Understanding hydrogen's unique safety challenges
Hydrogen is emerging as a cornerstone in the global energy transition, particularly within the transport sector. Its high energy content, zero emissions at the point of use, and potential for renewable production make it a compelling alternative fuel.
According to the International Energy Agency (IEA), the proliferation of hydrogen refuelling stations (HRS) has surged in recent years, underlining the growing importance of hydrogen infrastructure.
While hydrogen offers promising advantages, it also presents unique safety challenges. Understanding these is paramount to ensuring safe handling and storage:
- Wide flammable range: Hydrogen's flammability spans from 4% to 75% by volume, making it highly combustible.
- Lightweight nature: Being approximately 8 times lighter than air, hydrogen can swiftly disperse, posing challenges in containment.
- High storage pressure: Despite its low energy density by volume, hydrogen needs to be stored at high pressures for efficient vehicle ranges.
- Low ignition energy: Hydrogen ignites more readily than other fuel gases, increasing the risk of spontaneous ignition.
- Explosion potential: Hydrogen's high flame speed and propensity for deflagration to detonation transition necessitate careful risk management.
Establishing safety distances & challenges in safety assessment
A crucial safety measure in hydrogen refuelling stations is determining suitable safety or setback distances. These distances ensure adequate separation between equipment and exposure groups, such as people and buildings.
While various codes and standards offer guidance, the approach to determining safety distances can vary significantly. Factors like site layout and regional regulations influence the assessment process.
Designing to code offers simplicity but may result in overly conservative safety distances. Alternatively, deterministic or risk-informed assessments require detailed consequence modelling, often necessitating advanced tools like CFD. CFD simulations enable in-depth exploration of gas dispersion and explosion scenarios. By modelling real-world conditions, CFD tools like KFX and EXSIM provide insights into:
- Dispersion behavior
- Impact of layout adjustments
- Explosion consequences
Case Study: Exploring hazard scenarios for hydrogen refuelling stations
Watch the recording and get the full story:
0:02 Introduction
2:00 Key properties of hydrogen
4:56 Safety distances
8:53 Consequence modelling
10:39 Example: Fictitious HRS
12:58 Example: CFD gas dispersion analysis using KFX
18:07 Example: CFD gas explosion analysis using EXSIM
21: 39 Recent validation work for HRSs (EXSIM)
23: 41 Summary
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