Hydrogen Safety: Same Risks, Different Rules
As the world works to reduce its carbon footprint, hydrogen is increasingly discussed as a clean, viable fuel of the future. While hydrogen presents unique challenges, it's no more dangerous than other flammable substances—it’s just different. These differences require designers and operators to think differently, too.
This post is a broad introduction to hydrogen’s distinctive behaviours and the challenges they pose in design, storage, and use. In future updates, we’ll dig into each of these in more detail to explore how we can design inherently safe hydrogen facilities.
Dispelling the Myth: Was the Hindenburg a Hydrogen Disaster?
Whenever hydrogen is mentioned, many immediately think of the Hindenburg disaster. Yes, the airship's bladders were filled with highly flammable hydrogen—but the incident itself was not a hydrogen fire.
Here’s why:
Hydrogen burns with a pale blue flame—essentially invisible to the naked eye. The flames seen in Hindenburg footage are clearly visible.
Hydrogen is around 7% the density of air, meaning it disperses rapidly upwards. When the bladders ruptured, most hydrogen likely escaped before it could ignite.
Understanding these fundamental behaviours is crucial when designing hydrogen systems. Key Differences Between Hydrogen (H₂) and Methane (CH₄) / Liquefied Natural Gas (LNG)
This is not an exhaustive list, but each of these aspects will be explored further in future posts:
Specific Gravity (at STP)
H₂: 0.07 | CH₄: 0.5
Hydrogen is significantly lighter than air, which means that for outdoor releases, it rapidly disperses upwards and for indoor releases, it collects at the ceiling.
Flammable Range with Air
H₂: 4–75% | CH₄: 5–15%
Hydrogen has an extremely wide flammable range, increasing the probability of ignition.
Thermal Expansion (Liquid to Gas)
H₂: 1:847 | LNG: 1:600
Hydrogen gas expands significantly more when vaporised, creating unique storage and venting challenges.
Permeability and Material Interaction
Hydrogen atoms are tiny—smaller than CH₄ molecules—making it easier for H₂ to leak through materials.
Most hydrogen systems will leak to some degree—acceptable leak rates must be part of the design criteria and assessed by the Safey Engineer.
Hydrogen embrittlement is another concern, as H₂ can degrade some metals, increasing leaks or material failure.
Minimum Ignition Energy
H₂-Air: 0.017 mJ | CH₄-Air: 0.28 mJ
Hydrogen ignites far more easily, requiring careful control of ignition sources in plant design.
Fire Characteristics
Flame temperature:
H₂: 2,254°C | CH₄: 1,963°C
Flame visibility:
H₂: Invisible / Pale Blue | CH₄: Yellow / Orange
Thermal radiation:
H₂ flames emit significantly less radiant heat, making them harder to detect and more hazardous for personnel who may not realise there’s a fire until it’s too late.
Explosion Properties
This is a deep and complex topic that deserves its own post—stay tuned.
Wrap-up
From this overview, it’s clear that hydrogen has some very different behaviours compared to methane or LNG. These differences don’t make hydrogen inherently more dangerous—but they do require a different approach to designing and operating safe facilities.
More to come.
FAQs
1. IS HYDROGEN FUEL MORE DANGEROUS THAN PETROL/GASOLINE/NAPHTHA?
No. Hydrogen fuel systems in vehicles and at refueling stations are designed with strict safety standards and multiple layers of protection to keep the driver and public safe. They are no more dangerous than current fuels used in internal combustion engines when managed correctly.
2. IS HYDROGEN TOXIC OR POISONOUS?
No. Hydrogen is not toxic. It’s the simplest element in the universe, made of just one proton and one electron. Because of this, it doesn’t have the complex chemistry needed to be poisonous.
3. IS HYDROGEN A SAFETY HAZARD?
Yes – but so are all flammable gases. Hydrogen has a wide flammability range and ignites easily, but with proper engineering controls for generation, storage, and transport, it can be managed safely — similar to natural gas or other fuels.
4. IS HYDROGEN GAS EXPLOSIVE?
Yes, it can be. A hydrogen-air mixture is highly explosive. However, hydrogen is extremely light (low specific gravity) and disperses quickly in open air, making it less likely to form dangerous clouds outdoors. Enclosed spaces do present greater risks, and that's where specialist hydrogen safety engineers are essential.
5. HOW DO GREEN METHANOL AND AMMONIA RELATE TO HYDROGEN?
Hydrogen is difficult to store and transport. Converting it into methanol or ammonia makes handling much easier and safer. These fuels can be used directly or reconverted into hydrogen when needed.
6. CAN HYDROGEN SAFETY BE ASSESSED THE SAME WAY AS METHANE/LNG?
In a nutshell - no. Hydrogen does not behave the same as methane / LNG both inside the process and upon release. Hydrogen’s chemical and reactive properties introduce a unique set of challenges in keeping it safe. Having said that, hydrogen as a fuel is not new and there has, and continues to be, a lot of published research in hydrogen safety. Additionally, there are formally trained specialist hydrogen safety engineers to ensure that the generation, storage, transportation, and use of hydrogen is safe.
7. IF HYDROGEN IS THE FUEL OF THE FUTURE, WHY ARE COMPANIES ABANDONING HYDROGEN PROJECTS?
Not because of safety. Many projects are paused or shelved due to:
High current technology development, production and infrastructure costs
Current low and uncertain demand
Uncertainty in regulatory support and requirements
As these factors evolve, many in the industry expect hydrogen to make a strong comeback.
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