[ safety ]
One such characteristic is hydrogen ’ s broad flammability range , which extends from 4 % to 75 % by volume , dwarfing that of natural gas , which ignites within a narrower 5.3 % to 15 % range . As a result , hydrogen can more readily form flammable mixtures in the air , heightening the risk of ignition across a wider spectrum of conditions . Additionally , the energy required to ignite hydrogen is remarkably low – only 0.020 millijoules ( mJ ), compared to the 0.290 mJ needed for natural gas . This means even a static spark can set off a hydrogen explosion , necessitating stringent control measures to prevent accidental ignition , especially in environments where electronic devices or human contact are common .
Hydrogen ’ s flame velocity , measured at 3.2 meters per second , is eight times faster than that of natural gas . This leads to a significantly higher potential for explosive pressure buildup . In the event of ignition , the resulting explosion could be far more severe than one involving natural gas , demanding robust containment and mitigation strategies . Hydrogen ’ s low density and high diffusivity also mean that under similar conditions , it flows out of leaks 2.8 times faster than methane , leading to
rapid depressurization and potentially larger flammable clouds . If ignited , hydrogen burns quickly , potentially shortening the duration of the fire but increasing the intensity and immediate danger .
Despite these risks , hydrogen ’ s rapid dispersion into the atmosphere – thanks to its low molecular weight – can reduce the likelihood of hazardous gas clouds forming at ground level , offering a potential safety advantage over heavier gases like natural gas . However , this characteristic does not eliminate the risk of ignition , especially in confined spaces where hydrogen can accumulate .
Hydrogen ’ s complex safety profile underscores the need for sophisticated risk management strategies . While its properties necessitate rigorous safety measures , they also offer some advantages in terms of risk mitigation , particularly regarding dispersion . Understanding these traits is the first step toward safely integrating new hydrogen technologies and assets into the existing energy and manufacturing industries as critical factors in emission reductions and achieving climate targets .
The landmark FutureGrid high-pressure test facility at DNV ’ s Spadeadam Research and Testing Centre , used to demonstrate the safety of repurposing the UK ’ s National Transmission System ( NTS ) natural gas transmission assets for the safe and reliable transport of hydrogen .
Hydrogen Tech World | Issue 18 | October 2024 21