Hydrogen in Power Generation – A Safety Perspective
A major step in decarbonising the power industry is the use of hydrogen—or hydrogen/natural gas blends—in gas turbines to generate electricity. While replacing natural gas with hydrogen significantly reduces the plant’s carbon footprint, it’s not without substantial design and safety challenges.
I'll leave the functional and operational hurdles to the design engineers and focus on the safety challenges—the domain of the safety engineer.
Hydrogen Isn’t Just Another Fuel
As covered in previous posts, hydrogen behaves very differently from methane or natural gas. Key differences include:
Much lower density
Faster flame speeds (3 m/s H₂ vs. 0.3 m/s CH₄)
Higher flame temperatures
Wider flammability range
Higher thermal expansion
Larger fuel volumes required for equivalent energy output
Each of these factors presents safety challenges that must be understood and addressed—especially when dealing with high H₂/NG blends, which can introduce hybrid risk behaviours.
Key hydrogen Safety Challenges
1. Flammable Cloud Formation in Run-Up Piping
One of the most critical risks is the formation of a flammable gas cloud within the run-up piping. This can ignite through:
Static discharge (in pure H₂ scenarios)
Adiabatic compression during valve operations
External ignition sources, like hot surfaces
Due to hydrogen’s wide flammability range and high flame speed, ignition could lead to a deflagration-to-detonation transition (DDT) event—an extremely violent explosion. For low H₂ blends, a deflagration is more likely, but still hazardous.
2. Flame-Out and Cloud Formation in the Combustion Chamber
Because more hydrogen is needed compared to NG for the same output, the volume of combustible mixture within the ignition chamber can be significantly larger. In the event of a flame-out, this presents a serious risk of uncontrolled ignition or explosion.
3. Turbine Enclosure Ventilation and Pressure Peaking Phenomenon (PPP)
Perhaps the most complex and underappreciated issue is overpressure in the turbine enclosure. This isn’t necessarily due to ignition—hydrogen’s very low molecular weight allows it to:
Displace heavier air, increasing the number of gas moles in the enclosure
Lead to Pressure Peaking Phenomenon (PPP)—a rise in internal pressure without ignition
This pressure increase can easily exceed the typical 10 kPa structural resistance of a standard enclosure. In jetfire scenarios, overpressures can reach 22x higher than an unignited release.
The mitigation? A well-designed ventilation system, specifically tailored to hydrogen’s behaviour. Unlike conventional NG systems, PPP must be evaluated and factored into the design.
More Than Just Modelling
This is not an exhaustive list of the hazards a safety engineer must address. From the moment hydrogen is introduced to the system until it becomes H₂O and NOx, every stage of the process must be understood and assessed.
Modelling tools are essential—but for hydrogen applications, they can’t provide all the answers. Sound engineering judgement and deep knowledge of hydrogen behaviour are just as critical.
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.
See blog: https://www.alpha-systems.com.au/blog/hydrogen-safety-same-risks-different-rulesnbsp
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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