, which rapidly burned when exposed to the air.

In fires associated with hydrogen, the danger often lies with the support structure and the process of combustion, not the hydrogen itself. Hydrogen, when enclosed in airtight, non-combustible containers, can be as safe as gasoline, if not safer. If a hydrogen tank starts to leak, the gas disperses into the atmosphere, whereas gasoline pools on the ground and vaporizes, presenting a significant danger.

Hydrogen-powered vehicles are still in development due to the high cost of production. However, if hydrogen could be produced more economically, it could revolutionize transportation. Hydrogen tanks, when highly compressed, add significant weight to the vehicle, which is a crucial consideration for aircraft, where 'heavy' is a swear word.

Future Prospects for Hydrogen

Recent discoveries of large hydrogen deposits may reduce the reliance on expensive electrolysis for production. Scientists are looking into using liquid ammonia to extract hydrogen, which can be easily compressed and contains 75% hydrogen.

As technology evolves and the cost of hydrogen production decreases, it has the potential to become a more viable and safe alternative for airships and other applications. However, safety regulations and practical considerations will continue to play a significant role in the choice of gases used in airships.

In conclusion, while hydrogen is more buoyant, the safety, regulatory, and practical considerations of using helium make it the preferred gas for airships. As research and technology continue to evolve, the safety and practicality of using hydrogen will become more feasible.